Seminar #68 from Online Seminars for Municipal Arborists – May / June 2016
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Case Study
Do Soil Cells Work?
By John Atkins and edited by Len Phillips
This report documents the root patterns of trees growing in soil cells. Two 4-year old trees were excavated to examine the extent of root growth within a soil cell system and determine how roots interacted within the cells.
The inspection of two Hill’s Weeping Figs (Ficus microcarpa var. ‘Hillii’) took place in December 2015 at Singleton, New South Wales, Australia. The fig trees had been planted in engineered soil cell tree vaults in August 2011. The overall vigor and health of the trees was excellent.
Original Site Conditions
The original site soil was assessed as a sandy clay loam that had been considerably modified during the construction of a building on the site. The normal definitions of a topsoil and sub-soil were not clearly defined. The existing soil was noticeably dry to a depth of 5 feet (1.5 metres). Large and strongly bonded soil peds (soil peds are natural, relatively permanent aggregates, separated from each other by voids or natural surfaces of weakness) were noticeable throughout the soil profile. The existing soil had excellent water holding capacity, reasonable macro and micro-pore spaces, and strong chemical and physical bonds between soil particles.
On a larger scale, the site has an average annual rainfall of 24 inches (645 mm) with slight seasonal variations. The climate of the region is temperate, with hot summers and cool winters. Frost may occur from June to September and temperatures can regularly exceed 100°F (40°C) for several days from December to March. The highest recorded temperature was 112°F (45.9°C) in 2014.
Apart from the fig trees planted in close proximity to each other, the only other vegetation near the trees is Kikuyu turf with some weeds. Supplementary irrigation is present and was used initially to establish the trees during the hot summer months.
Planting Method
When the trees were planted in 2011, the soil was excavated to a depth of 4.4 feet (1.3 m). A 4 inch (100 mm) deep layer of gravel was installed at the bottom of the planting pit below the soil cells. Then the soil cells were installed and backfilled with a sandy loam soil blend. Porous piping was installed within the soil cells at a depth of approximately 20 inches (500 mm) below the final surface. An air vent system was installed within the planting zone. Next, a root barrier, geotextile fabric, and 1-½ inches (30 mm) of gravel were placed over the soil cells. The trees were planted, a tree grate was placed over the planted tree root balls, and the concrete surface was installed to complete the project.
Excavation Method
In December 2015, two trees were removed. First, a trench was dug around the tree vault zone to permit access to a depth of 5 feet (1.5 m) and then the tree canopy was removed. This was followed by the removal of the tree grate and the root barrier. Excavation of the gravel layer down to the soil cells was finished with air excavation of soil around the root zone and first layer of soil cells. No surface roots were observed. A photo of the roots and air vent system illustrates how well the tree grew.
As the removal of soil cells proceeded, the first insight into the patterns of root growth in the cells was revealed. In some cases, the soil cells had to be cut away as roots had penetrated the cells. Air excavation around the remaining roots and soil cells for next two layers clearly showed the downward initial root growth caused by the root barrier. The diameter and large number of roots present was observed, as well as the deep penetration of roots that had grown to a depth of 27 inches (700 mm) and then they spread through the soil cell voids in a linear fashion. The roots grew in all directions within the tree vault and were not limited in their spread by the soil cell system.
One unexpected observation was that the majority of root development was just above the porous pipes while the remaining roots grew at 90 degrees below the root barriers. The proliferation of roots about the porous piping was likely due to good gaseous exchange and water availability. The pipe itself may have caused a perched water table effect in the growing media just above the well aerated zone. It is possible that the water available to the roots in this zone was present longer than in the free draining soil. This combined with good gas exchange allowed the roots to proliferate in this area. Most lateral spreading roots were present at a depth of 24 – 28 inches (600 – 700 mm) or deeper. A few lateral roots were found at a depth exceeding 6 feet (1.8 metres) and had a spread exceeding 12 feet (4 metres) in all directions. Roots of 2 inches (45 mm) in diameter were observed at 12 feet (3.7 m) from the trunk. These roots had developed to this spread and thickness in only 4 years.
The development of roots within the soil cell was more common at the top of a cell than in the middle or bottom. It is likely that the flat surface of the top of each cell acted as some type of perched water table. The typical pattern of early root growth followed the top of the cells and expanded upwards into the less rigid voids within the next layer. Small openings within the cells frequently had roots growing through them. The constriction of roots at these points did not appear to reduce root growth and increased root diameter on either side of the cells was common.
Roots were able to grow well beyond the soil cell and into the surrounding site soil. The roots grew in an initial descending pattern, then continued horizontally at the same level until they penetrated the site soil. Typically, roots were found between 1 and 3 feet (300 and 900 mm) below the soil surface at the edge of the soil cell.
When roots reached the interface between the blended soil in the soil cell vault and the site soil, they rarely deflected in direction or angle. Roots were observed to grow directly into voids at the same depth and in the same direction as they were growing in the soil cell vault.
The excavator operator described the roots present in the tree vaults as “stronger” and more resistant to mechanical forces. This anecdotal statement was reinforced by the amount of difficulty he had in completely excavating the root system of the tree. He experienced fig roots in other locations to be more brittle.
Observations
The Hills Weeping Fig has been routinely observed at other locations to develop broad spreading roots at or just below the soil surface as they mature. This lateral surface root development is known to cause significant problems with pavements and hard surfaces. Here however, the root director system placed about the newly planted tree was found to direct roots in a downward pattern, minimizing the escape of surface roots.
The soil cell system combined with the use of the fabric membrane and gravel layer at the surface also limited the colonization of roots in the uppermost one foot (300 mm) of the soil. Damage to pavements and surfaces would likely be minimized in other locations using this construction method.
The mulching effect of the gravel layer and fabric membrane should be considered. Mulches are recognized for reducing moisture loss by evaporation and improving overall soil moisture content. In the trees that were excavated, the lateral spread and depth of most roots below the fabric membrane was similar to that previously observed in trees with an organic mulch layer.
The depth of root growth within the soil cell system was surprising. It is not typical of Hill’s Figs to develop roots to a depth of 5 feet (1.5 metres) in heavy clay soils, though it has been observed that they will develop roots at this depth in sands and sandy loams. The cell system encourages roots to develop at deeper levels improving root vault occupancy. The development of tree roots at lower depths is likely to improve tree stability and the overall resistance to wind throw.
Follow-up
As a result of the excavation, confirmation that improvements that were made to Citygreen's Stratacells in the subsequent generation of Stratacell manufacture were significant. Stratavault is the next generation from Stratacell. The excavation process also pointed out that the aeration pipes should be installed at deeper levels. This change will be made in all future installations.
References
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 .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.
Case Study
Do Soil Cells Work?
By John Atkins and edited by Len Phillips
This report documents the root patterns of trees growing in soil cells. Two 4-year old trees were excavated to examine the extent of root growth within a soil cell system and determine how roots interacted within the cells.
The inspection of two Hill’s Weeping Figs (Ficus microcarpa var. ‘Hillii’) took place in December 2015 at Singleton, New South Wales, Australia. The fig trees had been planted in engineered soil cell tree vaults in August 2011. The overall vigor and health of the trees was excellent.
Original Site Conditions
The original site soil was assessed as a sandy clay loam that had been considerably modified during the construction of a building on the site. The normal definitions of a topsoil and sub-soil were not clearly defined. The existing soil was noticeably dry to a depth of 5 feet (1.5 metres). Large and strongly bonded soil peds (soil peds are natural, relatively permanent aggregates, separated from each other by voids or natural surfaces of weakness) were noticeable throughout the soil profile. The existing soil had excellent water holding capacity, reasonable macro and micro-pore spaces, and strong chemical and physical bonds between soil particles.
On a larger scale, the site has an average annual rainfall of 24 inches (645 mm) with slight seasonal variations. The climate of the region is temperate, with hot summers and cool winters. Frost may occur from June to September and temperatures can regularly exceed 100°F (40°C) for several days from December to March. The highest recorded temperature was 112°F (45.9°C) in 2014.
Apart from the fig trees planted in close proximity to each other, the only other vegetation near the trees is Kikuyu turf with some weeds. Supplementary irrigation is present and was used initially to establish the trees during the hot summer months.
Planting Method
When the trees were planted in 2011, the soil was excavated to a depth of 4.4 feet (1.3 m). A 4 inch (100 mm) deep layer of gravel was installed at the bottom of the planting pit below the soil cells. Then the soil cells were installed and backfilled with a sandy loam soil blend. Porous piping was installed within the soil cells at a depth of approximately 20 inches (500 mm) below the final surface. An air vent system was installed within the planting zone. Next, a root barrier, geotextile fabric, and 1-½ inches (30 mm) of gravel were placed over the soil cells. The trees were planted, a tree grate was placed over the planted tree root balls, and the concrete surface was installed to complete the project.
Excavation Method
In December 2015, two trees were removed. First, a trench was dug around the tree vault zone to permit access to a depth of 5 feet (1.5 m) and then the tree canopy was removed. This was followed by the removal of the tree grate and the root barrier. Excavation of the gravel layer down to the soil cells was finished with air excavation of soil around the root zone and first layer of soil cells. No surface roots were observed. A photo of the roots and air vent system illustrates how well the tree grew.
As the removal of soil cells proceeded, the first insight into the patterns of root growth in the cells was revealed. In some cases, the soil cells had to be cut away as roots had penetrated the cells. Air excavation around the remaining roots and soil cells for next two layers clearly showed the downward initial root growth caused by the root barrier. The diameter and large number of roots present was observed, as well as the deep penetration of roots that had grown to a depth of 27 inches (700 mm) and then they spread through the soil cell voids in a linear fashion. The roots grew in all directions within the tree vault and were not limited in their spread by the soil cell system.
One unexpected observation was that the majority of root development was just above the porous pipes while the remaining roots grew at 90 degrees below the root barriers. The proliferation of roots about the porous piping was likely due to good gaseous exchange and water availability. The pipe itself may have caused a perched water table effect in the growing media just above the well aerated zone. It is possible that the water available to the roots in this zone was present longer than in the free draining soil. This combined with good gas exchange allowed the roots to proliferate in this area. Most lateral spreading roots were present at a depth of 24 – 28 inches (600 – 700 mm) or deeper. A few lateral roots were found at a depth exceeding 6 feet (1.8 metres) and had a spread exceeding 12 feet (4 metres) in all directions. Roots of 2 inches (45 mm) in diameter were observed at 12 feet (3.7 m) from the trunk. These roots had developed to this spread and thickness in only 4 years.
The development of roots within the soil cell was more common at the top of a cell than in the middle or bottom. It is likely that the flat surface of the top of each cell acted as some type of perched water table. The typical pattern of early root growth followed the top of the cells and expanded upwards into the less rigid voids within the next layer. Small openings within the cells frequently had roots growing through them. The constriction of roots at these points did not appear to reduce root growth and increased root diameter on either side of the cells was common.
