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