Certified Arborist Practice Test

The assertion is indeed true. Soil can retain water with varying degrees of tension, which can affect the accessibility of that water for tree roots. When soil particles are packed closely together or when the soil is of a fine texture, such as clay, the water is held tightly due to the small pore spaces between the particles. This can create a situation where, despite the presence of moisture, tree roots cannot absorb it effectively.

Factors such as soil texture, structure, and moisture content significantly influence the available water for plants. In very compacted soils or in soils with high clay content, water can be held in such a way that it becomes unavailable to roots, as the water molecules are bound too tightly to the soil particles. Conversely, in sandy soils, while they have large pore spaces and can drain quickly, they may not hold water effectively, allowing tree roots easier access to moisture. Thus, the statement accurately reflects the relationship between soil-water retention and root absorption capabilities.