Seminar #78 from Online Seminars for Municipal Arborists
April - June 2018
Sections Go directly to the section by clicking on the title below
April - June 2018
Sections Go directly to the section by clicking on the title below
Note: Click on green text in each section for more information and photos.
Tree Installation 2018 Updates
By Len Phillips
The way we should be planting trees in our cities today has changed. Thanks to many researchers, they have determined that there are better ways to plant trees in the city.
Semantics
First of all there is a lot more to planting a tree than just sticking it in a hole. For that reason alone, the biggest change in tree planting this year is to call it a tree installation rather than a tree planting. An installation sounds like we are undertaking a big project. And that is what tree planting in 2018 has become.
Fibrous Roots
A tree installation must start with selecting the appropriate tree for a given site. This has not changed for several years. However, recent research has proven that selecting trees with fibrous root systems provide the best chance for long-term success and a quick transplant shock recovery.
Soil Cells
For the past several years, the use of soil cells and structural soils have been recommended for ensuring there is enough suitable soil for a tree to develop into a mature, healthy specimen. Soil cells transfer a surface suitable for a sidewalk, plaza, or light traffic roadway to a compacted foundation 3 ft. (1 m) below grade while allowing plenty of ideal soil for growing tree roots in between and within the soil cells.
Stormwater Storage
The soil cells are now being designed to also provide stormwater storage which reduces the frequency of manual watering of a newly installed tree. Perforated pipe is laid from a storm drain to the roots of the tree. A second perforated pipe serves as an under-drain from below the root ball and is connected to the city storm drain system. This process cleans and cools the water as it passes through the soil.
Watering the Tree
According to the latest research, the best watering method after planting, is to use stormwater from the nearby catch basins, as mentioned above. The second best option is to require the planting contractor to keep the trees watered and alive for two years. If these options are not acceptable, have the municipal or land owner's tree maintenance crews be responsible for watering the new trees as needed.
Soil Cell Options
Soil cells are expensive and are being reserved for major street and sidewalk reconstruction projects. A less expensive alternative is to go with CU-Soil which uses soil coated stone to provide a sturdy surface for pavement and plenty of pore space for tree roots. A similar system from Sweden is the use of the Stockholm Solution. The Solution requires the installation of large rocks under a pavement with topsoil being washed into the pores between the stones. In Stockholm, this procedure is used for street and sidewalk reconstruction projects as well as for improving the growing conditions around existing trees that are suffering from compacted soil or the lack of sufficient growing area for the roots.
Root Barriers
During any tree installation project, plant the trees first and install root barriers if necessary to deflect roots downward. This will prevent the tree's roots from causing damage to the surface pavements. The tree installation should be done before finishing the job with the addition of the new pavement at the surface.
The Best Choice of Trees
The trees to be selected should be trees that will tolerate heat as climate change and global warming continues to harm heat intolerant trees.
Bare Root Trees
Continue to learn how to plant bare root trees. They are the least expensive to purchase and plant by contract and easiest to plant when using volunteers. Planting trees with bare roots will help the tree make their transition to the new soil. See more information on planting bare root trees.
B&B Tree Treatment
The latest research indicates that the burlap and the wire basket should be completely removed from the root balls of Balled & Burlapped trees at the time of planting. In addition, the soil in the root ball should be removed at the installation site enough to determine that there are no problem roots. Regardless of the planting method, be sure the flare is level with or one inch above the final grade when the installation is finished.
Stabilizing
Gone should be the above ground stakes to hold the tree from tipping over. Recent research has indicated that staking a tree causes more harm to the tree than using root stabilizers. If there is a concern that the lack of a soil ball might cause the tree to blow over or be knocked over by vandals, this is easily remedied with any of several root stabilizing options, such as a tree staple or long stakes that are driven through the root system and into the soil below the tree. See more information on root stabilization.
Surface Treatment of the Planting Pit
After the tree is installed and roots are stabilized if necessary, the best surface treatment is to consider using one of two living mulches. A living mulch is intended to beautify and replace the need for a tree grate or conventional mulch by using low maintenance plants to provide weed suppression, moderate the soil temperature, and provide a visual means to discourage people from walking close to the tree and causing soil compaction. The plants selected must be tolerant of compacted soil and abuse from careless pedestrians. Watering and after-installation care to the tree remains the same as using any surface treatment.
Porus Pavement
If this surface treatment with plants is not acceptable to the community leaders, the next best option is to go with porus pavement. This is a fully permeable paving product which allows water to freely drain through the surface. The porous pavement's non-skid, 50% rubber content and 50% stone aggregate surface along with a hard urethane binder ensures good traction even when wet.
The Future
All of the suggestions provided here represent the latest research results for growing trees in our cities. As global warming contines to break temperature records every year and super-storms continue to pound countries around the globe, installing and growing trees in our cities becomes more important and more challenging every year.
References
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
By Len Phillips
The way we should be planting trees in our cities today has changed. Thanks to many researchers, they have determined that there are better ways to plant trees in the city.
Semantics
First of all there is a lot more to planting a tree than just sticking it in a hole. For that reason alone, the biggest change in tree planting this year is to call it a tree installation rather than a tree planting. An installation sounds like we are undertaking a big project. And that is what tree planting in 2018 has become.
Fibrous Roots
A tree installation must start with selecting the appropriate tree for a given site. This has not changed for several years. However, recent research has proven that selecting trees with fibrous root systems provide the best chance for long-term success and a quick transplant shock recovery.
Soil Cells
For the past several years, the use of soil cells and structural soils have been recommended for ensuring there is enough suitable soil for a tree to develop into a mature, healthy specimen. Soil cells transfer a surface suitable for a sidewalk, plaza, or light traffic roadway to a compacted foundation 3 ft. (1 m) below grade while allowing plenty of ideal soil for growing tree roots in between and within the soil cells.
Stormwater Storage
The soil cells are now being designed to also provide stormwater storage which reduces the frequency of manual watering of a newly installed tree. Perforated pipe is laid from a storm drain to the roots of the tree. A second perforated pipe serves as an under-drain from below the root ball and is connected to the city storm drain system. This process cleans and cools the water as it passes through the soil.
Watering the Tree
According to the latest research, the best watering method after planting, is to use stormwater from the nearby catch basins, as mentioned above. The second best option is to require the planting contractor to keep the trees watered and alive for two years. If these options are not acceptable, have the municipal or land owner's tree maintenance crews be responsible for watering the new trees as needed.
Soil Cell Options
Soil cells are expensive and are being reserved for major street and sidewalk reconstruction projects. A less expensive alternative is to go with CU-Soil which uses soil coated stone to provide a sturdy surface for pavement and plenty of pore space for tree roots. A similar system from Sweden is the use of the Stockholm Solution. The Solution requires the installation of large rocks under a pavement with topsoil being washed into the pores between the stones. In Stockholm, this procedure is used for street and sidewalk reconstruction projects as well as for improving the growing conditions around existing trees that are suffering from compacted soil or the lack of sufficient growing area for the roots.
Root Barriers
During any tree installation project, plant the trees first and install root barriers if necessary to deflect roots downward. This will prevent the tree's roots from causing damage to the surface pavements. The tree installation should be done before finishing the job with the addition of the new pavement at the surface.
The Best Choice of Trees
The trees to be selected should be trees that will tolerate heat as climate change and global warming continues to harm heat intolerant trees.
Bare Root Trees
Continue to learn how to plant bare root trees. They are the least expensive to purchase and plant by contract and easiest to plant when using volunteers. Planting trees with bare roots will help the tree make their transition to the new soil. See more information on planting bare root trees.
B&B Tree Treatment
The latest research indicates that the burlap and the wire basket should be completely removed from the root balls of Balled & Burlapped trees at the time of planting. In addition, the soil in the root ball should be removed at the installation site enough to determine that there are no problem roots. Regardless of the planting method, be sure the flare is level with or one inch above the final grade when the installation is finished.
Stabilizing
Gone should be the above ground stakes to hold the tree from tipping over. Recent research has indicated that staking a tree causes more harm to the tree than using root stabilizers. If there is a concern that the lack of a soil ball might cause the tree to blow over or be knocked over by vandals, this is easily remedied with any of several root stabilizing options, such as a tree staple or long stakes that are driven through the root system and into the soil below the tree. See more information on root stabilization.
Surface Treatment of the Planting Pit
After the tree is installed and roots are stabilized if necessary, the best surface treatment is to consider using one of two living mulches. A living mulch is intended to beautify and replace the need for a tree grate or conventional mulch by using low maintenance plants to provide weed suppression, moderate the soil temperature, and provide a visual means to discourage people from walking close to the tree and causing soil compaction. The plants selected must be tolerant of compacted soil and abuse from careless pedestrians. Watering and after-installation care to the tree remains the same as using any surface treatment.
Porus Pavement
If this surface treatment with plants is not acceptable to the community leaders, the next best option is to go with porus pavement. This is a fully permeable paving product which allows water to freely drain through the surface. The porous pavement's non-skid, 50% rubber content and 50% stone aggregate surface along with a hard urethane binder ensures good traction even when wet.
The Future
All of the suggestions provided here represent the latest research results for growing trees in our cities. As global warming contines to break temperature records every year and super-storms continue to pound countries around the globe, installing and growing trees in our cities becomes more important and more challenging every year.
References
- Soil Cells, See information from our sponsor Deep Root
- CU-Soil, See information from our sponsor Amereq, Inc.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Celebrate Arbor Day
Edited by Len Phillips
The first Arbor Day was held on April 10, 1872 when Julius Sterling Morton proposed that this day be dedicated to planning and promoting the importance of trees. Morton was a Nebraska journalist and politician who served as President Grover Cleveland's secretary of agriculture, and was a proponent of major tree installation efforts. He also served as a member of Nebraska's state board of agriculture. On this first Arbor Day, more than one million trees were planted around the United States.
Birdsey Northrop of Connecticut was responsible for globalizing Arbor Day when he visited Japan in 1883 and delivered his Arbor Day and Village Improvement message. He also took his enthusiasm for Arbor Day to Australia, Canada, and Europe. Also in 1883, the American Forestry Association made Northrop the chairman of the committee to campaign for a National Arbor Day.
In 1970, U.S. President Richard Nixon made it official that most states declare the last Friday in April as National Arbor Day. This day was selected to coincide with the best tree planting weather throughout most of the United States. In 1972, the Arbor Day Foundation was formed to celebrate the 100th anniversary of the first Arbor Day. Four years later, the Foundation began the Tree City USA program with 42 communities in 15 states being honored. Today, more than 3,000 cities and towns are honored as Tree City USA communities.
By 1990, the Arbor Day Foundation was involved with the U.S. Forest Service to install trees in national forests that were in need of reforestation. In 2008, the Tree Campus USA program was launched as 29 colleges and universities were recognized for following best tree care practices on campus. Today there are more than 250 campuses recognized. Since its founding, the Arbor Day Foundation has distributed over 50 million tree seedlings for installation in national forests, cities, and towns all over the USA.
Despite all the glamour and celebration of installing trees on Arbor Day, the National Wildlife Foundation recently announced that there are between 60 and 200 million spaces along our city streets where trees could be planted.
What still needs to be done? More people have to learn about trees! How to install and care for them! And to know the benefits we all derive from trees!
