Context The role of protected areas as biodiversity repositories has become increasingly important in face of increased deforestation. By adding free-living exotic mammals, removing forest-dependent native ones, isolating forest patches from large protected areas and reducing landscape forest cover, human activities may drive mammal communities towards regional biotic homogenization. Objectives We assessed how landscape forest cover and proximity to the largest and best-preserved area of the Catimbau National Park—one of the largest protected areas of the Brazilian Caatinga—affect α- and β-diversity of medium- and large-sized mammals, considering native and exotic species. Methods Using camera traps (total effort of 2340 cameras/day), we obtained 823 records of 15 species (8 natives and 7 exotics) in 18 landscapes of 1-km radius. We estimated diversity metrics within and among landscapes and used generalized linear models to assess the effect of forest loss and isolation on diversity metrics. Results As expected, forest loss decreased α-diversity of native species and increased the diversity and relative abundance of exotics. However, proximity to the preserved area showed weak effect on α-diversity, suggesting that this area does not work regionally as source for natives neither as ecological trap for exotics. Supporting the biotic homogenization hypothesis, β-diversity of natives decreased and β-diversity of exotics increased in more deforested landscapes. Yet, species composition was weakly related to forest cover and isolation. Conclusions Our findings demonstrate that deforestation jeopardizes native species, favors exotics, and drives mammal communities towards biotic homogenization. Protected areas should be properly implemented to safeguard mammal diversity.

中文翻译：

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人类改造保护区中新型哺乳动物群落的景观尺度模式和驱动因素

背景 面对日益严重的森林砍伐，保护区作为生物多样性储存库的作用变得越来越重要。通过增加自由生活的外来哺乳动物、移除依赖森林的本土哺乳动物、将森林斑块与大型保护区隔离并减少景观森林覆盖，人类活动可能会推动哺乳动物群落走向区域生物同质化。目标 我们评估了景观森林覆盖率以及与卡廷博国家公园（巴西卡廷加最大的保护区之一）最大和保存最完好的区域的距离如何影响大中型哺乳动物的 α 和 β 多样性，考虑本地和外来物种。方法使用相机陷阱（总工作量 2340 个相机/天），我们在 1 公里半径的 18 个景观中获得了 15 个物种（8 个本地物种和 7 个外来物种）的 823 条记录。我们估计了景观内部和景观之间的多样性指标，并使用广义线性模型来评估森林损失和隔离对多样性指标的影响。结果 正如预期的那样，森林丧失降低了本地物种的 α 多样性，增加了外来物种的多样性和相对丰度。然而，靠近保护区对 α 多样性的影响较弱，这表明该地区既不是本地人的来源，也不是外来物种的生态陷阱。支持生物同质化假说，在更多的森林砍伐景观中，本地生物的β-多样性减少，而外来生物的β-多样性增加。然而，物种组成与森林覆盖和隔离的关系微弱。结论 我们的研究结果表明，森林砍伐危害本地物种，有利于外来物种，并推动哺乳动物群落走向生物同质化。应妥善实施保护区以保护哺乳动物的多样性。