Role of fire severity on forest resilience to wildfires: An integrated remote sensing approach

Abstract:

In recent decades, wildfires across western US forests have increased both in size and frequency due to warming temperatures, human ignitions, and other disturbances. Importantly, these wildfires show mixed-severity (i.e., unburned, low, moderate, and high) fire regimes causing effects from partial damage to complete removal of vegetation within individual fires and across fire events. Hence, a gradient of vegetation structure, composition, and moisture stress can result across fire severity classes. Resistance and recovery of individuals and the community are important components of resilience to disturbance. Forest resilience to wildfire thus can be gauged by the rate at which the forest recovers in structure, composition, and moisture stress post-fire. A suite of instruments mounted on the International Space Station (ISS) provides unprecedented opportunities to characterize vegetation structure (from GEDI), composition (from DESIS), and moisture stress (from ECOSTRESS) to assess wildfire impacts on ecosystems in spatially continuous scales. To capitalize on this opportunity, we will quantify the effects of burn severity on the recovery of canopy structural complexity (captured by canopy height, plant area index and foliage height diversity), physiological diversity (captured by chlorophyll, carotenoids, water content), and moisture stress (captured by evaporative stress), the key components of post-fire biomass accumulation. Our preliminary investigations show contrasting structural shifts and biomass recovery pathways in response to fire severity even within single fires. Our findings may provide important implications to understand forest resilience to wildfires and to identify potential state transitions characterized by structure, composition or moisture thresholds.