Caves and other subterranean features provide unique environments for many species. The importance of cave microclimate is particularly relevant at temperate latitudes where bats make seasonal use of caves for hibernation. White‐nose syndrome (WNS), a fungal disease that has devastated populations of hibernating bats across eastern and central North America, has brought renewed interest in bat hibernation and hibernaculum conditions. A recent review synthesized current understanding of cave climatology, exploring the qualitative relationship between cave and surface climate with implications for hibernaculum suitability. However, a more quantitative understanding of the conditions in which bats hibernate and how they may promote or mediate WNS impacts is required. We compiled subterranean temperatures from caves and mines across the western United States and Canada to (1) quantify the hypothesized relationship between mean annual surface temperature (MAST) and subterranean temperature and how it is influenced by measurable site attributes, and (2) use readily available gridded data to predict and continuously map the range of temperatures that may be available in caves and mines. Our analysis supports qualitative predictions that subterranean winter temperatures are correlated with MAST, that temperatures are warmer and less variable farther from the surface, and that even deep within‐cave temperatures tend to be lower than MAST. Effects of other site attributes (e.g., topography, vegetation, and precipitation) on subterranean temperatures were not detected. We then assessed the plausibility of model‐predicted temperatures using knowledge of winter bat distributions and preferred hibernaculum temperatures. Our model unavoidably simplifies complex subterranean environments and is not intended to explain all variability in subterranean temperatures. Rather, our results offer researchers and managers improved broad‐scale estimates of the geographic distribution of potential hibernaculum conditions compared to reliance on MAST alone. We expect this information to better support range‐scale estimation of winter bat distributions and projection of likely WNS impacts across the west. We suggest that our model predictions should serve as hypotheses to be further tested and refined as additional data become available.

中文翻译：

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连接地表和地下气候：对蝙蝠冬眠和其他洞穴居民的研究意义

洞穴和其他地下特征为许多物种提供了独特的环境。洞穴小气候的重要性在温带纬度特别重要，在温带，蝙蝠会季节性使用洞穴进行冬眠。白鼻综合症（WNS）是一种真菌性疾病，已经席卷了北美东部和中部的冬眠蝙蝠种群，这引起了人们对蝙蝠冬眠和冬眠条件的新兴趣。最近的综述综合了当前对洞穴气候学的理解，探索了洞穴与地表气候之间的定性关系，对冬眠适宜性有影响。但是，需要对蝙蝠冬眠的条件以及它们如何促进或介导WNS的影响有更定量的了解。我们对美国西部和加拿大的洞穴和矿山的地下温度进行了汇总，以（1）量化年平均地表温度（MAST）和地下温度之间的假设关系，以及该平均温度如何受可测站点属性的影响，以及（2）易于使用现有的网格数据可预测并连续绘制洞穴和矿山中可能存在的温度范围。我们的分析支持定性预测，即地下冬季温度与MAST相关，温度较温暖，离地表的变化较小，甚至深腔内温度也往往低于MAST。未检测到其他站点属性（例如，地形，植被和降水）对地下温度的影响。然后，我们使用冬蝙蝠分布和首选冬眠温度的知识，评估了模型预测温度的合理性。我们的模型不可避免地简化了复杂的地下环境，并且无意解释地下温度的所有变化。相反，与仅依赖MAST相比，我们的研究结果为研究人员和管理人员提供了对潜在冬眠病状况地理分布的更广泛的估计。我们希望这些信息能更好地支持冬季蝙蝠分布的范围规模估计以及对西部WNS可能影响的预测。我们建议，我们的模型预测应该作为假设，在有更多数据可用时进一步进行检验和完善。