The best place to learn about trees is at the Arbor Day ceremony. The ceremony should consist of Boy/Girl Scouts presenting the US flag, reading the local Arbor Day Proclamation, giving a history of Arbor Day and inviting children to prepare posters or read poems and writings about trees, and finally to show by example, the proper installation for successfully growing a tree.
There are many other projects that can be implemented to celebrate trees all summer long. For example:
Source
“Celebrate Arbor Day”, TreeServicesMagazine.com, April 2016.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA management credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Edited by Len Phillips
The first Arbor Day was held on April 10, 1872 when Julius Sterling Morton proposed that this day be dedicated to planning and promoting the importance of trees. Morton was a Nebraska journalist and politician who served as President Grover Cleveland's secretary of agriculture, and was a proponent of major tree installation efforts. He also served as a member of Nebraska's state board of agriculture. On this first Arbor Day, more than one million trees were planted around the United States.
Birdsey Northrop of Connecticut was responsible for globalizing Arbor Day when he visited Japan in 1883 and delivered his Arbor Day and Village Improvement message. He also took his enthusiasm for Arbor Day to Australia, Canada, and Europe. Also in 1883, the American Forestry Association made Northrop the chairman of the committee to campaign for a National Arbor Day.
In 1970, U.S. President Richard Nixon made it official that most states declare the last Friday in April as National Arbor Day. This day was selected to coincide with the best tree planting weather throughout most of the United States. In 1972, the Arbor Day Foundation was formed to celebrate the 100th anniversary of the first Arbor Day. Four years later, the Foundation began the Tree City USA program with 42 communities in 15 states being honored. Today, more than 3,000 cities and towns are honored as Tree City USA communities.
By 1990, the Arbor Day Foundation was involved with the U.S. Forest Service to install trees in national forests that were in need of reforestation. In 2008, the Tree Campus USA program was launched as 29 colleges and universities were recognized for following best tree care practices on campus. Today there are more than 250 campuses recognized. Since its founding, the Arbor Day Foundation has distributed over 50 million tree seedlings for installation in national forests, cities, and towns all over the USA.
Despite all the glamour and celebration of installing trees on Arbor Day, the National Wildlife Foundation recently announced that there are between 60 and 200 million spaces along our city streets where trees could be planted.
What still needs to be done? More people have to learn about trees! How to install and care for them! And to know the benefits we all derive from trees!
The best place to learn about trees is at the Arbor Day ceremony. The ceremony should consist of Boy/Girl Scouts presenting the US flag, reading the local Arbor Day Proclamation, giving a history of Arbor Day and inviting children to prepare posters or read poems and writings about trees, and finally to show by example, the proper installation for successfully growing a tree.
There are many other projects that can be implemented to celebrate trees all summer long. For example:
- Donate books about trees to the local library.
- Hold an Arbor Day picnic at your place of business and raffle off trees to the people attending.
- Work with the local newspaper to search for the oldest or largest of different trees growing in the city.
- Conduct a cleanup and tree trimming event at a local park or public property and have a picnic on the grounds when the job is done.
- Conduct classes on selecting a tree for a specific location, proper pruning, tree installation, and tree identification.
- Have neighborhood block parties and install trees as part of the festivities.
- Honor citizens who have provided outstanding support for trees and the tree care program in the city.
- Work with kids to produce a skit about trees and perform it for families or at the Arbor Day ceremony.
- Purchase some seedlings and give them to your employees to install in their yards, at their local school, or at their house of worship, with permission of the landowner of course.
Source
“Celebrate Arbor Day”, TreeServicesMagazine.com, April 2016.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA management credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
2018 Urban Tree of the Year
By Len Phillips
Liriodendron tulipifera, Tulip Tree, has been named the 2018 Urban Tree of the Year by a vote of the members of the Society of Municipal Arborists. This tree is pyramidal in youth and develops an oval form as it ages. It presents a grand and stately appearance at maturity. It is a large tree that needs a large site and trunk protection because it has soft bark that is easily damaged by mowers and vandals. It grows very well in urban locations such as parks, wide medians, and city parkways. Tulip Tree is also the state tree of Kentucky, Tennessee, and Indiana.
Trade Name: Tulip Tree
Botanical Name: Liriodendron tulipifera
Family: Magnoliaceae
Parentage: Native to eastern half of the US
USDA Hardiness Zone: 4 – 8
AHS Heat Zone: 8 - 1
Height: 70' – 100'
Spread: 35' – 60'
Growth Rate: Rapid, up to 200 years of age, 60' at 30 years. The champion is 500 years old.
Form: Oval
Flower: Tulip like yellowish green flowers with an orange center, blooms in June, tree has to be growing for 6 – 10 years before it blooms
Fruit: Pyramidal, dry pods 2" – 3" long, persistent thorough winter
Summer Foliage: Dense, squarish shaped, bright green in summer
Autumn Color: Golden yellow
Bark: Grayish brown with ridges
Habitat: People think it looks better in Europe than in native US habitats
Culture: Transplant B&B in spring, prefers deep, moist, well drained soil
Pest and Disease Resistance: Bothered by several minor diseases and pests, but aphids are the most serious
Storm Resistance: Fair, may break up in ice and severe wind storms
Root Structure and Depth: Fleshy and poorly branched root system
Site Requirements: Rich medium loam, moist, well drained, sun or partial shade, will not tolerate clay soils, drought or sunscald, prefers slightly acidic soil.
Salt Resistance: Poor
installation: Transplant B&B in spring
Pruning: Seldom needs pruning
Propagating: Hardwood cuttings and seeds, cultivars must be grafted to seedling root stock.
Design Uses: Excellent for large landscapes, needs space to be appreciated
Companions: Best with shade tolerant groundcovers
Site Requirements: Full sun to partial shade
Photo
Notable cultivars: Emerald City - L. tulipifera 'JFS-Oz': compact oval shape, deep green and glossy. Photo
Columnar - L. tulipifera 'Fastigiatum': 50 ft tall, 15 ft wide, fast growing.
Photo
Golden - L. tulipifera 'Glen Gold': yellow leaves. Photo
Little Volunteer - L. tulipifera 'Little Volunteer' – dwarf, smaller leaves. Photo
Sources:
This information has been gathered from personal observations of the author, living in Massachusetts, Zone 6 and information provided by our sponsor J. Frank Schmidt & Son.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
By Len Phillips
Liriodendron tulipifera, Tulip Tree, has been named the 2018 Urban Tree of the Year by a vote of the members of the Society of Municipal Arborists. This tree is pyramidal in youth and develops an oval form as it ages. It presents a grand and stately appearance at maturity. It is a large tree that needs a large site and trunk protection because it has soft bark that is easily damaged by mowers and vandals. It grows very well in urban locations such as parks, wide medians, and city parkways. Tulip Tree is also the state tree of Kentucky, Tennessee, and Indiana.
Trade Name: Tulip Tree
Botanical Name: Liriodendron tulipifera
Family: Magnoliaceae
Parentage: Native to eastern half of the US
USDA Hardiness Zone: 4 – 8
AHS Heat Zone: 8 - 1
Height: 70' – 100'
Spread: 35' – 60'
Growth Rate: Rapid, up to 200 years of age, 60' at 30 years. The champion is 500 years old.
Form: Oval
Flower: Tulip like yellowish green flowers with an orange center, blooms in June, tree has to be growing for 6 – 10 years before it blooms
Fruit: Pyramidal, dry pods 2" – 3" long, persistent thorough winter
Summer Foliage: Dense, squarish shaped, bright green in summer
Autumn Color: Golden yellow
Bark: Grayish brown with ridges
Habitat: People think it looks better in Europe than in native US habitats
Culture: Transplant B&B in spring, prefers deep, moist, well drained soil
Pest and Disease Resistance: Bothered by several minor diseases and pests, but aphids are the most serious
Storm Resistance: Fair, may break up in ice and severe wind storms
Root Structure and Depth: Fleshy and poorly branched root system
Site Requirements: Rich medium loam, moist, well drained, sun or partial shade, will not tolerate clay soils, drought or sunscald, prefers slightly acidic soil.
Salt Resistance: Poor
installation: Transplant B&B in spring
Pruning: Seldom needs pruning
Propagating: Hardwood cuttings and seeds, cultivars must be grafted to seedling root stock.
Design Uses: Excellent for large landscapes, needs space to be appreciated
Companions: Best with shade tolerant groundcovers
Site Requirements: Full sun to partial shade
Photo
Notable cultivars: Emerald City - L. tulipifera 'JFS-Oz': compact oval shape, deep green and glossy. Photo
Columnar - L. tulipifera 'Fastigiatum': 50 ft tall, 15 ft wide, fast growing.
Photo
Golden - L. tulipifera 'Glen Gold': yellow leaves. Photo
Little Volunteer - L. tulipifera 'Little Volunteer' – dwarf, smaller leaves. Photo
Sources:
This information has been gathered from personal observations of the author, living in Massachusetts, Zone 6 and information provided by our sponsor J. Frank Schmidt & Son.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Honeybee Collapse
By Len Phillips
Honeybees play a vital role in about one third of all the food we eat. This includes nuts from our city and suburban trees, vegetables, berries, and other fruits. When honeybees pollinate flowers, it occurs while they are collecting nectar. Pollen from the flower's stamen sticks to the hairs on the bee's body and when the bee visits the next flower, some of the pollen rubs off causing the flower to become fertilized.
However, the honeybee population is collapsing because of pests, pesticides, and other problems. This past spring, beekeepers everywhere lost more than 40% of their honeybees. This trend has been going on since 2006. The trend was first observed by almond growers in California. Two-thirds of the nation's commercial honeybees are involved in almond tree pollination. The pollination average for almond orchards is two hives per acre. Last year, California had nearly 900,000 acres of almond trees. This means there was a need for almost 2 million hives of honeybees.
As the almond farmers were searching for the necessary quantity of bees, they also started talking to the beekeepers, who were reporting a significant loss of bees during the year and did not have enough hives for the almond pollination season, which meant a crop loss for the almond farmer. It also indicated that there was some kind of problem and not just a short trend or an abnormality.
The beekeepers recognized that this problem was more than just one crop or an isolated concern. The problem became known as colony collapse disorder or CCD. It was happening when the worker bees left the hive but did not return. This left the queen with limited food and young bees, but no workers to tend the brood and gather food. As CCD spread, the plight of the honeybees made headlines across the country. People suddenly became aware of the honeybee's place in the food chain and their need to pollinate the almond trees.
Cause of CCD
Most arborists have heard that part of the cause of CCD is our use of pesticides to control pests in our trees. Since the hives of bees are coming from all over the US, trees that were treated with pesticides in other places, killed the bees before they could get to the almonds. There are plenty of reports about this problem and the efforts that arborists are taking to adjust the timing of the pesticide applications until after the flowers have finished blooming. But the CCD problem still persists.
