#20 Read About Tips for Managing the Urban Forest
Edited by Len Phillips, January 2023
Sections You may go directly to the section by clicking on titles listed here.
Edited by Len Phillips, January 2023
Sections You may go directly to the section by clicking on titles listed here.
Click on the green text in each section for more information
Tree Installation Checklist
What are the steps required to ensure that the new trees we install will thrive and grow to maturity? If the list below is followed precisely, every new urban tree should survive and thrive.
1. pre-planning to determine:
a) reason to plant – tree advisory board, political decision, society value, or professional directive
b) diversify tree installations with no more than 10% of any species and 20% of any genus
c) the amount of growing soil volume available to match tree size at maturity
d) sufficient budget for installing and maintenance
2. examine site
a) study soil – dry bulk density, 5% organic matter, texture, topography, volume of quality soil, pH
b) utility locations – overhead and underground
c) good drainage, ample soil moisture, test for drainage rate
d) amount of sun & shade
e) space necessary for tree at mature size and canopy coverage
f) USDA Hardiness Zone
3. stock selection
a) species – select the right tree for the right place, its growth habit and ultimate size
b) purchase good quality stock as recommended by the ANSI Z60 American Standard for Nursery Stock
c) select pest and disease resistant trees
d) select digging method most suitable for the tree – bare root, B&B, container, tree spade
e) must be non-invasive unless it is the only tree suitable for the site
f) size – smaller installation size provides more rapid growth and less transplant shock than larger size tree
g) select trees with fibrous roots and flare at the finish grade surface
h) install native trees in native soil; install improved cultivars in our cities
4. shipping
a) properly dug from the nursery and handled according to American Standards for Nursery Stock
b) keep roots moist at all times
c) bare root trees should have roots dipped in hydrogel and placed in a large plastic bag at the nursery
d) branches should be tied up to prevent breakage during shipping
e) trunk should be wrapped on thin-barked trees only – unwrap at installation site to check for injuries
f) upon arrival at the city, the trees should be stored in shade and where the trees can be frequently watered
5. installing correctly (as recommended by the ANSI Z60 American Standard for Nursery Stock)
a) dig the installation pit in saucer shape, 3 times the root ball diameter and only as deep as the root ball
b) loosen and aerate any compacted soil 3 to 5 times the root ball diameter
c) set tree on firm but not compacted soil
d) if the tree has a thin bark, orient the tree same as at nursery, so the largest branches are facing southwest
e) with the tree in the pit, carefully remove all containers, wire basket, rope, and burlap from root ball
f) inspect roots for deformities and arrange all roots to grow away from the trunk
g) remove broken, dead, damaged, or diseased branches and roots
h) the flare should be at one or two inches above finished grade
i) label the tree on a plan or map if long-term remembrance is necessary
j) remove all tags, tape, and trunk coverings from the branches and trunk
k) if soil conditions warrant, add amendments such as mycorrhizae, compost, biochar, fertilizer, etc.
l) backfill with soil removed from the pit
m) install root stabilizers as necessary
6. water
a) add water halfway through the installation process and jiggle tree to be sure soil contacts all roots
b) when all remaining soil has been added, build a berm around the entire installation area to hold water
c) water again when berm is completely finished, then add mulch
d) water 2 more times in first 24 hours
e) water daily for first 2 weeks, depending on rainfall
f) water weekly to the end of first growing season, depending on rainfall
g) large caliper trees may need weekly watering through dry periods in the next several growing seasons
7. maintenance
a) add composted mulch starting 6 inches from trunk and covering the entire excavated area 3 inches deep
b) weed as necessary
c) water as necessary
d) weekly inspections for first year
e) annual inspections as necessary
f) at 5 years remove one end of any co-dominant stems that appeared after installing
8. establishment defined
a) determine survival rate in 5, 10, or 20 years
b) evaluate species selections
c) measurement of root colonization in surrounding soil
d) measure growth rate of twigs
e) evaluation of installation program
What are the steps required to ensure that the new trees we install will thrive and grow to maturity? If the list below is followed precisely, every new urban tree should survive and thrive.
1. pre-planning to determine:
a) reason to plant – tree advisory board, political decision, society value, or professional directive
b) diversify tree installations with no more than 10% of any species and 20% of any genus
c) the amount of growing soil volume available to match tree size at maturity
d) sufficient budget for installing and maintenance
2. examine site
a) study soil – dry bulk density, 5% organic matter, texture, topography, volume of quality soil, pH
b) utility locations – overhead and underground
c) good drainage, ample soil moisture, test for drainage rate
d) amount of sun & shade
e) space necessary for tree at mature size and canopy coverage
f) USDA Hardiness Zone
3. stock selection
a) species – select the right tree for the right place, its growth habit and ultimate size
b) purchase good quality stock as recommended by the ANSI Z60 American Standard for Nursery Stock
c) select pest and disease resistant trees
d) select digging method most suitable for the tree – bare root, B&B, container, tree spade
e) must be non-invasive unless it is the only tree suitable for the site
f) size – smaller installation size provides more rapid growth and less transplant shock than larger size tree
g) select trees with fibrous roots and flare at the finish grade surface
h) install native trees in native soil; install improved cultivars in our cities
4. shipping
a) properly dug from the nursery and handled according to American Standards for Nursery Stock
b) keep roots moist at all times
c) bare root trees should have roots dipped in hydrogel and placed in a large plastic bag at the nursery
d) branches should be tied up to prevent breakage during shipping
e) trunk should be wrapped on thin-barked trees only – unwrap at installation site to check for injuries
f) upon arrival at the city, the trees should be stored in shade and where the trees can be frequently watered
5. installing correctly (as recommended by the ANSI Z60 American Standard for Nursery Stock)
a) dig the installation pit in saucer shape, 3 times the root ball diameter and only as deep as the root ball
b) loosen and aerate any compacted soil 3 to 5 times the root ball diameter
c) set tree on firm but not compacted soil
d) if the tree has a thin bark, orient the tree same as at nursery, so the largest branches are facing southwest
e) with the tree in the pit, carefully remove all containers, wire basket, rope, and burlap from root ball
f) inspect roots for deformities and arrange all roots to grow away from the trunk
g) remove broken, dead, damaged, or diseased branches and roots
h) the flare should be at one or two inches above finished grade
i) label the tree on a plan or map if long-term remembrance is necessary
j) remove all tags, tape, and trunk coverings from the branches and trunk
k) if soil conditions warrant, add amendments such as mycorrhizae, compost, biochar, fertilizer, etc.
l) backfill with soil removed from the pit
m) install root stabilizers as necessary
6. water
a) add water halfway through the installation process and jiggle tree to be sure soil contacts all roots
b) when all remaining soil has been added, build a berm around the entire installation area to hold water
c) water again when berm is completely finished, then add mulch
d) water 2 more times in first 24 hours
e) water daily for first 2 weeks, depending on rainfall
f) water weekly to the end of first growing season, depending on rainfall
g) large caliper trees may need weekly watering through dry periods in the next several growing seasons
7. maintenance
a) add composted mulch starting 6 inches from trunk and covering the entire excavated area 3 inches deep
b) weed as necessary
c) water as necessary
d) weekly inspections for first year
e) annual inspections as necessary
f) at 5 years remove one end of any co-dominant stems that appeared after installing
8. establishment defined
a) determine survival rate in 5, 10, or 20 years
b) evaluate species selections
c) measurement of root colonization in surrounding soil
d) measure growth rate of twigs
e) evaluation of installation program
Tree Installation Options
When an arborist, landscape architect, or urban forester is asked to recommend the best way to preserve or install new trees in the city, how do you respond? The following can be considered the best options for installing trees in conjunction with a city sidewalk in various site and sidewalk conditions. To start, preserve every existing tree possible. Then every new tree must have a minimum of 2 cubic feet (0.06 cm) of soil for every square foot (0.1 sm) of the future crown projected at maturity or 4 square feet (0.38 sm) of surface area for every inch (2.5 cm) of trunk diameter the tree is expected to attain, and this should be applied to all the options mentioned below.
Site Conditions – New construction including new sidewalks and new trees
Best Installation Option – During construction of new sidewalks, streets, utilities, and buildings – install all the trees in groves 10 to 20 ft. (3 – 6m) apart or included shrub beds. Be sure to select trees that are not considered surface rooted trees. For lists of shallow rooted and more desirable trees, see the lists in the opening section of this article. Scroll down the page to see the lists.
