Environmental and socio-economic effects of on farm tree planting on communities adjacent to Mgahinga Gorilla National Park, Southwestern Uganda

Abstract

Illegal extraction of forest resources such as timber, bean stakes, firewood, medicinal plants and building materials by the adjacent communities has contributed to forest degradation in Mgahinga Gorilla National park. This is attributed to the rapidly growing human population around the park which threaten biodiversity, and the integrity of this critical habitat. The objectives were to (i) assess forest cover changes on farmlands and the Mgahinga forest between 2004-2024, (ii) assess diversity and structure of on-farm trees in the farmlands adjacent to the Park and (iii) examine the benefits of on-farm tree planting to the adjacent communities. Three years (2004, 2014 and 2024) were considered for land use land cover assessment and Landsat 5, 8 and 9 images for the study area were downloaded from USGS Earth Explorer. A total of 100 households were selected from four villages. The households and villages were randomly selected. Trees were assessed in the home garden that was treated as a sample plot. A structured questionnaire was administered to households and an interview guide was administered to key informants. For quantitative data, accuracy assessment, image classification process, and change detection analysis were done in a GIS environment while data were subject to descriptive statistics, and regression analysis to explore the diversity, structure and farmer’s socio-economic characteristics. Data were also subjected to an independent t-test while qualitative data subjected to thematic analysis. Results revealed that LULC was remarkable in built-up areas, which expanded from 2.8% to 12.7. Planted forest increased from 0.7% in 2004 to 6.8% in 2014, then decreased to 5.0% in 2024. Tree diversity was higher in Muramba sub-county than Nyarusiza sub-county with the Shannon diversity indices of 0.68 and 0.41 respectively. Avocado, eucalyptus, and pawpaw (81.9%) were most common on farmlands. Majority (58%) of the household heads; they earned significantly from firewood more than males whereas male respondents earned more than females from fodder, and herbs (p = 0.001, 0.041, and 0.036, respectively). This study has shown a fourfold increase in the built-up area, along with fluctuations in the planted forest. Muramba s/c exhibited a higher tree diversity than Nyarusiza s/c and the results show high adoption of exotic tree species. The study findings could therefore inform policy instruments such as incentivized agroforestry practices, and also LGs alongside community stakeholders could design and enforce land-use regulations that balance livelihood needs with biodiversity conservation so that the spiking infrastructure developments and agriculture expansion do not affect wildlife as well as emphasizing the importance of home gardens in conserving indigenous trees.