Investigating Wildfire Impact on Ecosystem in California using NASA MODIS Measurements

Abstract

Wildfires have long been a vital part of the California ecosystem, as they clear dead vegetation. allow for increased soil fertility, and more. However, along with climate change, wildfires in California have become a severe hazard and increasingly harmful to the environment. In particular, wildfires can end up being detrimental to the health of surrounding vegetation in its area of effect, often leading to long-term native vegetation loss. The aim of this study is to analyze the impacts across the time period of 2001-2020 of the ZACA Wildfire in 2007 on vegetation health through a variety of variables, including the Normalized Difference Vegetation Index (NDVI), Vegetation Condition Index (VCI), Thermal Condition Index (TCI), and Vegetation Health Index (VHI). This study is based on an integrated analysis of NASA satellite remote sensing measurements, including Moderate Resolution Imaging Spectroradiometer (MODIS) monthly vegetation index products and land surface temperature products. Analysis of monthly NDVI time series of the ZACA Fire burned area found a large drop in vegetation health in the year of the ZACA fire, 2007, going from a mean NDVI of 0.5613 in 2006 to a mean of 0.4586 in 2007 and eventually, 0.3384 in 2008. The general trend shows a slow incline in vegetation health after the sudden drop in 2007 and 2008 caused by the fire. However, this incline over the course of fifteen years has yet to reach the former mean NDVI values before 2007. A similar trend can be observed with the VCI, TCI, and VHI, all of which face a similar drop through 2007 and 2008. Just like the NDVI, the VCI, TCI, and VHI have yet to catch up to their status before the 2007 ZACA Wildfire. These results demonstrate the impacts of wildfire on vegetation, along with the slow recovery process, providing insightful information on the short-term impacts of wildland fires on ecosystems and the long-term recovery process.