Regarding invasibility (factors that determine the susceptibility of an ecosystem to invasion), evidence from many studies, including palaeoecology, modern observationalstudies and experimental work at different scales (mainly small plots) shows that susceptibility/resistance of systems to invasion fluctuates markedly over time and space due to changing climatic conditions, disturbance, nutrients, availability of mutualists, and the availability and abundance of propagules to initiate and sustain invasions. Invasibility must thus be considered probabilistically rather than deterministically. Even areas currently thought to be resistant to invasion will probably be invaded as increased propagule pressure and elements of global change alter key processes in the system. A related aspect is the link between native species richness in a system and its capacity to accept new invaders.

Below-ground biodiversity and its role in maintaining ecosystem functioning and integrity, is a new field of research.

There is growing evidence that invading mplant species alter this diversity and may affect ecosystem functioning and resource pools in ways that are not well understood.