ISA Certified Arborist Practice Exam

A common sign of a healthy tree is thick, robust bark and vibrant foliage. Healthy trees typically exhibit strong bark that provides protection against environmental stressors, pathogens, and physical damage. The presence of vibrant foliage indicates that the tree is effectively photosynthesizing, which is crucial for its growth and energy production. Healthy leaves are usually deep green, indicating sufficient chlorophyll levels and adequate water and nutrient availability. These attributes combined signify that the tree is in good health and is thriving in its environment.

Other options present signs typically associated with unhealthy trees. For instance, leaf discoloration and wilting suggest stress or disease, frequent branch drop could indicate underlying structural issues or tree decline, and pest infestations on leaves usually point to a compromised health condition. These factors collectively undermine the vitality and longevity of a tree, contrasting sharply with the characteristics of a healthy tree.