生境破坏的空间结构对集合种群续存的影响

生境破坏及其影响是生态学亟待解决的问题之一,目前的研究主要集中在破坏数量,即遭破坏生境的比例,对物种续存的影响方面;其中最主要的结论是Levins原理和适合生境斑块最小数量(MASH),而关于生境破坏的空间结构的研究却比较稀少,在本文中,我们首先将偶对近似引入到集合种群的研究当中,并替代原有的均匀场假设.然后我们对生境破坏导致的集合种群大小、空间结构以及分布等做了全面讨论.结果显示:随破坏比例的增加,集合种群大小将下降并且其分布将远离破坏生境.进一步聚集式分布结构将瓦解.随着破坏规则化的下降,集合种群将萎缩并使其聚集结构崩溃,在破坏生境周围集合种群起初将增加然后迅速消失.根据这些结果,我们可以对边界效应进行分析:不能用破坏比例描述生境破坏的程度和影响,而只能用破坏区域边界的长短来描述.根据边界效应,我们可以得出在一连通生境上物种保护的条件是生境破坏后剩余的适合生境比例应该大于破坏前原始生境的一半.居住在斑块环境中的物种比连续生境中生存的物种可以更好地抵抗生境破坏带来的影响.

Influences of Habitat Destruction with Spatially Structure on Metapopulation Persistence

Habitat destruction is one of the most important desiderate problemin ecology, and researches always focus on the influences of destruction quantity, that is the fraction of destroyed habitat, on species' persistence, in which the most importantresult is the Levins rule and the minimum amount of suitable habitat (MASH). The im-portance of spatial structure of habitat destruction is scarcely concerned. In this paper,we first introduce the pair approximation into the study of metapopulation, ubstitutingfor the mean-field approximation. And then, we fully discuss the size, spatial structureand distribution of metapopulation induced by habitat destruction with spatial struc-ture. The results show that with the increases of destroyed fraction, the metapopulationsizes will decrease and distribute far away from the destroyed habitat, the clusteringstructure of metapopulation will collapses. With the decreases of destroyed clusteringdegree, the metapopulation will atrophy and the clustering structure will break down,and the metapopulation will increases and then disappears near the destroyed habitat.According to these esults, we can analyze the edge effect it is not the fraction of habi-tat destruction but the boundary length of destroyed habitat that can depict the fullinfluences of habitat destruction. With the edge effect, we cursorily suggest that the re-maining habitat under destruction should prior to half of the origin to protect the speciesagainst extinction in a connective habitat. And the species living in patchy habitat willhave more resistance to habitat destruction than those residing in continuous habitat.