The relationship between biodiversity and stability has received much attention traditionally, and past decades have seen substantial progress in disentangling the relationship between biodiversity and ecosystem function such as biomass production. By contrast, there is much less theoretical exploration about the relationship between biodiversity and ecological resilience, despite increasing recognition of the importance of multiplicity of ecosystem regimes and their shifts upon anthropogenic impacts on biodiversity. Here I extend two well-known mathematical models of regime shifts, one about alternation between phytoplankton and macrophyte regimes in shallow lakes and the other between under- and over-grazed vegetation regimes in grazing systems, to allow for multiple species in phytoplankton and  vegetation components, respectively. I use the models to analyze the relationship between species composition and equilibrium resilience by focusing on complementarity and selection effects and their underlying mechanisms. Preliminary analysis suggests that environmental drivers control the coexistence of multi-species assemblages through the response traits of involved species and the effect trait composition of species assemblage determines the resilience of equilibria. I will use model results to derive implications on ecosystem regime management under continuing threats to biodiversity.