planting trees
Center for Watershed Protection
in urban areas
USDA Forest Service, Northeastern Area, State and Private Forestry
Slideshow Content
• Site assessment for urban tree planting
• Basic planting design
• Special considerations for urban tree
planting
• Site preparation
• Planting and maintenance techniques
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Site Assessment for Urban Tree
Planting
• Collect detailed information about
conditions at previously identified
planting sites
• Use information to: develop planting
plan, determine what to plant, where to
plant and what special methods are
needed to reduce urban impacts on
trees
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Impacts of Urbanization on Trees
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Air pollution
Poor soils
Exposure to wind
Drought
Flooding/standing
water
• Increased
temperature
• Competition
Center for Watershed Protection
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Disease
Damage from humans
Damage from animals
Salt from roads
Inadequate soil
volume
• Improper maintenance
• Conflicts with
infrastructure
USDA Forest Service, Northeastern Area, State and Private Forestry
Urban Reforestation Site
Assessment (URSA)
Major Sections:
• General site information
• Climate
• Topography
• Vegetation
• Soils
• Hydrology
• Potential planting conflicts
• Planting and maintenance
logistics
• Site sketch
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Basic Planting Design
• Plant species – diversity is important, select
species that are appropriate for the site and
tolerant of urban conditions
• Plant materials – select from balled and
burlapped, container grown, bare root
• Plant spacing – based on desired density,
should account for plant survival rates
• Planting plan – should include species list,
sketch, planting dimensions, instructions,
supply list, site preparation, schedule and
cost estimate
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Urban Tree Selection Guide
• Specific to the mid-Atlantic and Northeastern U.S.
• Used to select species that can tolerate the
environmental conditions at the site and perform
specific functions
• Chart 1: Environmental Conditions - hardiness zone,
soil moisture, sun exposure, soil composition, and
tolerance of drought, inundation, pests/disease, soil
compaction , salt, and pH
• Chart 2: Tree Characteristics – growth rate, mature
height, canopy spread, form/habit, root structure, fruits,
flowers
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Example Planting Plan Sketch
Source: Omaha Public Power District
Special Considerations for Urban
Tree Planting
• Calculate soil volume
• Evaluate potential for stormwater
treatment
• Recommend setbacks between trees
and infrastructure
• Other methods to reduce infrastructure
conflicts
• Protect trees from human and animal
impacts
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Calculate Soil Volume
• Typical tree pit in an
urban area is only 4 feet
by 4 feet in area – about
50 ft3 of soil
• Tree roots are typically
confined to the pit due
to compacted soils
• Use designs that
provide as much soil as
possible for trees
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Calculate Soil Volume
Source: Jim Urban
Evaluate Potential for Stormwater
Treatment
• Many urban trees either receive too much
stormwater runoff or do not receive enough
water because surrounding pipes and
pavement direct water away
• Stormwater management and planting
strategies should be used to manage runoff
at planting sites that receive too much water
and to direct runoff to other planting sites to
provide treatment and reduce irrigation needs
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Evaluating Potential for
Stormwater Treatment
Sites should be evaluated to determine if
they are:
• Under-capacity: currently does not receive
runoff; runoff bypasses the site in pipe/ditch or
is infiltrated
• At-capacity: receive sheetflow only
• Over-capacity: receive excessive runoff
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Recommended Setbacks Between Trees
and Infrastructure
Trees vs. Pavement
• Tree roots
crack or lift
pavement if
inadequate
setbacks are
used
• 10 to 15 foot
setbacks are
recommended
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Trees vs. Utilities
• Falling limbs can cause power outages, trees
can grow into wires
• Maintenance/repair of utilities can damage
tree
• Recommended setbacks from overhead
wires:
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10 feet for small trees
15-20 feet for medium trees
20 to 40 feet for large trees
Trees planted under overhead wires must be 10 to
15 feet below the height of the wires at maturity
• Recommended setback from underground
utilities is 10-15 feet
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Trees vs. Sewer and Drainage
Pipes
• Tree roots can clog or break sewer and
drainage pipes –although most damage
occurs with older sewer systems
• Trees that cause damage to sewer
pipes are often removed
• Recommended setbacks:
• 15-25 feet between trees and perforated
pipes
• 10 feet between trees and sewer lines
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Trees vs. Buildings
• Tree roots may crack foundations if planted too
close to buildings
• Root growth may become one-sided and cause
tree to topple from high winds.
