Climate-Induced Vegetation Stress Detected Through Remote Sensing of Hydroclimatic Indicators

Abstract

Maintaining agricultural viability and managing water resources under rising global temperatures requires understanding the complex relationship between climate variability and vegetation dynamics. This study investigated the effects of hydroclimatic variability and long-term trends on vegetation response in the Meri & ccedil;-Ergene Basin, one of T & uuml;rkiye's most agriculturally productive and climate-sensitive regions. The monthly precipitation (pr), average temperature (Tave), reference evapotranspiration (ET0), and soil moisture (SM) were analyzed for 1975-2024 while the land surface temperature (LST) and Normalized Difference Vegetation Index (NDVI) were assessed between 2001 and 2024. Seasonal anomaly analysis revealed negative SM anomalies and frequent positive anomalies in the Tave, LST, and ET0, especially in spring and summer. The NDVI anomalies were more favorable in the spring and autumn but constrained in summer. Trend analyses (ITA/IPTA) showed increasing trends in the Tave, LST, and ET0, and declining trends in the SM. Correlation results indicated strong positive ET0-LST-Tave relationships (r > 0.90) and strong negative ET0-SM correlations (as low as -0.83). The NDVI showed moderate correlations with the LST but weak associations with the pr and SM, indicating a shift toward temperature-driven vegetation behavior. The findings demonstrate that vegetation dynamics, as represented by NDVI, are progressively affected by temperature anomalies. Warming trends specifically increase evapotranspiration demand and expedite phenological processes, resulting in stronger correlations between NDVI and both Tave and LST. This transition toward temperature sensitivity signifies that vegetation greenness in the study area is increasingly influenced by thermal factors rather than being solely limited by precipitation. These findings underscore the basin's vulnerability to warming and drying, highlighting the need for climate-resilient agriculture, improved irrigation planning, and adaptive land use strategies.