Changes in species diversity often result from species losses and gains. The dynamic nature of beta diversity (spatial variation in species composition) that derives from such temporal species turnover, however, has received relatively little attention. Here, we disentangled extinction and colonization components of beta diversity by using the sets of species that went locally extinct and that newly colonized the study sites. We applied this concept of extinction and colonization beta diversity to ground vegetation communities that have been repeatedly surveyed in forests where fire and harvesting were experimentally applied. We first found that fire and harvesting caused no effect on beta diversity two years after the treatments. From this result, we might conclude that they did not alter the ways in which species assemble across space. However, when we analyzed the extinction and colonization beta diversity between pre-treatment and two years after the treatments, both measures were found to be significantly lower in burnt sites compared to unburnt sites (i.e., the groups of excluded and newly-colonized species both showed low beta diversity in the burnt sites). These results indicate that the fire excluded similar subsets of species across space, making communities become more heterogeneous, but at the same time induced spatially uniform colonization of new species, causing communities to homogenize. Consequently, the effects of these two processes canceled each other out. The relative importance of extinction and colonization components per se also changed temporally after the treatments. Fire and harvesting showed synergetic negative impacts on extinction beta diversity between pre-treatment and ten years after the treatments. Overall, analyses using extinction and colonization beta diversity allowed us to detect nonrandom dis- and re-assembly dynamics in ground vegetation communities. Our results suggest that common practices of analyzing beta diversity at one point in time can mask significant variation driven by disturbance. Acknowledging the extinction-colonization dynamics behind beta diversity is essential for understanding the spatiotemporal organization of biodiversity.

中文翻译：

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跨扰动梯度划分β多样性的殖民化和灭绝成分

物种多样性的变化往往源于物种的损失和增加。然而，源于这种时间物种更替的β多样性（物种组成的空间变化）的动态性质相对较少受到关注。在这里，我们通过使用在当地灭绝和新殖民研究地点的物种集来解开 beta 多样性的灭绝和殖民成分。我们将这种灭绝和殖民 beta 多样性的概念应用于在森林中反复调查的地面植被群落，在这些群落中，试验性地应用了火灾和收获。我们首先发现，在处理两年后，火和收获对 beta 多样性没有影响。从这个结果，我们可以得出结论，它们并没有改变物种跨空间聚集的方式。然而，当我们分析处理前和处理后两年之间的灭绝和定殖 β 多样性时，发现与未烧毁的地点相比，焚烧地点的这两项措施显着降低（即，排除的和新定殖的物种组都显示出低燃烧地点的β多样性）。这些结果表明，火灾排除了跨空间的相似物种子集，使群落变得更加异质，但同时引发了新物种在空间上的统一定植，导致群落同质化。因此，这两个过程的影响相互抵消。灭绝和定植成分本身的相对重要性也在处理后随时间发生变化。在处理前和处理后 10 年之间，火灾和收获对灭绝 β 多样性显示出协同的负面影响。总体而言，使用灭绝和殖民β多样性的分析使我们能够检测地面植被群落中的非随机分解和重新组装动态。我们的结果表明，在一个时间点分析 beta 多样性的常见做法可以掩盖由干扰驱动的显着变化。承认β多样性背后的灭绝-殖民化动态对于理解生物多样性的时空组织至关重要。我们的结果表明，在一个时间点分析 beta 多样性的常见做法可以掩盖由干扰驱动的显着变化。承认β多样性背后的灭绝-殖民化动态对于理解生物多样性的时空组织至关重要。我们的结果表明，在一个时间点分析 beta 多样性的常见做法可以掩盖由干扰驱动的显着变化。承认β多样性背后的灭绝-殖民化动态对于理解生物多样性的时空组织至关重要。