Identifying climatic drivers of forage quantity and quality in Mediterranean rangelands using remote sensing

Rangelands are dynamic ecosystems shaped by fluctuations in precipitation, temperature, and grazing intensity. Accurate assessment of forage availability is critical for optimizing land use, preventing overgrazing, and mitigating degradation, especially under future climate change scenarios. This study employed a multi-scale approach to monitor pasture using Sentinel-2 satellite imagery, calibrated with ground truth measurements, and enhanced with drone-derived vegetation cover estimates. The research was conducted in a Mediterranean grassland ecosystem under varying grazing intensities in northeastern Israel. A time series of Sentinel-2 images from 2018 to 2023 was analyzed to monitor five vegetation growth cycles. We evaluated how climate variables, such as temperature, rainfall, and vapor pressure deficit (VPD), impacted forage availability and nutritional quality. Over the past three decades, significant climatological trends showed increasing temperatures and more concentrated winter rainfall. Correlation analysis between field data and Sentinel-2 imagery demonstrated strong agreement (R² = 0.73 for biomass and 0.72 for forage quality), validating the effectiveness of this integrated remote sensing approach. Moderate grazing reduced forage quantity but improved its quality, while extreme weather events, including drought and heatwaves, negatively impacted forage biomass and quality. Key meteorological indices, including the Standardized Precipitation-Evapotranspiration Index (SPEI) and the Simple Daily Intensity Index (SDII), were found to influence forage quantity, indicating that drought stress and concentrated rainfall events reduced biomass production. Higher values of daily temperature range and vapor pressure deficit adversely impacted forage quality. This study highlights the importance of adaptive management strategies to mitigate the projected reductions in forage quantity and quality due to climate change. The methodologies developed offer novel insights into improving ecological monitoring for sustainable rangeland management under changing climatic conditions.