Which of the following is a key indicator of forest health?

Tree vitality and biodiversity levels are crucial indicators of forest health because they reflect the overall condition and resilience of an ecosystem. Healthy trees exhibit strong growth, robust canopy coverage, and resistance to diseases and pests. Biodiversity, which encompasses the variety of species within the forest, contributes to ecosystem stability and functionality.

A forest with high biodiversity is typically more resilient to environmental stresses, such as climate change, pests, and diseases, and can support a wider range of wildlife. Conversely, a lack of diversity can make a forest more susceptible to catastrophic events and can lead to a decline in forest health over time.

While high timber yield, age of trees, and the number of recreational facilities can provide some insight into certain aspects of a forest's condition or usage, they do not directly measure the ecological integrity or the health of the ecosystem itself in the same way that tree vitality and biodiversity do.