Mncwabe Ntuthuko Prosperous, Odindi John, Matongera Trylee Nyasha, Mutanga Onisimo
Discipline of Geography and Environmental Science, School of Agricultural Earth and Environmental Sciences, University of KwaZulu-Natal, Scottsville, Pietermaritzburg, 3209, South Africa.
Centre for Transformative Agricultural and Food Systems, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Scottsville, Pietermaritzburg, 3209, South Africa.
Environ Monit Assess. 2025 Mar 17;197(4):411. doi: 10.1007/s10661-025-13808-x.
Bush encroachment is a globally recognized phenomenon linked to adverse effects, including the degradation of grasslands and loss in biodiversity, thereby challenging the conservation of keystone and flagship species, the recreational value of landscapes and local livelihoods. Therefore, a comprehensive analysis of bush encroachment is essential to gain insights into its past, present and future encroachment, as well as the severity of transitions. Using RapidEye and PlanetScope satellite imagery, this study adopted Intensity Analysis to examine past and current bush encroachment trends for the periods 2009-2014, 2014-2019 and 2019-2023, while the Cellular Automata (CA) model was used to project future encroachment trends for 2028 and 2033 within a protected area. The results indicated a continuous increase in bush encroachment within the study area. Analysis of land cover intensities shows an intensive change in the research area's land cover in the first period (2009-2014) compared to subsequent periods. In the first two periods (i.e. 2009-2014 and 2014-2019), woody vegetation gains were more pronounced at the expense of grasslands. However, during the 2019-2023 period, woody vegetation gains were less intensive to grasslands. Moreover, throughout the study period, most grassland gains occurred in bare areas, whilst the primary cause of grassland losses was bush encroachment. The projection of future encroachment trends indicates a continued increase in woody vegetation over the next decade. The results also indicate that bush encroachment is projected to expand by 5.50 and 6.67% in 2028 and 2033, respectively. These findings highlight the urgent need to assess and enhance management schemes within the study area. Gaining critical insights into bush encroachment progression trends and transition intensities can help prioritise landscape management efforts and support decision-making for the restoration of grasslands.
灌木入侵是一种全球公认的现象，与包括草原退化和生物多样性丧失在内的负面影响相关联，从而对关键物种和旗舰物种的保护、景观的游憩价值以及当地生计构成挑战。因此，对灌木入侵进行全面分析对于深入了解其过去、现在和未来的入侵情况以及转变的严重程度至关重要。本研究利用RapidEye和PlanetScope卫星图像，采用强度分析方法来研究2009 - 2014年、2014 - 2019年和2019 - 2023年期间过去和当前的灌木入侵趋势，同时使用细胞自动机（CA）模型预测保护区内2028年和2033年未来的入侵趋势。结果表明，研究区域内灌木入侵持续增加。土地覆盖强度分析显示，与后续时期相比，研究区域在第一个时期（2009 - 2014年）土地覆盖发生了剧烈变化。在前两个时期（即2009 - 2014年和2014 - 2019年），木本植被增加以草原减少为代价，这种情况更为明显。然而，在2019 - 2023年期间，木本植被相对于草原的增加强度较小。此外，在整个研究期间，大部分草原增加发生在裸地，而草原减少的主要原因是灌木入侵。未来入侵趋势预测表明，在接下来的十年中木本植被将持续增加。结果还表明，预计灌木入侵在2028年和2033年将分别扩大5.50%和6.67%。这些发现凸显了在研究区域内评估和加强管理方案的迫切需求。深入了解灌木入侵的进展趋势和转变强度有助于确定景观管理工作的优先级，并为草原恢复的决策提供支持。