Roots were able to grow well beyond the soil cell and into the surrounding site soil. The roots grew in an initial descending pattern, then continued horizontally at the same level until they penetrated the site soil. Typically, roots were found between 1 and 3 feet (300 and 900 mm) below the soil surface at the edge of the soil cell.
When roots reached the interface between the blended soil in the soil cell vault and the site soil, they rarely deflected in direction or angle. Roots were observed to grow directly into voids at the same depth and in the same direction as they were growing in the soil cell vault.
The excavator operator described the roots present in the tree vaults as “stronger” and more resistant to mechanical forces. This anecdotal statement was reinforced by the amount of difficulty he had in completely excavating the root system of the tree. He experienced fig roots in other locations to be more brittle.
Observations
The Hills Weeping Fig has been routinely observed at other locations to develop broad spreading roots at or just below the soil surface as they mature. This lateral surface root development is known to cause significant problems with pavements and hard surfaces. Here however, the root director system placed about the newly planted tree was found to direct roots in a downward pattern, minimizing the escape of surface roots.
The soil cell system combined with the use of the fabric membrane and gravel layer at the surface also limited the colonization of roots in the uppermost one foot (300 mm) of the soil. Damage to pavements and surfaces would likely be minimized in other locations using this construction method.
The mulching effect of the gravel layer and fabric membrane should be considered. Mulches are recognized for reducing moisture loss by evaporation and improving overall soil moisture content. In the trees that were excavated, the lateral spread and depth of most roots below the fabric membrane was similar to that previously observed in trees with an organic mulch layer.
The depth of root growth within the soil cell system was surprising. It is not typical of Hill’s Figs to develop roots to a depth of 5 feet (1.5 metres) in heavy clay soils, though it has been observed that they will develop roots at this depth in sands and sandy loams. The cell system encourages roots to develop at deeper levels improving root vault occupancy. The development of tree roots at lower depths is likely to improve tree stability and the overall resistance to wind throw.
Follow-up
As a result of the excavation, confirmation that improvements that were made to Citygreen's Stratacells in the subsequent generation of Stratacell manufacture were significant. Stratavault is the next generation from Stratacell. The excavation process also pointed out that the aeration pipes should be installed at deeper levels. This change will be made in all future installations.
References
- Coder, K., “Root Growth Control: Managing Perceptions and Realities” pp 51 – 82 from “The Landscape Below Ground II: Proceedings of a Second International Workshop on Tree Root Development in Urban Soils”, International Society of Arboriculture, Champaign, IL USA. 1998.
- Percival, G.C. & C. N. Sheriffs, “Identification of drought tolerant woody perennials using chlorophyll fluorescence”, Journal of Arboriculture, International Society of Arboriculture IL USA, 2002.
- Kelsey, P., “Soil mixes for Urban Sites” The Landscape Below Ground II: Proceedings of a Second International Workshop on Tree Root Development in Urban Soils, International Society of Arboriculture, Champaign, IL USA. pp 154 – 165, 1998.
- Maxwell, K. & Johnson, G. N, “Chlorophyll fluorescence – a practical guide” Journal of Experimental Botany, Vol 51, No. 345, pp 659 668. 2000.
- Percival, G. C.,“Workshop on Chlorophyll fluorescence – notes” Bartlett Tree Research Company, Reading UK, 2005.
Sources
- Atkins, John, “Roots in Citygreen Stratacells® An evaluation of root growth patterns”, Treeology, 2015.
- Citygreen StrataCells
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 .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.
Veteran Tree Management
Edited by Len Phillips
Veteran trees are those that have reached a mature size and have started the last phase of life on this planet. This final process includes the tree shedding larger limbs, developing cavities, and become shorter and wider. Trees in this process must economize their energy allocation and fluid transport distances. This decline or retrenchment allows the tree to continue living for many more years.
Stages of Tree Growth
Youth – A tree's self-management begins in the early stages when most of the energy produced by a tree is used for growth. There is a rapid increase in size as the crown and leaf area grows from a seedling to a fully mature tree.
Middle Age – When the optimum crown size is reached, the amount of food produced from the leaves remains much the same each year and results in a more or less constant volume of wood being generated throughout the tree. However, as the tree trunk increases in diameter, the constant volume of wood is spread thinner and the rings in the trunk decline in width.
Ancient – The final stage is reached when the successive increments added to the tree, seen as the rings of wood, have an increasing cross-sectional area, but with thinner space between growth rings and probably irregular gaps where no growth may occur. The crown dies back and branches may be lost. Damage and decay also reduce productivity of the tree’s functions. The result is that as the leaf area declines, less new photosynthetic material is produced and the tree is less able to maintain a complete cover of woody material over the trunk. However, as it declines the tree expands its function of biodiversity through retrenchment.
Retrenchment
The late ancient stage is also called retrenchment, which is where a tree sheds parts and restructures itself. This does not mean that the tree is about to die, but it is a condition that can last for many decades or even centuries. Retrenchment is brought on by drought, disease, insect damage, root disturbance, or pollution. The response from the tree results in a new balance between the area of woody material and that of the leaves. A tree in the last phase of its life that has retrenched can be very healthy and vigorous despite extensive decay and dieback. This stage may be also be the longest stage in the life of the tree. The ancient stage can be further subdivided into three phases.
Tree species vary in the proportion of time they spend in each of these retrenchment phases. All the phases are a continuous process and of variable length.
Other Aspects of the Ancient Stage
Veteran trees that are retrenching tend to show a diminished growth rate and a drop in reproductive output. They are also slower to cover over wounds if damaged. They tend to develop other features and characteristics to a greater extent than younger trees such as cavities in the trunk, seepage, dead loose bark, dead wood in the canopy and physical damage. One important point to note is that, as the tree ages it becomes more valuable for a wide range of other organisms and its habitat value increases.
A normal tree reaches the veteran stage when the size of the crown is not large enough to produce enough food to maintain the same cross-sectional area for each annual ring. During the process of retrenchment the photosynthetic area is reduced, as does the surface area of the woody branches, so that less food is required by the tree. Reducing the size of the crown at intervals delays the veteran stage in a tree’s life when the demand for water and nutrients outstrips its ability to increase the root area to absorb them. A reduced crown also reduces the risk of wind throw, owing to the relatively lower stature because of shorter branch lengths and a smaller wind sail area of leaves.
Wounds to the tree result in the drying out of an area of wood, causing decay. The larger the amount of wounding such as found on an old tree with all branches removed, will result in more drying out and dieback. This will increase the chance of infection by micro-organisms. The ability of the tree to compartmentalize will be reduced because of its severely reduced photosynthetic area. It seems that few trees are able to cope with this situation. If some branches are retained on the tree, the amount of exposure, drying out, and infection by micro-organisms is decreased. However, these areas will be restricted to strips of xylem and phloem associated with the cut branches. For this reason, and to keep the sap wood active, it is best to retain good connections of xylem and phloem throughout the tree, thus maintaining channels of living tissue between the roots and shoots. In some old trees that have been cut back heavily on one side, this connection has been broken and the tree has died back completely thus resulting in a lop-sided tree.
The process of decay in wood is a complex subject and the details are only just starting to be understood. There are many different agents involved which make it very difficult to establish the relative importance of each. What is clear however, is that fungi have a fundamental role in the process.
It is thought that the sapwood of a healthy tree has such a high moisture content that it is unsuitable for the growth of most fungi. However, when the tree is mechanically damaged or is stressed in some way, parts of it may become more suitable for fungal growth. The loss of a branch, for example, allows air in and causes drying out of the wood around the wound and this enables fungal growth. Stress brought on by drought or the severing of roots may cause the tree to stop photosynthesizing from a branch. This branch then dies back and dries out because the flow of sap is no longer there. The drier conditions activate some of the latent fungi or fungi entering via the dead or broken wood. Most of the fungi capable of causing extensive decay depend on wounds or dead branches or roots as entry points. Some of these fungi species grow only in heartwood, while others are confined to sapwood or are able to colonize in any location. A wide range of factors determine whether or not decay becomes extensive enough to weaken the tree significantly. Some pathogenic fungal species and vascular diseases are able to cause death or dysfunction to parts of the tree even without stress or major injury. This minority of species are a primary cause of dysfunction in the sapwood or of death of the cambium.
As the fruiting bodies of the fungi are the only parts that are usually noticed they are often misinterpreted. A small number of species can cause the death of a tree but a much larger number produce fruiting bodies only when the tree (or that part of it with fungal fruiting bodies) has died from other causes (i.e. they are saprophytic). This leads to many misconceptions as to the role of fungi.
We need to secure the long term future of these veterans by promoting best management and conservation practices. We also need to lobby governments to recognize and protect these trees and encourage research to show people how to enjoy old trees.
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 .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
Veteran trees are those that have reached a mature size and have started the last phase of life on this planet. This final process includes the tree shedding larger limbs, developing cavities, and become shorter and wider. Trees in this process must economize their energy allocation and fluid transport distances. This decline or retrenchment allows the tree to continue living for many more years.
Stages of Tree Growth
Youth – A tree's self-management begins in the early stages when most of the energy produced by a tree is used for growth. There is a rapid increase in size as the crown and leaf area grows from a seedling to a fully mature tree.
Middle Age – When the optimum crown size is reached, the amount of food produced from the leaves remains much the same each year and results in a more or less constant volume of wood being generated throughout the tree. However, as the tree trunk increases in diameter, the constant volume of wood is spread thinner and the rings in the trunk decline in width.
Ancient – The final stage is reached when the successive increments added to the tree, seen as the rings of wood, have an increasing cross-sectional area, but with thinner space between growth rings and probably irregular gaps where no growth may occur. The crown dies back and branches may be lost. Damage and decay also reduce productivity of the tree’s functions. The result is that as the leaf area declines, less new photosynthetic material is produced and the tree is less able to maintain a complete cover of woody material over the trunk. However, as it declines the tree expands its function of biodiversity through retrenchment.
Retrenchment
The late ancient stage is also called retrenchment, which is where a tree sheds parts and restructures itself. This does not mean that the tree is about to die, but it is a condition that can last for many decades or even centuries. Retrenchment is brought on by drought, disease, insect damage, root disturbance, or pollution. The response from the tree results in a new balance between the area of woody material and that of the leaves. A tree in the last phase of its life that has retrenched can be very healthy and vigorous despite extensive decay and dieback. This stage may be also be the longest stage in the life of the tree. The ancient stage can be further subdivided into three phases.
- Early ancient – Occurs over a period of years when the amount of dieback exceeds growth.
- Mid-ancient – When the annual rings cannot form all the way round the stem because of discontinuities. Once a tree has reached the mid-ancient stage, nothing should be done to encourage the speeding up of the aging process and the focus should be to keep it in this phase for as long as possible.
- Senescent – The terminal decline of the tree, leading to death.
Tree species vary in the proportion of time they spend in each of these retrenchment phases. All the phases are a continuous process and of variable length.
