The 'fluctuating resources theory of invasibility' proposed by Davis, Grime, and Thompson posits that invasion is limited by access to available resources, for example, light, nutrients, and water, and that an invading species will be more successful at invading a community if it does not encounter intense competition for these resources from resident species. Intermittent resource enrichment or release from competition (often due to disturbance) increases community susceptibility to invasions, and inva sions occur if this situation coincides with availability of suitable propagules (Figure 2). The larger the difference between gross resource supply and resource uptake, the more susceptible the community is to invasion. Experimental evidence shows that even very short fluctua tions in resource availability (as short as 1 week) can greatly enhance plant invasion success (expressed as survi val and cover of alien plants) up to 1 year after such events.
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