Wildfire severity and vegetation recovery drive post-fire evapotranspiration in a southwestern pine-oak forest, Arizona, USA

Abstract

Post-fire stand water balance is a critical factor influencing tree regeneration and survival, which are often modulated by fire severity. We examined influences of the post-fire vegetation matrix and fire severity on diurnal, seasonal, and multi-year variation in evapotranspiration (ET) by analyzing the relationship between post-fire vegetation and ECOsystem Spaceborne Thermal Radiometer Experiment on the International Space Station (ECOSTRESS) ET data using multivariate and linear mixed effects modeling. Unlike many high-severity fire sites where ET drops after burning, post-fire ET was high at shrubland sites that burned at high fire severity in southern Arizona, USA. In this study, post-fire ET was driven by plant species composition and tree canopy cover. ET was significantly higher in the morning and midday in densely vegetated post-fire shrublands than pine-dominated forests that remained 5–7 years after wildfire. Our results demonstrate that plant functional traits such as resprouting and desiccation tolerance drive post-fire ET patterns, and they are likely to continue to play critical roles in shaping post-fire plant communities and forest water cycling under future environmental change.