Other Aspects of the Ancient Stage
Veteran trees that are retrenching tend to show a diminished growth rate and a drop in reproductive output. They are also slower to cover over wounds if damaged. They tend to develop other features and characteristics to a greater extent than younger trees such as cavities in the trunk, seepage, dead loose bark, dead wood in the canopy and physical damage. One important point to note is that, as the tree ages it becomes more valuable for a wide range of other organisms and its habitat value increases.
A normal tree reaches the veteran stage when the size of the crown is not large enough to produce enough food to maintain the same cross-sectional area for each annual ring. During the process of retrenchment the photosynthetic area is reduced, as does the surface area of the woody branches, so that less food is required by the tree. Reducing the size of the crown at intervals delays the veteran stage in a tree’s life when the demand for water and nutrients outstrips its ability to increase the root area to absorb them. A reduced crown also reduces the risk of wind throw, owing to the relatively lower stature because of shorter branch lengths and a smaller wind sail area of leaves.
Wounds to the tree result in the drying out of an area of wood, causing decay. The larger the amount of wounding such as found on an old tree with all branches removed, will result in more drying out and dieback. This will increase the chance of infection by micro-organisms. The ability of the tree to compartmentalize will be reduced because of its severely reduced photosynthetic area. It seems that few trees are able to cope with this situation. If some branches are retained on the tree, the amount of exposure, drying out, and infection by micro-organisms is decreased. However, these areas will be restricted to strips of xylem and phloem associated with the cut branches. For this reason, and to keep the sap wood active, it is best to retain good connections of xylem and phloem throughout the tree, thus maintaining channels of living tissue between the roots and shoots. In some old trees that have been cut back heavily on one side, this connection has been broken and the tree has died back completely thus resulting in a lop-sided tree.
The process of decay in wood is a complex subject and the details are only just starting to be understood. There are many different agents involved which make it very difficult to establish the relative importance of each. What is clear however, is that fungi have a fundamental role in the process.
It is thought that the sapwood of a healthy tree has such a high moisture content that it is unsuitable for the growth of most fungi. However, when the tree is mechanically damaged or is stressed in some way, parts of it may become more suitable for fungal growth. The loss of a branch, for example, allows air in and causes drying out of the wood around the wound and this enables fungal growth. Stress brought on by drought or the severing of roots may cause the tree to stop photosynthesizing from a branch. This branch then dies back and dries out because the flow of sap is no longer there. The drier conditions activate some of the latent fungi or fungi entering via the dead or broken wood. Most of the fungi capable of causing extensive decay depend on wounds or dead branches or roots as entry points. Some of these fungi species grow only in heartwood, while others are confined to sapwood or are able to colonize in any location. A wide range of factors determine whether or not decay becomes extensive enough to weaken the tree significantly. Some pathogenic fungal species and vascular diseases are able to cause death or dysfunction to parts of the tree even without stress or major injury. This minority of species are a primary cause of dysfunction in the sapwood or of death of the cambium.
As the fruiting bodies of the fungi are the only parts that are usually noticed they are often misinterpreted. A small number of species can cause the death of a tree but a much larger number produce fruiting bodies only when the tree (or that part of it with fungal fruiting bodies) has died from other causes (i.e. they are saprophytic). This leads to many misconceptions as to the role of fungi.
We need to secure the long term future of these veterans by promoting best management and conservation practices. We also need to lobby governments to recognize and protect these trees and encourage research to show people how to enjoy old trees.
Source
- Government of the United Kingdom, “Veteran Trees: A guide to good management” (IN13), February, 2000.
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 .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.
Tree of the Seminar
By Len Phillips
Prairifire Crabapple is a tree with a round form that is well suited for urban sites and growing under the utility wires. It has good disease resistance, and leaves that turn maroon in spring to dark green in summer and bronze in autumn. Its' persistent maroon fruits provide food for wildlife all winter long.
Trade Name: Prairifire Crabapple
Botanical Name: Malus `Prairifire'
Family: Rosaceae
Parentage: Selection made in Illinois in 1982, now being replaced with newer cultivars
Height: 15'- 20'
Spread: 20'- 25'
Form: Wide and upright shape becoming rounded
Bloom Period: With bud break, late April – early May in most climates
Flower: Red buds, 1½" deep pink flowers, long lasting bloom
Fruit: Round, maroon, ½" diameter, abundant, persistent through winter, but eaten by winter
birds and robins in spring
Foliage: Glossy maroon in spring, red to dark green in summer, bronze in autumn
Bark: Reddish brown bark is attractive in winter, resembles cherry bark with prominent
lenticels
Habitat: Does very well throughout the U.S.
Hardiness Zone: 4 - 8
Site Requirements: Well drained soil, full sun, acid soil
Growth Rate: Vigorous, densely branched, full size in 30 years
Pest Problems: Very tolerant of most diseases and resistant to scab, mildew, and fireblight
Storm Resistance: Average for the species
Salt Tolerance: Average for the species
Planting: Transplants easily, select trees grown on own roots to avoid suckers, fibrous roots allow any transplanting technique, including bare root, in spring only, suitable for CU-Structural Soil planting
Pruning: Prune broken and dead branches at planting and 3 years later to mature form
Propagating: Budding, grafting, softwood cuttings
Design Uses: Excellent in parks, residential areas, golf courses, and commercial areas, use in wide planting area as it tends to be low branched
Companions: Use with ground covers such as Sedum, Ajuga, Galium, and Chrysoganum
Other Comments: One of the best red leafed crabapples, suckers occur from budded grafts, its popularity is declining in favor of newer clones.
Photo
Sources
This information has been gathered from personal observations of the author, living in Massachusetts, Zone 6 with a Prairifire Crab growing in his yard and information provided by 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, Tree Worker Specialist, Aerial Lift 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
Prairifire Crabapple is a tree with a round form that is well suited for urban sites and growing under the utility wires. It has good disease resistance, and leaves that turn maroon in spring to dark green in summer and bronze in autumn. Its' persistent maroon fruits provide food for wildlife all winter long.
Trade Name: Prairifire Crabapple
Botanical Name: Malus `Prairifire'
Family: Rosaceae
Parentage: Selection made in Illinois in 1982, now being replaced with newer cultivars
Height: 15'- 20'
Spread: 20'- 25'
Form: Wide and upright shape becoming rounded
Bloom Period: With bud break, late April – early May in most climates
Flower: Red buds, 1½" deep pink flowers, long lasting bloom
Fruit: Round, maroon, ½" diameter, abundant, persistent through winter, but eaten by winter
birds and robins in spring
Foliage: Glossy maroon in spring, red to dark green in summer, bronze in autumn
Bark: Reddish brown bark is attractive in winter, resembles cherry bark with prominent
lenticels
Habitat: Does very well throughout the U.S.
Hardiness Zone: 4 - 8
Site Requirements: Well drained soil, full sun, acid soil
Growth Rate: Vigorous, densely branched, full size in 30 years
Pest Problems: Very tolerant of most diseases and resistant to scab, mildew, and fireblight
Storm Resistance: Average for the species
Salt Tolerance: Average for the species
Planting: Transplants easily, select trees grown on own roots to avoid suckers, fibrous roots allow any transplanting technique, including bare root, in spring only, suitable for CU-Structural Soil planting
Pruning: Prune broken and dead branches at planting and 3 years later to mature form
Propagating: Budding, grafting, softwood cuttings
Design Uses: Excellent in parks, residential areas, golf courses, and commercial areas, use in wide planting area as it tends to be low branched
Companions: Use with ground covers such as Sedum, Ajuga, Galium, and Chrysoganum
Other Comments: One of the best red leafed crabapples, suckers occur from budded grafts, its popularity is declining in favor of newer clones.
Photo
Sources
This information has been gathered from personal observations of the author, living in Massachusetts, Zone 6 with a Prairifire Crab growing in his yard and information provided by 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, Tree Worker Specialist, Aerial Lift 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.
Green Spaces are at Risk in Serbia
By Natasa Spica
Urban plans define the purpose of parcels in any populated area. Between the blocks of housing and urban uses, there are street parcels and their boundaries. Within the street parcels are streets, sidewalks, the infrastructure, and a green bar also called nature strip, utility strip, or tree lawn in most cities. Sidewalks and roads have a clearly defined and unchanging width in Serbian cities and can be considered as "constants".
However the green bar, must be cut into smaller pieces for parking, vehicular access to buildings and for other reasons. The green bar also contains underground and overhead utilities as well as billboards, manholes, transformer stations, and other infrastructure. Often during the construction of streets, the green areas are replaced with garden cafes, newspaper boxes, and many other facilities, including an increase in the number of parking spaces. However, in Pančevo, Serbia, the construction of new parking lots is often without the consent of the authorities during the licensing and construction of development projects.
The sidewalks and roads can not be reduced in width; they can only increase. These changes are mostly related to improving the flow and movement of users. Each new project results in a reduction of the green bar. The green bars are unprotected and may not exist as excess free space, because their priority is to contain infrastructure. Thus, its purpose is subordinate to providing green areas and sidewalks for the pedestrians. Furthermore, the route of the underground infrastructure is easier to install and maintain if they are in the soil, and not under the sidewalks or roads.
Often a new development project does not have a green bar. The reason is to save money. When reconstruction occurs, a decrease in the area of lawn also occurs. The reason is that the priorities are for wider streets, wider sidewalks, more parking, new facilities, and new infrastructure, not for more green.
The original plans for the city show a Green Line that everyone understood was to be a one meter (3 ft.) wide parcel for the green bar. If re-parcellation was done on 2 or 3 parcels; one parcel for road and 1 or 2 parcels for green space with a sidewalk, the parcel for green bar is the one that would be protected. But, the standards for greenery were not well-founded and defined in detail. Furthermore the green bars are viewed more as a timber and grasslands strip that are not necessary in the city. Because of this, the green bars are considered optional for all except for biologists, ecologists, and those engaged in maintenance. The green bars are not viewed as part of a large system for the flow of clean, moist air throughout the city. Unfortunately trees and lawns are considered a nuisance, not a necessity nor an integral part of the environment.
Proposed Reparcellation Plan
A proposed reparcellation plan in Pančevo will require that any changes on the parcel "roads" would have to include the parcel called the "green area". Furthermore, none of the new infrastructure would be able to pass through the green area. This requirement would be under the supervision of the appropriate designer or landscape architect, designated by a competent institution that deals with the maintenance of green areas. In the event that there is no room for new infrastructure (under and above ground), it would not be able to pass through green area, so another solution must be found. Urban planners will probably disagree with the given solution, because construction will cost more, planners from other professions will have limits and everyone will need to adjust to these changes.
A new law that would better protect the green areas has not been adopted, so the green bar has become considered more of a popular political topic. At the present time, reparcellation is the only way to immediately and permanently protect this small piece of green landscape on the street. The priorities of the city are known and they must be fulfilled with clear and accurately defined changes in the green spaces.
A recent project of reconstruction for one street completely abolished more than 150 meters of green areas on both sides of the road. Parking was done without leaving even one opening in the parking lot in order to plant a new tree. The conflict arose after the trees were removed, and the positions that were defined in the old project were eliminated completely. Thus it is impossible to determine the actual area of this green belt that was lost.
