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

太平洋西北地区强烈的中纬度气旋受到的关注远远少于美国东南部飓风多发地区，但却产生了类似强度和频率的大风事件（hes）。这些风速高达180英里/小时的大风可以说是影响喀斯喀特山脉峰顶以西森林的最重要的干扰因素，这意味着它们对森林再生、森林演替和火灾制度产生了区域范围的影响。例如，自1880年以来，至少有5起hwe造成了超过10亿板英尺的森林破坏。最近，2006年和2007年的高温天气导致俄勒冈州西部和华盛顿州数百万居民停电。然而，尽管它们具有生态、社会和经济意义，但人们对太平洋西北部hwe的时间、范围、原因和后果知之甚少。本研究利用年轮的信息，将风事件与已知的十年至百年尺度的气候变化进行比较，并将其发生与森林动态和区域火灾周期联系起来，从而将这些hes置于更广泛的历史背景中。这些目标将通过基于太平洋西北10个地点收集的树木年轮数据的多世纪气候重建来实现，并通过采用一项研究方案来测量和比较hwe后树木生长在风吹伤的老树与附近未受损的年轻树木之间的反应。然后，在历史记录之前的一段时间内，可以确定与有记录的高热量环境破坏的树木生长异常相匹配的树木生长异常：1)使用树木生态学技术建立高热量环境300年的记录；2)量化hes的频率、严重程度、空间分布和天气成因；3)研究hes与全球和天气尺度气候现象、小冰期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相关的hes的生态后果。对hwe进行多世纪的重建和分析将为一个重要但鲜为人知的主题提供若干公共和科学利益。最重要的是建立科学基础，以便：1)在开始进行历史和仪器记录之前估计这些风事件的概率和严重程度；2)评估其生态和潜在经济影响；3)援助机构的准备。这些发现将有助于未来寻求将气候学和森林生态学结合起来的研究，因为它提供了一种方法方法，适用于其他受高温天气影响的温带地区，如美国东北部。这些结果还将促进对风暴如何影响火情的理解，并有助于在气候不确定的时代制定未来的森林管理做法。最后，该研究将在十年到世纪的尺度上展示高热量食物如何受到气候变化的影响，并确定高热量食物与人类引起的气候变化之间的可能联系。

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.