Collaborative Research: The Occurrence of Severe Pacific Northwest Windstorms: A Multi-Century Dendroclimatic Assessment of Their Ecological Impacts

太平洋西北部的强中纬度气旋受到的关注远低于美国东南部飓风多发地区，但产生类似量级和频率的大风事件（HWE）。 这些HWE，记录风速高达近180英里每小时，可以说是最重要的干扰剂塑造西部的喀斯喀特山脉波峰的森林，这意味着他们施加区域规模的影响，森林再生，森林演替和火灾制度。 例如，自1880年以来，至少有五个HWE每个都造成了超过10亿板英尺的森林吹倒。 最近，2006年和2007年的HWE导致俄勒冈州西部和华盛顿数百万居民停电。然而，尽管它们的生态，社会和经济意义，很少有人知道的时间，范围，原因和太平洋西北HWEs的后果。这项研究将这些HWE置于更广泛的历史背景下，通过使用年度树木年轮中的信息来比较风事件与已知的十年至百年尺度的气候变化，并将其发生与森林动态和区域火灾周期联系起来。这些目标将使用多世纪的气候重建的基础上收集的年轮数据在太平洋西北部的10个地点，并通过采用一项研究协议，测量和比较后HWE树木生长反应之间的风折断，老的树木，年轻的，附近的未受损的树木。然后，可以在历史记录之前的时期识别与被记录的HWE损害的树木中发现的那些相匹配的生长异常，以：1）使用树木生态学技术建立HWE的300年记录; 2）量化HWE的频率、严重性、空间分布和天气原因;（3）研究HWEs与全球和天气尺度气候现象、小冰期的结束以及人类活动对气候的影响之间的关系;以及，4）估计与排污和排污后火灾循环有关的HWE的生态后果。HWE的多世纪重建和分析将为一个重要但知之甚少的主题提供一些公共和科学利益。最重要的是建立科学基础：1）在历史和仪器记录开始之前估计这些风事件的概率和严重程度; 2）评估其生态和潜在的经济影响; 3）帮助机构做好准备。 这些研究结果将有利于未来的研究，寻求整合气候学和森林生态学提供了一种方法，适用于其他温带地区受HWE影响，如美国东北部。 这些结果还将促进对风暴如何影响火灾制度的理解，并有助于在气候不确定的时代制定未来的森林管理措施。 最后，该研究将展示HWE如何在十年到世纪尺度上受到气候变化的影响，并确定HWE与人类引起的气候变化之间可能的联系。

Strong midlatitude cyclones in the Pacific Northwest receive far less attention than the hurricane-prone regions of the southeastern U.S., yet generate high wind events (HWEs) of similar magnitude and frequency. These HWEs, with documented wind speeds up to almost 180 mph, are arguably the most important disturbance agent shaping forests west of the Cascade Range crest, which means that they exert a regional-scale influence on forest regeneration, forest succession, and fire regimes. For example, since 1880 at least five HWEs have each caused forest blowdowns exceeding one billion board feet. More recently, HWEs in 2006 and 2007 caused electrical power outages for millions of residents in western Oregon and Washington. However, despite their ecological, social, and economic significance, little is known about the timing, extent, cause, and consequences of Pacific Northwest HWEs. This research places those HWEs within a broader historical context by using the information in annual tree rings to compare wind events with known decadal-to-century-scale climate variations and to link their occurrence to forest dynamics and regional fire cycles. These objectives will be met using a multi-century climatic reconstruction based on tree-ring data collected at 10 sites in the Pacific Northwest and by employing a research protocol that measures and compares post-HWE tree-growth responses between wind-snapped, old-growth trees to those of younger, nearby undamaged trees. Growth anomalies matching those found in trees damaged by documented HWEs can then be identified for the period before the historical record to: 1) establish a 300-year record of HWEs using dendroecological techniques; 2) quantify the frequency, severity, spatial distribution, and synoptic causes of HWEs; 3) examine the relationship between HWEs and global and synoptic-scale climate phenomena, the end of the Little Ice Age, and anthropogenic influences on climate; and, 4) estimate the ecological ramifications of HWEs related to blowdown and post-blowdown fire cycles. A multi-century reconstruction and analysis of HWEs will provide several public and scientific benefits regarding an important but poorly understood topic. Foremost will be the establishment of a scientific basis for: 1) estimating the probability and severity of these wind events before the initiation of historical and instrumental records; 2) assessing their ecologic and potential economic impacts; and, 3) aiding agency preparedness. These findings will benefit future studies seeking to integrate climatology and forest ecology by providing a methodological approach applicable to other temperate regions affected by HWEs such as the northeastern United States. These results also will promote the understanding of how windstorms influence fire regimes and aid in the development of future forest management practices in an era of climatic uncertainty. Finally, the research will demonstrate how HWEs are influenced by climatic variability at the decadal-to-century scale and identify possible links between HWEs and human-induced climate change.