A positive complexity-stability relationship emerges in pollinator-plant-consumer tripartite networks disturbed by plant invasion

The relationship between network structure and system stability has been debated for decades. Recent studies have found that species invasions are able to change the structure-stability relationship in mutualistic or antagonistic bipartite networks. However, whether and how species invasion can alter the structure-stability in tripartite networks with both mutualistic and antagonistic interactions remain largely unexplored. Here, we establish a patch-occupancy dynamic (including species colonization-extinction processes) model to explore the effect of plant invasion (e.g., fragrant eupatorium herb invades native plant community in southern Yunnan, China) on the relationship between network structure (i.e., connectance, network size, modularity and nestedness) and community stability (robustness to invasion) in a pollinator-plant-consumer tripartite network (e.g., Lepidoptera insect-herbaceous vegetation-phytophagous insect tripartite network). Theoretical results show that nestedness and modularity have opposite effects on community stability. Specifically, our work reveals that, in both mutualistic and antagonistic bipartite networks, the effect of modularity on community stability is positive, whereas the effect of nestedness is negative. Moreover, increasing network size increases system stability. Finally, we find a positive connectance-stability relationship in both mutualistic and antagonistic bipartite networks. Overall, our patch-dynamic framework provides new insights into how species invasion affects the stability of tripartite networks with multiple interaction types.