基于植被净初级生产力和水分利用效率的埃塞俄比亚土地退化趋势及驱动因素分析

土地退化对减缓和适应气候变化有重要影响，并威胁到全世界的可持续发展，造成一系列社会、经济和生态问题，是目前全球面临的最大环境挑战之一。基于2001—2020年埃塞俄比亚的归一化植被指数（NDVI）、气象数据及土地覆盖数据，通过CASA模型计算获得植被净初级生产力（NPP）和水分利用效率（WUE），并使用Sen+MK趋势分析方法得到土地退化及其恢复趋势，同时采用多元逐步回归方法分析了土地退化及恢复的驱动因素。结果表明：2001—2020年，埃塞俄比亚土地退化整体呈现恢复趋势，恢复区域占全国面积的34.51%，主要分布在埃塞俄比亚西部以及索马里州；退化区域仅占全国面积的1.63%，主要分布在首都亚的斯亚贝巴。土地退化及恢复的主要驱动因素是人为与气候共同因素和人为单因素。土地退化的主要因素为人口的快速增长以及城市的扩张，土地恢复则与20年来实施的森林景观恢复以及可持续土地管理措施和政策有关。

Analysis of land degradation trends and driving factors in Ethiopia based on NPP-WUE

Land degradation has an important impact on mitigation and adaptation to climate change， which threatens the sustainable development of the world， causing a series of social， economic， and ecological problems. Land degradation is also one of the biggest challenges facing the world at present. Based on the NDVI， meteorological data， and land cover data of Ethiopia from 2001 to 2020， this study calculated NPP and WUE by CASA model， and used Sen+MK trend method to get the trend of land degradation and restoration. Finally， we analyzed the driving factors of land degradation and restoration by multiple stepwise regression method. The results show that the land degradation in Ethiopia showed a recovery trend from 2001 to 2020， and the area in the recovery period accounts for 34.51% of the national area， mainly distributed Western Ethiopia and The Somari State； while， the degraded area only accounts for 1.63% and mainly distributed Addis Abab. The main driving factors of land degradation and restoration are human and climate combined or human single factors. Furthermore， it is found that the primary factors of degradation in the study area are rapid population growth and urban expansion. Land restoration is related to the forest landscape restoration and sustainable land management measures implemented in the past 20 years. The results of this study could help Ethiopia continuously implement strict land governance policies and prevent the hazards caused by land degradation.