What type of wood responds to gravity?

The correct response is reaction wood, which pertains to the type of wood that forms in response to gravitational forces. This phenomenon occurs in trees that grow in environments where they may be subjected to lean or uneven growth due to the weight of foliage or disturbance from wind or other factors.

In hardwood trees, the reaction wood forms on the upper side of a leaning stem and is referred to as tension wood. It serves to provide support and help straighten the stem as the tree continues to grow. In contrast, coniferous trees form reaction wood on the lower side of the leaning stem, known as compression wood, which helps maintain stability and counteract the force of gravity.

Understanding reaction wood is crucial for tree risk assessment, as it can indicate past stress events and help assess the structural integrity of the tree. Evaluating the growth patterns and the presence of reaction wood can be integral in understanding the overall health and stability of the tree.