• Recommended setbacks:
• 15 feet for small trees
• 20-25 feet for large trees
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Other Recommended Setbacks
• 10 foot setback between trees and
lighting
• 10 foot setbacks between trees/shrubs
and the centerline of trails (for safety)
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Other Methods to Reduce
Infrastructure Conflicts
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Species selection
Alternative sidewalk design
Alternative sidewalk materials
Root guidance systems
Structural soils
Maintenance strategies
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Species Selection
• “The right tree in the right place”
• Selecting species with specific characteristics
can reduce infrastructure conflicts:
• Choose shallow-rooted species when planting
near sewer or drainage pipes
• When planting near overhead wires, choose
species with columnar form
• Species with a small trunk flare or root buttress
characteristics are ideal for planting next to
pavement
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Alternative Sidewalk Design
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Alternative Sidewalk Materials
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Reinforced or thicker concrete slabs
Asphalt
Pervious concrete
Decomposed granite and compacted
gravel
• Permeable pavers
• Recycled rubber
• Mulch
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Root Guidance Systems
• Direct root growth away from
infrastructure by restricting root growth
laterally or radially, or by directing roots
to appropriate areas
• Examples: root barriers, root paths,
steel plates, root channels, continuous
soil trench
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Structural Soils
Graphic by Matt Arnn
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Maintenance Strategies
• Use directional pruning instead of
topping when pruning trees near
overhead wires
• Use tunneling as an alternative to
trenching when installing or repairing
underground utilities near trees
• Use alternatives to root pruning to
minimize damage to trees
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Protect Trees from Human and
Animal Impacts
• Beaver
• Deer
• Human Impacts
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Lawnmowers
Damage from vehicles
Vandalism
Foot traffic
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Protect Trees from Deer
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Site Preparation Methods
• Trash and debris cleanup
• Invasive plant control
• Soil amendments
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Trash and Debris Cleanup
• May be done
with volunteers
• Evaluate the
site to
determine the
type and
volume of trash
• Implement
measures to
prevent future
dumping
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Invasive Plant Control Methods
• Hand removal
• Mowing
• Heavy equipment
removal
• Solarization
• Girdling
• Burning
• Chemical
• Cultural
• Biological
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Soil Amendments
• Compost: improves water and nutrientholding capacity, increases nutrients, reduces
compaction
• Gypsum: decreases soil salinity, increases
calcium and sulfur without affecting pH,
enhances structure of clay soils
• Limestone: decreases soil acidity
• Peat: increases organic matter, acidity, and
water and nutrient-holding capacity without
increasing nutrient content
• Sulphur: increases soil acidity
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Typical Characteristics of Urban
Soils
• Severe compaction
• Elevated pH
• Low organic matter
• Low nutrients
• Poor drainage
• Pollutants may be present
Compacted urban soil
Healthy soil
Source: Cornell Urban Horticulture Institute
Planting and Maintenance
Techniques
• Tree planting techniques
• Encourage natural regeneration
• Maintenance techniques
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Tree Planting Techniques
• Planting hole must be 2 to 3 times wider than
the root ball because roots spread out
laterally rather than going deep
• Do not plant tree too deep
• Technique varies with plant materials and
when planting on slopes
• Use tree shelters and mulch to protect tree if
necessary
• Stake only on very windy sites or with topheavy trees
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Tree Planting Specification
Copyright International Society of Arboriculture. Used with permission.
Mulching Trees
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Natural Regeneration
• Natural regeneration is the simplest and
cheapest way to reforest: simply stop mowing
• In urban areas, poor soils and lots of invasive
species and deer can make regeneration
difficult
• Good candidate sites have: desirable tree
seed sources nearby, adequate seed
dispersal methods, bare mineral soils with
good seed/soil contact, few invasive plants,
controlled deer populations, and no sodforming grasses (e.g., fescue)
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Encourage Natural Regeneration
To encourage natural
regeneration:
• Amend soils problems
• Control deer
• Control invasive species
• Disc soils if sod is present
• Install perches to encourage
seed dispersal by birds
• Supplement with plantings if
necessary
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry
Tree Inspection and Maintenance
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Post planting and long-term inspection
Watering
Pruning
Weed control
Integrated Pest Management
Center for Watershed Protection
USDA Forest Service, Northeastern Area, State and Private Forestry