Certified Arborist Test Soil Science and Root Management 2

Question 1

What is soil compaction and what is its primary effect on tree root development?

Accepted Answer

Increased bulk density that reduces pore space, limiting oxygen and root penetration

Answer

Soil compaction increases bulk density by reducing pore space, which limits oxygen diffusion to roots and increases mechanical resistance, inhibiting root elongation and leading to shallow, restricted root systems.

Question 2

What does cation exchange capacity (CEC) measure in soil, and why is it important for tree nutrition?

Accepted Answer

The soil's ability to hold and exchange positively charged nutrient ions

Answer

CEC is the measure of the soil's capacity to hold exchangeable cations (Ca²⁺, Mg²⁺, K⁺, NH₄⁺) on clay and organic matter surfaces — a high CEC indicates greater nutrient-holding capacity and reduced leaching.

Question 3

What is mycorrhizal symbiosis and how does it benefit trees?

Accepted Answer

A mutualistic association where fungi extend root absorption capacity in exchange for carbohydrates

Answer

Mycorrhizal fungi form mutualistic partnerships with tree roots — the fungal hyphae extend far beyond root tips to dramatically increase the absorption surface area for water and nutrients, particularly phosphorus, in exchange for photosynthetic sugars from the tree.

Question 4

What is the difference between macropores and micropores in soil, and how do they affect tree root function?

Accepted Answer

Macropores drain quickly and hold air; micropores hold water available to plants

Answer

Macropores (>0.08 mm) drain freely by gravity and are filled with air after drainage, providing oxygen to roots; micropores (<0.08 mm) retain water by capillarity, providing the plant-available water reserve between field capacity and wilting point.

Question 5

What are the symptoms and causes of iron chlorosis in trees growing in high-pH soils?

Accepted Answer

Yellowing of young leaves with green veins caused by iron being insoluble and unavailable at high pH

Answer

Iron chlorosis presents as interveinal chlorosis (yellow leaf tissue with green veins) on young leaves, because iron is immobile in the plant. High soil pH makes iron compounds insoluble and unavailable to roots despite often adequate iron levels in the soil.

Certified Arborist Test Practice Test

Certified Arborist Test Practice Test

Certified Arborist Test Soil Science and Root Management 2