ABSTRACT
What are the causes and effects of invasions, and why do some alien species become invasive and others do not? These are the primary questions that have motivated invasion ecology research over the last few decades. Williamson and Fitter (1996), in an effort to develop a predictive framework for biological invasions, proposed the “tens rule,” which states that 1/10 of all introduced species escape, 1/10 of those that escape become established, and 1/10 of those that become established become invasive. Although this rule is more of a generalization than an actual scientific rule, it illustrates that invasion is a multistep process, with many barriers that must be overcome in order for an alien plant to become invasive. Moreover, it implies that interactions between an alien plant and its new environment are a major determinant of whether or not the plant establishes and becomes invasive. Indeed, it is believed that a primary factor that affects the performance of alien species is the degree of resistance that they face in their new environment, and this is arguably the basis of most contemporary invasion hypotheses (Daneshgar and Jose 2008 and citations therein). The biotic resistance hypothesis (Maron and Vilà 2001), for example, states that an alien plant is more likely
7.1 Introduction .......................................................................................................................... 79 7.2 Interactions between alien plants and mycorrhizal fungi ............................................. 81 7.3 When alien plants become invasive: Implications for mycorrhizal fungal
communities .........................................................................................................................83 7.4 Posteradication legacy effects ............................................................................................86 7.5 Conclusions and future directions ....................................................................................88 References .......................................................................................................................................88