Cadastre
A new greening plan does not exist and the old plan is not repealed, as was previously the practice. In preparing the Cadastre (the official register of the quantity, value, and ownership of real estate used for apportioning taxes), it was impossible to answer the question of what to do with these old planting places. Other questions that were raised included whether to require and insist on breaking the asphalt and planting a new tree, because there is room and this must be what happens when you do not have the legal right to eliminate the old planting places.
The Cadastre is composed of an expert team of engineers set by the JKP “Zelenilo”, a public communal company, which is formed by the City and the City administration as the sole agency responsible for the maintenance of green areas. Maintenance needs of the green areas are made on the basis of project needs.
Legally, the city would have every right to plant a new tree anywhere because the new greening plan has not provided for review nor been approved. Avenues are the most important element of our new greening plan because they connect the major green spaces in the city, connecting themselves and the green areas outside the city. The avenues should provide more green spaces and prevent threats by urbanization and adverse environmental conditions. Unfortunately, at the present time, the city residents are threatened by the lack of avenues and green bars.
Benefits of Green Bar Vegetation
Grasslands help to reduce transpiration of water directly from the soil into the air, along with a slight increase in humidity in the early morning hours. Water transpiration through grass at least partially retains the morning dew and returns at least a little water back into the soil. This cycle of water, no matter how insignificant for the real needs, is very important during the dry season, and certainly better than bare soil or concrete.
Lawns are the basis for planting groups of plants, which are also an important element in any green bar vegetation surface. Therefore the health of residents is directly dependent on the existence of the lawns.
Hedges and trees can achieve greater heights, so they are a more important environmental element. Hedges protect the green bar from damage by vehicles and pedestrians who seek protection from smog and exhaust fumes as well as from the street noise. Most residents want hedges below the window to provide better air flow and silence. They also reduce the stench from garbage cans, vehicles, and various activities that cause odors, which can affect the increased occurrence of headaches and nausea among the city residents. It is similar with other groups of plants, but tree surface areas are greater than hedges. Anything that is planted will be irrigated and nurtured by the residents.
Decorative flower beds reduce anxiety and stress. Flower beds can contribute more to the environment than the lawn. Flowering plant importance comes in avenues where vehicles pass closely to pedestrians and where pollution can be a extremely high.
Utility Locations
Almost all utilities are placed at different depths, depending on the type of underground installation. Those that require less frequent maintenance, and whose replacement is facilitated by creating specific channels, can be on one level. The infrastructure which must be underground for security reasons, can go along the edge of the green bars but closer to objects. That would prevent the spread of the roots to the pipes, which can cause damage to the foundation and utilities if they are poorly installed and can leak. Utility protection devices exist and can be used not only as protection from damage, but also as a signal while digging. The sidewalk should then be tiled, not paved.
In the case of a street with a very narrow profile, all the infrastructure can concentrated on one side, and if there is any room for the green bar, it will not be compromised and exposed to constant destruction. Then, the city could add additional green plants in the left over space.
Conclusion
Green space must be secure. If the law is delayed, there are no standards that directly define the system of greenery, the tree line, the network for construction, and structure of each surface. If other professions involved in city designs are unaware of the existence, significance, and professionalism of landscape architects, then reparcellation is the only remaining logical solution to the problem. Any project of reconstruction near the green bars must not be allowed to drastically abolish trees and reduce green bars for the sake of increasing the number of parking spaces.
Natasa Spica is the project manager for mapping and urban forestry evaluation at Public Service Zelenilo in Pančevo, Serbia.
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 Natasa Spica
Urban plans define the purpose of parcels in any populated area. Between the blocks of housing and urban uses, there are street parcels and their boundaries. Within the street parcels are streets, sidewalks, the infrastructure, and a green bar also called nature strip, utility strip, or tree lawn in most cities. Sidewalks and roads have a clearly defined and unchanging width in Serbian cities and can be considered as "constants".
However the green bar, must be cut into smaller pieces for parking, vehicular access to buildings and for other reasons. The green bar also contains underground and overhead utilities as well as billboards, manholes, transformer stations, and other infrastructure. Often during the construction of streets, the green areas are replaced with garden cafes, newspaper boxes, and many other facilities, including an increase in the number of parking spaces. However, in Pančevo, Serbia, the construction of new parking lots is often without the consent of the authorities during the licensing and construction of development projects.
The sidewalks and roads can not be reduced in width; they can only increase. These changes are mostly related to improving the flow and movement of users. Each new project results in a reduction of the green bar. The green bars are unprotected and may not exist as excess free space, because their priority is to contain infrastructure. Thus, its purpose is subordinate to providing green areas and sidewalks for the pedestrians. Furthermore, the route of the underground infrastructure is easier to install and maintain if they are in the soil, and not under the sidewalks or roads.
Often a new development project does not have a green bar. The reason is to save money. When reconstruction occurs, a decrease in the area of lawn also occurs. The reason is that the priorities are for wider streets, wider sidewalks, more parking, new facilities, and new infrastructure, not for more green.
The original plans for the city show a Green Line that everyone understood was to be a one meter (3 ft.) wide parcel for the green bar. If re-parcellation was done on 2 or 3 parcels; one parcel for road and 1 or 2 parcels for green space with a sidewalk, the parcel for green bar is the one that would be protected. But, the standards for greenery were not well-founded and defined in detail. Furthermore the green bars are viewed more as a timber and grasslands strip that are not necessary in the city. Because of this, the green bars are considered optional for all except for biologists, ecologists, and those engaged in maintenance. The green bars are not viewed as part of a large system for the flow of clean, moist air throughout the city. Unfortunately trees and lawns are considered a nuisance, not a necessity nor an integral part of the environment.
Proposed Reparcellation Plan
A proposed reparcellation plan in Pančevo will require that any changes on the parcel "roads" would have to include the parcel called the "green area". Furthermore, none of the new infrastructure would be able to pass through the green area. This requirement would be under the supervision of the appropriate designer or landscape architect, designated by a competent institution that deals with the maintenance of green areas. In the event that there is no room for new infrastructure (under and above ground), it would not be able to pass through green area, so another solution must be found. Urban planners will probably disagree with the given solution, because construction will cost more, planners from other professions will have limits and everyone will need to adjust to these changes.
A new law that would better protect the green areas has not been adopted, so the green bar has become considered more of a popular political topic. At the present time, reparcellation is the only way to immediately and permanently protect this small piece of green landscape on the street. The priorities of the city are known and they must be fulfilled with clear and accurately defined changes in the green spaces.
A recent project of reconstruction for one street completely abolished more than 150 meters of green areas on both sides of the road. Parking was done without leaving even one opening in the parking lot in order to plant a new tree. The conflict arose after the trees were removed, and the positions that were defined in the old project were eliminated completely. Thus it is impossible to determine the actual area of this green belt that was lost.
Cadastre
A new greening plan does not exist and the old plan is not repealed, as was previously the practice. In preparing the Cadastre (the official register of the quantity, value, and ownership of real estate used for apportioning taxes), it was impossible to answer the question of what to do with these old planting places. Other questions that were raised included whether to require and insist on breaking the asphalt and planting a new tree, because there is room and this must be what happens when you do not have the legal right to eliminate the old planting places.
The Cadastre is composed of an expert team of engineers set by the JKP “Zelenilo”, a public communal company, which is formed by the City and the City administration as the sole agency responsible for the maintenance of green areas. Maintenance needs of the green areas are made on the basis of project needs.
Legally, the city would have every right to plant a new tree anywhere because the new greening plan has not provided for review nor been approved. Avenues are the most important element of our new greening plan because they connect the major green spaces in the city, connecting themselves and the green areas outside the city. The avenues should provide more green spaces and prevent threats by urbanization and adverse environmental conditions. Unfortunately, at the present time, the city residents are threatened by the lack of avenues and green bars.
Benefits of Green Bar Vegetation
Grasslands help to reduce transpiration of water directly from the soil into the air, along with a slight increase in humidity in the early morning hours. Water transpiration through grass at least partially retains the morning dew and returns at least a little water back into the soil. This cycle of water, no matter how insignificant for the real needs, is very important during the dry season, and certainly better than bare soil or concrete.
Lawns are the basis for planting groups of plants, which are also an important element in any green bar vegetation surface. Therefore the health of residents is directly dependent on the existence of the lawns.
Hedges and trees can achieve greater heights, so they are a more important environmental element. Hedges protect the green bar from damage by vehicles and pedestrians who seek protection from smog and exhaust fumes as well as from the street noise. Most residents want hedges below the window to provide better air flow and silence. They also reduce the stench from garbage cans, vehicles, and various activities that cause odors, which can affect the increased occurrence of headaches and nausea among the city residents. It is similar with other groups of plants, but tree surface areas are greater than hedges. Anything that is planted will be irrigated and nurtured by the residents.
Decorative flower beds reduce anxiety and stress. Flower beds can contribute more to the environment than the lawn. Flowering plant importance comes in avenues where vehicles pass closely to pedestrians and where pollution can be a extremely high.
Utility Locations
Almost all utilities are placed at different depths, depending on the type of underground installation. Those that require less frequent maintenance, and whose replacement is facilitated by creating specific channels, can be on one level. The infrastructure which must be underground for security reasons, can go along the edge of the green bars but closer to objects. That would prevent the spread of the roots to the pipes, which can cause damage to the foundation and utilities if they are poorly installed and can leak. Utility protection devices exist and can be used not only as protection from damage, but also as a signal while digging. The sidewalk should then be tiled, not paved.
In the case of a street with a very narrow profile, all the infrastructure can concentrated on one side, and if there is any room for the green bar, it will not be compromised and exposed to constant destruction. Then, the city could add additional green plants in the left over space.
Conclusion
Green space must be secure. If the law is delayed, there are no standards that directly define the system of greenery, the tree line, the network for construction, and structure of each surface. If other professions involved in city designs are unaware of the existence, significance, and professionalism of landscape architects, then reparcellation is the only remaining logical solution to the problem. Any project of reconstruction near the green bars must not be allowed to drastically abolish trees and reduce green bars for the sake of increasing the number of parking spaces.
Natasa Spica is the project manager for mapping and urban forestry evaluation at Public Service Zelenilo in Pančevo, Serbia.
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.
Ambrosia Beetle
Edited by Len Phillips
Common Name: Granulate Ambrosia Beetle (GAB)
Botanical Name: Xylosandrus crassiusculus
Origin: Native to southern Asia
Introduced to the U.S.: Mid-1970's
Host: All species of oak and beech.
Damage: This is a type of bark beetle/wood borer that bores into stems and branches of trees and introduces fungi into the galleries. Beetles contribute to decline of the tree by impeding water movement through the xylem. Most GAB that affect oaks and beech are secondary invaders of stressed trees. The ambrosia beetles are highly specialized and feed on fungi that they cultivate on the walls of their tunnels.
Look for frass that is expelled on the bark from the boring hole. Entrance holes on the bark are approximately 1/8" in diameter. Sap is sometimes evident on the bark.
