Spatial Heterogeneity, Spatial Scale, and Productivity

Invasive species are one of the most significant threats to native species diversity, and identifying the factors that make places more or less invasible has been one of the most important issues in the study of invasions (Wilcove et al., 1998; Pimentel et al., 2000). From a theoretical perspective, the reasons some communities are more invasible than others is a question that continues to intrigue ecologists (levine et al., 2004; Davies et al., 2005; Fridley et al., 2007; Stohlgren et al., 2008; Cadotte et al., 2009) because it underlies fundamental concepts in community ecology: species coexistence and assembly (Chesson, 2000; tilman, 2004). Therefore, its exploration offers insights into why communities are structured as they are. Serpentine systems have provided significant insight into the reasons some communities are more invasible than others because the environment within these systems is often extreme. Spatial heterogeneity, spatial scale, and productivity have all proven to be critical elements in understanding the invasibility of communities. Serpentine systems have allowed researchers to examine these elements in greater depth. First, serpentine systems are very spatially heterogeneous in soil chemistry, texture, rockiness, and toxicity. Importantly, this spatial heterogeneity can exist at very small scales, making it easier to examine the effects of it on communities. Second, because spatial heterogeneity can be at both small scales and large scales,