According to new research from the Canadian University of Guelph, when used properly, the three most common neonicotinoids used on flowering trees and crops are not harmful to honeybee colonies. Proper usage includes ensuring that treated crop seeds are coated and planted properly, thus preventing airborne contamination during field seeding. The study, published in the Journal of Toxicology and Environmental Health, analyzed 170 unpublished studies that pesticide manufacturers Bayer and Syngenta had submitted to regulatory agencies, as well as 64 peer-reviewed and published papers. The researchers acknowledged that clothianidin, imidacloprid, and thiamethoxam, the three most common neonicotinoids, can still harm individual honeybees as well as other pollinators, but proper usage does not impact honeybees at the level of the colony, or the reproductive unit. They hope that other researchers will use their results to further examine the impacts that neonicotinoids and other pesticides have on hives, as most studies tend to emphasize individual bee mortality instead of the colony as a whole.
Meanwhile, while studying environmental factors that contribute to bumble bee population declines, a team of researchers from Cornell University found that fungicides on trees might have an impact on bumble bees as well as honey bees, though the fungicides were previously thought to be benign to bees. Residue from fungicides used to control plant pathogens in crops are picked up by bees foraging for pollen and nectar. This in itself is not inherently harmful to the bees, but it is thought that the fungicide's interaction with insecticides gathered and deposited in the hive might increase the toxicity. In particular, the researchers focused on the fungicide chlorothalonil, sold under the names Bravo, Echo, and Daconil, and commonly used on crops including peanuts and potatoes. Chlorothalonil has been linked to Nosema, a fatal gut infection in bees, as well as stunted colony growth. Fungicides and insecticides combined in the hive, were also found to contribute to a decrease in the range of the bumblebees studied.
Researchers at Michigan State University have unlocked a key to maintain the insecticide's effectiveness to kill the pest without harming beneficial insects such as bees. This has to do with Tau-Fluvalinate (TF), an ingredient in certain pyrethroid insecticides. Honeybees and bumblebees are resistant to the effects of TF while other insect pests are not. The scientists will continue to investigate this link between insecticides and fungicides as well as fungicide-pathogen interactions to determine the best use of fungicides while protecting bees.
Varroa Mite
Looking into the hives, beekeepers discovered a second problem for the honeybee. It is the Varroa mite. The Varroa mite arrived from Asia and it lays its eggs within the honeybee brood where they pierce an adult honeybee's exoskeleton and feed on its internal fluid. The Varroa mites can also infect bees with deadly viruses. The Michigan State University researchers have discovered that the Varroa mites are controlled with TF, so this ingredient is the key to solving two of the causes of CCD.
Solutions
Beekeepers and almond growers are taking an active role to help the honeybee by planting bee-friendly flowers among their rows of almond trees to help facilitate a diverse diet for the honeybees.
Homeowners are being encouraged to let the clover and dandelions in their lawns grow and bloom. They are being told that these flowers are something that bees love. We should all be growing flowers that bees need to survive. Arborists are being encouraged to grow living mulches around the base of their recently installed public trees.
About half of a beekeeper's income is from renting the hives to orchards and farms where pollination services are required. The other half of the beekeeper's income is from selling the honey that the bees have produced. Selling the honey helps the beekeeper take care of their bees and fund research that helps to keep their bees healthy. One major activity currently under way is research to find a species or hybrid of honeybees that are resistant to the Varroa mite.
What happens if the bees disappear? We will still have food, but we will not have the variety and it will not be affordable. It will definitely change our quality of life and change our choices of food.
Source
Ponder, Stephanie E., “Bees in Peril”, The Costco Connection, July 2017.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA science credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
By Len Phillips
Honeybees play a vital role in about one third of all the food we eat. This includes nuts from our city and suburban trees, vegetables, berries, and other fruits. When honeybees pollinate flowers, it occurs while they are collecting nectar. Pollen from the flower's stamen sticks to the hairs on the bee's body and when the bee visits the next flower, some of the pollen rubs off causing the flower to become fertilized.
However, the honeybee population is collapsing because of pests, pesticides, and other problems. This past spring, beekeepers everywhere lost more than 40% of their honeybees. This trend has been going on since 2006. The trend was first observed by almond growers in California. Two-thirds of the nation's commercial honeybees are involved in almond tree pollination. The pollination average for almond orchards is two hives per acre. Last year, California had nearly 900,000 acres of almond trees. This means there was a need for almost 2 million hives of honeybees.
As the almond farmers were searching for the necessary quantity of bees, they also started talking to the beekeepers, who were reporting a significant loss of bees during the year and did not have enough hives for the almond pollination season, which meant a crop loss for the almond farmer. It also indicated that there was some kind of problem and not just a short trend or an abnormality.
The beekeepers recognized that this problem was more than just one crop or an isolated concern. The problem became known as colony collapse disorder or CCD. It was happening when the worker bees left the hive but did not return. This left the queen with limited food and young bees, but no workers to tend the brood and gather food. As CCD spread, the plight of the honeybees made headlines across the country. People suddenly became aware of the honeybee's place in the food chain and their need to pollinate the almond trees.
Cause of CCD
Most arborists have heard that part of the cause of CCD is our use of pesticides to control pests in our trees. Since the hives of bees are coming from all over the US, trees that were treated with pesticides in other places, killed the bees before they could get to the almonds. There are plenty of reports about this problem and the efforts that arborists are taking to adjust the timing of the pesticide applications until after the flowers have finished blooming. But the CCD problem still persists.
According to new research from the Canadian University of Guelph, when used properly, the three most common neonicotinoids used on flowering trees and crops are not harmful to honeybee colonies. Proper usage includes ensuring that treated crop seeds are coated and planted properly, thus preventing airborne contamination during field seeding. The study, published in the Journal of Toxicology and Environmental Health, analyzed 170 unpublished studies that pesticide manufacturers Bayer and Syngenta had submitted to regulatory agencies, as well as 64 peer-reviewed and published papers. The researchers acknowledged that clothianidin, imidacloprid, and thiamethoxam, the three most common neonicotinoids, can still harm individual honeybees as well as other pollinators, but proper usage does not impact honeybees at the level of the colony, or the reproductive unit. They hope that other researchers will use their results to further examine the impacts that neonicotinoids and other pesticides have on hives, as most studies tend to emphasize individual bee mortality instead of the colony as a whole.
Meanwhile, while studying environmental factors that contribute to bumble bee population declines, a team of researchers from Cornell University found that fungicides on trees might have an impact on bumble bees as well as honey bees, though the fungicides were previously thought to be benign to bees. Residue from fungicides used to control plant pathogens in crops are picked up by bees foraging for pollen and nectar. This in itself is not inherently harmful to the bees, but it is thought that the fungicide's interaction with insecticides gathered and deposited in the hive might increase the toxicity. In particular, the researchers focused on the fungicide chlorothalonil, sold under the names Bravo, Echo, and Daconil, and commonly used on crops including peanuts and potatoes. Chlorothalonil has been linked to Nosema, a fatal gut infection in bees, as well as stunted colony growth. Fungicides and insecticides combined in the hive, were also found to contribute to a decrease in the range of the bumblebees studied.
Researchers at Michigan State University have unlocked a key to maintain the insecticide's effectiveness to kill the pest without harming beneficial insects such as bees. This has to do with Tau-Fluvalinate (TF), an ingredient in certain pyrethroid insecticides. Honeybees and bumblebees are resistant to the effects of TF while other insect pests are not. The scientists will continue to investigate this link between insecticides and fungicides as well as fungicide-pathogen interactions to determine the best use of fungicides while protecting bees.
Varroa Mite
Looking into the hives, beekeepers discovered a second problem for the honeybee. It is the Varroa mite. The Varroa mite arrived from Asia and it lays its eggs within the honeybee brood where they pierce an adult honeybee's exoskeleton and feed on its internal fluid. The Varroa mites can also infect bees with deadly viruses. The Michigan State University researchers have discovered that the Varroa mites are controlled with TF, so this ingredient is the key to solving two of the causes of CCD.
Solutions
Beekeepers and almond growers are taking an active role to help the honeybee by planting bee-friendly flowers among their rows of almond trees to help facilitate a diverse diet for the honeybees.
Homeowners are being encouraged to let the clover and dandelions in their lawns grow and bloom. They are being told that these flowers are something that bees love. We should all be growing flowers that bees need to survive. Arborists are being encouraged to grow living mulches around the base of their recently installed public trees.
About half of a beekeeper's income is from renting the hives to orchards and farms where pollination services are required. The other half of the beekeeper's income is from selling the honey that the bees have produced. Selling the honey helps the beekeeper take care of their bees and fund research that helps to keep their bees healthy. One major activity currently under way is research to find a species or hybrid of honeybees that are resistant to the Varroa mite.
What happens if the bees disappear? We will still have food, but we will not have the variety and it will not be affordable. It will definitely change our quality of life and change our choices of food.
Source
Ponder, Stephanie E., “Bees in Peril”, The Costco Connection, July 2017.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA science credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Urban Forestry in Cambridge, Massachusetts
By David Lefcourt, Tree Warden
Cambridge is a city just across the Charles River from Boston, Massachusetts. The city has over 19,000 public trees. roughly 13,000 of which are street trees. 6,000 of those trees can be found in cemeteries, school grounds, and parks.
The Forestry Department has a budget of $1.9 million. This includes $400,000 for tree installation, $500,000 for two tree pruning contacts, $100,000 for Emerald Ash Borer treatments in anticipation of the EAB coming to the city within the next two years, and salaries for personnel.
Planting Program
Prior to tree installation, the city places stickers on the sidewalk indicating where a tree might be installed in the future. This gives residents a chance to discuss the proposed planting if there are special concerns. Species to be selected for installation are made in an attempt to maintain species diversity and to avoid canopy loss from pests or diseases. The tree installation specifications are updated as needed to utilize the latest research and methods.
I would prefer to install two inches or less diameter bare root trees, but is constrained by logistical issues. Mostly B&B trees are being installed, all the burlap and wire baskets must also be removed from the root balls. The roots must be exposed to eliminate any problems such as circling roots. During the installation process, the trees must be installed with the flare 1 to 2 inches above the finished grade. The tree must be watered to the point of the saturation in order to eliminate air pockets and to be sure the roots are all in contact with the soil. The tree is mulched but not against the trunk. Roots that are girdling, adventitious, and upward growing (“J” roots) are pruned off but sometimes the whole tree is rejected for significant root issues.
Watering Program
Irrigation bags are attached to the planting stakes instead of the tree trunk to avoid prolonged wetness on the trunks which might lead to disease problems. Tags are added to the bags to let residents know what the bags are for and to encourage residents to fill the bags when they notice they are empty.
The watering programs begin with the contractor who installed the tree providing water as a part of the 2-year warranty. The contractor must water the tree at least two times per week during the first 30 days after installation. After the first 30 days, the contractor gets paid each time they come into the city to water the trees. During the third and fourth year after installation, the watering is done by the forestry department crews who water early in the morning before going on to their other assignments, or the watering is being done by summer temporary employees who are called “Water by Bike Tree Ambassadors”. They use a water tank mounted on a trailer attached to a bicycle and they water 300 to 700 trees each summer.
Other Programs
Arbor Day in Cambridge is now celebrated for a whole week. It is designed to promote tree benefits and to introduce our new “Adopt-a-Tree” program. The city also hands out seedlings and information at two events during Arbor Week.
The tree inventory is a very useful tool for determining diversity. The Cambridge inventory indicates there are 130 species of trees growing in the city. Efforts during tree installation are focused on maintaining 10% or less of each genus.
