Which tree feature is crucial to monitor for signs of lightning damage?

Monitoring the bark condition and trunk integrity is essential for identifying signs of lightning damage because these areas are most directly affected when lightning strikes a tree. Lightning can cause significant physical harm to the bark and trunk, including charring, deep fissures, and even the complete loss of bark in some cases. When a tree is struck by lightning, it can also lead to internal damage, such as the disruption of water and nutrient transport within the trunk, which can ultimately affect the tree's health and stability.

In contrast, the other options may not provide as clear or immediate indications of lightning damage. The color of the leaves, for example, may reflect other health issues unrelated to lightning strikes. The height of the tree does not directly relate to the impact of a lightning strike, nor does the form of the branches, which typically indicates growth patterns or structural issues rather than damage from electrical discharge. Thus, focusing on bark condition and trunk integrity is key for assessing any immediate and potentially dangerous effects of a lightning strike on a tree.