Certified Arborist Practice Exam

What do acidic soils hold so tightly that tree roots face restrictions in water absorption?

1. Buckeye, Horsechestnut

2. Alkaline compounds

3. Nutrients

4. Water

The correct answer is: Water

Acidic soils have a tendency to tightly bind certain elements and compounds, which can affect tree root function. In the case of the given question, the focus is on what these soils hold tightly that can limit the ability of tree roots to absorb water effectively. Acidic soils often have a higher concentration of hydrogen ions, which can lead to a complex process of soil chemistry that affects how water is retained in the soil. When soils are too acidic, they can hinder the natural movement of water through the soil matrix. This is because the high levels of hydrogen ions can lead to structural changes in the soil that make it harder for water to infiltrate and be retained in a manner that is accessible to tree roots. Consequently, roots may find it more difficult to uptake sufficient water, which is vital for their health and growth. From a practical standpoint, the need for balanced pH levels in soil is essential for the optimal functioning of plant roots. If the pH is too low, beyond just nutrient availability, the soil's ability to hold and transmit water can become compromised, leading to restrictions in water absorption by the roots. Therefore, the correct choice reflects a significant challenge that tree roots encounter when growing in acidic soils.