Impact of invasive plants on food webs and pathways

Abstract

In natural ecosystems, energy mainly flows along food chains in food webs. Numerous studies have shown that plant invasions influence ecosystem functions through altering food webs. In recent decades, more attention has been paid to the effects of alien plants on local food webs. In this review, we analyze the influence of exotic plants on food webs and pathways, and explore the impacts of local food web characteris- tics on community invasibility. Invasive plants alter food webs mainly by changing basal resources and envi- ronment conditions in different ways. First, they are consumed by native herbivores due to their high avail- ability, and are therefore incorporated into the native food web. Second, if they show low availability to na- tive herbivores, a new food web is generated through introduction of new consumers or by changing the en- ergy pathway. Third, environmental changes induced by plant invasions may alter population density and feeding behavior of various species at different trophic levels, thus alien plants will affect the communities and food web structures along non-trophic pathways. The influence of the local food web on plant invasions depends on web size and trophic connections. Issues that deserve attention in future studies are raised and discussed. Future research should extend from short-term experiments to long-term monitoring. More quan- titative researches to define the responses of food web parameters are needed. In addition, recovering of food web structure and species interaction in restored habitats is an important issue requiring future research.