Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400, Klosterneuburg, Austria.
Department of Agricultural Sciences, University of Helsinki, PO Box 27, FI-00014, Helsinki, Finland.
Ecol Lett. 2020 Mar;23(3):506-517. doi: 10.1111/ele.13450. Epub 2019 Dec 20.
Habitat loss is one of the key drivers of the ongoing decline of biodiversity. However, ecologists still argue about how fragmentation of habitat (independent of habitat loss) affects species richness. The recently proposed habitat amount hypothesis posits that species richness only depends on the total amount of habitat in a local landscape. In contrast, empirical studies report contrasting patterns: some find positive and others negative effects of fragmentation per se on species richness. To explain this apparent disparity, we devise a stochastic, spatially explicit model of competitive species communities in heterogeneous habitats. The model shows that habitat loss and fragmentation have complex effects on species diversity in competitive communities. When the total amount of habitat is large, fragmentation per se tends to increase species diversity, but if the total amount of habitat is small, the situation is reversed: fragmentation per se decreases species diversity.
生境丧失是生物多样性持续减少的关键驱动因素之一。然而，生态学家仍在争论生境破碎化（独立于生境丧失）如何影响物种丰富度。最近提出的生境量假说认为，物种丰富度仅取决于局域景观中的总生境量。相比之下，实证研究报告了相反的模式：一些研究发现破碎化本身对物种丰富度有正效应，而另一些则有负效应。为了解释这种明显的差异，我们设计了一个竞争物种群落在异质生境中的随机、空间显式模型。该模型表明，生境丧失和破碎化对竞争群落中的物种多样性有复杂的影响。当总生境量很大时，破碎化本身往往会增加物种多样性，但如果总生境量很小，情况就会相反：破碎化本身会降低物种多样性。