Second Best Installation Option – The use of soil cells is the next best method for ensuring there is enough suitable soil for a tree to develop into a mature specimen. Soil cells transfer a compacted foundation 3 ft. (1 m) below grade to a surface suitable for a sidewalk, plaza, or light traffic roadway while allowing plenty of ideal soil for growing trees under the surface. The installation of root barriers to deflect roots downward should be included to prevent the tree's roots from causing damage to the surface pavement. The soil cells will also provide stormwater storage and reduce the frequency of manual watering of the newly installed trees. See more information.
Site Conditions – New sidewalks and preserve existing trees
Best Installation Option – Carefully examine the condition of the tree and the existing roots to provide care, protection, and root pruning as necessary. Modify the sidewalk design and location to accommodate the tree and its roots. This option is often the result of sidewalk replacements caused by roots that have damaged the existing sidewalks. The best and most common solution is to raise the sidewalk higher, which results in the roots being in deeper soil than before the new sidewalk is installed. Include S-curves around the trees and pavement alternatives found in this article.
Second Best Installation Option – Loosen and improve soil including that which will serve as a base for pavement. New sidewalks should be built and suspended on pilings above the tree roots or on the top of soil cells installed under the new sidewalk depending on the existing root locations. See Suspended Pavements article for more information.
Site Conditions – New trees and preserve existing trees
Two Best Installation Options
- Using an air tool, excavate as much soil as possible under and around any existing roots including the areas where the pavement is planned. Carefully examine the existing roots and prune if necessary. Follow the Stockholm Tree Pits procedures of adding layers of large rock, washing soil into the voids between the rocks, adding another layer of rocks, and continuing the process until the entire area that will become paved, is just below finished elevation.
- Install CU Structural Soil which consists of mixing one inch (2.5 cm) stone coated with soil and installing this mix into the area to be paved. After completing either option, add any new trees and root barriers as necessary, before finishing the job with the addition of a new pavement on the surface. See more information.
Site Conditions – New trees and preserve existing sidewalks
Best Installation Option – Consider relocating the installation site to the other side of the sidewalk, away from the curb and street, if the site is suitable and better soil is available. This assumes that the traffic volume and speed are not a pedestrian safety concern that might require trees as a safety barrier. This option may require a local easement or agreement with the abutting landowner if the trees will be installed on private property. In cities where this option is approved, the maintenance of the tree is also transferred to the private landowner. See more information.
Second Best Installation Option – Excavate as much soil as possible for the tree installation site to obtain 500 cu. ft. (14 cu meters) of space for installing good soil. Include going as deep as 4 feet (125 cm). Punch, auger, or wash out holes with tools or high pressure water from the bottom of the installation pit, under the sidewalk toward good soil, if it is available beyond the sidewalk, and let the tree's roots following the holes toward better soil and growing conditions. Select a tree that is suitable for the amount of soil available. See more information and scroll down to the section dealing with soil volume. Install the tree with excellent soil that is similar in texture to the existing soil around the installation pit.
Site Conditions – No trees and no sidewalks
Best Installation Option – All the installation options listed above are suitable. However, anticipate what the future might bring at this site and install the appropriate tree at the appropriate site for the future. For more information read the entire article.
Best Choice of Trees
Become familiar with how to install bare root trees. They are the least costly to purchase and install by contract and easiest to install when using volunteers. When installing them in city soils, the trees will not suffer from the transition to different soil than they were growing in at the nursery. See more information on installing bare root trees. If there is a concern that the lack of a soil ball might cause the tree to blow over, there are several root stabilizing options that are currently available. See more information on tree stabilization.
When an arborist, landscape architect, or urban forester is asked to recommend the best way to preserve or install new trees in the city, how do you respond? The following can be considered the best options for installing trees in conjunction with a city sidewalk in various site and sidewalk conditions. To start, preserve every existing tree possible. Then every new tree must have a minimum of 2 cubic feet (0.06 cm) of soil for every square foot (0.1 sm) of the future crown projected at maturity or 4 square feet (0.38 sm) of surface area for every inch (2.5 cm) of trunk diameter the tree is expected to attain, and this should be applied to all the options mentioned below.
Site Conditions – New construction including new sidewalks and new trees
Best Installation Option – During construction of new sidewalks, streets, utilities, and buildings – install all the trees in groves 10 to 20 ft. (3 – 6m) apart or included shrub beds. Be sure to select trees that are not considered surface rooted trees. For lists of shallow rooted and more desirable trees, see the lists in the opening section of this article. Scroll down the page to see the lists.
Second Best Installation Option – The use of soil cells is the next best method for ensuring there is enough suitable soil for a tree to develop into a mature specimen. Soil cells transfer a compacted foundation 3 ft. (1 m) below grade to a surface suitable for a sidewalk, plaza, or light traffic roadway while allowing plenty of ideal soil for growing trees under the surface. The installation of root barriers to deflect roots downward should be included to prevent the tree's roots from causing damage to the surface pavement. The soil cells will also provide stormwater storage and reduce the frequency of manual watering of the newly installed trees. See more information.
Site Conditions – New sidewalks and preserve existing trees
Best Installation Option – Carefully examine the condition of the tree and the existing roots to provide care, protection, and root pruning as necessary. Modify the sidewalk design and location to accommodate the tree and its roots. This option is often the result of sidewalk replacements caused by roots that have damaged the existing sidewalks. The best and most common solution is to raise the sidewalk higher, which results in the roots being in deeper soil than before the new sidewalk is installed. Include S-curves around the trees and pavement alternatives found in this article.
Second Best Installation Option – Loosen and improve soil including that which will serve as a base for pavement. New sidewalks should be built and suspended on pilings above the tree roots or on the top of soil cells installed under the new sidewalk depending on the existing root locations. See Suspended Pavements article for more information.
Site Conditions – New trees and preserve existing trees
Two Best Installation Options
- Using an air tool, excavate as much soil as possible under and around any existing roots including the areas where the pavement is planned. Carefully examine the existing roots and prune if necessary. Follow the Stockholm Tree Pits procedures of adding layers of large rock, washing soil into the voids between the rocks, adding another layer of rocks, and continuing the process until the entire area that will become paved, is just below finished elevation.
- Install CU Structural Soil which consists of mixing one inch (2.5 cm) stone coated with soil and installing this mix into the area to be paved. After completing either option, add any new trees and root barriers as necessary, before finishing the job with the addition of a new pavement on the surface. See more information.
Site Conditions – New trees and preserve existing sidewalks
Best Installation Option – Consider relocating the installation site to the other side of the sidewalk, away from the curb and street, if the site is suitable and better soil is available. This assumes that the traffic volume and speed are not a pedestrian safety concern that might require trees as a safety barrier. This option may require a local easement or agreement with the abutting landowner if the trees will be installed on private property. In cities where this option is approved, the maintenance of the tree is also transferred to the private landowner. See more information.
Second Best Installation Option – Excavate as much soil as possible for the tree installation site to obtain 500 cu. ft. (14 cu meters) of space for installing good soil. Include going as deep as 4 feet (125 cm). Punch, auger, or wash out holes with tools or high pressure water from the bottom of the installation pit, under the sidewalk toward good soil, if it is available beyond the sidewalk, and let the tree's roots following the holes toward better soil and growing conditions. Select a tree that is suitable for the amount of soil available. See more information and scroll down to the section dealing with soil volume. Install the tree with excellent soil that is similar in texture to the existing soil around the installation pit.
Site Conditions – No trees and no sidewalks
Best Installation Option – All the installation options listed above are suitable. However, anticipate what the future might bring at this site and install the appropriate tree at the appropriate site for the future. For more information read the entire article.
Best Choice of Trees
Become familiar with how to install bare root trees. They are the least costly to purchase and install by contract and easiest to install when using volunteers. When installing them in city soils, the trees will not suffer from the transition to different soil than they were growing in at the nursery. See more information on installing bare root trees. If there is a concern that the lack of a soil ball might cause the tree to blow over, there are several root stabilizing options that are currently available. See more information on tree stabilization.
Autumn Tree Installation
Autumn can be the perfect time to install new deciduous trees or shrubs because the autumn months of September through December often have distinct advantages over spring installations.
Advantages
Disadvantages
Some deciduous trees have a higher survival rate when installed in spring. Trees with fleshy roots and thin barked trees are less successful when installed in the autumn. The following lists may be used as a guide when selecting woody plant material for autumn installations.
