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.

对历史采集位点的重新调查表明，物种分布范围出现位移，其中以分布前缘扩张为主，该现象被归因于全球气候变暖。然而，目前开展的具有空间重复设计的群落尺度重调查极少，难以验证不同空间场景下物种的响应是否具备一致性。本研究针对加利福尼亚州山地北部、中部与南部的海拔梯度区域，重复开展了20世纪早期的小型哺乳动物调查。在本研究分析的34个物种中，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位移。但在三个区域中，三分之二的物种分布范围的单个或双侧海拔边界仍保持稳定；且在所有三个区域均有分布的22个物种中，无任何一个物种在所有区域同时沿同一方向改变其分布上下限。当发生分布位移时，高海拔物种通常会将其分布下限向高海拔方向收缩，而低海拔物种的响应则呈现异质性。对于高海拔物种而言，样点特异性的温度变化相较于降水变化，更能预测其分布位移的方向；而低海拔物种的位移方向则无法通过温度或降水变化进行预测。尽管本研究结果印证了此前山地物种分布主要向高海拔迁移的结论，但同时也凸显出：在空间重复的不同景观中，单个物种的响应差异程度之显著。