Impact of human disturbances on woody species diversity, structure and land cover change in and adjacent to Agoro Agu Central Forest Reserve, Uganda

Abstract

This study was conducted to assess impact of human disturbances on woody species diversity, structure and land cover change in and adjacent to Agoro Agu Central Forest Reserve (CFR) in Lamwo District. Specific objectives were; 1) to determine the influence of human disturbances on woody species diversity and structure 2) to determine the influence of other environmental variables on woody species distribution, 3) to establish the trends in land use/cover change in and adjacent to Agoro Agu CFR in the years 1987,2001 and 2010. Data collection involved ecological survey, use of Global Positioning System (GPS) and remotely sensed LANDSAT 7 Satellite Images of 1987, 2001 and 2010. Biophysical data on woody species was collected using systematic sampling. Transects of 1800 meters were laid running from settlements‟ edge towards the interior of the forest and devided into two equal parts of 900m each forming areas adjacent and in the forest respectively. Land use/cover analysis was carried out using Erdas Imagine 9.1 and ArcGIS 9.3. The study documented 97 woody species; 63 were common to both areas, whereas 20 woody species and 14 woody species were unique to areas in and adjacent to Agoro Agu CFR respectively. In both areas, Acacia hockii had the highest number of individuals. Shannon diversity index was 3.6 and 3.5 in and adjacent to Agoro Agu CFR respectively. Jaccard coefficient of community similarity was 0.65. Human disturbances such as cultivation, bushfire and tree cutting significantly influenced woody species diversity whereas other environmental variables such as slope, undergrowth, sandy soil, and fallow influenced distribution of woody species. The woody species population structure raises conservation concern because it showed a weak inverse J shape. Forest and woodland covers seem to be progressively changing to undesirable land use/covers such as grassland to subsistence farmland to bare land and the major changes occurred between 2001 and 2010. This trend is worrying as human population and activities increase in the adjacent communities in both Uganda and Republic of South Sudan. Therefore, there is need for continuous forest protection from human encroachment with attention paid to different woody species in different land uses. Besides, further studies which are more compressive in coverage considering both the socio-economic and physical aspects including modeling of species-environment variables to predict their occurrence in un-accessible areas will be vital. Immediate interventions that can halt conversion of forest and woodland to other un-desirable land uses are required. An Integrated environmental awareness and conservation education programme in adjacent communities to the CFR should form part of these interventions. Finally, with the relative return of peace in Northern Uganda including Agoru Agu CFR, special focus is required for improved livelihoods of the adjacent communities to promote forest-community co-existence and sustainability.