List of Trees Suitable for Autumn Installation
Acer spp. Maple
Aesculus spp. Buckeye
Amelanchier spp. Serviceberry
Celtis occidentalis Hackberry
Cercidiphyllum japonicum Katsura
Cercis canadensis Redbud
Fraxinus spp. Ash (install in non-EAB areas or resistant selections)
Ginkgo biloba Ginkgo
Gleditsia triacanthos spp. Honeylocust
Gymnocladus dioicus Kentucky Coffeetree
Juniperus spp. Juniper
Maclura pomifera Osage Orange
Malus spp. Crabapple (Check with local nurseries, as some locations say spring only)
Morus alba Mulberry
Phellodendron amurense Cork Tree
Pyrus calleryana Callery Pear
Robinia pseudoacacia Black Locust
Sophora japonica Japanese Pagoda Tree
Thuja occidentalis Arborvitae
Ulmus spp. Elm
Just be sure to install early enough so that the tree roots get a one month head start before the ground freezes.
List of Trees with a High Risk of Loss
Many nursery catalogs indicate certain trees have a high risk of failure if installed in autumn. If autumn installation is desired, use freshly dug or container stock to minimize the risk. Some of these risky trees are:
Betula spp. Birch
Carpinus spp. Hornbeam
Cornus florida Dogwood
Crataegus spp. Hawthorn
Koelreuteria paniculata Goldenraintree
Liquidambar spp. Sweet Gum
Liriodendron tulipifera Tulip Tree
Magnolia spp. Magnolia
Prunus spp. Flowering cherry
Taxus spp. Yews
Tilia spp. Linden
(Check with local nurseries, as some locations say autumn only)
List of Trees That Do Best with Spring Installation
Studies have determined that the tree species listed below will fail in autumn installations because the loss of roots interferes with the development of a tree's cold tolerance.
Abies spp. Fir
Carya spp. Hickory
Catalpa spp. Catalpa
Chamaecyparis nootkatensis Nootka Falsecypress
Cladrastis kentukea Yellowwood
Fagus sylvatica Beech
Juglans spp. Walnut
Larix spp. Larch
Nyssa sylvatica Tupelo, Sour Gum, Black Gum
Ostrya virginiana Hophornbeam
Oxydendrum arboreum Sourwood
Picea spp. Spruce (Check with local nurseries, as some locations say autumn only)
Pinus spp. Pine (Check with local nurseries, as some locations say autumn only)
Platanus spp. Plane Tree
Populus spp. Poplar, Aspen
Quercus spp. Oak
Salix spp. Willow
Sassafras albidum Sassafras
Sorbus aucuparia Mountain Ash
Taxodium distichum Bald Cypress
Tsuga canadensis Hemlock
Zelkova serrata Japanese Zelkova
Autumn can be the perfect time to install new deciduous trees or shrubs because the autumn months of September through December often have distinct advantages over spring installations.
Advantages
- Quick Establishment – Like autumn seeded lawns, installing trees in autumn have a chance to become established in the landscape during the late autumn and winter and are all ready to burst into growth by spring.
- Easier Weed Control – Autumn installation is done after the growing season has ended. This means that any weed seed in the soil is dormant, unlike in spring when it's highly energized and will compete with the tree for moisture and nutrients.
- More Time In Autumn – In the autumn, the labor crews have more time for installations than during the spring rush to get everything ready for summer activities. This is because there is a longer span of weeks suitable for planting and there are more good weather days than during the unsettled weather of spring.
- Better Weather – The weather is conducive for good root growth as the days are shorter, the heat wave has ended, and the moisture is evenly available. Tree roots grow anytime the soil temperature is 40° F (4° C) or higher, which may occur all winter long in the U.S. southern states. In northern states, the cooling soil temperatures can be delayed with an ample layer of mulch over the installation pit. During the winter months the root systems of autumn installed trees develop and become established as long as there are areas underground where the soil has not frozen solid. When spring arrives this expanded root system can support and take advantage of the spring growth surge.
- Physiology – From a physiological viewpoint, the cells of woody plants have lignified and are less subject to water stress in the autumn. This is unlike the succulent tissue typical of the spring. Shoot growth has stopped, yet functional leaves can still provide carbohydrates for root growth, which is capable of continuing until soil temperatures go below 40° F (4° C) at which point root growth stops. However, keep in mind that a dry autumn followed by a very cold winter can result in an increased mortality of autumn installed trees. Because of this, irrigation for newly installed trees in a dry autumn is as essential as water demands in a spring installation.
- Low Price – Another benefit to autumn installation is price. Some nurseries will lower their prices to sell leftover stock. However, avoid amazing bargains; if it dies, it is not a bargain.
- Sap Flow – Late autumn is the best time to install trees and shrubs because the sap has stopped rising.
Disadvantages
- Failure – Trees installed in autumn are more prone to winter failure than those installed in the spring, especially if the roots have not become established before the ground freezes. To minimize this problem, be sure to install the tree when there is at least one month for root growth before the soil temperature drops below 40° F (4° C).
Some deciduous trees have a higher survival rate when installed in spring. Trees with fleshy roots and thin barked trees are less successful when installed in the autumn. The following lists may be used as a guide when selecting woody plant material for autumn installations.
List of Trees Suitable for Autumn Installation
Acer spp. Maple
Aesculus spp. Buckeye
Amelanchier spp. Serviceberry
Celtis occidentalis Hackberry
Cercidiphyllum japonicum Katsura
Cercis canadensis Redbud
Fraxinus spp. Ash (install in non-EAB areas or resistant selections)
Ginkgo biloba Ginkgo
Gleditsia triacanthos spp. Honeylocust
Gymnocladus dioicus Kentucky Coffeetree
Juniperus spp. Juniper
Maclura pomifera Osage Orange
Malus spp. Crabapple (Check with local nurseries, as some locations say spring only)
Morus alba Mulberry
Phellodendron amurense Cork Tree
Pyrus calleryana Callery Pear
Robinia pseudoacacia Black Locust
Sophora japonica Japanese Pagoda Tree
Thuja occidentalis Arborvitae
Ulmus spp. Elm
Just be sure to install early enough so that the tree roots get a one month head start before the ground freezes.
List of Trees with a High Risk of Loss
Many nursery catalogs indicate certain trees have a high risk of failure if installed in autumn. If autumn installation is desired, use freshly dug or container stock to minimize the risk. Some of these risky trees are:
Betula spp. Birch
Carpinus spp. Hornbeam
Cornus florida Dogwood
Crataegus spp. Hawthorn
Koelreuteria paniculata Goldenraintree
Liquidambar spp. Sweet Gum
Liriodendron tulipifera Tulip Tree
Magnolia spp. Magnolia
Prunus spp. Flowering cherry
Taxus spp. Yews
Tilia spp. Linden
(Check with local nurseries, as some locations say autumn only)
List of Trees That Do Best with Spring Installation
Studies have determined that the tree species listed below will fail in autumn installations because the loss of roots interferes with the development of a tree's cold tolerance.
Abies spp. Fir
Carya spp. Hickory
Catalpa spp. Catalpa
Chamaecyparis nootkatensis Nootka Falsecypress
Cladrastis kentukea Yellowwood
Fagus sylvatica Beech
Juglans spp. Walnut
Larix spp. Larch
Nyssa sylvatica Tupelo, Sour Gum, Black Gum
Ostrya virginiana Hophornbeam
Oxydendrum arboreum Sourwood
Picea spp. Spruce (Check with local nurseries, as some locations say autumn only)
Pinus spp. Pine (Check with local nurseries, as some locations say autumn only)
Platanus spp. Plane Tree
Populus spp. Poplar, Aspen
Quercus spp. Oak
Salix spp. Willow
Sassafras albidum Sassafras
Sorbus aucuparia Mountain Ash
Taxodium distichum Bald Cypress
Tsuga canadensis Hemlock
Zelkova serrata Japanese Zelkova
Stretching Planting Funds
Many people consider municipal funding for tree management and installation as a pure luxury in the city budget and an item to be the first to cut when times are tough. This attitude is common because people see trees only as necessary for their beauty and have nothing to do with local government essentials such as improving public health, schools, and police.
Most recently arborists and landscape architects have been classifying trees as infrastructure and a solution to global warming. To some degree, this helps gain acceptance from public officials, but the municipal tree budgets are still low on the list of priorities.
