Abstract Quaking aspen (Populus tremuloides) forests throughout the western United States have experienced significant mortality in recent decades, which has been influenced by climate variability, especially drought. In the western portion of its range, where most precipitation arrives during winter as snowfall and summers are dry, snowdrifts that persist into the growing season provide soil moisture recharge that sustain aspen groves. Aspen groves are important locations of biodiversity within these landscapes. There is growing concern that reduced snowpack due to climate change may reduce the long-term persistence and productivity of aspen communities in these regions. In this study, we evaluated the potential for climate change and drought to reduce or eliminate isolated aspen communities in southwestern Idaho. We used a landscape simulation model integrated with inputs from an empirically derived biogeochemical model of growth, and a species distribution model of regeneration to forecast how changes in climate, declining snowpack, and competition with a conifer species is likely to affect aspen occupancy over the next 85-years. We found that simulated reductions in snowpack depth (and associated increases in climatic water deficit) caused a reduction in aspen persistence; aspen occupancy was reduced under all high emissions climate scenarios. Douglas-fir (Pseudotsuga menziesii) occupancy also declined under all future climates. Aspen regeneration declined over the course of all simulations, with an ensemble ratio of mortality/establishment increasing over the course of both low and high emissions climate scenarios. Climate-induced mortality of aspen clones increased in frequency under all climate scenarios and, under the most severe emissions scenarios, contributed to a substantial decline of aspen cover. Our research suggests that snowbanks will become an important determinant of long-term persistence of aspen under changing climate in the region.

中文翻译：

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白杨在依赖雪堆的生态系统中的长期持久性

摘要 近几十年来，美国西部的颤杨 (Populus tremuloides) 森林经历了显着的死亡，这受到气候变异，尤其是干旱的影响。在其范围的西部，由于降雪和夏季干燥，大部分降水在冬季到达，持续到生长季节的雪堆提供了维持白杨林的土壤水分补给。白杨树林是这些景观中生物多样性的重要位置。人们越来越担心气候变化导致的积雪减少可能会降低这些地区白杨社区的长期持久性和生产力。在这项研究中，我们评估了气候变化和干旱减少或消除爱达荷州西南部孤立的白杨群落的潜力。我们使用了一个景观模拟模型，该模型与来自经验派生的生物地球化学生长模型的输入相结合，以及一个物种再生分布模型来预测气候变化、积雪减少以及与针叶树物种的竞争可能如何影响下一个时期的白杨占有率85 年。我们发现，积雪深度的模拟减少（以及相关的气候水分亏缺增加）导致了白杨持久性的减少；在所有高排放气候情景下，白杨木的入住率都降低了。道格拉斯冷杉 (Pseudotsuga menziesii) 在所有未来气候下的入住率也有所下降。在所有模拟过程中，白杨树的再生都在下降，在低排放和高排放气候情景的过程中，死亡率/建立的整体比率都在增加。在所有气候情景下，气候引起的白杨无性系死亡率都在增加，并且在最严重的排放情景下，导致白杨覆盖率大幅下降。我们的研究表明，雪堤将成为该地区气候变化下白杨长期存在的重要决定因素。