Invasibility and vulnerability of plant communities to biological invasions: A spatially explicit stochastic modeling approach

The negative impacts of biological invasions pose serious treats to natural, economic and social systems. This work intends to answer several fundamental yet pressing questions related to biological invasions. This dissertation presents three theoretical studies that use spatially explicit stochastic modeling approach, specifically interacting particle systems, to conduct these investigations. Chapter 1 briefly introduces background information on biological invasions, and Chapter 2, 3 and 4 each explores the effects of abiotic and biotic factors on community invasibility and vulnerability to invasions. Chapter 5 briefly summarizes main findings in Chapter 2, 3 and 4 and pointed out future directions.; Chapter 2 examines the effect of plant resident community properties, including resident species richness and habitat size, on its invasibility and vulnerability to invasions. Both resident species richness and habitat size affected invasibility, and resident species richness also affected vulnerability to invasions. Larger habitat sizes led to higher frequencies of invading species and higher post-invasion resident species richness, resulting in a positive relationship between diversity and invasibility.; Chapter 3 investigates the impacts of demographic characteristics of plant species, propagule pressure and disturbance. Species invasiveness and its impacts on invaded communities were found to be affected by all traits considered, including age to reproduction, reproductive rate, competitive ability and dispersal range. Community invasibility and vulnerability increased with invader propagule pressure. Disturbance interacted with propagule pressure to either promote or reduce invasion success. The unimodal relationship between resident species richness and disturbance frequency at low and intermediate levels of propagule pressure supports the intermediate disturbance hypothesis.; Chapter 4 explored the role of habitat spatial configuration and its interaction with invasive species demographic characteristics in invasion dynamics, in the context of hierarchical river networks. Network spatial structure influenced species movement and interaction between invading species and resident species, resulting in increased invasibility and vulnerability of the more dendritic network to invaders with long dispersal range and strong competitive ability.; This work demonstrates community invasibility and vulnerability to invasions are determined jointly by multiple biotic and abiotic factors that interactively affect invasion process. Management of biological invasions requires the knowledge of collective impacts of multiple factors.