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

海岸山脉正在发生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，在那里，年度峰值雪水当量（SWE）是季节性供水可用性的主要驱动因素。虽然对该地区大部分地区的SWE的空间或时间特征知之甚少，但最近积雪的减少导致许多流域的流量减少。该地区历史上的SWE和径流记录很少，持续时间也很短，因此很难确定过去是否发生过类似的低雪事件，或者最近的河流干旱是否前所未有。拟议的研究旨在作为一个多尺度的树木年轮研究，这将使太平洋山脉内的雪动态有一个广泛的空间和时间的了解。对气候科学的重大贡献已经坚定地确立了树木年轮作为描述水文气候变率的宝贵代理数据来源，以及作为在十年至千年时间尺度上评估水文气候历史的有用工具，这些地区的记录很少或时间有限。该研究将详细描述深积雪对山铁杉生长产生负面限制而对道格拉斯冷杉生长产生积极影响的林分的气候响应。将对100多个看台进行采样，包括环宽度、早木和晚木密度，以及按照标准协议构建的蓝色强度年表。一旦年表的雪敏感性被建立，相关的预测因子将被用来构建跨越年表期间的代理雪记录。为了扩大和区域化重建，ClimateWNA将与年表结合使用，提供特定地点的积雪历史，时间序列和聚类分析，以及用于评估长期时空趋势的空间统计。总体而言，该研究将为历史SWE数据集的代表性提供重要见解，并允许对多世纪趋势，变异性和遥相关关系的创新理解。预计年表将在年至千年的时间尺度上产生关于自然SWE和雪变率的新信息，从而为描述导致空间和时间同步的水文气候事件的低频状态变化背后的因果因素提供至关重要的见解。这些发现提供了理解年代际变化和人为变暖对这种情况下瑞典径流变化的复合影响所需的见解，所有负责管理积雪减少对社区供水、水力发电和当地太平洋鲑鱼种群影响的人都在寻求这些信息。

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.