GIS Analysis of Fire Impact on Vegetation Using NDVI: A Case Study of the Special Nature Reserve “Carska Bara”, Serbia

Abstract

 Introduction: Wildfires in protected areas lead to damage and destruction of vegetation and endanger wildlife. The wildfire that occurred in the immediate vicinity of the Special Nature Reserve (SNR) and Ramsar site “Carska Bara” near Zrenjanin (northern Serbia) on October 15, 2018, affected approximately 800 ha, part of which extended into the northeastern sections of this protected area.

 Aim: The aim of this study is to identify which parts of the SNR were most severely affected by the wildfire, thereby contributing to the understanding of its impact on the protected area, as well as examining the processes that led to the occurrence of the wildfire.

 Materials and Methods: Sentinel-2A satellite images acquired before (October 14, 2018) and after (October 29, 2018) the fire were used in the analysis. The images were clipped to the boundaries of the protected area using QGIS 3.40. The NDVI (Normalized Difference Vegetation Index) represents an indicator of vegetation greenness and health. It is calculated as the ratio between the difference and the sum of reflectance in the near-infrared (NIR, Sentinel-2A Band 8) and red (RED, Sentinel-2A Band 4) spectral bands, where higher values indicate healthier and denser vegetation. By subtracting NDVI values before and after the fire, the differenced NDVI (dNDVI) was obtained, which highlights the areas most severely affected by the fire.

 Results: The analysis shows that 1.88% of the SNR territory was affected by a wildfire of very high intensity, and an additional 5.92% by a high-intensity wildfire. The remaining areas can be considered unburned. Although changes in NDVI values are observed between the two satellite images, they are mostly the result of phenological variations that naturally occur during the autumn period.

 Conclusion: Wildfires in Serbia most often occur as a consequence of agricultural land burning. It is necessary to improve the response time of emergency services during peak wildfire periods, especially in the vicinity of protected areas, which are the most vulnerable in hazardous situations.