Data from: Spatially heterogeneous impact of climate change on small mammals of montane California

Resurveys of historical collecting localities have revealed range shifts, primarily leading edge expansions, which have been attributed to global warming. However, there have been few spatially replicated community-scale resurveys testing whether species' responses are spatially consistent. Here we repeated early twentieth century surveys of small mammals along elevational gradients in northern, central and southern regions of montane California. Of the 34 species we analysed, 25 shifted their ranges upslope or downslope in at least one region. However, two-thirds of ranges in the three regions remained stable at one or both elevational limits and none of the 22 species found in all three regions shifted both their upper and lower limits in the same direction in all regions. When shifts occurred, high-elevation species typically contracted their lower limits upslope, whereas low-elevation species had heterogeneous responses. For high-elevation species, site-specific change in temperature better predicted the direction of shifts than change in precipitation, whereas the direction of shifts by low-elevation species was unpredictable by temperature or precipitation. While our results support previous findings of primarily upslope shifts in montane species, they also highlight the degree to which the responses of individual species vary across geographically replicated landscapes.

对历史采集点的重访调查揭示了物种分布范围的变动，主要表现为分布前缘扩张，该现象被归因于全球变暖。然而，当前开展的空间重复群落尺度重访调查仍较为稀缺，此类调查用于检验物种的响应是否具备空间一致性。本研究重复开展了20世纪早期针对加利福尼亚山地北部、中部与南部区域沿海拔梯度分布的小型哺乳动物的调查。在我们分析的34个物种中，有25个物种在至少一个区域出现了向高海拔或低海拔的分布范围变动。不过，三个区域内三分之二的分布范围在一个或两个海拔限度上保持稳定；且在所有三个区域均有分布的22个物种中，没有任何一个物种同时在所有区域内沿相同方向变动其分布上限与下限。当发生分布范围变动时，高海拔物种通常会将其分布下限向高海拔收缩，而低海拔物种则呈现出异质性响应。对于高海拔物种而言，样点特异性的温度变化相比降水变化，更能预测其分布范围变动的方向；而低海拔物种的分布范围变动方向则无法通过温度或降水变化进行有效预测。尽管本研究结果支持了此前关于山地物种主要发生向高海拔分布范围变动的结论，但同时也凸显出单个物种的响应在地理重复样区之间存在显著差异的程度。