The Effect of an Electric Conservation Fence on Vegetation Structure in the Western Serengeti

Growing human populations near protected area boundaries intensify human–wildlife conflicts and promote illegal livestock incursions. Such activities reduce herbaceous biomass, disrupt fire regimes, and facilitate the encroachment of woody species, thereby altering ecosystems. Electric conservation fencing has been used as a mitigation measure, yet large-scale ecological evaluations remain limited in East Africa, particularly in Tanzania. In 2020, a 30 km electric fence was constructed along the Ikorongo Game Reserve, part of the Greater Serengeti–Mara Ecosystem, to reduce conflict and protect reintroduced black rhinoceroses ( Diceros bicornis michaeli ), in alignment with the National Human–Wildlife Conflict Strategy. This study compared fenced and unfenced sites to evaluate the effects of fencing on herbaceous biomass, illegal livestock incursions, woody encroachment, vegetation cover, and herbaceous diversity and composition. We found that herbaceous biomass was significantly higher near fenced boundaries, whereas unfenced sites consistently showed reduced biomass near the edges. Livestock incursions were higher near unfenced boundaries and absent within fenced areas. Sapling density followed a similar pattern, mirroring the distribution of livestock presence. Patterns of diversity also diverged: unfenced sites exhibited greater herbaceous diversity, particularly near boundaries, while fenced areas supported more distinct herbaceous composition. Herbaceous composition was shaped primarily by fire frequency, distance from boundaries, and rainfall. Overall, results demonstrate that fencing mitigates illegal livestock grazing pressure and enhances herbaceous biomass, thereby influencing vegetation dynamics. However, fencing may also reduce herbaceous diversity near boundaries. These findings highlight the ecological trade-offs of conservation fencing, which involves balancing livestock exclusion with biodiversity conservation at landscape scales.