Long-term snow variability from tree-rings in the British Columbia Pacific Ranges

沿海山区持续和加速的水文气候变化正在产生持久的生态、经济和社会后果。这些变化在太平洋山脉值得注意，那里的年度峰值雪水当量(SWE)是季节性供水的主要驱动因素。虽然人们对这一地区SWE的空间或时间特征知之甚少，但最近积雪的减少导致了许多流域的径流减少。该地区的历史SWE和径流记录稀少且持续时间短，因此很难确定过去是否发生过类似的低雪事件，或者最近的径流干旱是否史无前例。拟议的研究旨在作为一项多尺度的树木年轮研究，使人们能够广泛了解太平洋山脉内的积雪动力学。对气候科学的重大贡献使树木年轮成为描述水文气候变异性的宝贵替代数据来源，并成为在记录很少或记录时间有限的区域评估十年至数千年时间尺度上的水文气候历史的有用工具。这项研究将详细说明深厚积雪对山地铁杉生长的负面影响和对道格拉斯冷杉生长的积极影响的林地的气候反应。将对100多个支架进行采样，按照标准协议构建年轮宽度、早材和晚材密度以及蓝色强度年表。一旦建立了年表的降雪敏感性，将使用相关的预报器来构建跨越年表持续时间的代用降雪记录。为了扩大重建范围并将其区域化，将结合年表使用气候WNA，以提供特定地点的降雪历史、时间序列和集群分析，以及用于评估长期空间和时间趋势的空间统计数据。总体而言，这项研究将为SWE历史数据集的代表性提供重要的见解，并允许以创新的方式理解多个世纪的趋势、变异性和遥相关关系。预计年表将产生关于年至千年时间尺度上的自然SWE和雪变异性的新信息，从而为描述导致空间和时间同步的水文气候事件的低频制度变化背后的因果因素提供至关重要的见解。这些发现提供了所需的洞察力，以了解在这种情况下，年代际变化和人为变暖对SWE产生的径流最近变化的复合影响，所有负责管理积雪减少对社区供水、水电发电和当地太平洋鲑鱼种群影响的人都在寻求信息。

Ongoing and accelerating hydroclimatic changes in the Coast Mountains are having lasting ecological, economic and social consequences. These changes are noteworthy in the Pacific Ranges, where the annual peak snow water equivalent (SWE) is the primary driver of seasonal water supply availability. While little is known about the spatial or temporal characteristics of SWE within much of this area, recent snowpack declines have led to reduced streamflow in many watersheds. Historical SWE and runoff records are sparse and of short duration in this region, making it difficult to determine whether similar low snow events have occurred in the past, or whether recent streamflow droughts are unprecedented. The proposed research is intended as a multi-scale tree-ring study that would enable a broad spatial and temporal understanding of snow dynamics within the Pacific Ranges. Significant contributions to climate science have firmly established tree-rings as invaluable sources of proxy data for describing hydroclimate variability, and as useful tools for evaluating hydroclimate history on decadal to millennia timescales in regions with few or limited-duration records. The research will detail the climate response of forest stands where deep snowpacks negatively limit the growth of mountain hemlock trees and positively influence the growth of Douglas-fir trees. Over 100 stands will be sampled, with ring width, earlywood and latewood density, and blue intensity chronologies constructed following standard protocols. Once the snow sensitivity of the chronologies is established, relevant predictors will be used to construct proxy snow records spanning the duration of the chronologies. To broaden and regionalize the reconstructions, ClimateWNA will be used in conjunction with the chronologies to provide site-specific snow histories, with time series and cluster analysis, as well as spatial statistics used to evaluate long-term spatial and temporal trends. Overall, the research will provide important insights into the representativeness of historical SWE datasets, as well as allow for an innovative understanding of multi-century trends, variability and teleconnection relationships. It is expected the chronologies will generate new information on natural SWE and snow variability on annual to millennial timescales, thereby providing the insights crucial for describing the causal factors behind the low-frequency regime shifts that lead to spatially and temporally synchronous hydroclimatic events. The findings provide the insights needed to understand the compounding impact of decadal variability and anthropogenic warming on recent changes to SWE-generated runoff in this setting, information sought after by all those charged with managing the impact of declining snowpacks on community water-supplies, hydroelectric power generation and local Pacific Salmon populations.**