The city has also developed an “Adopt-a-Tree” program for abutters or neighbors to provide water and report tree problems to the tree department.
Engineering Cooperation
I work closely with the city's Engineering department to protect trees during sidewalk reconstruction. Bump-outs to preserve trees and their roots are sometimes utilized despite the loss of parking spaces. When contracts have been established to replace or reset curbing, the contract requires that all roots must be protected. To accomplish this, the contractor should use a narrow excavation bucket on the street side of the curb, and any root larger than two inches in diameter must be approved by myself before it can be cut. I should also be called to the site at all difficult situations.
During sidewalk reconstruction projects, new tree wells require the soil to contain sand based structural soil under the sidewalk to provide better soil for tree growth. The sand based structural soil is used in all new sidewalk renovations where new trees are installed. Some bicycle lanes which abut tree wells are being built over the sand based structural soil to allow more rooting volume for the trees.
The Engineering Department is also using “Flexi-pave” around tree wells to allow water to reach the roots of newly installed trees. This department has a requirement that any project that might involve tree work must have a certified arborist on the job site and this person is the only one who can work on the tree.
The Future
Future plans for the city include developing an urban forestry master plan for the existing and future tree canopy. We are also planning on adding biochar to some newly installed trees to see how well the trees respond to this treatment.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA management credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
By David Lefcourt, Tree Warden
Cambridge is a city just across the Charles River from Boston, Massachusetts. The city has over 19,000 public trees. roughly 13,000 of which are street trees. 6,000 of those trees can be found in cemeteries, school grounds, and parks.
The Forestry Department has a budget of $1.9 million. This includes $400,000 for tree installation, $500,000 for two tree pruning contacts, $100,000 for Emerald Ash Borer treatments in anticipation of the EAB coming to the city within the next two years, and salaries for personnel.
Planting Program
Prior to tree installation, the city places stickers on the sidewalk indicating where a tree might be installed in the future. This gives residents a chance to discuss the proposed planting if there are special concerns. Species to be selected for installation are made in an attempt to maintain species diversity and to avoid canopy loss from pests or diseases. The tree installation specifications are updated as needed to utilize the latest research and methods.
I would prefer to install two inches or less diameter bare root trees, but is constrained by logistical issues. Mostly B&B trees are being installed, all the burlap and wire baskets must also be removed from the root balls. The roots must be exposed to eliminate any problems such as circling roots. During the installation process, the trees must be installed with the flare 1 to 2 inches above the finished grade. The tree must be watered to the point of the saturation in order to eliminate air pockets and to be sure the roots are all in contact with the soil. The tree is mulched but not against the trunk. Roots that are girdling, adventitious, and upward growing (“J” roots) are pruned off but sometimes the whole tree is rejected for significant root issues.
Watering Program
Irrigation bags are attached to the planting stakes instead of the tree trunk to avoid prolonged wetness on the trunks which might lead to disease problems. Tags are added to the bags to let residents know what the bags are for and to encourage residents to fill the bags when they notice they are empty.
The watering programs begin with the contractor who installed the tree providing water as a part of the 2-year warranty. The contractor must water the tree at least two times per week during the first 30 days after installation. After the first 30 days, the contractor gets paid each time they come into the city to water the trees. During the third and fourth year after installation, the watering is done by the forestry department crews who water early in the morning before going on to their other assignments, or the watering is being done by summer temporary employees who are called “Water by Bike Tree Ambassadors”. They use a water tank mounted on a trailer attached to a bicycle and they water 300 to 700 trees each summer.
Other Programs
Arbor Day in Cambridge is now celebrated for a whole week. It is designed to promote tree benefits and to introduce our new “Adopt-a-Tree” program. The city also hands out seedlings and information at two events during Arbor Week.
The tree inventory is a very useful tool for determining diversity. The Cambridge inventory indicates there are 130 species of trees growing in the city. Efforts during tree installation are focused on maintaining 10% or less of each genus.
The city has also developed an “Adopt-a-Tree” program for abutters or neighbors to provide water and report tree problems to the tree department.
Engineering Cooperation
I work closely with the city's Engineering department to protect trees during sidewalk reconstruction. Bump-outs to preserve trees and their roots are sometimes utilized despite the loss of parking spaces. When contracts have been established to replace or reset curbing, the contract requires that all roots must be protected. To accomplish this, the contractor should use a narrow excavation bucket on the street side of the curb, and any root larger than two inches in diameter must be approved by myself before it can be cut. I should also be called to the site at all difficult situations.
During sidewalk reconstruction projects, new tree wells require the soil to contain sand based structural soil under the sidewalk to provide better soil for tree growth. The sand based structural soil is used in all new sidewalk renovations where new trees are installed. Some bicycle lanes which abut tree wells are being built over the sand based structural soil to allow more rooting volume for the trees.
The Engineering Department is also using “Flexi-pave” around tree wells to allow water to reach the roots of newly installed trees. This department has a requirement that any project that might involve tree work must have a certified arborist on the job site and this person is the only one who can work on the tree.
The Future
Future plans for the city include developing an urban forestry master plan for the existing and future tree canopy. We are also planning on adding biochar to some newly installed trees to see how well the trees respond to this treatment.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA management credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Outstanding Inventors of Trees
Thomas Molnar
By Len Phillips
Dr. Thomas J. Molnar is a man who is dedicating his career to improving hazelnut and dogwood trees. He began working with Corylus americana, Hazelnut, commonly found in Eastern U.S. Hazelnuts, also known as filberts, when compared to other species are a very low-input crop, needing very little supplemental irrigation, pesticides or fungicides. They can be grown in a diversity of soil types, including those that are less than ideal. Hazelnut trees are widely adapted, and depending on the cultivar, can be very cold hardy. It is Molnar's dream to see these underutilized nut trees growing as a street tree like a crop, while providing food for wildlife and humans.
Eastern Filbert Blight
Unlike many other plant pathogens that cause economic damage to agriculture in the U.S., the Eastern Filbert Blight is found naturally occurring in our forests associated with our native hazelnut, C. americana, which is very tolerant of the disease. Corylus americana is not grown commercially, due to its tiny, thick shelled nuts and spreading growth habit. Its European relative, Corylus avellana, however, is the species grown commercially, as it produces large nuts with thin shells and high quality kernels. Unfortunately, the European species is highly susceptible to the Eastern Filbert Blight disease, so it is not grown commercially in the U.S.. This disease has resulted in most of the world's commercially harvested hazelnuts only being grown in Turkey and a small section of Oregon, two of the few places on the planet where these trees can thrive in harmony with the blight.
The Eastern Filbert Blight is a fungal disease that causes stem cankers, branch die-back and eventual death of susceptible hazelnuts and it is the most limiting factor of C. avellana hazelnut production in North America.
Meanwhile, the growing popularity of Nutella, the creamy hazelnut and cocoa spread, has maxed out all the world's supply of hazelnuts in recent years. That has sent prices soaring and led to fears there are not enough disease resistant European trees to supply the surging demand for the popular Nutella and its hazelnut.
A major aspect of Molnar's current research is developing and characterizing the genetic resistance factors of Eastern Filbert Blight in C. americana. He has established breeding objectives in C. avellana hazelnuts to emphasize the selection of trees for high levels of disease and pest resistance, as well as for having cold hardiness.
After decades of study, Molnar and his team at Rutgers New Jersey Agricultural Experiment Station announced they have developed a new kind of hazelnut tree that can grow in New Jersey and the Northeast U.S. Molnar's approach for developing resistant plants includes using genetic sources of resistance found within Corylus americana combined with the large nuts with thin shells and high quality kernels of C. avellana. Molnar is very optimistic that new cultivars that meet these traits will be available in the next few years.
In addition to hazel nut trees for nut production, Molnar is also developing a new line of ornamental hazelnuts. He is selecting seedlings that exhibit the dark purple foliage color of the European species and those having the Eastern Filbert Blight resistance inherited from the American species. Also expected will be trees with attractive purple leaves and bright autumn color, as well as those with contorted and weeping branches. All these potentially new cultivars will also produce nuts, making them edible landscape plants. The resulting seedlings include a trait of bearing nut clusters with dark red or purple husks. The nuts are small but very ornamental and edible. The goal of this breeding program is to eventually develop disease resistant hazelnuts and a large number of cultivars with different colored leaves, contorted forms, and trees suitable for being street trees. The goal is also to produce a tree that improves the popularity of hazelnuts and a tree that has drought resistance and will grow well despite climate change.
Kousa Dogwood
As if Molnar's work on filberts is not enough to keep him busy, he is also working on dogwoods as a follow-up to the work of the retired Dr. Elwin Orton who developed the Stellar series of six different disease resistant, white flowering dogwoods. With the success of the Stellar series, Dr. Orton released the very large flowered Venus dogwood which is now considered to be the finest dogwood ever developed in terms of its beauty as well as its resistance to powdery mildew and dogwood anthracnose.
I have a Venus dogwood growing in my front yard, and it is a constant source of compliments from my neighbors when this tree is in bloom. Each flower is the size of my hand and each branch usually has a dozen or more flowers. The number of blooms on the tree does vary from year to year depending on the local climate. Two years ago my tree was completely white because there were so many blooms. Last year there were half the number of blooms, but I would not trade it for anything. I received my tree when it was a 4-foot (1.2 m) tall whip. Now 15 years later this tree is 20 feet (6 m) tall and wide.
Getting back to Molnar's work, he is focused on a Cornus kousa that has dark pink bracts. He was successful in developing a new cultivar that is the result of an open-pollination event of a female (seed) parent being a pink-bracted, an unreleased breeding selection designated as K187-44 which resulted from a cross of Cornus kousa ‘Satomi’ and C. kousa ‘Benifuji’ selected in 1996 by Dr. Orton. The male (pollen) parent of Molnar's new cultivar is unknown but from a limited breeding block of improved dogwood trees. The tree has been trademarked Cornus kousa 'Rutpink' Scarlet Fire®. This tree is producing an abundance of flowers every spring and is the first Cornus kousa to have dark pink bracts. This tree has had no incidents of powdery mildew or anthracnose. Several nurseries are growing this tree, but they are not yet large enough to be available in large quantities. However, the original tree began to flower at 4 years of age and budded trees are blooming after 2 years of growth. The leaves are an attractive dark green with purple tinges in new growth, especially on young plants. The moderately vigorous tree is well-branched and grows 3+ feet in first year and to 8 feet high in years 8-10. The tree is available in limited supply from nurseries in the New Jersey area. It was granted patent number USPP #28311 last summer.
Thomas Molnar is still quite young so there will probably be many more new trees being introduced by him in the future. With his goal of developing street trees with beauty, disease resistance, and edible fruits, municipal arborists should keep looking for his introductions to add to your “tried and true plant list” to see how well they do in your city.
Sources
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Thomas Molnar
By Len Phillips
Dr. Thomas J. Molnar is a man who is dedicating his career to improving hazelnut and dogwood trees. He began working with Corylus americana, Hazelnut, commonly found in Eastern U.S. Hazelnuts, also known as filberts, when compared to other species are a very low-input crop, needing very little supplemental irrigation, pesticides or fungicides. They can be grown in a diversity of soil types, including those that are less than ideal. Hazelnut trees are widely adapted, and depending on the cultivar, can be very cold hardy. It is Molnar's dream to see these underutilized nut trees growing as a street tree like a crop, while providing food for wildlife and humans.
