Özet:

Vachellia kirkii naturally grows along the Muvumba River near Nyagatare Township, north-eastern Rwanda, where irrigated rice cultivation thrives. In Rwanda, irrigated rice farming in wetlands is expanding to ensure the rapidly growing population’s food security. Deforestation and the loss of biodiversity are among the most critical consequences of rice farming expansion. This study aimed to evaluate V. kirkii forest cover and plant diversity and their changes over time in the Muvumba wetland and the surrounding savannah. High-resolution imagery and remote sensing techniques were used to generate land-use maps for 2008 and 2018 and to detect temporal changes. Random sampling was done to study vegetation structure and floristic composition. Thirty circular plots of 16 m diameter were established randomly in the V. kirkii forest, and fifteen 500 m long transects spaced at 50 m apart in the savannah. Trees and shrubs in both vegetation types were identified and counted. Grass and herbaceous species were identified in 1×1 m quadrants established at the center of each of the main plots. Vachellia kirkii individuals dominated as a monoculture near the river, and 49 other plant species were identified in the study area. During one decade (2008-2018), V. kirkii cover shrank by approximately 70%. Rice farming threatens V. kirkii forest and its associated plant species. There is a need for urgent, environmentally sustainable development measures to save V. kirkii forests and their associated biodiversity from extinction in this east-central African region.

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