An increase in biodiversity might lead to a decrease in the stability of an ecosystem when biodiversity is already high, causing a negative effect on certain components of stability such as resistance to environmental changes. This occurs because while species richness can increase temporal stability, it may simultaneously decrease an ecosystem's resistance to stressors like warming, especially when there is low response diversity (i.e., most species respond similarly to environmental changes). This results in a hump-shaped or U-shaped relationship where biodiversity boosts stability at low levels but undermines it at high levels due to a negative covariance between different stability components. Therefore, biodiversity can sometimes decrease overall ecosystem stability if species do not differ enough in how they respond to environmental changes, limiting the system's capacity to buffer those changes effectively.
Explanation of Stability Components
- Temporal stability (e.g., consistency over time) tends to increase with more species.
- Resistance (ability to withstand disturbances) can decrease if species respond similarly to stressors.
- Overall ecosystem stability combines multiple components and can show complex relationships with biodiversity.
Summary
An increase in biodiversity may reduce ecosystem stability when high species richness coincides with low response diversity, causing a reduction in resistance to environmental change despite improved temporal stability. This nuanced relationship highlights the importance of species' functional differences, not just species count, for maintaining ecosystem stability.
