Impact of different invasion methods of invasive species on omnivorous food webs

Abstract

Biological invasion results in a lot of problems about ecosystem and human life. To explore the mechanism of alien species invading a stable food web, a patch dynamic model is established to describe the patch occupancy of each species in the omnivorous food web. A species as invader will be introduced to the food web on different tropical level as predator or as prey. The impact of invasion on the persistence of all species in formed food webs under different habitat loss and habitat fragmentation is investigated. The results show: (1) Compared with invasive species being predators, invasive species being prey is easy to success in omnivorous food webs; Invasive species are much more tolerant of habitat loss and fragmentation when they invade an omnivorous food web in the role of prey than when they invade in the role of predator. (2) When invasive species is a predator in different trophic levels on omnivorous food webs, it shows different coexistence patterns varying with the role and habitat structure. The degree of habitat loss and habitat fragmentation also affects the habitat patch occupancy of the invasive species. On most habitat structure, the lower the trophic level of the invasion location, the more successful the invasion is. (3) When invasive species is a prey of species in omnivorous food webs, no matter what trophic level the invasive species is, it is easy to success. (4) The degree of habitat loss and fragmentation combined with colonization rate have certain impact on invasion result under different roles and trophic levels. The research gives some theoretical thinking of biological invasion, and it can be used as a guidance of biological control.