Whitebark pine is a symbol of the high country of the Cascades and Rocky Mountains, a keystone species that supports an intricate network of wildlife, and a vital component of high-elevation ecosystems throughout the western United States. Unfortunately, this species has experienced dramatic declines throughout its range over the past century due to both natural and anthropogenic causes. Fire suppression is commonly implicated as a contributing factor to its decline, yet extensive gaps exist in the knowledge of past fire regimes and structure of whitebark pine forests over much of the species range. This doctoral dissertation research will use a multi-scale approach to elucidate the complex interactions between past fire activity and the composition and structure of whitebark pine forests in the context of different biophysical settings and broad-scale climate variability. Specifically, answers to the following research questions will be sought: What were the historical ranges of variability in the fire regimes of whitebark pine forests throughout the central distribution of the species? What are the driving mechanisms for spatial and temporal variations in fire activity in these forests? How has fire suppression affected the structure of forests characterized by diverse disturbance regimes and biophysical settings? The study sites for this research will be set within three to four watersheds in each of several National Forests and Wilderness Areas along and east-west transect set from southwestern Montana to the Cascades of Oregon. At each site, forest structure and composition data will be obtained through stand surveys and dendroecological sampling, and fire history data will obtained by collecting partial cross sections from fire scarred trees, snags, and down material within the plot and the surrounding area. These data will be used to describe the stand and disturbance history of each site, explore the potential processes that led to these patterns, and compare and contrast these patterns both over time and space.
This research will fill both a physical gap in the network of available fire history sites and a theoretical gap in the understanding of mixed-severity fire regimes, the ecosystems they maintain, and the recent ecological changes they have undergone. This research will provide a framework to facilitate the development of management plans to preserve this declining species and the ecosystems it supports. All of the data collected will be archived at the publicly accessible International Tree-Ring Data Bank and the International Multiproxy Paleofire Database, and copies of all publications and reports produced from this project will be disseminated to the offices of each National Forest involved and the Whitebark Pine Ecosystem Foundation. This project will support multiple undergraduate students in field and laboratory settings, strengthening their future employment opportunities. Display samples will be offered as interpretive objects to all National Forest offices involved to help educate the public about the role of fire in whitebark pine ecosystems. A middle school science teacher will also assist in all aspects of this project, thereby garnering experiences in dendroecological research and whitebark pine ecology that he will share with his students.