With climate change on everyone's mind, people are looking for “green” solutions. Listed below are some ideas for getting more tree management funds within the limited municipal budget.
Cost Sharing Programs
The first step the municipal arborist or landscape architect must do is talk to the city budget director or treasurer to see if gifts can be accepted for use by the tree department to purchase and install trees within the city. The gifts should be tax deductible and specifically for installing trees on municipal property. With a gift tree fund set up, you can become very creative in ways to get more tree planting dollars.
Next, look at your own city and the various city budgets. Look at the line items and ask other city departments for funds to maintain trees on municipal properties such as the schools, the parks, the conservation properties. One of my favorites was to have the highway department pay the tree department for landscaping and maintaining their traffic islands. In a similar fashion, I liked to use parking meter receipts to cover the cost for tree and landscape enhancement and maintenance of the municipal parking lots. If you have private landowning organizations in the city, with the city finance director's approval, go to them with the same request.
You might have to ask for additional employees to do this additional work but the transfer of funds should be more than enough to cover your costs. By making the tree department important to other departments in the good times, trees become too important to cut in the bad times. Also, be creative with your employee assignments. I recall having one employee who became too ill to climb, but by assigning him to line clearing from the bucket truck, he continued to use his training and skills to work under the direction of the municipal electric company and was grateful he could keep working. Happy employees are also productive employees.
Many states and philanthropic organizations have funds available that can be used for installing trees on city property. Sometimes these funds require a match with the funds in your budget or funds already in the gift tree fund. Local citizens are sometimes willing to make donations for a specific installation project and will match city funds. Also, don’t be afraid to ask local corporate and civic organizations to contribute to your municipal tree planting fund especially if you can tie a tree installation effort into one of the organization’s projects. Garden clubs are a favorite group who like to plant trees. Many clubs have adopted city parks in need of beautification with flowers and new trees.
Alternative Funding Sources
Funds are often available from the US Forest Service that might be used for inventories, canopy mapping, installing trees, and sometimes even maintenance. Some cities are getting tree management funds from a wide range of grant programs. Also encourage your city to go after Complete Streets Program funds. While you are focused on federal grants, plan to spend a day at your computer studying grants.com for more ideas.
State and regional funds are also available for tree installation matching funds. Contact your state Urban Forestry Coordinator for more information. Also, make contact with special districts such as water districts, sewer districts, regional zoos or arboretums, shopping centers, colleges, and other large commercial or industrial complexes for financial support of beautification programs near their facilities that exist or are proposed.
Sometimes there are other city, state, or federal programs as well as private corporations who have set aside funds that are not directly related to tree installation, but may require landscaping as part of a development project. Be aware of these projects and be prepared to request that funds be available for installing street trees as a requirement for approval of the project. Also ask that the public trees growing adjacent to a project be pruned once or maintained in perpetuity by the developer. In a similar way, the city should require all local utility companies to replace all trees removed for line maintenance, near where the trees were removed. Alternative to this would be a cash donation from the utility to the municipal gift tree fund. In this case, let the utility know that only low-growing trees that would be installed under the overhead lines would be purchased, and these would not require any trimming past the first structural pruning.
Local groups such as garden clubs, Rotary and Kiwanis clubs and other civic organizations as well as private foundations, are often raising funds for local city improvement projects. Be involved with these groups to encourage beautification efforts so municipal trees become part of the project. Often simply mentioning the existence of a municipal tree planting fund will encourage private and corporation donations. Take advantage of your status as a public, non-profit agency, having professional staff and administrative support systems, when applying for private grants.
When an auto accident or large fire in the city has damaged public shade trees, seek insurance claims for reimbursement of the tree’s value. The funds can then be added to the tree installation fund for tree replacements during the next planting season.
By working with the planning board and other municipal departments, you can have a local code approved that will require that every tree removed for a development project be replaced elsewhere in the city. In a similar way, the city should require all local utility companies to replace all trees removed for line maintenance, near where the trees were removed. Alternative to this would be a cash donation from the utility to the municipal tree planting fund.
Many people also like to have a tree installed in memory of a loved one who was involved with the city or a civic organization. Sometimes the donor is willing to have an engraved stone or a bronze plaque placed at the base of the tree. Other times the donation should be noted in a gift remembrance book that is kept on public display. Publicizing this gift or dedicating the tree as part of the annual Arbor Day ceremony is a great way to encourage additional donations. These gift trees should be a bit larger and better than the normal trees purchased by the city. This effort usually encourages future gifts.
Once you have completed your tree inventory and prepared a street tree master plan, develop a 10-year environmental improvement plan to install “x” number of trees every year. By making this a justifiable capital project in the master plan, you should be able to more easily convince the city leaders to approve and fund this long-term capital improvement project.
Stormwater utility fees are now being assessed to all property owners to deal with stormwater management. The investment in installing and maintaining trees is an acceptable use of these funds.
Revenue sharing is still alive in many cities. This program usually helps the departments that have been underfunded.
Reimbursements
When an auto accident or large fire in the city has damaged public shade trees, you should write insurance claims for reimbursement of the tree’s property value or to pay for the tree's repair and maintenance, and have a contractor come in to do the job instead of using your own tree crews. If the tree is a total loss, add the funds to the tree gift fund for tree replacements during the next planting season and use the money to purchase more trees than are budgeted.
City employees should be reimbursed for the time they spend reviewing applications and inspecting city issued permits. This reimbursement should be included as a part of the permit fee.
Resident Options
By considering any of the following options, not only is there a chance of freeing up funds for additional tree purchases, but you can also build positive public relations with your city’s residents.
Tips for Getting a Lower Cost
By taking advantage of quantity discounts you may have to reduce the number of varieties you want, but the lower price allows the purchase of more trees. If you are coming up short in the numbers, try to combine your order with other departments and other cities to earn the quantity discounts. If you have a good relationship with the nurseries you often do business with, you might be able to take advantage of nursery overstock and accept trees as gifts or at a very low cost. These extra trees are very suitable for parks and conservation properties. Keep in mind that if you cannot get what you want this spring, there is always next year.
Try new varieties to learn about better and sometimes less expensive trees. Every once in a while, a tree comes along that does very well in your city and you are able to purchase them at better prices than what you usually spend. Sometimes you find a new tree that turns out to be unpopular, but the nursery grew more that it could sell. You may get them at a lower than normal cost.
Nurseries are also willing to offer discounts if they know they can sell a particular tree when it reaches the right size. So, if your city and local laws allow, write a long-term growers contract with a nursery to provide your list of trees in 3 or 4 years. Even if a bid is necessary, have 3 nurseries bid on the contract and select the one that grows the best trees. If you are required to bid for all trees consider this option.
One major cost saving tip is to install bare root trees, which are often half the cost of B&B trees. Bare root trees are easy the volunteers to install as well. Contractors will charge half to one-third the cost of installing B&B if they are installing bare root.
Planting smaller trees are less expensive than large trees, not only in the purchase price, but the planting price as well. Plus, the smaller trees will recover from the transplant shock much faster than the larger tree. From personal experience, I have seen a 1-1/2 inch (4 cm) diameter BR tree, out-grow a 4 inch (10 cm) B&B tree in 4 years.
If watering is included in the tree installation cost, use water bags to reduce watering time and cost after the installation. The water bags not only provide water at the desirable slow drip, they fill up in a few minutes. Keep track of how many trees a person can water in a day in your current program, then see how much time is saved with the water bags. Plus, the water bags can be reused for several years. Depending on your budget system, if the watering is paid out of the tree planting fund, then the money saved is available to install additional trees.
Most cities require all purchases to be made by bidding. However, there is usually a quote system that applies to small purchases. If each tree is considered a separate item, you may be able to obtain quotes for each tree separately and each size of tree quoted by the installation contractor. Quoted prices are usually lower than bid prices. The first year I did that, I was able to plant a hundred more trees the following year after using a contractor who bid the entire tree purchase and planting. For more information on this program see “A Tree Planting Program That Works”.
Long Term Ideas
One long term idea requires the use of a city-owned vacant lot to install a diverse forest of trees using low-cost whips from a wholesale nursery. This idea will require a minimal level of municipal staff or volunteers until the trees reach a size that will survive transplanting onto the city streets. When transplanting the trees over a series of years, be sure to leave enough growing on the vacant lot to create a long-term forest filled with a diversity of species.
