Western larch is a highly fire-adapted, deciduous conifer of the Columbia River Basin in the Northwest United States and Southwest Canada. Western larch requires specific climate conditions for regeneration – the germination and survival of seedlings that replace dying trees. Increases in temperature and increases in the size and severity of wildfires under climate change may impact natural western larch regeneration by shifting the geographic area where it is able to grow after disturbances. Since there is currently limited understanding of how changes in climate and fire may limit larch regeneration, exploring this question is important for post-fire management, especially where reforestation is necessary.

The objective of Spencer’s research is to support Northwest forest managers, including project partners at the Washington State Department of Natural Resources and the Bureau of Land Management, in making decisions that will help forests adapt to a warmer, drier future, where anticipated increases in temperature and wildfire activity may limit natural western larch regeneration. Using satellite data, climate data and data collected in the field, Spencer will identify the climatic conditions conducive to western larch regeneration, while accounting for wildfire activity and other environmental factors. The resulting model will show the likelihood of western larch regeneration in a given area under different climate scenarios, identifying areas where reforestation may or may not be suitable. Ultimately, these results will be incorporated into a publicly available U.S. Forest Service reforestation tool, ‘RegenMapper’, supporting managers in prioritizing post-fire reforestation.