The influence of bioclimatic and topographic variables on fire occurrence and frequency within the Ethekwini Municipal Area.

Abstract

Fires have been used for decades as a land management tool. Environments such as grasslands and fynbos depend on fire to maintain their ecological integrity. Fires can also become a disturbance in some ecological zones. Veldfires can be planned, but they can also occur naturally driven by a wide range of variables. However, due to changes in both local and global weather patterns, fires are occurring more frequently, posing a threat to the environment and society. The purpose of this study was to assess the influence of bioclimatic and topographic variables on fire occurrence and frequency within a biodiversity-rich urban landscape within the eThekwini Municipal Area. Remote sensing has become a valuable tool for detecting and monitoring fires globally; it is timeefficient and cost-effective. This study used MODIS Active fire product, which has high temporal resolution making it a valuable sensor for monitoring fires and gathering fire data from local to global scales. The interaction between topography, fuel lead and weather has been identified as the primary drivers of fire occurrence in different landscapes. Topographic variables were derived from a 30 m Digital Elevation Model using ArcGIS 10.4. The first part of this study focused on a wide range of topographic and climatic (temperature and precipitation) to determine the most influential drivers of fire occurrence using Maxent modelling algorithm. The results showed that mean temperature of the coldest quarter (33%), isothermality (12.3%), elevation (8.9%), and precipitation of the warmest month (8.8%) were the most influential predictor variables driving fire occurrence in the study area. The model obtained Area Under Curve (AUC) >0.7, indicating that Maxent is suitable for predicting fire probability in an urban landscape. The second part of this study evaluated the relationship between fire frequency and 25 bioclimatic and topographic variables using Pearsons Correlation. The results indicated that variables associated with temperature correlated more with fire frequency. This study can assist land managers in understanding fire probabilities across the municipality, identifying fire-prone regions, and monitoring them to reduce the impact of frequent unplanned fires while protecting ecological systems within the municipality's remnant and conserved urban spaces.