Remote Measurement of Short-term Post-fire Vegetation Regrowth in Sierra Nevadan Forests

Abstract:

Forest ecosystems in the Sierra Nevada are greatly influenced by wildfire disturbance. A study of vegetation regrowth following fire is essential for us to better understand and evaluate the effects of disturbances on ecological processes, such as carbon and nitrogen storage, soil erosion, water quality and forest dynamics. The rate of short-term vegetation recovery, as measured by Normalized Difference Vegetation Index (NDVI), was explored following fire over multiple years (1999-2006) in Sierra Nevadan forests. The role of both temporal (e.g. variations in multiple years’ precipitation) and landscape factors (e.g. altitude, slope, aspect, pre-fire and immediate post-fire vegetation status, and burn severity) were investigated in explaining the short-term vegetation regrowth following fire using remote sensing on the landscape scale. Our results indicate that spatial-temporal variability existed in the short-term post-fire vegetation regrowth. Pre-fire vegetation status, burn severity, immediate post-fire wet season precipitation and elevation were found to play important roles in short-term post-fire vegetation recovery trends. Consistent with a local forest gap model, our results also corroborate that water availability may be the limiting factor for the post-fire vegetation regrowth in the lower elevation of Sierra Nevadan forests. In the future, post-disturbance vegetation regrowth trends and related controlling environmental factors following various forest disturbances (e.g. insect outbreak and forest harvest) other than wildfire can also be studied and compared using the methodology proposed in this study.