Understanding Climate Impacts on Conifer Seedling Survival

Two-year-old, bare root ponderosa pine seedling

Increasing drought and disturbance associated with climate change is contributing to shifting and shrinking tree species range limits in the Northwest. Conifer seedlings are especially susceptible to drought and climate extremes. Although the U.S. Forest Service (USFS) invests time and money to annually restock and replant trees, there is increasing evidence of regeneration failure in low-elevation forests, emphasizing the need for improved strategies for informing planting decisions.

The purpose of this project is to regionally calibrate an ecohydrological model and pair it with a dynamic stress index to predict drought-induced seedling mortality at the landscape scale across the western US, using USFS seedling data to inform and validate the model. A landscape distribution of conifer seedling drought stress and mortality probability developed through this project can help inform USFS planting and regeneration decision-making processes. This research will help forest managers design more efficient planting strategies and work to mitigate the risk of regeneration failure in future reforestation efforts.