Wildfires In Xerophytic Shrublands of Lihué Calel National Park, La Pampa, Argentina

In recent years, there is growing evidence of changes in fire frequency, with varying intensities and magnitudes across ecosystems worldwide. La Pampa, located in central Argentina, is affected by significant annual wildfire activity. This study aimed to analyze variations in climatic and spectral indices over a 29-year period (1995–2023) to identify patterns that enhance the understanding of the fire regime in xerophytic shrublands. Additionally, trends in climatic variables were evaluated within the framework of global climate change. Meteorological data and records of burned area were analyzed. The Standardized Precipitation and Evapotranspiration Index (SPEI) was calculated at four-time scales, and monthly Normalized Difference Vegetation Index (NDVI) data for shrubs and grasslands were obtained. Trend detection and correlation analysis between variables were performed using the Theil-Sen estimator and the non-parametric Mann-Kendall test. A SARIMA model was used to explore lagged correlations between selected variables. SPEI values typically ranged between -2 to 2, with SPEI-12 showing the highest correlation with large, severe fire events. NDVI for shrubland and grassland exhibited positive correlations with SPEI-24 and SPEI-6/SPEI-12, respectively. SPEI-12 and burned area displayed a significant negative correlation. Monitoring climatic and spectral indices over time helps identify periods of phytomass accumulation and ignition thresholds. In the context of climate change, the observed increasing trends in precipitation, mean temperature, and maximum temperature suggest a future with heightened fire frequency in xerophytic shrublands. This study underscores the importance of integrating climatic and vegetation indices to improve fire regime understanding and management in fire-prone ecosystems.