Life Cycle: Larvae that hatch from eggs laid in the galleries are reared on the cultivated fungi. GAB overwinter as larvae, pupae, adults, and eggs within infested trees. In early spring coinciding with new growth, adults emerge from infested trees and disperse. Females bore into stressed trees and lay eggs in galleries. Larvae that hatch from eggs feed on fungi produced in the galleries. Larvae pupate in galleries and adults emerge. One generation occurs each year.
Contributing Factors: Excess soil moisture, construction damage and similar stress are major predisposition factors to attacks. GAB are attracted to trees with bleeding lesions, slime flux or other conditions that produce alcohols.
Management: Maintaining healthy trees and shrubs is the first line of defense against the ambrosia beetles attacking weak hosts. This includes proper fertility, maintaining proper soil pH, and adequate soil moisture.
Chemical Treatments: Chemical control is not an option for these beetles if the host is already very weak or dying. Increase vitality through irrigation as needed and mulching the root zone. On stressed oaks and beech apply Masterline Permethrin Plus-C or Baseline/Onyx sprays to the lower stem and scaffold limbs during bud swell in spring. Apply a second application in June.
Photo: USDA
Sources
Editor's Note: No endorsement by mention of product names is assumed by Online Seminars. The use of trade or product names is for the information and convenience of the readers. Such mention does not constitute an evaluation, recommendation, endorsement, or approval of any product to the exclusion of others.
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
Common Name: Granulate Ambrosia Beetle (GAB)
Botanical Name: Xylosandrus crassiusculus
Origin: Native to southern Asia
Introduced to the U.S.: Mid-1970's
Host: All species of oak and beech.
Damage: This is a type of bark beetle/wood borer that bores into stems and branches of trees and introduces fungi into the galleries. Beetles contribute to decline of the tree by impeding water movement through the xylem. Most GAB that affect oaks and beech are secondary invaders of stressed trees. The ambrosia beetles are highly specialized and feed on fungi that they cultivate on the walls of their tunnels.
Look for frass that is expelled on the bark from the boring hole. Entrance holes on the bark are approximately 1/8" in diameter. Sap is sometimes evident on the bark.
Life Cycle: Larvae that hatch from eggs laid in the galleries are reared on the cultivated fungi. GAB overwinter as larvae, pupae, adults, and eggs within infested trees. In early spring coinciding with new growth, adults emerge from infested trees and disperse. Females bore into stressed trees and lay eggs in galleries. Larvae that hatch from eggs feed on fungi produced in the galleries. Larvae pupate in galleries and adults emerge. One generation occurs each year.
Contributing Factors: Excess soil moisture, construction damage and similar stress are major predisposition factors to attacks. GAB are attracted to trees with bleeding lesions, slime flux or other conditions that produce alcohols.
Management: Maintaining healthy trees and shrubs is the first line of defense against the ambrosia beetles attacking weak hosts. This includes proper fertility, maintaining proper soil pH, and adequate soil moisture.
Chemical Treatments: Chemical control is not an option for these beetles if the host is already very weak or dying. Increase vitality through irrigation as needed and mulching the root zone. On stressed oaks and beech apply Masterline Permethrin Plus-C or Baseline/Onyx sprays to the lower stem and scaffold limbs during bud swell in spring. Apply a second application in June.
Photo: USDA
Sources
- Gorsuch, Clyde S. ”Ambrosia Beetles”, Department of Entomology, Soils, and Plant Sciences, Clemson University, September 2003.
- USDA Forest Service, “Granulate Ambrosia Beetle”, Fact Sheet
Editor's Note: No endorsement by mention of product names is assumed by Online Seminars. The use of trade or product names is for the information and convenience of the readers. Such mention does not constitute an evaluation, recommendation, endorsement, or approval of any product to the exclusion of others.
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.
Oak Hybrids
Edited by Len Phillips
The following oaks are hybrids of two species that have resulted in a unique tree well suited for our city landscapes. They offer unique forms, fast growth, dark green leaves, and mildew resistance. One important note for those of you dealing with autumn leaf cleanup in the city, some of these trees retain their leaves all winter and drop off in the spring.
Crimson Spire™ Oak – Quercus robur x Q. alba ‘Crimschmidt’ Plant Patent: #9103 Zone: 4 – 8 Height: 45' Spread: 15' Shape: Columnar, tightly fastigiate Foliage: Dark green to bluish-green Fall Color: Rusty red.
This columnar selection originated as a hybrid of Q. robur and Q. alba. The white oak parentage provides dark green, mildew resistant foliage and reddish fall color. The brown leaves stay on the tree all winter and drop in the spring. The fastigiate growth habit is inherited from the English oak family. Its dense foliage creates living screens for blocking unsightly views and muffling traffic sounds. This tree has its own website.
Photo
Forest Knight® Oak – Quercus robur x alba ‘Tabor’ Plant Patent: #21382 Zone: 4 – 8 Height: 50' Spread: 40' Shape: Broadly oval Foliage: Dark green, glossy Fall Color: Orange-red.
Sturdy, symmetrical, and broadly oval, this cultivar develops into an excellent street tree. Its good form and strong branching combine with mildew resistant foliage and orange-red fall color to provide a truly unique and heat resistant tree. This tree was selected by Earl Cully from a tree in Urbana, IL. Photo
Heritage® Oak – Quercus × macdanielii 'Clemons’ Plant Patent: #11431 Zone: 4 – 9 Height: 50' Spread: 40' Shape: Broadly pyramidal to oval Foliage: Dark green, glossy Fall Color: Yellow.
The broadly pyramidal form and handsome dark green foliage with excellent mildew and tatter resistance combine to make this an excellent street tree. This English x bur oak hybrid has better cold tolerance than the English oak species. Photo
Kindred Spirit® Oak – Quercus robur x bicolor ‘Nadler’ Plant Patent: #17604 Zone: 4 – 8 Height: 30’ Spread: 6’ Shape: Tightly columnar Foliage: Medium green Fall Color: Yellow to yellow-brown.
Among the tightest of columnar trees, this oak's growth habit, mildew and drought resistance, and tolerance of urban soils make this hybrid of English and swamp white oak ideal for narrow city streets. This Earl Cully selection is the sister seedling of Regal Prince®, whose foliage is more glossy while this tree's form is significantly tighter. Photo
Prairie Stature™ Oak – Quercus x bimundorum ‘Midwest’ Zone: 3 – 8 Height: 50' Spread: 40' Shape: Broadly pyramidal Foliage: Dark green Fall Color: Yellow-orange to red.
A hybrid of English and white oak, this tree has proven to be very cold hardy in North Dakota State University trials. It's dark green foliage shows mildew resistance and will change to a good red color in autumn. This tree will tolerate most soils and is well suited for inner city environments. It does retain brown leaves all winter long. Photo
Regal Prince® Oak – Quercus robur x bicolor ‘Long’ Plant Patent: #12673 Zone: 4 – 8 Height: 45’ Spread: 18’ Shape: Columnar to narrow oval Foliage: Glossy, bright green Fall Color: Yellow.
This oak is mildew-resistant and its summer foliage is glossy, clean and bright green. This adaptable hybrid of English and Swamp White Oak is notable for an excellent columnar form. Photo
Skinny Genes® Oak – Quercus robur x alba ‘JFS-KW2QX’ Plant Patent: #24442 Zone: 4 – 8 Height: 45’ Spread: 10’ Shape: Columnar, tightly fastigiate Foliage: Dark green, glossy Fall Color: Yellow to tawny yellow.
Columnar and fastigiate in form, this hybrid of English and White Oak is very narrow. The glossy, very dark green foliage is mildew resistant and clean through the summer months before turning yellow in autumn. A living exclamation point, this slender spire was selected from second-generation seedlings and is a sister of Crimson Spire™. Photo
Streetspire® Oak – Quercus robur x alba ‘JFS-KW1QX’ Zone: 4 – 8 Height: 45' Spread: 14' Shape: Narrow, columnar Foliage: Dark green Fall Color: Rusty red.
The dark green leaves on this narrow columnar tree are tolerant of heat in the summer and they are mildew resistant. The leaves turn red in autumn and they fall to reveal stiff upright branches. It is similar to Crimson Spire™, but does not hold brown foliage through the winter. The wide crotch angles and short up-sweeping branches create a storm resistant structure. Photo
Sources
This information has been gathered from personal observations of the author, living in Massachusetts, Zone 6, and information provided by J. Frank Schmidt & Son nursery.
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, Tree Worker Specialist, Aerial Lift 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
The following oaks are hybrids of two species that have resulted in a unique tree well suited for our city landscapes. They offer unique forms, fast growth, dark green leaves, and mildew resistance. One important note for those of you dealing with autumn leaf cleanup in the city, some of these trees retain their leaves all winter and drop off in the spring.
Crimson Spire™ Oak – Quercus robur x Q. alba ‘Crimschmidt’ Plant Patent: #9103 Zone: 4 – 8 Height: 45' Spread: 15' Shape: Columnar, tightly fastigiate Foliage: Dark green to bluish-green Fall Color: Rusty red.
This columnar selection originated as a hybrid of Q. robur and Q. alba. The white oak parentage provides dark green, mildew resistant foliage and reddish fall color. The brown leaves stay on the tree all winter and drop in the spring. The fastigiate growth habit is inherited from the English oak family. Its dense foliage creates living screens for blocking unsightly views and muffling traffic sounds. This tree has its own website.
Photo
Forest Knight® Oak – Quercus robur x alba ‘Tabor’ Plant Patent: #21382 Zone: 4 – 8 Height: 50' Spread: 40' Shape: Broadly oval Foliage: Dark green, glossy Fall Color: Orange-red.
Sturdy, symmetrical, and broadly oval, this cultivar develops into an excellent street tree. Its good form and strong branching combine with mildew resistant foliage and orange-red fall color to provide a truly unique and heat resistant tree. This tree was selected by Earl Cully from a tree in Urbana, IL. Photo
Heritage® Oak – Quercus × macdanielii 'Clemons’ Plant Patent: #11431 Zone: 4 – 9 Height: 50' Spread: 40' Shape: Broadly pyramidal to oval Foliage: Dark green, glossy Fall Color: Yellow.
The broadly pyramidal form and handsome dark green foliage with excellent mildew and tatter resistance combine to make this an excellent street tree. This English x bur oak hybrid has better cold tolerance than the English oak species. Photo
Kindred Spirit® Oak – Quercus robur x bicolor ‘Nadler’ Plant Patent: #17604 Zone: 4 – 8 Height: 30’ Spread: 6’ Shape: Tightly columnar Foliage: Medium green Fall Color: Yellow to yellow-brown.
Among the tightest of columnar trees, this oak's growth habit, mildew and drought resistance, and tolerance of urban soils make this hybrid of English and swamp white oak ideal for narrow city streets. This Earl Cully selection is the sister seedling of Regal Prince®, whose foliage is more glossy while this tree's form is significantly tighter. Photo
Prairie Stature™ Oak – Quercus x bimundorum ‘Midwest’ Zone: 3 – 8 Height: 50' Spread: 40' Shape: Broadly pyramidal Foliage: Dark green Fall Color: Yellow-orange to red.
