Multi-Scale Reconstructions of Human-Climate-Fire Interactions in Mixed-Conifer Forests of the Northern Rockies

Montana State University, Bozeman MT

Investigators

Abstract

This research project will reconstruct historical fires over the past several thousand years in mixed-conifer forests on tribal lands in the northern Rockies. Similar forests are widespread in the interior of western North America, but little is known about their historical fire dynamics, and even less is known about how humans may have influenced those fires. Recent large fires and projections of increased fire activity in the decades ahead have prompted land-management agencies in the U.S. to initiate widespread restoration efforts aimed at reducing fire risk and hazard. At the same time, wildfire suppression costs in the western U.S. have risen to more than $1 billion annually and now consume nearly one-half of the U.S. Forest Service budget. There is a critical need to better understand the historical context for applying fuel treatments intended to reduce fire risk in mixed-severity forest types across the western U.S. The need to better understand the historical context for forest management is particularly compelling on tribal lands, where tribal members and forest managers have a strong interest in preserving historical continuity and incorporating culturally important practices into their management strategies. The project will clarify the role of ancient and recent human influence on fire regimes and mixed-conifer forests. Project results will provide a mechanistic understanding of factors shaping current forest stand characteristics. The project will contribute to scientific debates concerning the influence of both ancient and recent human activities on temperate forests. The project will enhance basic understanding of ecological resilience in the face of changing climatic conditions and land use, and it will facilitate the development of science-based management for ecosystems experiencing multiple natural and human-caused stressors. This project will help educate and train a new generation of fire and forest managers and researchers by employing more than ten undergraduates and two graduate students, including Native American students and students from tribal colleges. The project also will help build research capacity at a tribal college. This project will address the following questions related to past and future controls on fire and forest ecosystems: How variable were fire regimes in mixed-conifer forests of the northern Rockies? Are drier mixed-conifer forests inherently more resilient than mesic ones to recent increases in fire activity, insect outbreaks, and land-use change? Are treatments aimed at restoring baseline ecosystem dynamics in mixed-conifer forests representative of historical natural and human disturbance processes? How can lessons from past fire-human-climate interactions help land managers support forest resilience with future forest management in ways that ultimately reduce fire suppression costs? The investigators will answer these questions by combining fire and vegetation histories reconstructed from lake sediments and tree rings sampled from a network of paired sites in which early human activity was intensive versus paired sites that were largely isolated from early human activity. They will compare these histories of fire to multi-century reconstructions of climate. This project will clarify interactions between natural and human factors that influence ecosystem change in order to inform restoration and management strategies that support forest resiliency in ways that ultimately reduce the cost of wildfire risk and hazard.