Spatiotemporal vegetation dynamics in response to precipitation and land surface temperature in the Welmel watershed, southeastern Ethiopia

Abstract

The relationship between changes in vegetation patterns and climate variability remains unclear. Understanding how vegetation dynamics are impacted by changing environmental conditions is crucial for effective ecological restoration and the mitigation of potential ecosystem disturbances. This study aimed to evaluate the response of seasonal and annual vegetation to climatic factors in the Welmel watershed, southeastern Ethiopia, between 1993 and 2022. The study utilized data from the Landsat satellite-derived normalized difference vegetation index (NDVI) and land surface temperature (LST), Climate Hazards Group Infrared Precipitation with Stations for precipitation, and TerraClimate for evapotranspiration datasets from the Google Earth Engine platform. The results showed a statistically significant increase in the NDVI at an annual scale, with a rate of 0.0028 (p = 0.003) across the entire watershed. Moreover, there was a noticeable decrease in the NDVI in forest, wood, and cultivated land, suggesting that the NDVI values have consistently declined due to land use land cover changes. There was a positive correlation between the NDVI and precipitation annually, whereas a negative correlation was observed between the NDVI and LST. On a seasonal scale, a strong and significant positive correlation was observed between the average NDVI and precipitation from March to May. However, a negative correlation was found between the NDVI and average LST during the June to August and March to May seasons. These findings provide valuable insights into vegetation dynamics and offer important guidance for ecological restoration, land management, and the development of climate adaptation strategies in the region.