Here are a couple of ideas that will require a new policy. The first idea will require residents wanting a public tree removed to provide funds to replant the tree elsewhere in the city. If you have access to a company that specializes in tree spade work, many homeowners will pay to dispose of unwanted trees. The second idea is similar but pertains to trees on private property. This would be a new law or regulation that requires a permit to remove trees on private property. A fee system for the permit would provide some funds for additional tree planting somewhere else or the law could require tree replacement one for one on another property. The payment would cover the cost of having the tree spade remove the tree and plant it on city property.
One great grassroots program is in Greenpoint Brooklyn - the home of the original ALB infestation. It's the Greenpoint Tree Corps and it was initiated by a Greenpoint resident. They primarily do tree pit care - mulching (lots of kids involved with this), removal of weeds, adding compost, planting small rooting perennials. They developed a brochure entitled Tree Bed Care 101 which covers all the specifics. They have also facilitated the enlarging of tree pit openings through their advocacy in the community. They rely on partner organizations such as the North Brooklyn Parks Alliance for technical assistance and materials such as mulch and tools.
Finally, many cities have chosen to sell their urban wood, wood chips, and composted leaves generated by the tree department. The revenue from the sales can be placed in the tree installation fund to be used for purchasing additional trees the following year.
Many people consider municipal funding for tree management and installation as a pure luxury in the city budget and an item to be the first to cut when times are tough. This attitude is common because people see trees only as necessary for their beauty and have nothing to do with local government essentials such as improving public health, schools, and police.
Most recently arborists and landscape architects have been classifying trees as infrastructure and a solution to global warming. To some degree, this helps gain acceptance from public officials, but the municipal tree budgets are still low on the list of priorities.
With climate change on everyone's mind, people are looking for “green” solutions. Listed below are some ideas for getting more tree management funds within the limited municipal budget.
Cost Sharing Programs
The first step the municipal arborist or landscape architect must do is talk to the city budget director or treasurer to see if gifts can be accepted for use by the tree department to purchase and install trees within the city. The gifts should be tax deductible and specifically for installing trees on municipal property. With a gift tree fund set up, you can become very creative in ways to get more tree planting dollars.
Next, look at your own city and the various city budgets. Look at the line items and ask other city departments for funds to maintain trees on municipal properties such as the schools, the parks, the conservation properties. One of my favorites was to have the highway department pay the tree department for landscaping and maintaining their traffic islands. In a similar fashion, I liked to use parking meter receipts to cover the cost for tree and landscape enhancement and maintenance of the municipal parking lots. If you have private landowning organizations in the city, with the city finance director's approval, go to them with the same request.
You might have to ask for additional employees to do this additional work but the transfer of funds should be more than enough to cover your costs. By making the tree department important to other departments in the good times, trees become too important to cut in the bad times. Also, be creative with your employee assignments. I recall having one employee who became too ill to climb, but by assigning him to line clearing from the bucket truck, he continued to use his training and skills to work under the direction of the municipal electric company and was grateful he could keep working. Happy employees are also productive employees.
Many states and philanthropic organizations have funds available that can be used for installing trees on city property. Sometimes these funds require a match with the funds in your budget or funds already in the gift tree fund. Local citizens are sometimes willing to make donations for a specific installation project and will match city funds. Also, don’t be afraid to ask local corporate and civic organizations to contribute to your municipal tree planting fund especially if you can tie a tree installation effort into one of the organization’s projects. Garden clubs are a favorite group who like to plant trees. Many clubs have adopted city parks in need of beautification with flowers and new trees.
Alternative Funding Sources
Funds are often available from the US Forest Service that might be used for inventories, canopy mapping, installing trees, and sometimes even maintenance. Some cities are getting tree management funds from a wide range of grant programs. Also encourage your city to go after Complete Streets Program funds. While you are focused on federal grants, plan to spend a day at your computer studying grants.com for more ideas.
State and regional funds are also available for tree installation matching funds. Contact your state Urban Forestry Coordinator for more information. Also, make contact with special districts such as water districts, sewer districts, regional zoos or arboretums, shopping centers, colleges, and other large commercial or industrial complexes for financial support of beautification programs near their facilities that exist or are proposed.
Sometimes there are other city, state, or federal programs as well as private corporations who have set aside funds that are not directly related to tree installation, but may require landscaping as part of a development project. Be aware of these projects and be prepared to request that funds be available for installing street trees as a requirement for approval of the project. Also ask that the public trees growing adjacent to a project be pruned once or maintained in perpetuity by the developer. In a similar way, the city should require all local utility companies to replace all trees removed for line maintenance, near where the trees were removed. Alternative to this would be a cash donation from the utility to the municipal gift tree fund. In this case, let the utility know that only low-growing trees that would be installed under the overhead lines would be purchased, and these would not require any trimming past the first structural pruning.
Local groups such as garden clubs, Rotary and Kiwanis clubs and other civic organizations as well as private foundations, are often raising funds for local city improvement projects. Be involved with these groups to encourage beautification efforts so municipal trees become part of the project. Often simply mentioning the existence of a municipal tree planting fund will encourage private and corporation donations. Take advantage of your status as a public, non-profit agency, having professional staff and administrative support systems, when applying for private grants.
When an auto accident or large fire in the city has damaged public shade trees, seek insurance claims for reimbursement of the tree’s value. The funds can then be added to the tree installation fund for tree replacements during the next planting season.
By working with the planning board and other municipal departments, you can have a local code approved that will require that every tree removed for a development project be replaced elsewhere in the city. In a similar way, the city should require all local utility companies to replace all trees removed for line maintenance, near where the trees were removed. Alternative to this would be a cash donation from the utility to the municipal tree planting fund.
Many people also like to have a tree installed in memory of a loved one who was involved with the city or a civic organization. Sometimes the donor is willing to have an engraved stone or a bronze plaque placed at the base of the tree. Other times the donation should be noted in a gift remembrance book that is kept on public display. Publicizing this gift or dedicating the tree as part of the annual Arbor Day ceremony is a great way to encourage additional donations. These gift trees should be a bit larger and better than the normal trees purchased by the city. This effort usually encourages future gifts.
Once you have completed your tree inventory and prepared a street tree master plan, develop a 10-year environmental improvement plan to install “x” number of trees every year. By making this a justifiable capital project in the master plan, you should be able to more easily convince the city leaders to approve and fund this long-term capital improvement project.
Stormwater utility fees are now being assessed to all property owners to deal with stormwater management. The investment in installing and maintaining trees is an acceptable use of these funds.
Revenue sharing is still alive in many cities. This program usually helps the departments that have been underfunded.
Reimbursements
When an auto accident or large fire in the city has damaged public shade trees, you should write insurance claims for reimbursement of the tree’s property value or to pay for the tree's repair and maintenance, and have a contractor come in to do the job instead of using your own tree crews. If the tree is a total loss, add the funds to the tree gift fund for tree replacements during the next planting season and use the money to purchase more trees than are budgeted.
City employees should be reimbursed for the time they spend reviewing applications and inspecting city issued permits. This reimbursement should be included as a part of the permit fee.
Resident Options
By considering any of the following options, not only is there a chance of freeing up funds for additional tree purchases, but you can also build positive public relations with your city’s residents.
- Offer trees to be installed in front of a resident’s home on a 50/50 cost share with the city. This means that the resident will pay to maintain the tree, while the city will purchase and install the tree. One option to this concept would be that a resident can add funds if they want a tree larger than what is being provided by the city. This option will also work even if the city is paying the entire cost, but the resident wants a larger tree.
- Stormwater utility fees are now being assessed to all property owners to deal with stormwater management. The investment in installing and maintaining trees is an acceptable use of these funds.
- Some cities will allow residents to volunteer to install trees and perform maintenance duties, so municipal labor funds can be used to purchase additional trees. Some of these volunteer programs have become very popular. In every case, the volunteer must attend a Saturday morning training session, so they know how to properly install a tree. This is especially important if the volunteers are installing “light weight and easy to install” bare root trees.
- The cities that offer pruning programs for volunteers require a whole day training session, including hands on pruning. These pruning programs do not allow any tree climbing. The focus is on trimming trees that were installed within the past 5 years. The intent is to be sure the trees have a proper structural pruning for a long-term vigorous tree that requires very little maintenance as it matures.
Tips for Getting a Lower Cost
By taking advantage of quantity discounts you may have to reduce the number of varieties you want, but the lower price allows the purchase of more trees. If you are coming up short in the numbers, try to combine your order with other departments and other cities to earn the quantity discounts. If you have a good relationship with the nurseries you often do business with, you might be able to take advantage of nursery overstock and accept trees as gifts or at a very low cost. These extra trees are very suitable for parks and conservation properties. Keep in mind that if you cannot get what you want this spring, there is always next year.
