In the last 50 years, intensive agriculture has replaced large tracts of rainforests. Such changes in land use are driving niche-based ecological processes that determine local community assembly. However, little is known about the relative importance of these anthropogenic niche-based processes, in comparison to climatic niche-based processes and spatial processes such as dispersal limitation. In this study, we use a variation partitioning approach to determine the relative importance of land-use change (ranked value of forest loss), climatic variation (temperature and precipitation), and distance between transects, on bird beta diversity at two different spatial scales within the Western Ghats-Sri Lanka biodiversity hotspot. Our results show that the drivers of local community assembly are scale dependent. At the larger spatial scale, distance was more important than climate and land use for bird species composition, suggesting that dispersal limitation over the Palk Strait, which separates the Western Ghats and Sri Lanka, is the main driver of local community assembly. At the smaller scale, climate was more important than land use, suggesting the importance of climatic niches. Therefore, to conserve all species in a biodiversity hotspot, it is important to consider geographic barriers and climatic variation along with land-use change.

中文翻译：

---

西高止山脉-斯里兰卡生物多样性热点地区鸟类β多样性的驱动因素与规模有关：土地利用，气候和距离的作用。

在过去的50年中，集约化农业取代了大片的雨林。土地利用的这种变化正在推动基于生态位的生态过程，这些过程决定了当地社区的集会。但是，与基于气候生态位的过程和空间过程（例如扩散限制）相比，这些基于人为生态位的过程的相对重要性知之甚少。在这项研究中，我们使用变化分区方法来确定土地利用变化（森林丧失的等级值），气候变化（温度和降水）以及样带之间的距离在两种不同空间尺度上对鸟类β多样性的相对重要性。西高止山脉-斯里兰卡生物多样性热点地区。我们的结果表明，当地社区集会的推动力与规模有关。在更大的空间尺度上 距离远比气候和土地利用对鸟类的物种组成更为重要，这表明将西高止山脉与斯里兰卡隔开的帕克海峡的扩散限制是当地社区集会的主要驱动力。在较小的规模上，气候比土地利用更为重要，这说明了气候生态位的重要性。因此，为了保护生物多样性热点中的所有物种，重要的是要考虑地理障碍和气候变化以及土地利用的变化。