Effects of Habitat Fragmentation on Plant-Insect Communities

Abstract

Changes in landscape structure due to human activities includes habitat destruction and the fragmentation of the remaining habitat patches (Harris, 1984). This process of habitat fragmentation has been perceived as “the principle threat to most species in the temperate zone” (Wilcove et al., 1986) or “the single greatest threat to biological diversity” (Noss, 1991). Although habitat fragmentation occurs naturally, it is mostly caused by the expansion and intensification of anthropogenic land use (Burgess and Sharpe, 1981). For example, in the Australian wheat belt region 93% of the native vegetation has been cleared, mostly during the last 50 years (Saunders et al., 1993). Estimating the current effects of fragmentation on species diversity is often difficult (Margules et al., 1994), and most investigations have studied the effects a posteriori (Villard and Taylor, 1994). As mentioned by Didham et al. (1998), little attention has been paid to alteration in the trophic structure of communities due to habitat fragmentation, because most studies have focused on single species or several species within one trophic level. Since habitat fragmentation does not affect all species equally, results from systems with such reduced levels of complexity cannot be extrapolated to explain responses of food-web or community interactions.