Which of the following factors does NOT contribute to tree failure?

A healthy root system is critical for the overall stability and longevity of a tree. It serves as the foundation that anchors the tree securely in the soil, enabling it to withstand various stresses such as wind and soil erosion. When a tree has a robust and well-developed root system, it can effectively absorb nutrients and water, which contributes to the tree's health and resilience against environmental challenges.

In contrast, factors such as exceeding load carrying capacity, environmental stressors, and structural integrity of nearby trees can significantly impact a tree’s risk of failure. A tree that is subjected to forces greater than it can support may experience structural failure. Environmental stressors like drought, flooding, or extreme weather can weaken a tree's health and stability. Similarly, the structural integrity of nearby trees may influence the stability of the tree in question through competition for resources or potential impacts during events like storms.

In summary, a healthy root system directly contributes to a tree's ability to withstand various pressures, making it a factor that does not contribute to tree failure.