Modulation of biodiversity-invasion relationships by resource availability: commensal species defend invaders in a changing world

Biological invasion brings disturbance to localenvironment, such as reducing available niches or altering species interactions. In order to reduce the undesired consequences brought by invasion, the determining factors suppressing invasion become important. The success of invasion depends on resident species and resource availability. Resident community with high species richness can better suppress invasion via intensive resource competition. Niche overlap between resident community and the invader is one of the determinant factors for invasion success. Moreover, invasion success also depends on trophic networks within the resident community. Communities with species which compete less for resources can better enhance their invasion resistance. Resources can be consumed complementarily by diverse species in the community, thereby less vacant resources are left for the invader.
Besides the function of community richness, single species in the community may also contribute differently on reducing invasion success. This identity effect can be modulated by resource availability in the environment. From low to high resource availability, relative important resident species which can suppress invasion shift from having a high niche overlap with the invader to fast growing species. The ratio of elemental nutrients (C, N, P) can also modulate the identity effect of resident species in the community on invasion reduction.