Aims To examine the potential mechanistic predictors of germination and first-year survival in two species of Great Basin sub-alpine trees along an elevation gradient on three soil types. Methods Using a network of experimental gardens, we sowed limber pine and Great Basin bristlecone pine along elevational gradients at three sites on three different soil types. We collected germination and first-year survival data of each species while measuring temperature, soil water content, and other environmental variables to examine the potential predictors of first-year survival in these two species. Results Thanks to consecutive anomalously wet and dry years, we found germination and first-year survival to be largely limited by soil type, soil water content, and precipitation timing. Limber pine germination and survival showed weak negative responses while bristlecone pine germination and survival showed stronger negative responses to temperature. Conclusions Young trees are more sensitive to water limitation than to temperature and soil type has a strong moderating effect on water availability. Precipitation timing affected this availability with winter snowpack being less important in establishment than summer monsoonal rain. These results point to the importance of substrate and understanding limitations on all life stages when attempting to predict species range shifts.

中文翻译：

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物种分布范围转移机制：大盆地狐尾松和林柏松的萌发和早期存活

目的 研究在三种土壤类型上沿海拔梯度的两种大盆地亚高山树木的发芽和第一年存活率的潜在机械预测因子。方法使用实验花园网络，我们在三种不同土壤类型的三个地点沿海拔梯度播种了椴树松和大盆地狐尾松。我们在测量温度、土壤含水量和其他环境变量的同时收集了每个物种的发芽和第一年存活率数据，以检查这两个物种第一年存活率的潜在预测因子。结果 由于连续异常干湿年份，我们发现发芽和第一年存活率在很大程度上受到土壤类型、土壤含水量和降水时间的限制。林木萌发和存活对温度表现出较弱的负响应，而狐尾松萌发和存活对温度显示出更强的负响应。结论 幼树对水分限制比对温度更敏感，土壤类型对可用水量有很强的调节作用。降水时间影响了这种可用性，冬季积雪在建立中不如夏季季风降雨重要。这些结果表明，在试图预测物种范围变化时，基质的重要性和理解所有生命阶段的局限性。降水时间影响了这种可用性，冬季积雪在建立中不如夏季季风降雨重要。这些结果表明，在试图预测物种范围变化时，基质的重要性和理解所有生命阶段的局限性。降水时间影响了这种可用性，冬季积雪在建立中不如夏季季风降雨重要。这些结果表明，在试图预测物种范围变化时，基质的重要性和理解所有生命阶段的局限性。