Try new varieties to learn about better and sometimes less expensive trees. Every once in a while, a tree comes along that does very well in your city and you are able to purchase them at better prices than what you usually spend. Sometimes you find a new tree that turns out to be unpopular, but the nursery grew more that it could sell. You may get them at a lower than normal cost.
Nurseries are also willing to offer discounts if they know they can sell a particular tree when it reaches the right size. So, if your city and local laws allow, write a long-term growers contract with a nursery to provide your list of trees in 3 or 4 years. Even if a bid is necessary, have 3 nurseries bid on the contract and select the one that grows the best trees. If you are required to bid for all trees consider this option.
One major cost saving tip is to install bare root trees, which are often half the cost of B&B trees. Bare root trees are easy the volunteers to install as well. Contractors will charge half to one-third the cost of installing B&B if they are installing bare root.
Planting smaller trees are less expensive than large trees, not only in the purchase price, but the planting price as well. Plus, the smaller trees will recover from the transplant shock much faster than the larger tree. From personal experience, I have seen a 1-1/2 inch (4 cm) diameter BR tree, out-grow a 4 inch (10 cm) B&B tree in 4 years.
If watering is included in the tree installation cost, use water bags to reduce watering time and cost after the installation. The water bags not only provide water at the desirable slow drip, they fill up in a few minutes. Keep track of how many trees a person can water in a day in your current program, then see how much time is saved with the water bags. Plus, the water bags can be reused for several years. Depending on your budget system, if the watering is paid out of the tree planting fund, then the money saved is available to install additional trees.
Most cities require all purchases to be made by bidding. However, there is usually a quote system that applies to small purchases. If each tree is considered a separate item, you may be able to obtain quotes for each tree separately and each size of tree quoted by the installation contractor. Quoted prices are usually lower than bid prices. The first year I did that, I was able to plant a hundred more trees the following year after using a contractor who bid the entire tree purchase and planting. For more information on this program see “A Tree Planting Program That Works”.
Long Term Ideas
One long term idea requires the use of a city-owned vacant lot to install a diverse forest of trees using low-cost whips from a wholesale nursery. This idea will require a minimal level of municipal staff or volunteers until the trees reach a size that will survive transplanting onto the city streets. When transplanting the trees over a series of years, be sure to leave enough growing on the vacant lot to create a long-term forest filled with a diversity of species.
Here are a couple of ideas that will require a new policy. The first idea will require residents wanting a public tree removed to provide funds to replant the tree elsewhere in the city. If you have access to a company that specializes in tree spade work, many homeowners will pay to dispose of unwanted trees. The second idea is similar but pertains to trees on private property. This would be a new law or regulation that requires a permit to remove trees on private property. A fee system for the permit would provide some funds for additional tree planting somewhere else or the law could require tree replacement one for one on another property. The payment would cover the cost of having the tree spade remove the tree and plant it on city property.
One great grassroots program is in Greenpoint Brooklyn - the home of the original ALB infestation. It's the Greenpoint Tree Corps and it was initiated by a Greenpoint resident. They primarily do tree pit care - mulching (lots of kids involved with this), removal of weeds, adding compost, planting small rooting perennials. They developed a brochure entitled Tree Bed Care 101 which covers all the specifics. They have also facilitated the enlarging of tree pit openings through their advocacy in the community. They rely on partner organizations such as the North Brooklyn Parks Alliance for technical assistance and materials such as mulch and tools.
Finally, many cities have chosen to sell their urban wood, wood chips, and composted leaves generated by the tree department. The revenue from the sales can be placed in the tree installation fund to be used for purchasing additional trees the following year.
Living Mulch
In the practice of general plant care, a living mulch is a ground cover plant growing at the base of a tree. Living mulches are sometimes used at locations where the tree is growing in a sidewalk cut-out and the living mulch (plants) are growing around the tree. The living mulch is intended to beautify and replace the need for a tree grate or conventional mulch by using plants to provide weed suppression, control of the soil temperature, and a visual means to discourage people from walking close to the tree and causing soil compaction. Living mulches can reduce water runoff and erosion, and filter surface water runoff for use by the tree. Living mulches have also been shown to increase the population of organisms which enhance the quality of the soil, which in turn, benefits the tree. Living mulches are intended to grow for many years in harmony with the tree. Opponents of this concept believe the living mulch robs the tree of soil moisture, nutrients, and microorganisms. But the fact is that these plants actually help the tree by preventing evaporation of soil moisture and converting nutrients into forms that are useful for the tree.
Plant selection for creating a living mulch is not an easy task. While just about any plant might grow in harmony with a tree in a conventional landscape, very few will thrive living in the sidewalk cutout surrounded by concrete or sun-heated bituminous pavement. The planting of the ground covers may occur anytime including right after the tree has been installed. The plants should be planted on a grade of no more than 1 inch (2.5 cm) below the sidewalk elevation to hold runoff water for the plants and the tree. The living mulch plants should be carefully placed around the outside edge of the sidewalk cutout to avoid any conflict with the newly developing tree roots and the underground root stabilizing system.
Never plant anything within 12" (30 cm) of the flare. No part of the tree's trunk and bark should ever be covered with anything that retains moisture. Doing so encourages rot. In addition, any planting of small ground covers needs to be done carefully so as not to damage the existing tree's roots. Open areas should still be mulched with composted wood chips so the soil is never left bare from the sidewalk to the flare.
Most Desirable Living Mulches
The following, in this author's opinion, are the best living mulches because they are vigorous ground covers and will tolerate pedestrian traffic, winter snowplow damage, and erratic weather conditions:
White clover Trifolium repens - Clovers with their deep roots, provide resistance to soil compaction. Legume living mulches also have some important positive effects on the nutrient cycling that benefit the tree. For example, clover fixes the atmospheric nitrogen that is important for tree growth and it is effective for enhancing and recycling the soil's nutrients. Clover has the ability to grow in sun or shade, maintain a low profile, thrive if repeatedly mowed and it will withstand foot traffic. It is considered by many as the best choice for a living mulch. In established stands, it also may provide some nitrogen suitable for use by the tree.
Vinca Vinca minor – Vinca does well in all light conditions and, once established, is fairly tolerant of a less than desirable site and soil conditions. Vinca is a shallow rooted creeper that tolerates soil compaction and pedestrian foot traffic, once it is established. It should be planted with quart size plants that have large root systems to reduce the time for the plant to become established. These larger plants are quite developed and fewer plants are needed so there's a lot less disturbance in the sidewalk cutout area. Impact on the tree is minimal.
Creepers
Creepers are plants that can grow to cover the soil from the outside edge of the sidewalk cutout where there is more light, and they may grow toward the trunk of the tree with time. These are all shallow rooted perennials with roots in the top 6 inches (15 cm) of soil, and therefore, above the tree's main roots. They are all tolerant of varying sun exposures. Creepers do require weeding and extra water for the first few years but once established, the plants look outstanding all year. All the plants cool the roots and discourage any compacting foot traffic. Reports indicate that there has to be some assumed nutrient competition between tree and the ground cover but these reports also indicate that both the tree and the creepers appear to be living in harmony. Some of the best creepers for this function, include:
Undesirable Living Mulches
Not only are the plants listed below considered invasive in many locations, they can also cause moisture retention, root rot, and other problems for the tree. Many of these plants can also climb over the entire tree. NOT recommended are:
Annuals – Growing annuals under young trees is the exception to the application of beneficial living mulches. Annuals are aggressive growers and they can cause growth reduction to the tree because of the competition for soil nutrients. In addition, planting of annuals causes consistent damage to the tree's roots. Annuals also need lots of water and weekly maintenance.
Shrubs – Often young trees have been installed and combined with nice flowering shrubs. Over time the trees will win the competition and the shrubs look terrible and need to be removed, so they are not a good choice in the sidewalk cut out areas.
Juniperus horizontalis – Creeping Juniper is a very popular group of junipers that require a lot of maintenance to keep them from growing over the flare and sidewalk, while also encouraging pest and disease problems causing harm to the tree. These problems are in addition to the problems mentioned above, with annuals and shrubs.
