Allometric Model Development in Lodgepole Pine Forests of the Greater Yellowstone Ecosystem

Changes in climatic patterns in western North America may modify natural fire regimes, resulting in alterations in forest structure and productivity (Amiro et al. 2000). More frequent fues would create substantial landscape-scale heterogeneity and, consequently, variability in how individual trees and stands allocate biomass in response to the differences in forest structure (Chapin et al. 2002; Turner et al. 2004). For example, in the lodgepole pine (Pinus contorta var. latifolia [Engelm. ex Wats.] Critchfield) forests of the Greater Yellowstone Ecosystem (GYE), recent and historic fires have created a complex mosaic of forest stand structures and aboveground net primary production (NPP) (Turner et al. 1997, 2004). The quantification of forest structure and function at large spatial scales requires accurate measurements of aboveground and belowground tree biomass. Allometric equations for estimating above­ and belowground biomass of lodgepole pine have been developed in Alberta, Canada, southeastern British Columbia, southeastern WY, and in Washington and Oregon (Johnstone 1971; Comeau and Kimmins 1989; Pearson et al. 1984; Gholz et al. (1979, respectively). More recently, allometric equations for young lodgepole pine saplings have also been developed in Yellowstone National Park (YNP) for aboveground biomass by Turner et al. (2004), and for belowground biomass by Litton et al. (2003). However, because of variability in latitude, growing conditions, substrate and climate, existing equations that predict biomass for mature lodgepole pine trees are not appropriate for use in the GYE, and new allometric equations specific for the GYE are needed. In this study, we will develop new allometric equations for predicting above- and belowground biomass in mature lodgepole pine forests of the GYE. The specific objectives of this study were to: (1) develop allometric models for predicting above and belowground biomass of mature lodgepole pine trees in the GYE, and determine how these equations differ with stand density and age; (2) compare and contrast allometric equations developed in this study to allometric equations developed in other locations to determine applicability across geographic loc-ations independent of forest structure.