ISA Certification ClassTree Selection
The wrong tree on the wrong site can be more of a liability then an asset. Selecting the right tree for a particular site is one of the most important decisions to ensure long-term benefits, beauty and satisfaction.
All trees have Cultural Requirements:
•Light •Water •Soil conditions•Growing space•Others
Each planting site has Environmental Characteristics:
•Temperature extremes•Soil pH•Light levels•Others
Adaptability: The tree species genetic ability to adjust to different conditions.
Some trees are more adaptable then others. Some species are found all over the country while others only grow in specific locations.
Acclimation:The process by which a given tree adapts to its environment.
Physiological changes- internal (such as chemical )
Morphological changes- external (larger leaves, thicker bark)
Site Analysis
• Site analysis is a record of the pertinent existing site conditions that will effect site selection. This information is compared to the functional goals (what you want to achieve with the planting) allowing for the appropriate selection of trees.
Site ConsiderationsPlanting site: utilities (overhead and under ground), buildings, sidewalks, paved surfaces,intersections, plans for future development
Water availability: type of soil, run off, surface type, too much (down spout, low area)
Soil: pH, nutrients, salts, drainage, compactionsoil texture, bulk density,CEC, soil volume
Light levels: too much, too little, reflection, artificial
Site Considerations continued
Climate: hardiness zone, microclimate, precipitation,exposure, sunlight (too much or too little)
Other plantings: trees and shrubs, beds, turf
Maintenance to be provided: Irrigation, postplanting care, ongoing maintenance
Once the site has been analyzed, the next step
is to consider the Design Criteria (based on
the functions the tree is expected to serve)
Landscape Functions include engineering
and architectural considerations such as
controlling pedestrian traffic,hiding unsightly
building features, blocking wind, providing
shade, etc….
Tree species considerationsGrowth Rate: Fast growing trees are often tolerant of poor soil conditions and neglect BUT, often have weak wood that breaks and decays easily and are short-lived
Size at Maturity: height, spread, root zone requirements
Growth Habit/Form
Insect and Disease Resistance: different from immunity
Species considerations cont.
pH Requirements
Salt Tolerance
Light Requirements
Known Problems: pests, poor structure weak wood,surface roots, messy fruit/flowers/leaves, thorns
Attributes: flowers, fruit, bark, interesting foliage,
good fall color
Species considerations cont.
Maintenance Requirements
Hardiness: based on the lowest minimum
temperature, but the maximum temperature may also
be important to a trees success
Tolerance to Drainage Problems
Seed Source: where did the genetics of the tree
come
Hardiness
Where did the genetics come from? Is the seed source of the tree from within your hardiness zone?
Nursery conditions where the tree is grown: Was it an upland or lowland nursery? Does it match the planting site.
Does the tree have factors that make it a liability? thorns? messy fruit? attract bees?
Other questions
Native vs. Introduced Species
Native Species: grow well in their natural zone. Thereis sometimes a question as to whether or not a speciesis native
Introduced Species: (non-native) some have becomenaturalized (reproducing and thriving in their newsettings for decades). Some have the possibility ofbecoming invasive or carrying in non-native pests or diseases
Selecting trees at the nursery
What to look for at the nursery• Vigorous growth (shoot extension)• Good branch spacing• Trunk taper• Foliage evenly distributed in the upper 2/3 • Avoid many upright branches• Look for single trunk and spreading branches• Look for mechanical damage• ANSI ASC Z60, American standards for nursery
stock• Collected plants?
Included Bark
Multiple Leader on Evergreen
Dieback of leader and Co-dominant Stems
Healthy Terminal Buds
Stem Cankers
Multiple Leaders
Evidence of fungus on stem
Large wound on stem
Look for root Flare
No Root Flare
B&B Planted too deep 1
B&B Planted too deep 2
B&B Planted too deep 3
B&B Planted too deep 4
Checking proper depth
Graft Unions
Key terms
• Acclimation
• Adaptability
• Design criteria
• Growth rate
• Hardiness
• Introduced species
• Native species
• Pest resistance
• Site analysis
• Site considerations