Certified Forester Practice Exam

What effect does tension wood have on trees?

1. It weakens the structure of the tree

2. It helps the trunk or branches return to a vertical position

3. It causes the tree to grow larger in diameter

4. It reduces water absorption in the roots

The correct answer is: It helps the trunk or branches return to a vertical position

Tension wood is a specialized type of wood that forms on the upper side of leaning or leaning branches, predominantly in hardwood species. The primary effect of tension wood is to aid the tree in restoring and maintaining an upright position. This occurs because the cellulose fibers in tension wood are more highly developed and oriented towards the growth direction, providing extra strength and structural support to the tree trunk and branches as they attempt to reposition themselves vertically. As the tree grows, the formation of tension wood allows it to effectively balance itself, which is crucial for maximizing light exposure and overall health. Therefore, the role of tension wood is significant in enhancing the mechanical stability of the tree as it adapts to its environment, including overcoming distortions caused by gravity or competing vegetation. While other options suggest effects like structural weakening, increased diameter growth, or changes in water absorption, these are not characteristics associated with tension wood. Instead, tension wood is specifically tailored by the tree to improve its ability to stand tall and grow robustly in its surroundings.