Doctoral Dissertation Research: Disturbance Interactions in a Rocky Mountain Subalpine Forest

最近的研究强调了自然干扰在许多森林生态系统发展中的重要性。科罗拉多州的森林以大规模干扰为特征，历史回归间隔往往短于优势树种的寿命。因此，干扰是这些森林发展的一个重要因素。火灾和大风是非常重要的干扰形式，一再影响科罗拉多州森林的结构和功能。1997年，一场大风暴吹倒了科罗拉多州西北部泽克山荒野及其周围超过10,000公顷的森林，提供了一个难得的研究机会。本研究的目的是探讨影响林分对风干扰敏感性的四个主要因素：(1)林分的火灾历史；(2)林分的物种组成；(3)林分的风扰历史；(4)林分的地形特征。这项研究将结合传统的树木年代学技术和利用地理信息系统(GIS)的分析来研究这片科罗拉多亚高山森林中火和风干扰制度之间的相互作用。数据将在实地收集，并输入地理信息系统进行描述性分析。这些数据将使用多变量回归和其他多变量统计进行分析，以将林分对这四类环境因素的风害敏感性联系起来。这项研究将量化火灾和大规模排污在亚高山森林中的作用，并深入了解不同干扰之间的相互作用如何决定森林结构、组成和健康。这些见解将使森林管理能够在自然干扰造成的限度内进行。由于全球气候变化可能会增加灾难性风的频率和强度，因此了解大规模井喷对森林生态系统的影响可能特别重要。因此，这项研究将指导这些森林的管理决策，不仅提供关于亚高山森林干扰的重要空间信息，而且还通过解决一个地点以前的干扰历史如何影响其对未来干扰的反应这一基本上未回答的问题。地理信息系统为生态系统过程的空间分析提供了新的机遇。这项研究将把基于地理信息系统的分析与已用于森林动态时间分析的成熟的树木年代学程序结合起来。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立研究生涯。

Recent research has highlighted the importance of natural disturbances in the development of many forest ecosystems. Colorado forests are characterized by large-scale disturbances with historical return intervals often shorter than the life span of dominant tree species. Disturbances therefore are an important factor in the development of these forests. Fire and high winds are very important forms of disturbance that repeatedly have affected the structure and function of Colorado forests. In 1997 a major windstorm blew down over 10,000 hectares of forest in and around the Mount Zirkel Wilderness in northwestern Colorado, providing a rare research opportunity. The objectives of this study are to investigate the effect of four main factors on susceptibility for forest stands to wind disturbance: (1) a stand's fire history; (2) a stand's species composition; (3) a stand's wind disturbance history and; (4) a stand's topographic characteristics. This study will combine traditional dendrochronological techniques with analyses employing a geographic information system (GIS) to study the interactions between fire and wind disturbance regimes in this Colorado subalpine forest. Data will be collected in the field and entered into the GIS for descriptive analysis. These data will be analyzed using multivariate regression and other multivariate statistics to relate stand susceptibility to wind damage to these four categories of environmental factors. This study will quantify the roles of fire and large-scale blowdowns in subalpine forests and lend insight into how interactions among different disturbances determine forest structure, composition, and health. These insights will allow management of forests to be within the limits that result from natural disturbances. The effects of large-scale blowdowns on forest ecosystems may be especially important to understand since global climate change may increase the frequency and intensity of catastrophic winds. This research therefore will guide management decisions of these forests by not only yielding important spatial information about disturbances in subalpine forests but also by addressing the largely unanswered question of how a site's previous disturbance history affects its response to future disturbances. Geographic information systems provide new opportunities for the spatial analysis of ecosystem processes. This research will combine GIS-based analyses with well-established dendrochronological procedures that have been used for temporal analysis of forest dynamics. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.