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

海岸山脉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是值得注意的，那里的年度峰值雪水当量（SWE）是季节性供水可用性的主要驱动力。虽然很少有人知道的空间或时间特性的SWE在这一领域的大部分，最近积雪的下降，导致减少径流在许多流域。历史SWE和径流记录是稀疏的，在这个地区的持续时间短，很难确定是否类似的低雪事件发生在过去，或者最近的径流干旱是前所未有的。拟议的研究旨在作为一个多尺度的树木年轮研究，将使广泛的空间和时间的了解雪的动态范围内的太平洋山脉。对气候科学的重大贡献已经牢固地确立了树木年轮作为描述水文气候变异性的替代数据的宝贵来源，以及作为在记录很少或持续时间有限的地区评估十年到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森林的气候反应，在那里，深厚的积雪会对山地铁杉的生长产生负面影响，并对道格拉斯冷杉的生长产生积极影响。将对100多个林分进行采样，并根据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。一旦建立了年表的雪敏感性，相关的预测将被用来构建代理雪记录跨越年表的持续时间。为了扩大重建范围并使其区域化，ClimateWNA将与年表结合使用，以提供特定地点的降雪历史，并进行时间序列和聚类分析，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，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。预计年表将产生新的信息，自然SWE和雪的变化，每年到千年的时间尺度，从而提供的见解至关重要的低频政权转变，导致时空同步水文气候事件背后的因果因素的描述。这些发现提供了了解十年变化和人为变暖对这种环境中SWE产生的径流最近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.