Eastern Filbert Blight
Unlike many other plant pathogens that cause economic damage to agriculture in the U.S., the Eastern Filbert Blight is found naturally occurring in our forests associated with our native hazelnut, C. americana, which is very tolerant of the disease. Corylus americana is not grown commercially, due to its tiny, thick shelled nuts and spreading growth habit. Its European relative, Corylus avellana, however, is the species grown commercially, as it produces large nuts with thin shells and high quality kernels. Unfortunately, the European species is highly susceptible to the Eastern Filbert Blight disease, so it is not grown commercially in the U.S.. This disease has resulted in most of the world's commercially harvested hazelnuts only being grown in Turkey and a small section of Oregon, two of the few places on the planet where these trees can thrive in harmony with the blight.
The Eastern Filbert Blight is a fungal disease that causes stem cankers, branch die-back and eventual death of susceptible hazelnuts and it is the most limiting factor of C. avellana hazelnut production in North America.
Meanwhile, the growing popularity of Nutella, the creamy hazelnut and cocoa spread, has maxed out all the world's supply of hazelnuts in recent years. That has sent prices soaring and led to fears there are not enough disease resistant European trees to supply the surging demand for the popular Nutella and its hazelnut.
A major aspect of Molnar's current research is developing and characterizing the genetic resistance factors of Eastern Filbert Blight in C. americana. He has established breeding objectives in C. avellana hazelnuts to emphasize the selection of trees for high levels of disease and pest resistance, as well as for having cold hardiness.
After decades of study, Molnar and his team at Rutgers New Jersey Agricultural Experiment Station announced they have developed a new kind of hazelnut tree that can grow in New Jersey and the Northeast U.S. Molnar's approach for developing resistant plants includes using genetic sources of resistance found within Corylus americana combined with the large nuts with thin shells and high quality kernels of C. avellana. Molnar is very optimistic that new cultivars that meet these traits will be available in the next few years.
In addition to hazel nut trees for nut production, Molnar is also developing a new line of ornamental hazelnuts. He is selecting seedlings that exhibit the dark purple foliage color of the European species and those having the Eastern Filbert Blight resistance inherited from the American species. Also expected will be trees with attractive purple leaves and bright autumn color, as well as those with contorted and weeping branches. All these potentially new cultivars will also produce nuts, making them edible landscape plants. The resulting seedlings include a trait of bearing nut clusters with dark red or purple husks. The nuts are small but very ornamental and edible. The goal of this breeding program is to eventually develop disease resistant hazelnuts and a large number of cultivars with different colored leaves, contorted forms, and trees suitable for being street trees. The goal is also to produce a tree that improves the popularity of hazelnuts and a tree that has drought resistance and will grow well despite climate change.
Kousa Dogwood
As if Molnar's work on filberts is not enough to keep him busy, he is also working on dogwoods as a follow-up to the work of the retired Dr. Elwin Orton who developed the Stellar series of six different disease resistant, white flowering dogwoods. With the success of the Stellar series, Dr. Orton released the very large flowered Venus dogwood which is now considered to be the finest dogwood ever developed in terms of its beauty as well as its resistance to powdery mildew and dogwood anthracnose.
I have a Venus dogwood growing in my front yard, and it is a constant source of compliments from my neighbors when this tree is in bloom. Each flower is the size of my hand and each branch usually has a dozen or more flowers. The number of blooms on the tree does vary from year to year depending on the local climate. Two years ago my tree was completely white because there were so many blooms. Last year there were half the number of blooms, but I would not trade it for anything. I received my tree when it was a 4-foot (1.2 m) tall whip. Now 15 years later this tree is 20 feet (6 m) tall and wide.
Getting back to Molnar's work, he is focused on a Cornus kousa that has dark pink bracts. He was successful in developing a new cultivar that is the result of an open-pollination event of a female (seed) parent being a pink-bracted, an unreleased breeding selection designated as K187-44 which resulted from a cross of Cornus kousa ‘Satomi’ and C. kousa ‘Benifuji’ selected in 1996 by Dr. Orton. The male (pollen) parent of Molnar's new cultivar is unknown but from a limited breeding block of improved dogwood trees. The tree has been trademarked Cornus kousa 'Rutpink' Scarlet Fire®. This tree is producing an abundance of flowers every spring and is the first Cornus kousa to have dark pink bracts. This tree has had no incidents of powdery mildew or anthracnose. Several nurseries are growing this tree, but they are not yet large enough to be available in large quantities. However, the original tree began to flower at 4 years of age and budded trees are blooming after 2 years of growth. The leaves are an attractive dark green with purple tinges in new growth, especially on young plants. The moderately vigorous tree is well-branched and grows 3+ feet in first year and to 8 feet high in years 8-10. The tree is available in limited supply from nurseries in the New Jersey area. It was granted patent number USPP #28311 last summer.
Thomas Molnar is still quite young so there will probably be many more new trees being introduced by him in the future. With his goal of developing street trees with beauty, disease resistance, and edible fruits, municipal arborists should keep looking for his introductions to add to your “tried and true plant list” to see how well they do in your city.
Sources
- Martin, Susan, “Preserving a Vision”, Nursery Management, October 2017.
- Ag Products, 'Scarlet Fire', Rutgers School of Environmental and Biological Sciences, 2017.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Climate Change
Edited by Len Phillips
According to a recent study, continuing to burn fossil fuels at the current rate and not planting millions of trees could bring atmospheric carbon dioxide to its highest concentration in 50 million years, jumping from 400 parts per million now to more than 900 parts per million by the year 2100 and 5,000 parts per million in 300 years. Researchers behind the study published their results in the journal Nature Communications, which evaluated carbon dioxide levels in the atmosphere for the past half a billion years. The study indicates that after millions of years in the absence of human activity, the global climate was relatively stable.
This new study speaks to the effects of human influence over the climate. Now, just a few hundred years since the start of the Industrial Revolution and the burning of fossil fuels, the greenhouse gas emissions are on track to cause unprecedented warming. The research suggests that if humans continue to burn through all the fossil fuels on Earth, the amount of carbon dioxide in the air that we breathe and high temperature will prove fatal to all human beings.
To come to these grim conclusions, the researchers constructed a continuous record of atmospheric carbon dioxide concentrations spanning the last 420 million years. They created this record by compiling more than 1,500 estimates of atmospheric carbon dioxide concentrations drawn from 112 published studies that used the carbon isotope composition of ancient soil samples and by examining the abundance of pores on the leaves of fossilized plants. The pores are an indicator of how much carbon dioxide was available for the prehistoric plants to draw from the air when they were alive.
The findings suggest that until humans started rapidly burning fossil fuels at the beginning of the Industrial Revolution, the Earth's climate had been relatively stable for millions of years and carbon dioxide concentrations were declining as forests and plants were growing everywhere. Before the Industrial Revolution, carbon dioxide concentrations had averaged about 280 parts per million. However, due to the human consumption of fossil fuels, which led to the emission of greenhouse gases, all this stability changed and is now increasing at a record-breaking pace. Current concentrations of carbon dioxide emissions are at their highest level in human history, hovering around 400 parts per million and they are continuing to rise.
If we continue burning fossil fuels, greenhouse gas emissions will soon hit a level that that the planet's warming will probably be greater than at almost any point in the past 420 million years. If humans were to burn through all the fossil fuels on Earth, that would result in both the highest carbon dioxide level and the highest global temperature in the history of this planet and mankind would cease to exist by the year 2400.
The Intergovernmental Panel on Climate Change has presented estimates of how much the Earth might warm under a business-as-usual path. It suggests that the Earth could warm by nearly 48 degrees Fahrenheit. But there are many factors that could affect temperature trends in the coming centuries that remain uncertain. This includes changes in terrestrial vegetation or the amount of carbon dioxide that soil and the ocean can absorb. As a result, long-term warming could end up being even more intense than is estimated.
The study helps address a kind of paradox in the Earth's climate history. Based on the knowledge of the way stars generate energy, scientists know that our solar system's young sun would have been much dimmer millions of years ago. Over time, its intensity has increased and is likely to continue doing so for millions or even billions of years into the future.
If the sun has been getting hotter for millions of years, then one would expect the planet's climate to have steadily warmed during this time as well. But there is ample evidenced from the fossil record to suggest the planet's climate actually remained mostly stable for the millions of years before humans began burning fossil fuels. Scientists have assumed that this stability came from a long term low level of atmospheric carbon dioxide levels, which offset the warming caused by a brightening sun. The low level of carbon dioxide levels was maintained by the abundant plant growth on the land and in the oceans that absorbed the carbon dioxide.
The new study supports this idea. The researchers' study suggests that while there have been fluctuations throughout history, the long-term average carbon dioxide concentrations generally declined as a result of natural processes related to the formation of the Earth. Thanks to human activity, carbon dioxide levels are rising again, on tract to break millennial-scale records if mitigation efforts are not undertaken.
Mitigation can consist of many factors. Stopping the release of carbon dioxide into the atmosphere, growing vegetation at every possible location on the earth's surface, growing more plants and trees, and developing carbon sinks in soil and the oceans will all contribute to stabilizing the carbon dioxide levels, and hopefully, mankind will survive for more than the next 300 years.
We must all work together to continue planting and growing new trees rather than cutting down the trees we already have!
Source
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA science credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Edited by Len Phillips
According to a recent study, continuing to burn fossil fuels at the current rate and not planting millions of trees could bring atmospheric carbon dioxide to its highest concentration in 50 million years, jumping from 400 parts per million now to more than 900 parts per million by the year 2100 and 5,000 parts per million in 300 years. Researchers behind the study published their results in the journal Nature Communications, which evaluated carbon dioxide levels in the atmosphere for the past half a billion years. The study indicates that after millions of years in the absence of human activity, the global climate was relatively stable.
This new study speaks to the effects of human influence over the climate. Now, just a few hundred years since the start of the Industrial Revolution and the burning of fossil fuels, the greenhouse gas emissions are on track to cause unprecedented warming. The research suggests that if humans continue to burn through all the fossil fuels on Earth, the amount of carbon dioxide in the air that we breathe and high temperature will prove fatal to all human beings.
To come to these grim conclusions, the researchers constructed a continuous record of atmospheric carbon dioxide concentrations spanning the last 420 million years. They created this record by compiling more than 1,500 estimates of atmospheric carbon dioxide concentrations drawn from 112 published studies that used the carbon isotope composition of ancient soil samples and by examining the abundance of pores on the leaves of fossilized plants. The pores are an indicator of how much carbon dioxide was available for the prehistoric plants to draw from the air when they were alive.
The findings suggest that until humans started rapidly burning fossil fuels at the beginning of the Industrial Revolution, the Earth's climate had been relatively stable for millions of years and carbon dioxide concentrations were declining as forests and plants were growing everywhere. Before the Industrial Revolution, carbon dioxide concentrations had averaged about 280 parts per million. However, due to the human consumption of fossil fuels, which led to the emission of greenhouse gases, all this stability changed and is now increasing at a record-breaking pace. Current concentrations of carbon dioxide emissions are at their highest level in human history, hovering around 400 parts per million and they are continuing to rise.
