Assessing the extent of Busaga natural forest encroachment in Ndiza mountainous landscape

Abstract

Rwanda's forests have been increasingly cleared and converted to agricultural and settlement land due to high population growth and the escalating demand for agricultural activities. Busaga Natural Forest, like many other forests outside protected areas in Rwanda, has faced significant encroachment and biodiversity loss, reducing from 300 hectares to 158.7 hectares by 2015. The forest that was once rich in wildlife, has seen a drastic decline in fauna due to hunting and habitat destruction. Despite various management actions, such as the creation of live fences, encroachment persists, driven by the dense and growing population with limited land resources. This study aimed to assess the extent of encroachment and driving factors in Busaga Natural Forest over the past two decades (2002-2023) combining geo-information (remote sensing and GIS) techniques and tools and field based observation and survey. Landsat 7 and Landsat 8 were digitally classified using Maximum likelihood classifier and forest cover dynamics were assessed using a per-pixel machine-learning approach (regression tree), the encroached areas were mapped and analysed changes in forest cover over 21 years period by intersecting both forest cover maps. The results indicate a continuous encroachment in the forest area which is equal to 3.3 ha whereas 3.4 ha was restored between 2002 and 2023, and 7 ha remained unchanged (Non-forest area) 0.15ha per year, with significant encroachment occurring along the forest boundaries. By integrating biomass analysis with canopy cover in addition to forest cover dynamics, provide a holistic view of forest dynamics, emphasizing both the challenges and successes in forest conservation and management. Thus, Busaga forest was degraded by 0.156 ha per year over 21 years according to the results which is equal to 4.74 %. The study reveals that despite legal protections and management efforts, Busaga Natural Forest continues to face threats from agricultural encroachment and illegal logging. The degradation rate underscores the necessity for a more integrated approach involving local communities, enhanced monitoring, and stricter enforcement of conservation policies. In addition, the findings serve as precise information on restoration efforts in conservation areas, which is currently unavailable for policymakers and conservationists working to preserve Rwanda's natural forests.