Population explosion and human activities especially the pressures of land use and habitat destruction on environment, is one of the most important causes of the loss of species diversity. Species diversity is the bases of the survival and development of human being. Therefore, the study on the effects of human activities on species diversity is a hot issue of global biodiversity conservation. We have put forward a non-autonomous model of multispecies competitive coexistence model about the effects of human activities which is the function of time. Moreover, we have studied dynamically the effects of human activities on species diversity by simulating the response of species diversity of wetland waterfowls to human-caused habitat successive destruction as a case study. The simulated results showed that:
(1) When waterfowls are subject to successive habitat destruction, the responsive characteristics of superior-superior competitors are different from those of inferior-inferior competitors. For superior-superior competitors, the abundances of them will decline continually. The declining speed of more superior competitors is much higher than the less superior competitors because the more superior a species is, the more sensitive to habitat loss it is, which leads to the competitive rank and dominance species changing. For inferior-inferior competitors, the successive habitat destruction will lead to lots of much inferior competitors go extinct due to inadaptability to habitat loss and the rest oscillate quasi-periodically.
(2) When habitat destruction stop, for superior-superior competitors, the originally more superior competitors still decline continually and die out at the end, and originally less superior competitors keep as the dominance species; for inferior-inferior competitors, many inferior competitors will go extinct quickly, and the rest will oscillate quasi-periodically. All the living species will come to a new equilibrium after about 3000yr. As mentioned above, although habitat destruction stop, some species still go extinct, which reveals there is a time debt for species extinction to respond to past habitat destruction, that is to say, there are some “living dead" species in present destroyed habitat. So more and more attentions must be taken to it from conservation biologists, or else, the number of endangered species will be underestimated and further the development of effective decision-making of biological conservation are affected disadvantageously.