If we continue burning fossil fuels, greenhouse gas emissions will soon hit a level that that the planet's warming will probably be greater than at almost any point in the past 420 million years. If humans were to burn through all the fossil fuels on Earth, that would result in both the highest carbon dioxide level and the highest global temperature in the history of this planet and mankind would cease to exist by the year 2400.
The Intergovernmental Panel on Climate Change has presented estimates of how much the Earth might warm under a business-as-usual path. It suggests that the Earth could warm by nearly 48 degrees Fahrenheit. But there are many factors that could affect temperature trends in the coming centuries that remain uncertain. This includes changes in terrestrial vegetation or the amount of carbon dioxide that soil and the ocean can absorb. As a result, long-term warming could end up being even more intense than is estimated.
The study helps address a kind of paradox in the Earth's climate history. Based on the knowledge of the way stars generate energy, scientists know that our solar system's young sun would have been much dimmer millions of years ago. Over time, its intensity has increased and is likely to continue doing so for millions or even billions of years into the future.
If the sun has been getting hotter for millions of years, then one would expect the planet's climate to have steadily warmed during this time as well. But there is ample evidenced from the fossil record to suggest the planet's climate actually remained mostly stable for the millions of years before humans began burning fossil fuels. Scientists have assumed that this stability came from a long term low level of atmospheric carbon dioxide levels, which offset the warming caused by a brightening sun. The low level of carbon dioxide levels was maintained by the abundant plant growth on the land and in the oceans that absorbed the carbon dioxide.
The new study supports this idea. The researchers' study suggests that while there have been fluctuations throughout history, the long-term average carbon dioxide concentrations generally declined as a result of natural processes related to the formation of the Earth. Thanks to human activity, carbon dioxide levels are rising again, on tract to break millennial-scale records if mitigation efforts are not undertaken.
Mitigation can consist of many factors. Stopping the release of carbon dioxide into the atmosphere, growing vegetation at every possible location on the earth's surface, growing more plants and trees, and developing carbon sinks in soil and the oceans will all contribute to stabilizing the carbon dioxide levels, and hopefully, mankind will survive for more than the next 300 years.
We must all work together to continue planting and growing new trees rather than cutting down the trees we already have!
Source
- Foster, G. L. et al. “Future climate forcing potentially without precedent in the last 420 million years”, Nature Communications 8, 14845 doi: 10.1038/ncomms14845 (2017).
- Harvey, Chelsea, “A dire warning on climate change”, Boston Globe, April 5, 2017
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA science credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Trees with Tales
By Len Phillips
Shagbark Hickory
Shagbark hickory, Carya ovata, is a tall, long-living member of the walnut family that can live more than 350 years, in part because of its moderately slow-growth rate. Shagbark will grow to a height of 70 to 90 feet (20-27 m) sometimes to 120 ft. (37m) and a record of over 150 feet (48m) high. It will spread 50 to 70 feet (15-20 m) and have a trunk diameter of 2 – 3 feet (0.7 – 1 m). The shagbark hickory is considered “stately”. The trees can be found from southern Maine, across southern Quebec and Ontario to Minnesota, south along the Appalachian mountain range to Georgia and eastern Texas. It is considered a climax species in the Eastern hardwood forest.
Forty years is considered the amount of time it takes a hickory tree to reach its commercial nut-producing potential. Trees that are 200, even 300 years in age can still produce large quantities of nuts. Mast years for shagbark hickories in the forest occur every one to three years, and population spikes among the mammals who eat shagbark nuts fluctuate on the same cycle. When I was a child, I remember going through the fields and forest with my grandfather to a large hickory tree at the edge of the forest, behind our house. As I recall, every year that we went back there, the birds and animals had beaten us to the nuts, and there were very few left for us to gather.
Flowers
This tree features greenish yellow flowers that appear from April to May. The male flowers appear in pendulous catkins and the female flowers in short spikes. Female flowers give way to the edible nuts. Each nut is encased in a moderately thick husk which splits open in four sections when ripe in autumn. Cross-pollination generally produces a more abundant crop of better quality nuts.
Nuts
Shagbark hickory nuts were a significant food source for the Algonquin Indians. Native Americans relied upon shagbark hickory nuts whose meat is high in fat and protein, and low in carbohydrates. The nuts are sweet and nourishing and were also a dietary staple to all who ate them. Red and gray squirrels, raccoons, chipmunks, and mice are major consumers of hickory nuts. Other consumers include black bears, red fox, rabbits, and bird species such as mallards, wood ducks, bobwhites, and wild turkey. Migrating yellow-rumped warblers and rose-breasted grosbeaks eat the nuts that are found along the routes to their southern winter habitats. The nuts are a popular food among people and squirrels alike.
The most prodigious appetite for shagbark hickory nuts belongs to gray squirrels. In fact, the competition for nuts between early settlers and squirrels in Pennsylvania prompted a bounty in the 1700’s (three pence per dead squirrel) that brought in 640,000 carcasses and nearly bankrupted the colonial treasury. However, there were plenty of hickory nuts for the settlers for the next several years.
Growing from seed
Hickory nuts ripen in September and should be collected as soon as they drop. Remove the green husk and soak the nuts in a bucket of water overnight. Any nuts that float may be empty. Do not leave nuts sitting around at room temperature or the seeds will desiccate and lose viability. To grow shagbark hickory from seed, plant the nuts in a deep pot or cold frame, placed outdoors, and protect the nuts from rodents with wire screening. Squirrels will find your pots within a couple of hours if unprotected. The nuts will germinate in the spring after winter stratification. Trees are tap-rooted, so transplant to a permanent location before the tap-root gets too long.
Appearance
Shagbark hickory is a very shaggy-looking tree. The shagbark hickory’s bark is light gray and smooth when the tree is young. Its bark darkens with age to become charcoal color, and begins to appear shingled with long warped shreds of bark. Bark patterns are often more pronounced as a tree ages because the bark furrows deepen, ridges protrude, and exfoliation is more dramatic – all of which illustrate the dynamic process that creates tree bark. Large trees produce considerable litter through twig, bark, leaf, and nut drop.
Hickory bark harbors a forest’s worth of lichens, mosses, fungi, small vertebrates, invertebrates, and microorganisms. More than 133 fungi are associated with shagbark hickories, but there are very few that actually damage the tree seriously. Shagbark hickories also host approximately 180 species of insects and mites, but the bark's chemistry and architecture minimize their incursions. Bats and brown creepers also roost and nest beneath the shagbark’s flaking bark.
The leaves are smooth, medium yellow-green, odd-pinnate, compound leaves, with each leaf usually having 5 finely-toothed, broadly lance-shaped, pointed leaflets. The leaflets range from 3–7 in. (7–18 cm) long. The leaves turn from summer green to yellow and then golden brown in autumn.
Growth
Shagbark hickory grows best in humus soil, rich, moist, and well-drained loams in full sun to partial shade. This tree needs a very large space within which to grow. It is difficult to transplant because of its deep taproot. The trees are unsuitable to commercial or orchard production due to the long time it takes for a tree to produce sizable crops and the unpredictable nut output from year to year.
Wood
The wood itself is important and versatile. Shagbark hickory is a heavy wood which burns slowly and yields the same amount of heat as coal. Besides heat, early settlers used the wood for tool handles, basket-making, barrel and bucket hoops, ladders, gun stocks, and furniture-making. Hickory wood and wood chips are often used to cure and smoke meats.
Appreciate Shagbark Hickory for its valuable wood and the nuts it provides to a vast number of forest creatures and people as well as being a long-living stately tree.
Sources
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
By Len Phillips
Shagbark Hickory
Shagbark hickory, Carya ovata, is a tall, long-living member of the walnut family that can live more than 350 years, in part because of its moderately slow-growth rate. Shagbark will grow to a height of 70 to 90 feet (20-27 m) sometimes to 120 ft. (37m) and a record of over 150 feet (48m) high. It will spread 50 to 70 feet (15-20 m) and have a trunk diameter of 2 – 3 feet (0.7 – 1 m). The shagbark hickory is considered “stately”. The trees can be found from southern Maine, across southern Quebec and Ontario to Minnesota, south along the Appalachian mountain range to Georgia and eastern Texas. It is considered a climax species in the Eastern hardwood forest.
Forty years is considered the amount of time it takes a hickory tree to reach its commercial nut-producing potential. Trees that are 200, even 300 years in age can still produce large quantities of nuts. Mast years for shagbark hickories in the forest occur every one to three years, and population spikes among the mammals who eat shagbark nuts fluctuate on the same cycle. When I was a child, I remember going through the fields and forest with my grandfather to a large hickory tree at the edge of the forest, behind our house. As I recall, every year that we went back there, the birds and animals had beaten us to the nuts, and there were very few left for us to gather.
Flowers
This tree features greenish yellow flowers that appear from April to May. The male flowers appear in pendulous catkins and the female flowers in short spikes. Female flowers give way to the edible nuts. Each nut is encased in a moderately thick husk which splits open in four sections when ripe in autumn. Cross-pollination generally produces a more abundant crop of better quality nuts.
Nuts
Shagbark hickory nuts were a significant food source for the Algonquin Indians. Native Americans relied upon shagbark hickory nuts whose meat is high in fat and protein, and low in carbohydrates. The nuts are sweet and nourishing and were also a dietary staple to all who ate them. Red and gray squirrels, raccoons, chipmunks, and mice are major consumers of hickory nuts. Other consumers include black bears, red fox, rabbits, and bird species such as mallards, wood ducks, bobwhites, and wild turkey. Migrating yellow-rumped warblers and rose-breasted grosbeaks eat the nuts that are found along the routes to their southern winter habitats. The nuts are a popular food among people and squirrels alike.
The most prodigious appetite for shagbark hickory nuts belongs to gray squirrels. In fact, the competition for nuts between early settlers and squirrels in Pennsylvania prompted a bounty in the 1700’s (three pence per dead squirrel) that brought in 640,000 carcasses and nearly bankrupted the colonial treasury. However, there were plenty of hickory nuts for the settlers for the next several years.
Growing from seed
Hickory nuts ripen in September and should be collected as soon as they drop. Remove the green husk and soak the nuts in a bucket of water overnight. Any nuts that float may be empty. Do not leave nuts sitting around at room temperature or the seeds will desiccate and lose viability. To grow shagbark hickory from seed, plant the nuts in a deep pot or cold frame, placed outdoors, and protect the nuts from rodents with wire screening. Squirrels will find your pots within a couple of hours if unprotected. The nuts will germinate in the spring after winter stratification. Trees are tap-rooted, so transplant to a permanent location before the tap-root gets too long.
Appearance
Shagbark hickory is a very shaggy-looking tree. The shagbark hickory’s bark is light gray and smooth when the tree is young. Its bark darkens with age to become charcoal color, and begins to appear shingled with long warped shreds of bark. Bark patterns are often more pronounced as a tree ages because the bark furrows deepen, ridges protrude, and exfoliation is more dramatic – all of which illustrate the dynamic process that creates tree bark. Large trees produce considerable litter through twig, bark, leaf, and nut drop.
