Ecological Effects of Biodiversity - Effects On Community Stability

Effects On Community Stability

• Averaging Effect If all species have differential responses to changes in the ecosystem over time, then the averaging of these responses will cause a more temporally stable ecosystem if more species are in the ecosystem.. This effect is a statistical effect due to summing random variables.
• Negative Covariance Effect If some species do better when other species are not doing well, then when there are more species in the ecosystem, their overall variance will be lower than if there were fewer species in the system. This lower variance indicates higher stability. This effect is a consequence of competition as highly competitive species will negatively covary.
• Insurance Effect If an ecosystem contains more species then it will have a greater likelihood of having redundant stabilizing species, and it will have a greater number of species that respond differently to perturbations. This will enhance an ecosystem's ability to buffer perturbations.
• Resistance to Invasion Diverse communities may use resources more completely than simple communities because of a diversity effect for complementarity. Thus invaders may have reduced success in diverse ecosystems, or there may be a reduced likelihood that an invading species will introduce a new property or process to a diverse ecosystem.
• Resistance to Disease A decreased number of competing plant species may allow the abundances of other species to increase, facilitating the spread of diseases of those species.