Biodiversity and Ecosystem Resilience

Ecosystem resilience, one of several measures of ecosystem stability, is the degree, manner, and rate of recovery of an ecosystem to a pre disturbance condition (Majer 1989). Although debated, biodiversity is thought to increase ecosystem resilience. One argument is that greater species diversity provides more pathways for recovery. For this reason, some proponents of sustainable forestry require that forest managers maintain both species and structural diversity in managed stands. Often, this objective is approached by managing structural diversity directly, thereby increasing species diversity indirectly. This approach argues that forests that have a diverse vertical structure will generally support a greater variety of animal life than forests with a simple structure: the greater the number and spatial variability of canopy layers and canopy tree species, the greater the possibility for specialization in the animal community and, in theory, the greater the number of animal species. Increasing structural diversity involves the development of a multilayered tree canopy, the retention of a minimum number of large rotting logs on the ground, and the maintenance of large standing dead tree stems in the stand (Kimmons 1997).

Kimmons (1997) points out that, however, the generalization that more diverse forests are more stable forests is not always supported by data. In some forests, some measures of stability will increase as various measures of biodiversity increase. In other forests, there appears to be no simple relationship between various measures of diversity and stability (Kimmons 1997).