ISA Certified Arborist Practice Exam

What can be an effect of increased soil compaction on tree roots?

1. Increased oxygen availability

2. Enhanced nutrient absorption

3. Decreased water and oxygen availability

4. Faster growth of root systems

The correct answer is: Decreased water and oxygen availability

Increased soil compaction significantly affects the health of tree roots, primarily by decreasing water and oxygen availability. When soil becomes compacted, the air spaces between soil particles diminish, leading to reduced porosity. This lack of space makes it challenging for both air and water to penetrate the soil, directly impacting the roots of trees. Roots require oxygen for respiration, which is critical for their growth and overall health. Compacted soil restricts the amount of oxygen that can reach the root system, resulting in stress for the tree. Additionally, water movement through compacted soil is hindered, making it difficult for roots to access the moisture necessary for survival. Consequently, trees in compacted soil often experience poor growth, reduced vigor, and may become more susceptible to diseases and pests. Understanding the relationship between soil compaction and root health is vital for anyone involved in arboriculture, as it directly pertains to managing soil conditions to promote healthy plant growth.