Experimentally evaluating effects of postfire drought on establishment, growth and survival of two widespread western conifer species; lodgepole pine and Douglas-fir

This research seeks to understand how drought following wildfires affects the establishment of two widespread Rocky Mountain tree species, lodgepole pine and Douglas-fir. In Yellowstone National Park, warming, drying conditions are leading to increased frequency of severe wildfires that kill existing trees and trigger regeneration of the forest. These trends are expected to continue. Many tree species in Yellowstone are well adapted to fire. Yet, early and abundant seedling establishment after fire is critical for forests to recover. Tree seedlings are particularly sensitive to drought, and evidence suggests that sufficiently dry postfire conditions could cause widespread tree-seedling mortality, with ecological consequences that may last decades. This research will determine how seedlings from two tree species respond to drought conditions expected in the mid-21st century and will identify the physiological mechanisms that drive seedling response to dry conditions. The results of this study will advance understanding of how forests in the western United States will respond to environmental change over coming decades and provide useful information for western land managers who are grappling with increased wildfires.