Vegetation cover estimates for trees, shrub-grass mosaics, and grassland and bare ground, were quantified in the savanna-woodland of Bwabwata National Park, north-east Namibia. Changes in woody cover were analysed using repeat photographs in combination with aerial photographs and recent satellite imagery taken between 1996 and 2019. Cover estimates for each vegetation type were obtained using object-based classification techniques and a non-parametric random forest classifier algorithm in eCognition Trimble software. Results show that over the two decades under investigation (1996–2019), trees declined (−10.6%), and the shrub-grass mosaic vegetation type increased (8.1%) across the park. The largest decline in trees occurred in the western land use areas (−36%), which also experienced the greatest increase in the shrub-grass mosaic (17%), when compared with areas in the east (11%). Variation of woody cover estimates is attributed to different seasonal fire management practices in the east versus the west of the park. The fire history (2000–2018) revealed that late dry season fires were frequent in the west, whereas in the east, early dry season fires were frequent. The stages of encroachment recorded in this study have consequences for biodiversity, people’s livelihoods, and tourism.

在纳米比亚东北部 Bwabwata 国家公园的稀树草原林地中，对树木、灌木-草马赛克、草地和裸地的植被覆盖估计进行了量化。使用重复照片以及 1996 年至 2019 年间拍摄的航空照片和最近的卫星图像分析了木质覆盖的变化。使用基于对象的分类技术和 eCognition Trimble 中的非参数随机森林分类器算法获得了每种植被类型的覆盖估计软件。结果显示，在所调查的二十年间（1996-2019 年），整个公园的树木减少（-10.6%），灌木-草镶嵌植被类型增加（8.1%）。西部土地利用区的树木下降幅度最大（-36%），灌木-草马赛克的增长也最大（17%），与东部地区（11%）相比。木质覆盖估计的变化归因于公园东部和西部不同的季节性火灾管理实践。火灾历史（2000-2018 年）显示，西部旱季后期火灾频繁，而东部旱季初期火灾频繁。本研究记录的侵占阶段对生物多样性、人们的生计和旅游业产生了影响。