Caution
Not all trees are created equal. Each requires specific light, soil, and moisture conditions to survive and remain healthy. Some tree species are extremely sensitive to major soil disturbance. Installing living mulch beneath trees that are sensitive to having their roots disturbed may necessitate having the living mulch scaled back or carried out over a few years.
In the practice of general plant care, a living mulch is a ground cover plant growing at the base of a tree. Living mulches are sometimes used at locations where the tree is growing in a sidewalk cut-out and the living mulch (plants) are growing around the tree. The living mulch is intended to beautify and replace the need for a tree grate or conventional mulch by using plants to provide weed suppression, control of the soil temperature, and a visual means to discourage people from walking close to the tree and causing soil compaction. Living mulches can reduce water runoff and erosion, and filter surface water runoff for use by the tree. Living mulches have also been shown to increase the population of organisms which enhance the quality of the soil, which in turn, benefits the tree. Living mulches are intended to grow for many years in harmony with the tree. Opponents of this concept believe the living mulch robs the tree of soil moisture, nutrients, and microorganisms. But the fact is that these plants actually help the tree by preventing evaporation of soil moisture and converting nutrients into forms that are useful for the tree.
Plant selection for creating a living mulch is not an easy task. While just about any plant might grow in harmony with a tree in a conventional landscape, very few will thrive living in the sidewalk cutout surrounded by concrete or sun-heated bituminous pavement. The planting of the ground covers may occur anytime including right after the tree has been installed. The plants should be planted on a grade of no more than 1 inch (2.5 cm) below the sidewalk elevation to hold runoff water for the plants and the tree. The living mulch plants should be carefully placed around the outside edge of the sidewalk cutout to avoid any conflict with the newly developing tree roots and the underground root stabilizing system.
Never plant anything within 12" (30 cm) of the flare. No part of the tree's trunk and bark should ever be covered with anything that retains moisture. Doing so encourages rot. In addition, any planting of small ground covers needs to be done carefully so as not to damage the existing tree's roots. Open areas should still be mulched with composted wood chips so the soil is never left bare from the sidewalk to the flare.
Most Desirable Living Mulches
The following, in this author's opinion, are the best living mulches because they are vigorous ground covers and will tolerate pedestrian traffic, winter snowplow damage, and erratic weather conditions:
White clover Trifolium repens - Clovers with their deep roots, provide resistance to soil compaction. Legume living mulches also have some important positive effects on the nutrient cycling that benefit the tree. For example, clover fixes the atmospheric nitrogen that is important for tree growth and it is effective for enhancing and recycling the soil's nutrients. Clover has the ability to grow in sun or shade, maintain a low profile, thrive if repeatedly mowed and it will withstand foot traffic. It is considered by many as the best choice for a living mulch. In established stands, it also may provide some nitrogen suitable for use by the tree.
Vinca Vinca minor – Vinca does well in all light conditions and, once established, is fairly tolerant of a less than desirable site and soil conditions. Vinca is a shallow rooted creeper that tolerates soil compaction and pedestrian foot traffic, once it is established. It should be planted with quart size plants that have large root systems to reduce the time for the plant to become established. These larger plants are quite developed and fewer plants are needed so there's a lot less disturbance in the sidewalk cutout area. Impact on the tree is minimal.
Creepers
Creepers are plants that can grow to cover the soil from the outside edge of the sidewalk cutout where there is more light, and they may grow toward the trunk of the tree with time. These are all shallow rooted perennials with roots in the top 6 inches (15 cm) of soil, and therefore, above the tree's main roots. They are all tolerant of varying sun exposures. Creepers do require weeding and extra water for the first few years but once established, the plants look outstanding all year. All the plants cool the roots and discourage any compacting foot traffic. Reports indicate that there has to be some assumed nutrient competition between tree and the ground cover but these reports also indicate that both the tree and the creepers appear to be living in harmony. Some of the best creepers for this function, include:
- Ajuga – Ajuga reptans
- Peanut – Arachis repens
- Epimedium – Epimedium
- Wild Woodland Strawberry – Fragaria vesca
- Coral Bells – Heuchera spp.
- Mini and dwarf Hosta vareities – Hosta spp.
- Yellowroot (Golden Seal) – Hydrastis canadensis
- Liriope – Liriope muscari
- Cupflower – Mazus repens
- Pachysandra – Pachysandra
- Ginseng – Panax quinquefolius
- Woodland Phlox – Phlox divaricata
- Stonecrop – Sedum spp.
- Comfrey – Symphytum officinale
- Creeping Thyme – Thymus serpyllum
- Turkish Speedwell – Veronica liwanensis
- Barren Strawberry – Waldsteinia ternata
- Hardy Ferns – Several species are suitable for living mulch, especially in somewhat shady areas.
Undesirable Living Mulches
Not only are the plants listed below considered invasive in many locations, they can also cause moisture retention, root rot, and other problems for the tree. Many of these plants can also climb over the entire tree. NOT recommended are:
- Porcelain Berry – Ampelopsis brevipedunculata
- Climbing Euonymus – Euonymus fortunei
- English Ivy – Hedera helix
- Kudzu– Pueraria lobata
- Bittersweet – Solanum dulcamara
- Poison Ivy – Toxicodendron radicans
- Grape – Vitis spp.
- Wisteria – Wisteria spp.
Annuals – Growing annuals under young trees is the exception to the application of beneficial living mulches. Annuals are aggressive growers and they can cause growth reduction to the tree because of the competition for soil nutrients. In addition, planting of annuals causes consistent damage to the tree's roots. Annuals also need lots of water and weekly maintenance.
Shrubs – Often young trees have been installed and combined with nice flowering shrubs. Over time the trees will win the competition and the shrubs look terrible and need to be removed, so they are not a good choice in the sidewalk cut out areas.
Juniperus horizontalis – Creeping Juniper is a very popular group of junipers that require a lot of maintenance to keep them from growing over the flare and sidewalk, while also encouraging pest and disease problems causing harm to the tree. These problems are in addition to the problems mentioned above, with annuals and shrubs.
Caution
Not all trees are created equal. Each requires specific light, soil, and moisture conditions to survive and remain healthy. Some tree species are extremely sensitive to major soil disturbance. Installing living mulch beneath trees that are sensitive to having their roots disturbed may necessitate having the living mulch scaled back or carried out over a few years.
Tree Stats
It is time for all the arborists and landscape architects who are sports fans to look at a tree’s statistics when they have finished looking at their team and player stats. The following is a compilation of many items that illustrate the stats of a tree.
Benefits and products provided by tree leaves:
Tree flowers provide:
Tree fruits can produce:
Products and aesthetic value provided by tree bark:
Tree roots are useful for the obvious benefit to the tree and they also:
Tree wood will provide:
Trees exchange oxygen and carbon dioxide at the following approximate rates:
Trees can live for an average of:
The oldest living individual tree in the world is a bristlecone pine (Pinus longaeva) with a confirmed age of 5,062 years old. It is located in California's White Mountains.
A tree’s location beside a house will provide the following benefits:
City trees grow best with:
Trees in groups will:
Aesthetic value provided by trees:
Psychological value provided by trees:
Negative affects of trees:
At time of installation, trees need:
Trees consist of approximately:
Sources
The test that follows contains 80 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 4.0 CEUs* for a passing grade. SAF members will earn 1.0 Cat. 1-CT credit for a passing grade. The cost for taking this test is $20 per credit. 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. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 4 CEUs toward Certified Arborist, 2.5 CEUs toward Utility Specialist, 4 CEUs toward Municipal Specialist, 2.5 CEUs toward Tree Worker Specialist, 2.5 CEUs toward Aerial Lift Specialist,2.5 CEUs toward BCMA practice credits,1.25 toward BCMA-Management, or 1 toward BCMA-Science.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA and MTOA members may submit your ISA certification record to these organizations and receive credits one for one.
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.
It is time for all the arborists and landscape architects who are sports fans to look at a tree’s statistics when they have finished looking at their team and player stats. The following is a compilation of many items that illustrate the stats of a tree.
Benefits and products provided by tree leaves:
- tea,
- medicines such as aspirin ingredients that come from the bark of willow trees,
- cellulose fiber,
- seasonal color,
- fragrance,
- mulberry leaves and silk worms produce silk thread,
- various shapes identify species,
- dust and pollutant filtration,
- cool air currents in hot weather,
- provide a reduction to the formation of ozone,
- 1000 cubic yards of leaves will eventually become about 200 cubic yards of composted leaf mold.
