Buenau Kate E, Rassweiler Andrew, Nisbet Roger M
Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California 93106, USA.
Ecology. 2007 Dec;88(12):3022-31. doi: 10.1890/06-1850.1.
Many species that compete for space live on heterogeneous landscapes and interact at local scales. The quality, amount, and structure of landscapes may have considerable impact on the ability of species to compete or coexist, yet basic models of space competition do not include that level of detail. We model space competition between two species with positive feedback through recruitment facilitation, which creates the potential for alternative stable states to occur. We compare the predictions of a spatially implicit model with a simulation model that includes explicit space and landscape structure. We create structured landscapes in which we specify the amount of habitat and degree of fragmentation and ask how landscape structure, dispersal strategy, and scale affect the presence of alternative stable states, or bistability. We find that structured landscapes can reduce the range of parameter values that lead to bistability in our model, but they do not eliminate bistability. The type of landscape and the dispersal distance for each species also influence the amount of environmental change needed for abrupt community shifts to occur. Coexistence of the two competitors is possible under certain conditions when connectivity is low. Consequently, landscape structure may lead to considerable disparity between the predictions of simple models and actual dynamics on complex landscapes during environmental change.
许多争夺空间的物种生活在异质性景观中，并在局部尺度上相互作用。景观的质量、数量和结构可能会对物种竞争或共存的能力产生相当大的影响，但空间竞争的基本模型并未包含这一详细程度。我们通过招募促进作用建立了具有正反馈的两个物种之间的空间竞争模型，这为替代稳定状态的出现创造了可能性。我们将空间隐含模型的预测结果与包含明确空间和景观结构的模拟模型进行了比较。我们创建了结构化景观，在其中指定栖息地的数量和破碎化程度，并询问景观结构、扩散策略和尺度如何影响替代稳定状态或双稳性的存在。我们发现结构化景观可以缩小导致模型双稳性的参数值范围，但并不能消除双稳性。景观类型和每个物种的扩散距离也会影响群落突然转变所需的环境变化量。在连通性较低的某些条件下，两个竞争者有可能共存。因此，在环境变化期间，景观结构可能导致简单模型的预测结果与复杂景观上的实际动态之间存在相当大的差异。
