ABSTRACT
Invasion is not a novel phenomenon; however, it is one that has increased tremendously during the past few years because of rapidly expanding trade and transport among countries. It is one of the most important impacts humans have ever produced on the earth’s ecosystems (Sharma et al. 2005b). In fact, it has led to globalization of world biota, further resulting in biotic homogenization (Drake et al. 1989). Invasive species belong to an array of taxonomic groups, and hence it is very difficult to classify them (Crawley 1997). Invasion may occur as a result of human
introductions or because of accidental entries of species into alien habitats. Upon entry into the alien environment, these species bring about a number of changes in the native ecosystems, such as altering the structure and composition of plant communities; reducing agricultural productivity, wildlife, biodiversity, and fodder availability; changing soil structure; affecting health of human beings and livestock; and causing huge economic costs (Moore 2000; Sala et al. 2000; Pimentel et al. 2005; Herron et al. 2007; Khuroo et al. 2007). The ecological impact of invasive plants can be far reaching, and in addition to native plant communities, they may affect other components of the ecosystem. In fact, the impact of invasive species on global biodiversity is the second greatest after habitat fragmentation (Drake et al. 1989). It is one of the most significant ecological issues catching the attention of the people worldwide.