A hybrid of English and white oak, this tree has proven to be very cold hardy in North Dakota State University trials. It's dark green foliage shows mildew resistance and will change to a good red color in autumn. This tree will tolerate most soils and is well suited for inner city environments. It does retain brown leaves all winter long. Photo
Regal Prince® Oak – Quercus robur x bicolor ‘Long’ Plant Patent: #12673 Zone: 4 – 8 Height: 45’ Spread: 18’ Shape: Columnar to narrow oval Foliage: Glossy, bright green Fall Color: Yellow.
This oak is mildew-resistant and its summer foliage is glossy, clean and bright green. This adaptable hybrid of English and Swamp White Oak is notable for an excellent columnar form. Photo
Skinny Genes® Oak – Quercus robur x alba ‘JFS-KW2QX’ Plant Patent: #24442 Zone: 4 – 8 Height: 45’ Spread: 10’ Shape: Columnar, tightly fastigiate Foliage: Dark green, glossy Fall Color: Yellow to tawny yellow.
Columnar and fastigiate in form, this hybrid of English and White Oak is very narrow. The glossy, very dark green foliage is mildew resistant and clean through the summer months before turning yellow in autumn. A living exclamation point, this slender spire was selected from second-generation seedlings and is a sister of Crimson Spire™. Photo
Streetspire® Oak – Quercus robur x alba ‘JFS-KW1QX’ Zone: 4 – 8 Height: 45' Spread: 14' Shape: Narrow, columnar Foliage: Dark green Fall Color: Rusty red.
The dark green leaves on this narrow columnar tree are tolerant of heat in the summer and they are mildew resistant. The leaves turn red in autumn and they fall to reveal stiff upright branches. It is similar to Crimson Spire™, but does not hold brown foliage through the winter. The wide crotch angles and short up-sweeping branches create a storm resistant structure. Photo
Sources
This information has been gathered from personal observations of the author, living in Massachusetts, Zone 6, and information provided by J. Frank Schmidt & Son nursery.
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, Tree Worker Specialist, Aerial Lift 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.
Tree Growth Retardants
Edited by Len Phillips
In years past, the sole method available for municipal arborists and utility foresters to reduce tree and shrub size was mechanical trimming. To reduce time and costs during the 1970's, chemical tree growth retardants, usually called TGRs, were developed as an inexpensive approach to limit the growth rate of trees and to enhance their tolerance to the harsh environmental conditions often found in urban areas.
History of TGRs
Utility arborists were the first tree care professionals to see the potential of growth retardants that were being used in agriculture, as a tool for tree maintenance. Mechanical trimming was a costly operation and a chemical alternative was very attractive. Research in the late 1950s for a chemical control of tree growth following trimming for electric line clearance, was funded by the electric utility industry. The results of that early research led to the use of a synthetic auxin called napthaleneacetic acid (NAA). This NAA product was painted onto the surface of pruning cuts.
Although very effective in reducing the regrowth of branches, coating each cut surface took a lot of time and was not cost effective. So in the late 1970s researchers developed several cell elongation inhibitors called paclobutrazol (PBZ), uniconazole, and flurprimidol that came on the market for trunk injection. Due to their low water solubility, it was considered necessary to dissolve these new growth retardants in either methyl alcohol or isopropyl alcohol. The active ingredients of these formulations were very effective in reducing tree growth.
However, in the 1980s, problems associated with the trunk injection of these TGRs begin to appear. Cracks in the bark and cambium, weeping from injection holes, and internal wood discoloration from the alcohol carriers led to a decline in use of TGRs. Uniconazole was removed from the market. Flurprimidol, sold as Cutless Tree Implants®, was pressed into tablets for insertion into shallow holes drilled in tree trunks. However, the drilling and compartmentalization around the tablets prevented the release of flurprimidol into the tree. This resulted in limited use of the implants and their use gradually declined. Today, only paclobutrazol remains for use on trees. Satisfactory performance of this TGR as a growth retardant, as well as the unrelated benefits to tree health has resulted in a rebound in use of this TGR.
PBZ Treatments
PBZ (Paclobutrazol) is a gibberelin biosynthesis inhibitor that reduces the internodal growth in many species and is commonly used on trees under utility lines or anywhere else the plant size needs to be controlled. The product has also been used to stimulate root regeneration after transplanting. It has been studied for the purpose of stabilizing declining trees that have insufficient fine root development. Treatment with PBZ should be part of a complete tree care program including mulching.
PBZ, sold as Cambistat 2SC® or Profile 2SC®, is applied as a water suspension. Both formulations are approved by the EPA for soil injection or application as a basal drench. The dose rate is determined by the trunk diameter. The water suspension of PBZ can either be injected into the soil at about 150 psi to 6 inches deep and as close to the tree trunk as possible or poured into a shallow trench around the base of the tree. When it is applied to the soil, it is taken up by the roots and transported via the xylem to the upper parts of the tree. The product label provides detailed information for proper application. Treatments can be made anytime the soil is not frozen or saturated with water. Foliar application of PBZ is mostly ineffective.
How PBZ Works
PBZ suppresses growth by blocking the production of the hormone gibberellin. Gibberellins in trees stimulate cell elongation. When gibberellin production is inhibited, cell division still occurs, but the new cells do not elongate. The result is shoots with the same numbers of leaves and internodes compressed into a shorter length. The consequence is increased production of the hormone abscisic acid and the chlorophyll component phytol, both of which are beneficial to tree growth and health. The consequence is that PBZ treated trees have greater tolerance to environmental stresses and resistance to diseases.
Morphological modifications of leaves induced by treatment with PBZ include smaller stomatal pores, thicker leaves, and the increased number and size of surface appendages on leaves that may provide physical barriers to some fungal, bacterial, and insect infestations.
Shoot Growth Reduction
Treated trees have more compact crowns and somewhat smaller and darker green leaves, but otherwise look normal. As a consequence of the reduced growth in height, there is a parallel reduction in biomass removed when trees eventually require trimming.
Cambial Growth Reduction
Although the principal focus of research with PBZ has been on growth in length of shoots, reduced growth in diameter of the trunk and branches of woody plants have also been found in some tree species. Expansion of cells produced by the vascular cambium also depend on gibberellins.
Root Growth Reduction
Effects of PBZ on root growth vary and are not clearly defined but it generally enhances the development of root growth. Root response to PBZ is an important question because root growth and vigor influence not only water uptake but many other aspects of tree health.
Greener Leaves
Trees treated with PBZ have leaves with a dark green color because of a higher chlorophyll content. This is because the cells in leaves of treated trees are smaller so the amount of chlorophyll is more concentrated in the leaf.
Reduced Water Stress
PBZ can be used by arborists to improve resistance to drought stress. PBZ not only interferes with gibberellin production, it also affects the synthesis of the hormone abscisic acid. The combined effect on both the production and breakdown of abscisic acid in leaves will cause the stomates to close, reducing water loss from leaves through transpiration. The reduced stomatal opening reduces shoot growth that results in less leaf and stem surface area for transpiration. This results in more fine roots to absorb water and structural changes in leaves that reduce moisture loss. The improvement of water relations in PBZ treated trees is an important secondary benefit of using a TGR.
Effects on Fungal Diseases
Protection from common bacterial and fungal diseases such as anthracnose and bacterial leaf scorch that attack urban trees is another benefit of using PBZ. There are numerous studies showing significantly reduced growth of several other fungal pathogens. The fungicide property of PBZ is due to the inhibition of steroid production in fungi. The increased resistance of PBZ-treated trees to bacteria is not thought to be a direct effect on the pathogen, but rather due to alteration in leaf surface structure or the size of stomatal pores that make infection more difficult.
The many benefits of PBZ can be explained with an understanding of PBZs ability to combine with iron containing enzymes and reducing the production of several important compounds for tree growth and development. Because of its many positive effects on trees, PBZ is quickly evolving from use solely on trees under electric distribution lines to an important tool for commercial landscape and arboricultural practices where both growth suppression and improved tree health are desired.
However, PBZ is a potentially dangerous tree growth retardant used in several nutrient products currently available in local garden centers. It is prohibited for use on plants to be ingested or sold for human consumption. The use of paclobutrazol has been limited to use on trees and ornamental plants. Additionally, it is imperative that the label rates be followed. Normally, a mid-range mixture is sufficient to achieve desired results. Using too much chemical , treating sensitive trees, or treating species not listed on label can/will result in severe leaf deformation. Several years ago it was called Cambistat phytotoxicity but with the introduction of other brands of TGR’s that is probably not the name now used. A more appropriate term would be TGR phytotoxicity.
Sources
Editor's Note: No endorsement by mention of product names is assumed by Online Seminars. The use of trade or product names is for the information and convenience of the readers. Such mention does not constitute an evaluation, recommendation, endorsement, or approval of any product to the exclusion of others.
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, Utility 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.
Edited by Len Phillips
In years past, the sole method available for municipal arborists and utility foresters to reduce tree and shrub size was mechanical trimming. To reduce time and costs during the 1970's, chemical tree growth retardants, usually called TGRs, were developed as an inexpensive approach to limit the growth rate of trees and to enhance their tolerance to the harsh environmental conditions often found in urban areas.
History of TGRs
Utility arborists were the first tree care professionals to see the potential of growth retardants that were being used in agriculture, as a tool for tree maintenance. Mechanical trimming was a costly operation and a chemical alternative was very attractive. Research in the late 1950s for a chemical control of tree growth following trimming for electric line clearance, was funded by the electric utility industry. The results of that early research led to the use of a synthetic auxin called napthaleneacetic acid (NAA). This NAA product was painted onto the surface of pruning cuts.
Although very effective in reducing the regrowth of branches, coating each cut surface took a lot of time and was not cost effective. So in the late 1970s researchers developed several cell elongation inhibitors called paclobutrazol (PBZ), uniconazole, and flurprimidol that came on the market for trunk injection. Due to their low water solubility, it was considered necessary to dissolve these new growth retardants in either methyl alcohol or isopropyl alcohol. The active ingredients of these formulations were very effective in reducing tree growth.
However, in the 1980s, problems associated with the trunk injection of these TGRs begin to appear. Cracks in the bark and cambium, weeping from injection holes, and internal wood discoloration from the alcohol carriers led to a decline in use of TGRs. Uniconazole was removed from the market. Flurprimidol, sold as Cutless Tree Implants®, was pressed into tablets for insertion into shallow holes drilled in tree trunks. However, the drilling and compartmentalization around the tablets prevented the release of flurprimidol into the tree. This resulted in limited use of the implants and their use gradually declined. Today, only paclobutrazol remains for use on trees. Satisfactory performance of this TGR as a growth retardant, as well as the unrelated benefits to tree health has resulted in a rebound in use of this TGR.