Tree flowers provide:
- beauty,
- fragrance,
- herbal tinctures,
- pollen for butterflies and bees,
- seeds to perpetuate the species and provide food for many living creatures.
Tree fruits can produce:
- fruits and juices such as apples, pears, apricots, oranges, grapefruits, peaches, bananas, mangoes, persimmons, plums, and apricots,
- edible nuts such as walnuts, pecans, hickories, almonds, pistachios, etc.
- products from nuts such as cocoa and olive oil,
- berries such as quinine from the cinchona tree, wine from the serviceberry (Amelanchier) and gin from the juniper.
Products and aesthetic value provided by tree bark:
- spices such as cinnamon and nutmeg,
- olive oil,
- rubber,
- taxol,
- maple syrup,
- turpentine,
- thorns, furrows, exfoliation, textures, and colors.
Tree roots are useful for the obvious benefit to the tree and they also:
- enrich the soil,
- reduce erosion,
- hold the soil to prevent landslides,
- intercept rainwater runoff up to 12% for an average size tree,
- total 15 to 20 cubic feet (4.2 – 5.5 cubic meters) of roots per square foot of surface area,
- a 40 feet (12 m) tall tree’s roots will absorb 50 gallons (190 liter) of dissolved nutrients and convert it with sunlight to 100 pounds (45 kg) of food and 60 cubic feet (1.7 cubic meters) of oxygen.
Tree wood will provide:
- firewood,
- paper,
- food,
- wildlife food, shelter, and habitat,
- lumber products,
- branches that are fun to climb,
- a sturdy material, that pound for pound is stronger than steel.
Trees exchange oxygen and carbon dioxide at the following approximate rates:
- one average tree takes in 13 to 26 pounds (6 – 12kg) of carbon dioxide in a year and gives off enough oxygen to keep 4 people breathing in a year,
- 2.47 average trees transpire 4,000 gallons (15,000 liters) of water a day,
- one average tree can lift and transpire one ton of water every summer day,
- this same average tree can lift water up its trunk at a rate of 150 feet (46m) per hour,
- a 1,000 square feet (94 square meters) plot of trees absorbs 1.2 million calories of heat energy that equates to air conditioning for 2 houses,
- 20 trees offset the pollution of driving a car for 60 miles (100K),
- a 30-inch (0.75 m) dbh tree provides 70 times the ecological benefits of a 3-inch (7.5 cm) dbh tree.
Trees can live for an average of:
- 100 – 200 years in a forest,
- 25 – 50 years in the suburbs,
- 7 – 10 years in an urban installation site.
The oldest living individual tree in the world is a bristlecone pine (Pinus longaeva) with a confirmed age of 5,062 years old. It is located in California's White Mountains.
A tree’s location beside a house will provide the following benefits:
- reduce air conditioning needs by 15% to 50%,
- reduce winter heating needs by 4% – 22%,
- lower the urban heat island by 3° – 5°F (1° – 2.6°C),
- cool the rooms of a house by 20°F (11°C),
- cool bare ground beneath a tree by 35°F (20°C),
- increase the value of living space by US$4 per square foot,
- increase a home’s value by 6% – 10% and land value by 7%,
- reduce the light intensity in winter by 20% – 75%, depending on the species,
- reduce fog 6 – 10 times more effectively than grass,
- absorb 50 pounds (22.3 kg) of airborne particulates per year,
- trees growing on streets absorb 4 times more airborne particulates than on streets without trees.
City trees grow best with:
- no use of string trimmers, mowers, plants or mulch within 6 – 8 inches (20 cm.) of the trunk flare.
- mulch applied 2 – 3 inches (5-7 cm) thick and 1 – 2 inches (2.5–5 cm.) of new mulch each year, keeping the trunk flare revealed.
- understory companion plants and other trees. The tallest tree in the world is a coast redwood (Sequoia sempervirens), named Hyperion. It is measured at 379.3 ft (115.61 m) and is growing among many other redwoods in northern California.
- The loneliest tree in the world is a Sitka spruce. This tree is located about 400 miles (643 km) south of New Zealand. There, on the subantarctic Campbell Island named Motu Ihupuku, stands a Sitka spruce whose nearest neighbor is 170 miles (273 km) away.
Trees in groups will:
- form a windbreak or shelter break which will slow wind speed by as much as 50%.
- create windbreaks which will increase snow accumulation just beyond the windbreak.
- form windbreaks which will cause heavy air particles to drop out of the air flow.
- hide and diffuse noise by 6 – 8 decibels for every 100 feet (30 m) of buffer.
Aesthetic value provided by trees:
- color, form, texture, and pattern,
- softer architecture and road appearance,
- vistas and focal points,
- define spaces,
- screen views,
- direct pedestrians and traffic,
- reduce glare from lights,
- provide shade, fragrance, and a quiet setting,
- provide psithurism (the sound of wind blowing through a forest),
- emphasize the seasons.
Psychological value provided by trees:
- cleaner air,
- faster healing,
- improved morale,
- sentimental trees,
- living memorials,
- human well-being,
- increased productivity,
- a sense of community, pride, and responsibility.
Negative affects of trees:
- susceptible to storm damage,
- potential source for grounding lightning strikes,
- potential obstacle for vehicle damage,
- roots clog broken pipes, lift cracked sidewalks, and damage wet foundations,
- require pruning for utility service, viewing signage, and safety clearance,
- pollen from wind pollinated male flowers may cause allergic reaction,
- leaves, fruit, and flowers may require clean up,
- suckers and dead branches may require constant removal,
- maintenance costs for pruning, watering, pest control, etc.
- for every 4 trees that are cut down in the United States, one tree is replaced.
At time of installation, trees need:
- 5 square feet (4.5 s. meters) of soil area for each square inch (6.5 s.cm.) of trunk at breast height,
- suitable soil at least 30 inches (0.75 m.) deep,
- 1,000 cubic feet (30 c. meters) of soil to thrive in a parking lot,
- a minimum of 2 cubic feet (0.06 cm) of soil for every square foot (0.1 sm) of the future crown projection or 4 square feet (4.4 sm) of surface area for every inch (2.5 cm) of trunk diameter the tree is expected to attain,
- a minimum of 700 cubic feet (20 c. meters) of soil for large trees,
- a minimum of 500 cubic feet (14 c. meters) of soil for medium trees,
- a minimum of 300 cubic feet (8 c. meters) of soil for small trees,
- an ideal soil has 50% pore space, divided between air-filled and water-filled pores, 45% is composed of mineral materials, and 5% organic material,
- fungi in the soil to promote tree root growth,
- wire basket removed at installation time,
- guy wires or stakes removed after one season,
- root stabilizers at the time of installation never need removal.
Trees consist of approximately:
- 5% leaves,
- 15% twigs,
- 60% trunk,
- 15% buttress roots,
- 5% absorbing roots.
Sources
- Special thanks to the members of LinkedIn’s Urban Forestry Discussion Group for providing many of these ideas.
- Daley, Richard, ‘Tree-mendous Facts”, Greenstreets, City of Chicago, 1998.
- “Fall Planting”, Long Island Horticultural News, October 1994.
- Gerhold, Henry D. PhD, “Fall Planting”, City Trees, The Journal of the Society of Municipal Arborists, Vol. 30 No. 6.
- Gulick, Jennifer, “Budgeting and Funding 101”, Public Works, March 2016.
- Harris, Richard W., “Arboriculture – Care of Trees, Shrubs, and Vines in the Landscape”, Prentice-Hall, Inc. Englewood Cliffs, NJ.
- Perry, Thomas, “Typical Tree Roots and How to Examine Them”, City Trees, January, February, 1994.
- Phillips, Leonard, “The Value of a Tree”, City Trees, July/August 1992.
- Sarcule, Mac, “Autumn Tree Planting”, True Soil Blog, September 3, 2007.
The test that follows contains 80 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 4.0 CEUs* for a passing grade. SAF members will earn 1.0 Cat. 1-CT credit for a passing grade. The cost for taking this test is $20 per credit. 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. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 4 CEUs toward Certified Arborist, 2.5 CEUs toward Utility Specialist, 4 CEUs toward Municipal Specialist, 2.5 CEUs toward Tree Worker Specialist, 2.5 CEUs toward Aerial Lift Specialist,2.5 CEUs toward BCMA practice credits,1.25 toward BCMA-Management, or 1 toward BCMA-Science.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA and MTOA members may submit your ISA certification record to these organizations and receive credits one for one.
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.