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。科罗拉多森林具有大尺度扰动的特点，其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，反复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齐克尔山（Mount Zirkel）荒野及其周围超过1万公顷的森林，为研究提供了难得的机会。本研究的目的是探讨四个主要因素对林分对风干扰易感性的影响：(1)林分的火灾历史；(2)林分的物种组成；(3)林分风扰动历史；(4)林分地形特征。本研究将传统的树木年代学技术与地理信息系统（GIS）相结合，研究科罗拉多亚高山森林中火和风扰动机制之间的相互作用。数据将在实地收集，并输入地理信息系统进行描述性分析。这些数据将使用多元回归和其他多元统计来分析林分对风害的易感性与这四类环境因素的关系。这项研究将量化亚高山森林中火灾和大规模排污的作用，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在自然干扰造成的限度之内。由于全球气候变化可能会增加灾难性风的频率和强度，因此了解大规模吹落对森林生态系统的影响可能尤为重要。因此，这项研究将指导这些森林的管理决策，不仅可以获得亚高山森林中干扰的重要空间信息，还可以解决一个悬而未决的问题，即一个地点以前的干扰历史如何影响其对未来干扰的反应。地理信息系统为生态系统过程的空间分析提供了新的机会。这项研究将把基于地理信息系统的分析与已建立的用于森林动态时间分析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.