Certified Arborist Test Soil Science and Root Management 3

Question 1

What is the approximate percentage of a tree's root system that typically extends beyond the drip line?

Accepted Answer

Most roots remain within the drip line but a significant portion extends 2-3 times the drip line radius

Answer

Roots rarely extend beyond the drip line in most tree species

Answer

Root systems extend to exactly the drip line in proportion to crown spread

Answer

Root systems in urban environments are compressed to within 6 inches of the trunk

Question 2

What is the purpose of a percolation test (perc test) in tree planting site assessment?

Accepted Answer

Determining how quickly water drains through the soil to assess drainage suitability

Answer

Measuring the concentration of soluble salts in the irrigation water supply

Answer

Testing the compressive strength of soil to predict root penetration resistance

Answer

Evaluating the cation exchange capacity before soil amendment planning

Question 3

What is the difference between nutrient deficiency and nutrient toxicity symptoms, and which is more commonly encountered in urban trees?

Accepted Answer

Deficiency causes chlorosis or stunting from insufficient supply; toxicity causes burn or necrosis from excess — deficiency is more common but both occur in urban settings

Answer

Toxicity causes uniform yellowing; deficiency causes tip burn — toxicity is more common in urban soils

Answer

Deficiency affects roots invisibly; toxicity affects leaves visibly — they cannot be distinguished in the field

Answer

Toxicity only occurs with artificial fertilization; deficiency only in sandy soils — neither is common in urban trees

Question 4

What is the 'critical root zone' (CRZ) and how is it calculated for construction site tree protection?

Accepted Answer

A radius calculated as 1 foot per inch of trunk diameter (DBH), representing the minimum area requiring protection

Answer

The zone within 6 feet of the trunk where all roots are concentrated and most sensitive

Answer

The area beneath the crown drip line where feeder roots are densest in undisturbed soil

Answer

A standardized 15-foot exclusion zone required by law around all protected trees

Question 5

What is the purpose of soil pH management in tree care, and what are the two most common methods for lowering soil pH?

Accepted Answer

pH management improves nutrient availability; methods are elemental sulfur and acidifying nitrogen fertilizers (ammonium sulfate)

Answer

pH management prevents root decay; methods are calcium carbonate application and wood ash treatment

Answer

pH management controls soil microbe populations; methods are lime and copper sulfate applications

Answer

pH management affects water movement; methods are gypsum and peat moss incorporation

Question 6

What are girdling roots, and how are they detected and treated?

Accepted Answer

Roots that grow circumferentially around the trunk base, gradually compressing the vascular tissue

Answer

Roots that grow straight down to anchor the tree in flood-prone soils

Answer

Adventitious roots that form on the trunk above the soil line during waterlogging

Answer

A cluster of tangled surface roots that interfere with lawn maintenance