- 期刊
Spatiotemporal Changes in Actual Evapotranspiration, Soil Moisture, the Normalized Difference Vegetation Index, and Land Use/Land Cover in the Gedeo Coffee-Based Agroforestry System of Southern Ethiopia
摘要
Mapping and quantifying changes in land use/land cover (LULC) and their drivers guides the identification of areas vulnerable to change and the design of sustainable land management strategies. In the Gedeo zone of Southern Ethiopia, policies and strategies are required to protect coffee-based agroforestry from the destabilizing effects of climate change, a declining resource base, and unplanned changes in land use. Accordingly, this study analyzed trends in LULC, soil moisture, actual evapotranspiration, and the normalized difference vegetation index (NDVI) over the preceding 30 years by using remote sensing, geographic information systems, and secondary data. Using Landsat images from the years 1993, 2008, and 2023, we mapped six major LULC types: wetlands, grassland, settlements, bare land, forest land, and cultivated land including crop lands and agroforestry systems. The NDVI exhibited a significant decreasing trend in the regions of Dilla, Raphe, and Wonago, indicating hot spots of LULC changes. Cultivated land and forest land underwent the most extensive LULC changes, with rates of 45.1% and -22%, respectively. LULC types with high environmental importance, namely grassland and wetlands, decreased annually by 10.8% and 4.3%, respectively. Settlements increased by 12.2% at the expense of coffee-based agroforestry systems, which have been the backbone of the local economy. The preceding three decades have seen rapid urban growth and development at the cost of sustainable quality coffee production in and around the study area. The root causes underlying LULC changes have been urbanization, climate change, population growth, and a lack of public awareness regarding the consequences of LULC changes. LULC changes, including the conversion of wetlands to cultivated land and uncontrolled settlements along the finest coffee belt, have threatened food and income security and have undermined ecological sustainability initiatives, as evidenced by the decreasing NDVI throughout the study period. These observed trends run counter to the standards of protecting land of agricultural significance from urban and periurban encroachment. Accordingly, the drivers of LULC changes must be regulated; otherwise, scarce natural resource bases will soon be unavailable to contribute to sustainable ecosystem services and the livelihoods of small holder farmers.