Investigating Surface Temperature from First Principles: Seedling Survival, Microclimate Buffering, and Implications for Forest Regeneration

Forests are extremely important ecosystems with large impacts on global water, energy, and biogeochemical cycling, and they provide numerous ecosystems services to human populations. Even though these systems consist of long-lived vegetation, forests are constantly experiencing changes to their extent and composition through the interacting forces of disturbance dynamics and climate change. In semi-arid landscapes like the western United States, patterns of recurring wildfire and subsequent seedling recruitment and forest regeneration are important in establishing the distribution of forests on the landscape. In this context, climate, hydrology, and existing vegetation all act together to limit the current and potential range of forest tree species. Most studies of forest persistence and regeneration use empirical observations and models that are unable to investigate the underlying climatic and hydrologic drivers of forest range shifts or extrapolate to novel temporal or spatial conditions. Here, we aim to study forest persistence and regeneration from first principles, identifying patterns of seedling survival in response to soil surface temperature, an integrative representation of the energy and water balance. We then use a process-based model to examine surface temperatures as a constraint on seedling establishment and forest persistence across the western United States.