Localized replacement rather than generalized degradation: Impacts of cropland expansion on rangeland health in semiarid Argentina

Abstract

Driven by global commodity demand and capital investment, cropland expansion in Argentina has fragmented ecologically fragile semiarid rangelands and dry forests, intensifying pressure on traditional grazing systems. Using Landsat imagery and Continuous Change Detection and Classification (CCDC) algorithms integrated with a random forest classifier, we produced annual land-use maps (1990–2020) for the Caldenal–SL region (the Caldenal rangeland within San Luis Province), achieving high accuracy (overall: 92.7 %, Kappa: 0.873). Over three decades, native rangelands decreased by 4081 km2 (18.37 % of the region; net loss: 3478 km2), with 82.95 % converted to cropland (net gain: 3154 km2) and 16.92 % transitioning to forest cover (net gain: 324 km2). Cropland expansion peaked between 2000 and 2003, coinciding with Argentina´s soybean boom and associated market incentives. Vegetation health, assessed via NDVI/EVI slope trends derived from the CCDC harmonic regression model, showed significant improvement in permanent rangelands—defined as areas with stable land cover and no spectral breakpoints—reaching 53.70 %–95.54 %, and notably exceeding the proportions of stable (2.32 %–25.64 %) and degraded areas (2.14 %–20.66 %). Livestock-density hotspots were concentrated in the eastern agropastoral transition zone, characterized by higher rainfall, suggesting a shift from extensive to intensive grazing, thereby mitigating grazing pressure on permanent rangelands. Our findings highlight the urgent need for robust legal frameworks, innovative production strategies, and market-driven incentives to sustainably balance agricultural expansion with ecological stability and biodiversity conservation in semiarid pastoral landscapes.