PBZ Treatments
PBZ (Paclobutrazol) is a gibberelin biosynthesis inhibitor that reduces the internodal growth in many species and is commonly used on trees under utility lines or anywhere else the plant size needs to be controlled. The product has also been used to stimulate root regeneration after transplanting. It has been studied for the purpose of stabilizing declining trees that have insufficient fine root development. Treatment with PBZ should be part of a complete tree care program including mulching.
PBZ, sold as Cambistat 2SC® or Profile 2SC®, is applied as a water suspension. Both formulations are approved by the EPA for soil injection or application as a basal drench. The dose rate is determined by the trunk diameter. The water suspension of PBZ can either be injected into the soil at about 150 psi to 6 inches deep and as close to the tree trunk as possible or poured into a shallow trench around the base of the tree. When it is applied to the soil, it is taken up by the roots and transported via the xylem to the upper parts of the tree. The product label provides detailed information for proper application. Treatments can be made anytime the soil is not frozen or saturated with water. Foliar application of PBZ is mostly ineffective.
How PBZ Works
PBZ suppresses growth by blocking the production of the hormone gibberellin. Gibberellins in trees stimulate cell elongation. When gibberellin production is inhibited, cell division still occurs, but the new cells do not elongate. The result is shoots with the same numbers of leaves and internodes compressed into a shorter length. The consequence is increased production of the hormone abscisic acid and the chlorophyll component phytol, both of which are beneficial to tree growth and health. The consequence is that PBZ treated trees have greater tolerance to environmental stresses and resistance to diseases.
Morphological modifications of leaves induced by treatment with PBZ include smaller stomatal pores, thicker leaves, and the increased number and size of surface appendages on leaves that may provide physical barriers to some fungal, bacterial, and insect infestations.
Shoot Growth Reduction
Treated trees have more compact crowns and somewhat smaller and darker green leaves, but otherwise look normal. As a consequence of the reduced growth in height, there is a parallel reduction in biomass removed when trees eventually require trimming.
Cambial Growth Reduction
Although the principal focus of research with PBZ has been on growth in length of shoots, reduced growth in diameter of the trunk and branches of woody plants have also been found in some tree species. Expansion of cells produced by the vascular cambium also depend on gibberellins.
Root Growth Reduction
Effects of PBZ on root growth vary and are not clearly defined but it generally enhances the development of root growth. Root response to PBZ is an important question because root growth and vigor influence not only water uptake but many other aspects of tree health.
Greener Leaves
Trees treated with PBZ have leaves with a dark green color because of a higher chlorophyll content. This is because the cells in leaves of treated trees are smaller so the amount of chlorophyll is more concentrated in the leaf.
Reduced Water Stress
PBZ can be used by arborists to improve resistance to drought stress. PBZ not only interferes with gibberellin production, it also affects the synthesis of the hormone abscisic acid. The combined effect on both the production and breakdown of abscisic acid in leaves will cause the stomates to close, reducing water loss from leaves through transpiration. The reduced stomatal opening reduces shoot growth that results in less leaf and stem surface area for transpiration. This results in more fine roots to absorb water and structural changes in leaves that reduce moisture loss. The improvement of water relations in PBZ treated trees is an important secondary benefit of using a TGR.
Effects on Fungal Diseases
Protection from common bacterial and fungal diseases such as anthracnose and bacterial leaf scorch that attack urban trees is another benefit of using PBZ. There are numerous studies showing significantly reduced growth of several other fungal pathogens. The fungicide property of PBZ is due to the inhibition of steroid production in fungi. The increased resistance of PBZ-treated trees to bacteria is not thought to be a direct effect on the pathogen, but rather due to alteration in leaf surface structure or the size of stomatal pores that make infection more difficult.
The many benefits of PBZ can be explained with an understanding of PBZs ability to combine with iron containing enzymes and reducing the production of several important compounds for tree growth and development. Because of its many positive effects on trees, PBZ is quickly evolving from use solely on trees under electric distribution lines to an important tool for commercial landscape and arboricultural practices where both growth suppression and improved tree health are desired.
However, PBZ is a potentially dangerous tree growth retardant used in several nutrient products currently available in local garden centers. It is prohibited for use on plants to be ingested or sold for human consumption. The use of paclobutrazol has been limited to use on trees and ornamental plants. Additionally, it is imperative that the label rates be followed. Normally, a mid-range mixture is sufficient to achieve desired results. Using too much chemical , treating sensitive trees, or treating species not listed on label can/will result in severe leaf deformation. Several years ago it was called Cambistat phytotoxicity but with the introduction of other brands of TGR’s that is probably not the name now used. A more appropriate term would be TGR phytotoxicity.
Sources
- Chaney, William R., “Growth Retardants: A Promising Tool for Managing Urban Trees”, Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN.
- Advanced Nutrients, “The Truth about Paclobutrazol”, 2016.
Editor's Note: No endorsement by mention of product names is assumed by Online Seminars. The use of trade or product names is for the information and convenience of the readers. Such mention does not constitute an evaluation, recommendation, endorsement, or approval of any product to the exclusion of others.
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, Utility 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.
Green Plant Systems
Edited by Len Phillips
Trees and plants bring a green urban vision into reality. The use of green climbing, hanging, and standing plant systems is an interesting way to enhance the urban environment. Plus, they provide cleaner air benefits to the city residents and they can lower the local urban heat island temperatures. Arborists and other municipal employees may be called upon to oversee the construction and maintenance of green plant systems.
Most climbing, hanging, and standing plant systems offer a range of ways to support all tree and plant species. These considerations consist of direction, wall size, coverage requirement, flowering species, appearance, evergreen or deciduous, maintenance levels and space, etc. All these systems can be grouped into a general category of “Green Walls”.
Types of Green Walls
There are four basic ways that a wall is covered with greenery. They all require a growing medium, such as soil, a means of providing green leaves to cover a wall, and an integrated water delivery system.
1. Green Walls
Green walls have the growing media supported on the face of the wall. Green walls may be indoors or outside; they may be freestanding or attached to an existing wall; and come in a great variety of sizes. Green walls are seeing a surge in popularity. Approximately 80% of all green walls have been constructed since 2009. Many green walls have been constructed by institutions, government buildings, and in public places such as airports and modern downtown buildings.
2. Green Facades
Green facades create a green or vegetated surface with soil only at the base. Climbing plants grow up the face of the wall. Green facades may take several seasons before achieving maturity. Growth rates depend on climate, choice of species, depth of the soil bed, orientation, nutrition, and the irrigation regime. Green facades can be attached to existing walls or built as freestanding structures. They are used to shade glazed facades, to provide degrees of privacy and security, to screen or embellish parking structures, to cool down the temperature of buildings, patios, and walkways, and are built as arbors, trellis structures, baffles, or fences.
3. Living Walls
Living wall systems are composed of pre-vegetated panels, modules, planted blankets, or bags that are affixed to a structural wall or free-standing frame. They are also called biowalls, 'mur'vegetal, vertical gardens, or modular green walls. These modules can be made of plastic, expanded polystyrene, synthetic fabric, clay, and concrete and support a great diversity and density of plant species. Living wall systems can appear as a lush mixture of groundcovers, ferns, low shrubs, perennial flowers, and edible plants. They will contain more plants than a green facade might. Many living wall installations can be found in both tropical and temperate locations. Living walls can perform well in full sun, shade and have interior applications.
4. Living Retaining Walls
Living retaining walls are engineered living structures that are designed to stabilize a slope, while supporting vegetation contained in their structure. They provide the structural strength to resist the lateral forces exerted by angles greater than the natural angle of repose of the soil and they protect the slope from erosion or failure. They are often modular for ease of installation and made from geo-textile bags. They are used in conjunction with interlocking units of metal, concrete, plastic cellular confinement mats or woven willow plants. Some systems can perform on slopes up to 88 degrees and many have capacity for variable slope angles as flat as 45 degrees.
All living retaining wall systems must allow for a suitable volume of soil at the face of the system. The growing media must be sheltered from erosion, be accessible to the introduction of new or replacement plant material either from plugs or seed, and provide for long term plant growth. The mature living retaining wall is intended to be fully covered by its internally supported vegetation such that the underlying structural elements that are no longer visible as the wall become additional green space and habitat for the city.
Growing Media
Green walls are often constructed of modular panels that hold a growing medium and can be categorized according to various types of growing media used.
Loose Media
Loose media walls tend to be "soil-on-a-shelf" or "soil-in-a-bag" type systems. Loose medium systems have their soil packed into a shelf or bag and are then installed onto the wall. These systems require their media to be replaced at least once a year on exterior sites and approximately every two years on interior locations. Loose soil systems are not well suited for areas with any seismic activity. Most importantly, because these systems can easily have their medium blown away by wind-driven rain or heavy winds, these should not be used in applications over 8 feet high.
There are some systems in Asia that have solved the loose media erosion problem by use of shielding systems to hold the media within the green wall system even when soil liquefaction occurs under seismic load. In these systems, the plants can still up-root themselves in the liquefied soil and therefore it is required that the plants be secured to the system to prevent them from falling from the wall. Loose-soil systems without physical media erosion systems are best suited for the home gardener where occasional replanting is desired from season to season or year to year. Loose-soil systems with physical media erosion systems are well suited for all green wall applications.
Mat Media
Mat type systems tend to be either coir fiber or felt mats. Mat media are quite thin, even in multiple layers, and as such cannot support a vibrant root systems of mature plants for more than three to five years before the roots overtake the mat and water is not able to adequately wick through the mats. The method to repair these systems is to replace sections by cutting the mat out of the wall and replacing it with new mat.
Unfortunately, this process compromises the root structures of the neighboring plants on the wall and often kills many surrounding plants soon after the repair process. These systems are best used on the interior of a building and are a good choice in areas for small plants. It is important to note that mat systems are particularly water inefficient and often require constant irrigation due to the thin nature of the medium and its inability to hold water and provide a buffer for the plant roots. This inefficiency often requires that these systems have a water re-circulation system put into place. Mat media are better suited for small installations no more than eight feet in height where repairs are easily completed.
Sheet Media
Semi-open cell polyurethane sheet media utilizing an egg crate pattern has successfully been used in recent years for both outdoor roof gardens and vertical walls. The water holding capacity of these engineered polyurethanes vastly exceeds that of coir and felt based systems. Polyurethanes do not biodegrade, and hence stay viable as an active substrate for 20+ years. Vertical wall systems utilizing polyurethane sheeting typically employ a sandwich construction where a water proof membrane is applied to the back of the polyurethane sheeting. Typically two sheets with irrigation lines in between is laid and then a mesh or anchor braces/bars secure the assembly to the wall. Pockets are cut into the face of the first urethane sheet into which plants are inserted. Soil is typically removed from the roots of any plants prior to insertion into the urethane mattress substrate. A flaked or chopped noodle version of the same polyurethane material can also be added to existing structural media mixes to boost water retention.
Structural Media
Structural media are growth medium "blocks" that are not loose, nor mats, but which incorporate the best features of both into a block that can be manufactured into various sizes, shapes and thicknesses. These media have the advantage that they do not break down for 10 to 15 years, can be made to have a higher or lower water holding capacity depending on the plant selection for the wall. They can have their soils customized to suit the plants, and are easily handled for maintenance and replacement.
