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

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

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.