Assessing the Impact of Burn Severity on Vegetation: A Time Series Analysis of the Meadow Valley Wildfire

Abstract Submission: Wildfires are increasingly frequent and intense due to climate change-induced droughts, increased temperatures, and human activities, significantly impacting ecosystems, particularly vegetation and hydrological processes. The Meadow Valley wildfire burned through vast areas of the Meadow Valley Wilderness Range in Nevada from 7th July 2020 to 19th July 2020 igniting 59,291 acres. Despite extensive research on wildfire impacts, the combined effects of wildfire on vegetation, evapotranspiration, and soil moisture remain underexplored, especially concerning the effects of burn severity. In this research, we analyze the impact of wildfire severity on vegetation by comparing pre- and post-fire Normalized Burn Ratio (NBR), Normalized Difference Vegetation Index (NDVI), evapotranspiration, and soil moisture. NDVI and NBR are calculated from Landsat-8 Operational Land Imager, Evapotranspiration data is obtained from OpenET and soil moisture data is obtained from the Soil Moisture Active Passive satellite. The time series analysis is conducted for study sites selected, each measuring 90m x 90m, inside and outside the fire perimeter. The period for time series analysis is from 3 years before to 4 years after the wildfire. A paired t-test is applied to assess vegetation and soil moisture differences from pre- to post-fire conditions. Additionally, an ANOVA is used to determine the influence of different burn severity levels obtained through NBR on post-fire NDVI, evapotranspiration, and soil moisture. The higher burn severity leads to more pronounced declines in NDVI and significant negative disruptions in soil moisture and evapotranspiration. This research provides a deeper understanding of how wildfire-induced changes in vegetation and hydrological processes vary with burn severity, offering critical insights for post-fire ecosystem recovery.

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