Spatio-temporal analysis of vegetation dynamics and its relationship with climate variability in northwestern Ethiopia

Abstract

Understanding vegetation-climate interactions is essential for designing effective land management and environmental protection strategies. However, the impacts of climate variability on vegetation dynamics in northwestern Ethiopia remain insufficiently understood. This study analysed the spatiotemporal patterns of vegetation change and key climatic variables, along with their interrelationships, over the period 2001–2024 by integrating Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) data with NASA POWER climate datasets. Spatiotemporal trends were evaluated using the Mann–Kendall test and Theil–Sen slope estimator, while correlation analysis and residual trend analysis were applied to decouple climatic drivers from non-climatic influences. At the regional scale, mean annual NDVI exhibited a weak, non-significant upward trend (Z = 0.397, p = 0.691); annual precipitation showed a weak, non-significant declining trend (Z=-0.023, Sen’s slope =-0,524 mm yr − 1 , p = 0.981); and temperature displayed a significant warming trend (Z = 3.620. Sen’s slope = 0.049 °c yr − 1 , p = 0.001). Seasonally, NDVI increased during winter and spring but declined during summer, and it is correlated positively with temperature. Residual trend analysis revealed significant non-climatic influences, suggesting that localized factors, potentially including land-use/land cover changes or other local environmental shifts, contributed to NDVI declines in the western, southwestern, and northwestern areas, and to increases in the eastern and northeastern areas. These findings reveal priority areas for targeted land management and climate adaptation strategies in northwestern Ethiopia.