Hickory bark harbors a forest’s worth of lichens, mosses, fungi, small vertebrates, invertebrates, and microorganisms. More than 133 fungi are associated with shagbark hickories, but there are very few that actually damage the tree seriously. Shagbark hickories also host approximately 180 species of insects and mites, but the bark's chemistry and architecture minimize their incursions. Bats and brown creepers also roost and nest beneath the shagbark’s flaking bark.
The leaves are smooth, medium yellow-green, odd-pinnate, compound leaves, with each leaf usually having 5 finely-toothed, broadly lance-shaped, pointed leaflets. The leaflets range from 3–7 in. (7–18 cm) long. The leaves turn from summer green to yellow and then golden brown in autumn.
Growth
Shagbark hickory grows best in humus soil, rich, moist, and well-drained loams in full sun to partial shade. This tree needs a very large space within which to grow. It is difficult to transplant because of its deep taproot. The trees are unsuitable to commercial or orchard production due to the long time it takes for a tree to produce sizable crops and the unpredictable nut output from year to year.
Wood
The wood itself is important and versatile. Shagbark hickory is a heavy wood which burns slowly and yields the same amount of heat as coal. Besides heat, early settlers used the wood for tool handles, basket-making, barrel and bucket hoops, ladders, gun stocks, and furniture-making. Hickory wood and wood chips are often used to cure and smoke meats.
Appreciate Shagbark Hickory for its valuable wood and the nuts it provides to a vast number of forest creatures and people as well as being a long-living stately tree.
Sources
- Missouri Botanical Garden, 'Carya ovata', Plant Finder
- Wild Seed Project, Shagbark hickory Carya ovata, January 2015
- Wikipedia, “Carya ovata”, 27 May 2017
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Critical Root Zones for Trees
By Len Phillips
Field investigation and research in the last two decades have destroyed the myth that the root system extends only to the drip line of a tree's canopy. Another commonly held myth is that all mature trees have a taproot that is the most vulnerable portion of the root system. This is also not true. Another perspective that dry climate trees have similar root systems to trees growing in climates that receive abundant rainfall during the growing season has to be re-considered. The trees growing in areas that do not receive rainfall during the growing season must have root systems that find water deep below the dry soil in the top 18 to 24 inches (50 – 60 cm) of soil profile. A tree's root system varies in width, depth, and structural characteristics with the species of tree, as well as with the soils and moisture levels. The only way to know where tree roots are growing is to find them through careful excavation or with root radar.
Critical Root Zone for Trees
A Critical Root Zone (CRZ) is the area under the tree crown where the most important roots for tree stability and survival are growing. These are the vital roots that collect nutrients and moisture for the tree, and they must be protected for the tree to survive. It is very important to determine the minimum area around the tree trunk that must be left undisturbed.
The health of the CRZ can be damaged by:
CRZ Size
Some reports indicate that the CRZ is the same as the tree's drip line. Others indicate that the CRZ will typically be represented by a concentric circle centering on the tree's trunk with a radius equal in feet to one and one-half times the number of inches of the trunk diameter. For example: The CRZ radius of a 20-inch (60 cm) diameter tree is 30 feet (10 m). However, this is unreliable because species, soils, and every site will create variable results.
The other important factor in conserving trees during construction is the design of the structure. Flat slabs covering the CRZ will cause more damage to the soil and the tree than bridged construction where a few piers are inserted into the ground and the structure rests on the piers instead of on the soil. The more soil that can be left uncovered, permeable, and un-compacted, the more groundwater infiltration, roots, and healthier soils will be retained.
CRZ Formula
In an attempt to calculate the location of a tree’s critical root zone using information such as the tree’s age, the trees condition, and the species tolerance for root disturbance, the following CRZ formula was developed:
(dbh of tree) x (distance from trunk – condition rating from Table) = radius (in feet) of CRZ
Critical Root Zone Determination for Trees with a Condition Rating of 2 – 5 (5 being best)
Distance Condition rating of
Species tolerance Tree Age from Trunk – 4 or 5 2 or 3
Good Young (<20% of life expectancy) ____________________0.5’ 0.62’
Mature (20 – 80% of life expectancy _________________0.75’ 0.94’
Over mature (>80% of life expectancy) _______________1.0’ 1.25’
Moderate Young ________________________________________0.75’ 0.94’
Mature _______________________________________ 1.0' 1.25’
Over mature ____________________________________1.25’ 1.56’
Poor Young ________________________________________1.0’ 1.25’
Mature _______________________________________ 1.25 1.56’
Over mature ____________________________________ 1.5' 1.88'
Note: For trees with a poor condition rating of 1, a determination should be made, with assistance of a qualified arborist, as to whether or not the tree can be saved or is worth investing resources into the effort.
Examples:
1) 60 year-old, 32” dbh live oak (Quercus virginiana), with a Condition Rating of 4 (good tolerance, mature age): 32 x 0.75 = 24’ CRZ radius
2) 15 year-old, 10” dbh tulip tree (Liriodendron tulipifera), with a Condition Rating of 2 (poor tolerance, young age): 10 x 1.25 = 12.5’ CRZ radius
Preferred CRZ Determinations
Relying on formulas or guesswork alone will not suffice when engineering a parking lot to the nearest inch in elevation or the nearest fraction of a foot horizontally for a sewage line. The latest research indicates that in order to successfully determine the extent of the CRZ and to build in close proximity to significant or specimen trees, it is important to have an accurate depiction of a tree's underground structure. Because nature is variable, textbook answers and ballpark formulas will never be sufficient to make decisions on tree conservation. Sample trees within representative soils and moisture levels can be tracked to determine representative root widths, depths and responses to particular site conditions. However, site investigation, combined with field experience and root radar, is the best way to determine the CRZ location. Investigative digging in conjunction with an air tool to find roots that might be within the construction zone, is another common sense approach employed by experienced urban forestry professionals.
It’s important to know all aspects about site conditions, the available space, the construction practices, and how to select a tree species that will adapt to the site environment. These need to be based on comprehensive inventories of the urban tree resources and should assess the aesthetic, social, environmental and economic functions of the urban forest. The intent is to match and grow the right tree in the right place for the right reasons.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA management credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
By Len Phillips
Field investigation and research in the last two decades have destroyed the myth that the root system extends only to the drip line of a tree's canopy. Another commonly held myth is that all mature trees have a taproot that is the most vulnerable portion of the root system. This is also not true. Another perspective that dry climate trees have similar root systems to trees growing in climates that receive abundant rainfall during the growing season has to be re-considered. The trees growing in areas that do not receive rainfall during the growing season must have root systems that find water deep below the dry soil in the top 18 to 24 inches (50 – 60 cm) of soil profile. A tree's root system varies in width, depth, and structural characteristics with the species of tree, as well as with the soils and moisture levels. The only way to know where tree roots are growing is to find them through careful excavation or with root radar.
Critical Root Zone for Trees
A Critical Root Zone (CRZ) is the area under the tree crown where the most important roots for tree stability and survival are growing. These are the vital roots that collect nutrients and moisture for the tree, and they must be protected for the tree to survive. It is very important to determine the minimum area around the tree trunk that must be left undisturbed.
The health of the CRZ can be damaged by:
- cutting roots,
- excavating soil,
- applying chemicals,
- compacting the soil,
- applying any fill material or vertical barriers in the soil that impedes the flow of water or air to the roots.
CRZ Size
Some reports indicate that the CRZ is the same as the tree's drip line. Others indicate that the CRZ will typically be represented by a concentric circle centering on the tree's trunk with a radius equal in feet to one and one-half times the number of inches of the trunk diameter. For example: The CRZ radius of a 20-inch (60 cm) diameter tree is 30 feet (10 m). However, this is unreliable because species, soils, and every site will create variable results.
The other important factor in conserving trees during construction is the design of the structure. Flat slabs covering the CRZ will cause more damage to the soil and the tree than bridged construction where a few piers are inserted into the ground and the structure rests on the piers instead of on the soil. The more soil that can be left uncovered, permeable, and un-compacted, the more groundwater infiltration, roots, and healthier soils will be retained.
CRZ Formula
In an attempt to calculate the location of a tree’s critical root zone using information such as the tree’s age, the trees condition, and the species tolerance for root disturbance, the following CRZ formula was developed:
(dbh of tree) x (distance from trunk – condition rating from Table) = radius (in feet) of CRZ
Critical Root Zone Determination for Trees with a Condition Rating of 2 – 5 (5 being best)
Distance Condition rating of
Species tolerance Tree Age from Trunk – 4 or 5 2 or 3
Good Young (<20% of life expectancy) ____________________0.5’ 0.62’
Mature (20 – 80% of life expectancy _________________0.75’ 0.94’
Over mature (>80% of life expectancy) _______________1.0’ 1.25’
Moderate Young ________________________________________0.75’ 0.94’
Mature _______________________________________ 1.0' 1.25’
Over mature ____________________________________1.25’ 1.56’
Poor Young ________________________________________1.0’ 1.25’
Mature _______________________________________ 1.25 1.56’
Over mature ____________________________________ 1.5' 1.88'
Note: For trees with a poor condition rating of 1, a determination should be made, with assistance of a qualified arborist, as to whether or not the tree can be saved or is worth investing resources into the effort.
Examples:
1) 60 year-old, 32” dbh live oak (Quercus virginiana), with a Condition Rating of 4 (good tolerance, mature age): 32 x 0.75 = 24’ CRZ radius
2) 15 year-old, 10” dbh tulip tree (Liriodendron tulipifera), with a Condition Rating of 2 (poor tolerance, young age): 10 x 1.25 = 12.5’ CRZ radius
Preferred CRZ Determinations
Relying on formulas or guesswork alone will not suffice when engineering a parking lot to the nearest inch in elevation or the nearest fraction of a foot horizontally for a sewage line. The latest research indicates that in order to successfully determine the extent of the CRZ and to build in close proximity to significant or specimen trees, it is important to have an accurate depiction of a tree's underground structure. Because nature is variable, textbook answers and ballpark formulas will never be sufficient to make decisions on tree conservation. Sample trees within representative soils and moisture levels can be tracked to determine representative root widths, depths and responses to particular site conditions. However, site investigation, combined with field experience and root radar, is the best way to determine the CRZ location. Investigative digging in conjunction with an air tool to find roots that might be within the construction zone, is another common sense approach employed by experienced urban forestry professionals.
It’s important to know all aspects about site conditions, the available space, the construction practices, and how to select a tree species that will adapt to the site environment. These need to be based on comprehensive inventories of the urban tree resources and should assess the aesthetic, social, environmental and economic functions of the urban forest. The intent is to match and grow the right tree in the right place for the right reasons.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA management credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Irrigation vs. Bioretention for Trees
By Len Phillips
Is irrigation of street trees using municipal water, the tried-and-true method and therefore the best solution for watering the city's trees? Or can the stormwater from a street be diverted to the soil around a street tree and might it be used to water the tree every time it rains? If the contaminated water from a heavily traveled street is allowed to flow through the soil containing roots of a street tree, will the water become cleaner and what impact might the contaminants have on the tree? Suppose there is a heavy rain and the soil is saturated. How long will it take before tree roots begin to show signs of rotting?
As I began my search for answers, I came across a recently completed action plan that might answer some of these questions. This action plan is from the Province of Ontario, Canada.
