The effect of habitat destruction on metapopulations with the Allee-like effect: A study case of Yancheng in Jiangsu Province, China

摘要

At the metapopulation level, there is a phenomenon called Allee-like effect that leads to metapopulation extinction thresholds at low habitat occupancy, analogous but essentially different with Allee effect at the local population level. Rare metapopulations are more susceptible to the Allee-like effect, which will increase the extinction risk of those living in fragmented habitats. Hitherto, no adequate attention has been paid to this phenomenon in metacommunity Here, the Allee-like effect is introduced into a metapopulation spatial competition model of multi-species under different habitat change, and the 29 rare species inhabiting in Yancheng wetlands of Jiangsu Province are taken as study cases. Simulation results show that the Allee-like effect enable the proportion abundance of all species to fluctuate in different periods. The continuous oscillation will greatly increase the probabilities of stochastic extinction of the most vulnerable species. Strong Allee-like effect is especially unfavorable for those sub-dominant and inferior species, which is a destabilizing factor to rare species coexistence. Habitat destruction may be fatal to a rare metapopulation system with the Allee-like effect. As 29% of the natural wetlands are destroyed in Yancheng, the most 11 vulnerable species will go extinct in the weak-strong order with a time delay of 304-890 years in response to the past habitat loss. TWO projects of habitat restoration are also brought forward for species diversity conservation. Besides the existing natural wetlands of 3200 km(2), an extra of 1801-2064 km(2) habitat should be added to conserve all species. These conclusions will be helpful for species conservation and will provide theoretical guidance to construct nature reserves.