Green Wall Function
Green walls are found most often in urban environments where the plants reduce overall temperatures of the building. The primary cause of heat build-up in cities is the absorption of solar radiation by roads and buildings in the city and the storage of this urban heat in the building material and its subsequent re-radiation. Plant surfaces however, as a result of transpiration, do not rise more than 8-10°F (4-5°C) above the ambient and are sometimes cooler.
Green walls may also be a means for water reuse. The plants may purify slightly polluted or gray water by absorbing the dissolved nutrients. Bacteria mineralize the organic components to make them available to the plants.
Green walls are particularly suitable for cities, as they provide a good use of available vertical surface areas. They are also suitable in arid areas, as the circulating water on a vertical wall is less likely to evaporate than in horizontal gardens.
The living wall could also function for urban agriculture, urban gardening, or for its beauty as art. It is sometimes built indoors to help alleviate the sick building syndrome
All of the green walls reduce the energy needed for heating and cooling through shading and transpiration. They also remove pollutants and carbon dioxide from the air, insulate buildings and rooms for sound, promote eco-marketing, and beautify the surroundings.
Benefits of Green Walls
A well designed and properly maintained green wall can improve the appearance of a building, revitalize an aging facade, or add a new element to the building. The benefits include:
Active Living Walls
A tree next to an active living wall pulls or forces air through the plants leaves, roots and growth medium of the wall and then into the building's HVAC system to be recirculated throughout the building. A problem with these systems is that building code still requires all the standard air filtration equipment that would have to be installed anyway, despite the living wall's installation. This means that active living walls do not improve air quality to the point that the installation of other air quality filtration systems can be removed to provide a cost-savings.
Therefore, the added cost of design, planning and implementation of an active living wall is still in question. With further research and UL standards to support the air quality data from the living wall, building codes may some day allow for our buildings to have their air filtered by plants.
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, Utility 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.
Edited by Len Phillips
Trees and plants bring a green urban vision into reality. The use of green climbing, hanging, and standing plant systems is an interesting way to enhance the urban environment. Plus, they provide cleaner air benefits to the city residents and they can lower the local urban heat island temperatures. Arborists and other municipal employees may be called upon to oversee the construction and maintenance of green plant systems.
Most climbing, hanging, and standing plant systems offer a range of ways to support all tree and plant species. These considerations consist of direction, wall size, coverage requirement, flowering species, appearance, evergreen or deciduous, maintenance levels and space, etc. All these systems can be grouped into a general category of “Green Walls”.
Types of Green Walls
There are four basic ways that a wall is covered with greenery. They all require a growing medium, such as soil, a means of providing green leaves to cover a wall, and an integrated water delivery system.
1. Green Walls
Green walls have the growing media supported on the face of the wall. Green walls may be indoors or outside; they may be freestanding or attached to an existing wall; and come in a great variety of sizes. Green walls are seeing a surge in popularity. Approximately 80% of all green walls have been constructed since 2009. Many green walls have been constructed by institutions, government buildings, and in public places such as airports and modern downtown buildings.
2. Green Facades
Green facades create a green or vegetated surface with soil only at the base. Climbing plants grow up the face of the wall. Green facades may take several seasons before achieving maturity. Growth rates depend on climate, choice of species, depth of the soil bed, orientation, nutrition, and the irrigation regime. Green facades can be attached to existing walls or built as freestanding structures. They are used to shade glazed facades, to provide degrees of privacy and security, to screen or embellish parking structures, to cool down the temperature of buildings, patios, and walkways, and are built as arbors, trellis structures, baffles, or fences.
3. Living Walls
Living wall systems are composed of pre-vegetated panels, modules, planted blankets, or bags that are affixed to a structural wall or free-standing frame. They are also called biowalls, 'mur'vegetal, vertical gardens, or modular green walls. These modules can be made of plastic, expanded polystyrene, synthetic fabric, clay, and concrete and support a great diversity and density of plant species. Living wall systems can appear as a lush mixture of groundcovers, ferns, low shrubs, perennial flowers, and edible plants. They will contain more plants than a green facade might. Many living wall installations can be found in both tropical and temperate locations. Living walls can perform well in full sun, shade and have interior applications.
4. Living Retaining Walls
Living retaining walls are engineered living structures that are designed to stabilize a slope, while supporting vegetation contained in their structure. They provide the structural strength to resist the lateral forces exerted by angles greater than the natural angle of repose of the soil and they protect the slope from erosion or failure. They are often modular for ease of installation and made from geo-textile bags. They are used in conjunction with interlocking units of metal, concrete, plastic cellular confinement mats or woven willow plants. Some systems can perform on slopes up to 88 degrees and many have capacity for variable slope angles as flat as 45 degrees.
All living retaining wall systems must allow for a suitable volume of soil at the face of the system. The growing media must be sheltered from erosion, be accessible to the introduction of new or replacement plant material either from plugs or seed, and provide for long term plant growth. The mature living retaining wall is intended to be fully covered by its internally supported vegetation such that the underlying structural elements that are no longer visible as the wall become additional green space and habitat for the city.
Growing Media
Green walls are often constructed of modular panels that hold a growing medium and can be categorized according to various types of growing media used.
Loose Media
Loose media walls tend to be "soil-on-a-shelf" or "soil-in-a-bag" type systems. Loose medium systems have their soil packed into a shelf or bag and are then installed onto the wall. These systems require their media to be replaced at least once a year on exterior sites and approximately every two years on interior locations. Loose soil systems are not well suited for areas with any seismic activity. Most importantly, because these systems can easily have their medium blown away by wind-driven rain or heavy winds, these should not be used in applications over 8 feet high.
There are some systems in Asia that have solved the loose media erosion problem by use of shielding systems to hold the media within the green wall system even when soil liquefaction occurs under seismic load. In these systems, the plants can still up-root themselves in the liquefied soil and therefore it is required that the plants be secured to the system to prevent them from falling from the wall. Loose-soil systems without physical media erosion systems are best suited for the home gardener where occasional replanting is desired from season to season or year to year. Loose-soil systems with physical media erosion systems are well suited for all green wall applications.
Mat Media
Mat type systems tend to be either coir fiber or felt mats. Mat media are quite thin, even in multiple layers, and as such cannot support a vibrant root systems of mature plants for more than three to five years before the roots overtake the mat and water is not able to adequately wick through the mats. The method to repair these systems is to replace sections by cutting the mat out of the wall and replacing it with new mat.
Unfortunately, this process compromises the root structures of the neighboring plants on the wall and often kills many surrounding plants soon after the repair process. These systems are best used on the interior of a building and are a good choice in areas for small plants. It is important to note that mat systems are particularly water inefficient and often require constant irrigation due to the thin nature of the medium and its inability to hold water and provide a buffer for the plant roots. This inefficiency often requires that these systems have a water re-circulation system put into place. Mat media are better suited for small installations no more than eight feet in height where repairs are easily completed.
Sheet Media
Semi-open cell polyurethane sheet media utilizing an egg crate pattern has successfully been used in recent years for both outdoor roof gardens and vertical walls. The water holding capacity of these engineered polyurethanes vastly exceeds that of coir and felt based systems. Polyurethanes do not biodegrade, and hence stay viable as an active substrate for 20+ years. Vertical wall systems utilizing polyurethane sheeting typically employ a sandwich construction where a water proof membrane is applied to the back of the polyurethane sheeting. Typically two sheets with irrigation lines in between is laid and then a mesh or anchor braces/bars secure the assembly to the wall. Pockets are cut into the face of the first urethane sheet into which plants are inserted. Soil is typically removed from the roots of any plants prior to insertion into the urethane mattress substrate. A flaked or chopped noodle version of the same polyurethane material can also be added to existing structural media mixes to boost water retention.
Structural Media
Structural media are growth medium "blocks" that are not loose, nor mats, but which incorporate the best features of both into a block that can be manufactured into various sizes, shapes and thicknesses. These media have the advantage that they do not break down for 10 to 15 years, can be made to have a higher or lower water holding capacity depending on the plant selection for the wall. They can have their soils customized to suit the plants, and are easily handled for maintenance and replacement.
Green Wall Function
Green walls are found most often in urban environments where the plants reduce overall temperatures of the building. The primary cause of heat build-up in cities is the absorption of solar radiation by roads and buildings in the city and the storage of this urban heat in the building material and its subsequent re-radiation. Plant surfaces however, as a result of transpiration, do not rise more than 8-10°F (4-5°C) above the ambient and are sometimes cooler.
Green walls may also be a means for water reuse. The plants may purify slightly polluted or gray water by absorbing the dissolved nutrients. Bacteria mineralize the organic components to make them available to the plants.
Green walls are particularly suitable for cities, as they provide a good use of available vertical surface areas. They are also suitable in arid areas, as the circulating water on a vertical wall is less likely to evaporate than in horizontal gardens.
The living wall could also function for urban agriculture, urban gardening, or for its beauty as art. It is sometimes built indoors to help alleviate the sick building syndrome
All of the green walls reduce the energy needed for heating and cooling through shading and transpiration. They also remove pollutants and carbon dioxide from the air, insulate buildings and rooms for sound, promote eco-marketing, and beautify the surroundings.
Benefits of Green Walls
A well designed and properly maintained green wall can improve the appearance of a building, revitalize an aging facade, or add a new element to the building. The benefits include:
- green walls can act as an effective deterrent to vandalism.
- green walls can help extend the life of a building’s façade, acting as a buffer to extreme bad weather and ultraviolet light. http://thinkingoutsidetheboxwood.com/wp-content/uploads/2013/09/DSC3005.jpg
- green walls improve air quality by absorbing carbon dioxide and releasing oxygen, while also trapping pollutants.
- green walls provide an added layer of insulation in winter months, keeping heat in and a cover from the sun in summer months to help keep the building cool. http://cdn.greendiary.com/wp-content/uploads/2012/07/green-living-walls_TiAab_11446.jpg
- green walls absorb sound for the benefit of the building’s occupants and the local area as well.
- green walls provide habitat for birds and other wildlife, including offering alternative nesting for wildlife displaced during construction.
Active Living Walls
A tree next to an active living wall pulls or forces air through the plants leaves, roots and growth medium of the wall and then into the building's HVAC system to be recirculated throughout the building. A problem with these systems is that building code still requires all the standard air filtration equipment that would have to be installed anyway, despite the living wall's installation. This means that active living walls do not improve air quality to the point that the installation of other air quality filtration systems can be removed to provide a cost-savings.
Therefore, the added cost of design, planning and implementation of an active living wall is still in question. With further research and UL standards to support the air quality data from the living wall, building codes may some day allow for our buildings to have their air filtered by plants.
Sources
- Bennett, Coleman & Co., Ltd. "Vertical gardens a green solution for urban setting", The Times of India. Feb 14, 2013.
- Jackson, Tracy, “About Green Walls”, Green Roofs for Healthy Cities, 2014.
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