Browsing by Author "Sheil, D."

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    Dynamics of forest cover conversion in and around Bwindi impenetrable forest, Southwestern Uganda
    (Journal of Applied Sciences and Environmental Management, 2011) Twongyirwe, R; Majaliwa, J. G. M.; Ebanyat, P.; Tenywa, M. M.; Sheil, D.; Heist, M. V.; Oluka, M.; Kumar, L.
    Forest cover has been converted to agricultural land use in and around the protected areas of Uganda. The objectives of this study were; to examine the dynamics of forest cover change in and around Bwindi impenetrable forest between 1973 and 2010 and to identify the drivers of forest cover change. The trend in forest cover change was assessed by analyzing a series of orthorectified landsat imageries of 1973, 1987 and 2001 using unsupervised and supervised classification. Land use/cover map for 2010 was reconstructed by analyzing 2001 image, validated and/or reconstructed by ground truthing, use of secondary data and key informant interviews. A series of focused group discussions and key informant interviews were also used to identify drivers of land use/cover change. Policies and institutional arrangements that could have affected forest cover change for the studied time period were also identified. Results showed that protected forest and woodlot in unprotected area had declined by 7.8% and 70.7% respectively as small scale farming and tea plantations had increased by 13.9% and 78.3% respectively between 1973 and 2010. The conversions were attributed to land use pressure due to population growth, change in socio-economic conditions and institutional arrangements. The severe loss of woodlot outside the protected area not only poses a potential threat to the protected forest but also calls for intervention measures if efforts to mitigate climate change impacts are to be realized
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    Environmental and anthropogenic changes in and around the Budongo Forest Reserve
    (Nova Science Publishers, Inc., 2012) Babweteera, F.; Sheil, D.; Reynolds, V.; Plumptre, A. J.; Zuberbuhler, K.; Hill, C. M.; Webber, A.; Tweheyo, M.
    Budongo Forest Reserve (BFR) is a medium altitude, moist semi-deciduous forest, covering an area of 825 km2 of which about 50% is forest and the rest is grassland (Figure 3.1). Budongo has for a long period been the centre for studies in tropical silviculture and botanical work in the East African region (e.g. Eggeling 1947, Plumptre 1996, Sheil et al. 2000, Babweteera et al., 2000). Budongo Forest Reserve (31o 22' – 31o 46' E and 1o 37' – 2o 03' N) was gazetted by the British Colonial Administration in the early 1930s although timber extraction started as early as 1910. Initially the logging planned to remove all old timber trees over 1.3 m DBH followed by felling smaller trees 80 years later. The ultimate aim was to create a two-stage uniform crop of trees which would be felled over a 40 year polycyclic interval. However, due to the slow recovery of valued timber of suitable sizes harvesting was changed to monocyclic felling on an 80 year rotation and the felling limit lowered to 85 cm DBH (Dawkins, 1958 and Philip, 1965). Enrichment planting with mahoganies (Khaya anthotheca and Entandrophragma spp.) was carried out between the 1940s and 50s but was quickly abandoned after it was found that many seedlings died and that natural regeneration in logged areas was as good as that in planted areas. Later planting of saplings was started but elephants often ate and killed these. Consequently, during the 1950s and 1960s arboricide treatments were carried out on trees with low market value („weed species‟), together with climber cutting, to open up the canopy and encourage the spread of mixed forest which favoured regeneration of the mahoganies. However, the treatments were stopped in the 1970s when more tree species became marketable and the cost of the arboricide became too high.
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    Variability Of Soil Organic Carbon Stocks Under Different Land Uses: A Study In An Afro-Montane Landscape In Southwestern Uganda
    (Geoderma, 2013) Twongyirwe, R.; Sheil, D.; Majaliwa, J.G.M.; Ebanyat, P.; Tenywa, M.M.; Kumar, L.
    We explore and compare quantities and patterns of Soil Organic Carbon (SOC) in protected forest and neighboring land around Bwindi Impenetrable National Park (a mountain protected area in Southwestern Uganda). We assessed paired sites of natural forest and major land uses (potato, tea and grazing lands) converted between 1973 and 2010. These pairings were replicated at three altitudinal zones. Plots (20m by 50m) were demarcated within each site. Five composite soil and core samples were obtained from 0 to 15cm (top-soil) and 15–30cm (sub-soil) at each plot. In total, 192 composite soil and core samples were collected. Within forest we found marked site to site variation in SOC from 54.6 to 82.6Mg/ha. There was a tendency for higher SOC in converted land, associated with higher bulk density suggesting quality based land use selection with forest left on inferior soils. Cultivation, landscape position, slope and sampling depth were all significantly (P<0.05) related to variation in SOC stocks following forest conversion but time since conversion had no detectable impact. Interestingly, there was no significant relationship between SOC in the top and sub-soils. Higher SOC is largely determined by higher bulk density. The large SOC stocks in these afro-montane soils are less predictable and more persistent than anticipated.