Ontario's Climate Ready Action Plan
Ontario’s Climate Ready Adaptation Strategy and Action Plan indicated that climate change is predicted to result in extreme flooding (but hopefully not as bad as what happened in Texas, Florida, and Puerto Rico in the summer of 2017). The extreme floods will be placing more strain on everyone's aging water, wastewater, and stormwater infrastructure. When combined with increased runoff from urbanization, the Great Lakes could also experience a strain on water quality that will likely damage the fish and wildlife habitats.
Mentioned in this action plan is the growing interest in innovative stormwater management techniques including low impact development (LID). For example, the action plan calls for distribution pipes to be installed within the LID facility to send stormwater through perforated pipes into a bioretention soil media containing the perfect soil for growing the trees planted as part of the LID. As the stormwater percolates through the soil column, the tree will use as much of the water and nutrients as it needs while the excess water and nutrients migrate to the bottom of the bioretention system. The water discharges through an under-drain connected to the city’s stormwater sewer system. This design dictates that there is no permanent water storage within the soil volume, so there will be no rotting roots and the soil volume will act as a filter to clean and cool the water. Win-Win!
Stormwater treatment and water benefits are provided for smaller rainfall events as the capacity of the system allows. Larger rain events that exceed the capacity of the bioretention system bypass the system through overflow pipes within the existing catch basins and discharge directly into the existing storm sewer system.
Usually, in most cities, stormwater is handled by drains and underground pipes instead of open land containing streams and trees. The open land can absorb most of the water during a normal rain event. However, because there are buildings and pavements in the city, stormwater management must be conducted entirely underground. The system needs to be designed to handle a 100-year rain event (5 inches or 125 mm per 24 hours).
Examples
The examples below, will illustrate projects that are similar to the Climate Ready Action Plan and are already working well under the following city streets.
City of Boise
In the past, Boise, Idaho struggled to grow trees to maturity in its urban core. The trees were typically planted in small 4ft. by 4ft. (1.2 m.) square wells. The lack of soil space in combination with extremely hot and dry summers, resulted in poor health and long-term damage to the city's trees. In addition to this, the storm drain system drained largely untreated runoff directly into Boise River through a series of large pipes that are now under-sized.
This presented a set of challenges for Boise's urban foresters, city planners, and construction companies. These diverse groups decided to join forces and form a strategic partnership to create a long-term plan for their urban forest and stormwater drainage system. The group decided to try using soil cells because they have been proven to provide conditions to grow large trees and treat rainwater on-site. To date, over 100 trees have been planted in soil cells totaling about 100,000 cubic feet of soil, which will nurture the tree's long-term growth, provide runoff reduction, and improve water quality. The design includes connecting the existing catch basins to a 4”(10 cm) perforated pipe for water distribution. The under-drain sits at the base of the soil cell system and is connected to the city storm drain system. The catch basins have not been over flowing and are performing quite well in controlling runoff. The trees are rapidly growing and the soil provides improved water quality.
Mississauga, ON
Another example of this stormwater treatment system is located on Central Parkway in Mississauga, Ontario. This system was designed like the others, however, the city conducted a study to determine the performance of the system. Findings from 2015 show a 97% average stormwater volume reduction and a 96% peak flow reduction. In addition, the system helped to replicate a natural water balance in an urban setting, contributing to erosion control, improved water quality, and protection of the natural aquatic habitat, downstream. The system minimizes infrastructure and maintenance costs while allowing runoff to filter through the soil, where it can be cleaned and cooled before re-entering the storm sewer.
Copenhagen, Denmark
The City of Copenhagen's tree planting program was designed to provide a 30% stormwater volume reduction.
In addition, the integration of urban trees into LID practices improves runoff water quality, while improving root growth and tree vitality leading to increased tree canopy cover.
Cleaning Stormwater
Many cities apply salt on their streets in winter and this salty run-off could kill the trees. Besides the benefits of soil cells described above, there are three alternatives to prevent winter groundwater damage to the trees.
Soil and trees remove pollutants and hydrocarbons from stormwater through several processes:
The best soil mix for urban tree planting is specified in items 10 and 11 in Online Seminars Specifications. The bioretention soil will slow the discharge of stormwater runoff as well as provide a soil suitable for tree and plant growth. For hydrocarbon removal, the soil blend will need a higher clay and organic content level. The organic content supports good microbial growth which supports bio-degradation of hydrocarbons and good plant growth which also supports microbial degradation and phytoremediation processes.
Stormwater can contain many contaminants that are important to consider. As far as hydrocarbons are concerned, studies are clear that green infrastructure solutions that incorporate soil and plants are very effective at treatment and removal.
Sources
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
By Len Phillips
Is irrigation of street trees using municipal water, the tried-and-true method and therefore the best solution for watering the city's trees? Or can the stormwater from a street be diverted to the soil around a street tree and might it be used to water the tree every time it rains? If the contaminated water from a heavily traveled street is allowed to flow through the soil containing roots of a street tree, will the water become cleaner and what impact might the contaminants have on the tree? Suppose there is a heavy rain and the soil is saturated. How long will it take before tree roots begin to show signs of rotting?
As I began my search for answers, I came across a recently completed action plan that might answer some of these questions. This action plan is from the Province of Ontario, Canada.
Ontario's Climate Ready Action Plan
Ontario’s Climate Ready Adaptation Strategy and Action Plan indicated that climate change is predicted to result in extreme flooding (but hopefully not as bad as what happened in Texas, Florida, and Puerto Rico in the summer of 2017). The extreme floods will be placing more strain on everyone's aging water, wastewater, and stormwater infrastructure. When combined with increased runoff from urbanization, the Great Lakes could also experience a strain on water quality that will likely damage the fish and wildlife habitats.
Mentioned in this action plan is the growing interest in innovative stormwater management techniques including low impact development (LID). For example, the action plan calls for distribution pipes to be installed within the LID facility to send stormwater through perforated pipes into a bioretention soil media containing the perfect soil for growing the trees planted as part of the LID. As the stormwater percolates through the soil column, the tree will use as much of the water and nutrients as it needs while the excess water and nutrients migrate to the bottom of the bioretention system. The water discharges through an under-drain connected to the city’s stormwater sewer system. This design dictates that there is no permanent water storage within the soil volume, so there will be no rotting roots and the soil volume will act as a filter to clean and cool the water. Win-Win!
Stormwater treatment and water benefits are provided for smaller rainfall events as the capacity of the system allows. Larger rain events that exceed the capacity of the bioretention system bypass the system through overflow pipes within the existing catch basins and discharge directly into the existing storm sewer system.
Usually, in most cities, stormwater is handled by drains and underground pipes instead of open land containing streams and trees. The open land can absorb most of the water during a normal rain event. However, because there are buildings and pavements in the city, stormwater management must be conducted entirely underground. The system needs to be designed to handle a 100-year rain event (5 inches or 125 mm per 24 hours).
Examples
The examples below, will illustrate projects that are similar to the Climate Ready Action Plan and are already working well under the following city streets.
City of Boise
In the past, Boise, Idaho struggled to grow trees to maturity in its urban core. The trees were typically planted in small 4ft. by 4ft. (1.2 m.) square wells. The lack of soil space in combination with extremely hot and dry summers, resulted in poor health and long-term damage to the city's trees. In addition to this, the storm drain system drained largely untreated runoff directly into Boise River through a series of large pipes that are now under-sized.
This presented a set of challenges for Boise's urban foresters, city planners, and construction companies. These diverse groups decided to join forces and form a strategic partnership to create a long-term plan for their urban forest and stormwater drainage system. The group decided to try using soil cells because they have been proven to provide conditions to grow large trees and treat rainwater on-site. To date, over 100 trees have been planted in soil cells totaling about 100,000 cubic feet of soil, which will nurture the tree's long-term growth, provide runoff reduction, and improve water quality. The design includes connecting the existing catch basins to a 4”(10 cm) perforated pipe for water distribution. The under-drain sits at the base of the soil cell system and is connected to the city storm drain system. The catch basins have not been over flowing and are performing quite well in controlling runoff. The trees are rapidly growing and the soil provides improved water quality.
Mississauga, ON
Another example of this stormwater treatment system is located on Central Parkway in Mississauga, Ontario. This system was designed like the others, however, the city conducted a study to determine the performance of the system. Findings from 2015 show a 97% average stormwater volume reduction and a 96% peak flow reduction. In addition, the system helped to replicate a natural water balance in an urban setting, contributing to erosion control, improved water quality, and protection of the natural aquatic habitat, downstream. The system minimizes infrastructure and maintenance costs while allowing runoff to filter through the soil, where it can be cleaned and cooled before re-entering the storm sewer.
Copenhagen, Denmark
The City of Copenhagen's tree planting program was designed to provide a 30% stormwater volume reduction.
In addition, the integration of urban trees into LID practices improves runoff water quality, while improving root growth and tree vitality leading to increased tree canopy cover.
Cleaning Stormwater
Many cities apply salt on their streets in winter and this salty run-off could kill the trees. Besides the benefits of soil cells described above, there are three alternatives to prevent winter groundwater damage to the trees.
- Switch to calcium chloride, calcium magnesium acetate, magnesium chloride or beet juice instead of sodium chloride to treat roads in winter. It costs more but you use less product and it is better for the trees and the urban environment in addition to preventing corrosion of concrete structures.
- For more highly trafficked and treated retail streets the city should assist the spring rains to flush the system of sodium chloride before the trees start new growth every spring.
- Design a winter by-pass into the drainage system to close off the stormwater in-take to the trees, during winter.
Soil and trees remove pollutants and hydrocarbons from stormwater through several processes:
- Sedimentation is slowing water flow so the contaminates will settle to the bottom and clean water is available at the surface level.
- Filtration is the physical removal of solid contaminates when stormwater passes through the soil.
- Adsorption is the attachment of contaminate ions to the surface of clay and organic particles in soil, locking them in place.
- Microbial degradation is the breakdown of contaminates by microorganisms in the soil.
- Phytoremediation is tree uptake of solid contaminates via bio-degradation in the tree root rhizosphere.
The best soil mix for urban tree planting is specified in items 10 and 11 in Online Seminars Specifications. The bioretention soil will slow the discharge of stormwater runoff as well as provide a soil suitable for tree and plant growth. For hydrocarbon removal, the soil blend will need a higher clay and organic content level. The organic content supports good microbial growth which supports bio-degradation of hydrocarbons and good plant growth which also supports microbial degradation and phytoremediation processes.
Stormwater can contain many contaminants that are important to consider. As far as hydrocarbons are concerned, studies are clear that green infrastructure solutions that incorporate soil and plants are very effective at treatment and removal.
Sources
- Special thanks to Deeproot staff members for providing several examples of projects that dealt with stormwater retention systems.
- Buchanan, Patty, ”Treating Hydrocarbons with Green Infrastructure”, Deeproot, August 28, 2017.
- Credit Valley Conservation, “Central Parkway – Low Impact Development Infrastructure, Performance and Risk Assessment”, May 2016
- Gooden, Ben, “Tree Valuation”, Online Seminar #77.
- Ontario's “Climate Ready Action Plan”, cited above.
- Personal communication from Martin Theill Johansen
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.