INTRODUCTION Analyzing trends of land use systems and the changes occurred overtime is an effective way of assessing the impacts of land use/land cover (LULC) changes on ecosystem function. It provides important insights for understanding the spatial patterns of land use processes. The rangelands of southern Ethiopia are adversely affected by increased human population pressure, encroachment of crop cultivation, and bush encroachment. Hence, it is vital to understand the trends of rangeland vegetation cover dynamics. METHODS This paper evaluates land use/land cover changes and spatial patterns between 1987 and 2003 in Yabelo (5426 km2), Borena rangelands of southern Ethiopia. We used a combination of three Landsat Thematic Mapper (TM) 1987, Landsat TM 1995 and Enhanced Thematic Mapper Plus (ETM+) 2003, and local perceptions. A pixel-based supervised classification with maximum likelihood classifier was used to classify images. The accuracy of classification was assessed for 1987 (81.8 %), 1995 (84.6 %), and 2003 (81.3 %). RESULTS The results showed that the Borana rangelands had undergone substantial changes during the last 16 years. Between 1987 and 2003, we observed a considerable increase in woodland cover (11.7 %), bushland cover (17 %), cultivated land (72.5 %), and settlements (79.8 %). The results showed a rapid decline in grassland cover (7.7 %), shrubby grassland cover (86 %), and bareland (0.7 %). The spatial pattern analysis indicate that the Borana rangeland was fragmented and characterized by the proliferation of large numbers of patches with a decline in patch index, increased patch density, and irregular shape of patches within a landscape. Local communities' perceptions indicate that recurrent drought, increased human population size, and expansion of cultivation were largely responsible for the observed LULC changes in the study area. CONCLUSIONS LULC changes contribute to rangeland degradation and weaken the traditional practices of rangeland management. We suggest appropriate management measures to halt the impact of disturbances on LULC dynamics and its implication on the livelihoods of the Borana pastoralists.

中文翻译：

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在埃塞俄比亚南部的博拉纳，将大草原牧场转换为灌木为主的景观。

引言分析土地利用系统的趋势以及随着时间的推移发生的变化是评估土地利用/土地覆盖率（LULC）变化对生态系统功能的影响的有效方法。它为了解土地利用过程的空间格局提供了重要的见识。埃塞俄比亚南部的牧场受到人口压力上升，农作物侵占和灌木丛侵害的不利影响。因此，了解牧场植被覆盖动态的趋势至关重要。方法本文评估了埃塞俄比亚南部博雷纳草原的亚贝洛（5426 km2）1987年至2003年之间的土地利用/土地覆盖变化和空间格局。我们结合使用了三种Landsat专题映射器（TM）1987，Landsat TM 1995和增强型专题映射器Plus（ETM +）2003，以及当地的认知。具有最大似然分类器的基于像素的监督分类用于对图像进行分类。分别对1987年（81.8％），1995年（84.6％）和2003年（81.3％）的分类准确性进行了评估。结果结果表明，在过去的16年中，Borana牧场发生了重大变化。在1987年至2003年之间，我们观察到林地覆盖率（11.7％），灌木林覆盖率（17％），耕地（72.5％）和定居点（79.8％）都有显着增加。结果表明，草地覆盖率（7.7％），灌木丛草地覆盖率（86％）和荒地（0.7％）迅速下降。空间格局分析表明，Borana草地被破碎，其特征是大量斑块的扩散，斑块指数下降，斑块密度增加，景观内斑块形状不规则。当地社区的看法表明，反复干旱，人口规模增加和耕种面积扩大是造成研究区域内观察到的土地利用变化的变化的主要原因。结论LULC的变化加剧了牧场的退化，削弱了牧场管理的传统做法。我们建议采取适当的管理措施，以制止干扰对LULC动态的影响及其对Borana牧民的生计的影响。