Protecting Ecosystems from Underground Invasions - Seed Bank Dynamics in a Semi-Arid Shrub-Steppe

Abstract

Plant invasions threaten natural and managed ecosystems throughout the world (Hobbs & Humphries, 1995). Invasive plants reduce species diversity through competition with native plant species, leading to local reductions in populations of native species. According to E.O. Wilson: “on a global basis...the two great destroyers of biodiversity are, first habitat destruction and, second, invasion by exotic species” (Simberloff et al., 1997). In some cases invasive plants act more as “passengers” than “drivers” of ecological change in degraded ecosystems (MacDougall & Turkington, 2005). In either capacity invasive plants are a significant biotic element to consider in evaluating the integrity of a given type of ecosystem. The spread of non-native plants throughout the world has a homogenizing impact on regional floras, particularly given the tendency of certain invasive species in forming monocultures or near monocultures. Yet the seriousness of plant invasions is sometimes called into question (Larson, 2007) and because invasion biology is a relatively young field (Davis, 2009), further research is required to better assess the impacts of invasive species on ecosystem function.