NRU :: Browsing by Author "Mwavu, Edward N."

Browsing by Author "Mwavu, Edward N."

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Agrobiodiversity of homegardens in a commercial sugarcane cultivation land matrix in Uganda
(International Journal of Biodiversity Science, Ecosystem Services & Management, 2016) Mwavu, Edward N.; Ariango, Esther; Ssegawa, Paul; Kalema, Vettes N.; Bateganya, Fred; Waiswa, Daniel; Byakagaba, Patrick
ABSTRACT Understanding biodiversity in homegardens embedded in landscapes dominated by commercial monoculture agriculture is critical for sustainable management of agrobiodiversity and meeting rural households’ needs in the face of global changes. We assessed agrobiodiversity in the 120 homegardens and its contribution to rural household livelihood strategies within a commercial monoculture sugarcane cultivation land matrix in eastern Uganda. We recorded a total of 68 plant species from 46 genera representing 27 families. Species richness spanned 6 to 19 species, and α-diversity (H’) ranged from 0.6 to 2.3; with 86.67% of the homegardens having H’ >1. Species composition differed significantly (global RANOSIM = 0.153, p < 0.001) among the villages. The most important and commonly maintained plants were those that provided food, fuelwood and money income and included Zea mays L., Manihot esculenta, Phaesolus spp., Coffea sp., Musa spp., Ipomea batatus and Artocarpus heterophyllus. Most of the crops cited as useful by households were also frequent and visible in many of the homegardens. Although homegardens still hold some valuable plants, there is also loss of important plants from the agricultural system including cowpeas, soya beans, bambara groundnuts, finger millet, cotton, aerial yams and oysternut essential for sustaining household livelihoods. This loss, precipitated by increased land-use/cover change to commercial sugarcane plantations threatens agrobiodiversity conservation and the benefits households derive from homegardens. Our findings underline the importance of homegardens in the conservation of indigenous agrobiodiversity, and indicate that with the continued expansion of commercial sugarcane cultivation this opportunity may be lost.
Control of water hyacinth (Eichhornia crassipes) in Rwanda: a survey of local residents’ perceptions
(Nineteenth Australasian Weeds Conference, 2014) Seburanga, Jean L.; Kaplin, Beth A.; Bizuru; Mwavu, Edward N.; Gatesire, Theodette
Community support and participation is an important factor to achieving successful results in weed management. This study sought to gain an insight into local residents’ perceptions of control of water hyacinth using a face-to-face survey. The results showed that biological control was poorly understood by local residents and was perceived as ineffective by those who did have some understanding. Mechanical removal was clearly perceived to be the most efficient method among those used to control water hyacinth in both Mukungwa floodplain and Bulera Lake basin, though the effect was only short-lived. It is recommended that, in the absence of sustained foreign support, biological control of water hyacinth be reviewed in Rwanda and, perhaps, other least developed countries because in these areas there is lack of sufficient funds for a consistent application and the approach is currently poorly understood by the local population in Rwanda.
Expansion of Commercial Sugarcane Cultivation among Smallholder Farmers in Uganda: Implications for Household Food Security
(Land, 2018) Mwavu, Edward N.; Kalema, Vettes K.; Bateganya, Fred; Byakagaba, Patrick; Waiswa, Daniel; Enuru, Thomas; Mbogga, Michael S.
Understanding the impact of commercial agriculture in the face of global change is critical to support strategies that ensure food security and alleviate poverty among households. We assessed the contribution of commercial sugarcane cultivation to household-level food security among smallholder farmers in Busoga sub-region, eastern Uganda. Land use changes are motivated by quick commercial gains rather than sustained food production; a situation that influences food security. The majority of households cultivate few crop varieties, lack adequate and nutritious foods, and have inadequate income to purchase food to meet their needs. Inadequacy of food within some commercial sugarcane-cultivating households suggests that generating income does not necessarily increase food security. To cope with food insecurity, households offer labour in exchange for food, borrow food, ration food, and at times steal. This is exacerbated by increasing food crop failures, large family sizes, trade in food items, and declining availability of food and land for food production. Commercial sugarcane cultivation is the main driver of food insecurity but given its perceived economic benefits, future sugarcane plantations expansion in the region is probably inevitable. Therefore, future policy should be designed to provide triple-win strategies (i.e., food security, poverty alleviation, and climate change adaptation) that provide sustainable livelihoods.
The Impacts of Changes in Land Use on Woodlands in an Equatorial African Savanna
(Land degradation & development, 2015) Kalema, Vettes N.; Witkowski, Edward T. F.; Erasmus, Barend F. N.; Mwavu, Edward N.
Savanna landscapes are vitally important in providing both ecological and economic services that sustain local livelihoods and national economies, particularly for sub-Saharan African countries whose economies are mainly agrarian. Development prospects in savanna landscapes are however dependent on actions to avoid and to slow or reverse degradation and that are aided with a clear understanding of trends in land use/cover changes, their causes and implications for conservation. We analysed land use/cover changes based on three Landsat satellite images (1984, 1995 and 2000/2001) and the influence of human utilization on the changes in an equatorial African savanna, central Uganda, for the period 1984–2000/2001. The land cover classification and change analysis clearly identified the dominant land cover types, revealing a severe reduction in woodland cover with dense woodlands decreasing by 64%, over a 17-year period. Consequently, medium woodland, open woodland and cultivation/settlements areas cover increased by 31%, 3% and 80%, respectively. The cover change analysis results were corroborated with interview results that also attributed the woodland cover loss to increasing commercial charcoal production, expanding livestock grazing, subsistence crop cultivation and an insecure land use tenure system. Indeed, the major land use types in the savanna are charcoal production, shifting crop cultivation and livestock rearing. The decreasing woody vegetation cover threatens the savanna’s ability to continue providing ecosystems services to support the livelihoods of people who mainly depend on natural resources and are vulnerable to the impacts of climate change.
Indigenous knowledge of wild plants collected in Darfur, Sudan
(Ethnobotany Research and Applications, 2020) Hegazy, Ahmad K.; Hosni, Hasnaa A.; Lovett- Doust, Lesley; Kabiel, Hanan F.; Badawy, El-Shafie M.; Mwavu, Edward N.
The lives of the “Fur”, indigenous people of Darfur, Sudan are intimately connected to local wild plants, but the traditional uses of these plants are, so far, poorly documented. Many species are indigenous to the region, but others are introduced, and have naturalized over millennia. Methods: For a month each summer from 2014- 2016, using questionnaire interviews, direct observation of practices, and a literature review, 58 species were identified. An “importance value” for each was determined, based on the intensity and season(s) of use, in eight use categories. For each species, a “concordance ratio” characterized the degree of agreement between indigenous knowledge and our current “scientific understanding” of their value. Results: All species were multi-use; animal forage, “other functional uses”, traditional medicine, and construction predominated. Some species are declining due to overharvesting by the growing local population, exacerbated by conflict and refugee encampments. Most of the species are used in traditional medicines, but active ingredients have been scientifically confirmed for only half of them. Surprisingly, several species with known medicinal ingredients are not used locally. Conclusions: The “Fur” people have long combined agriculture with pastoralism and wildcrafting. For this to be sustainable, it is critical to understand cultural contexts and recognize multi-use species. This can help identify new medicines, and guide sustainable development of local resources, adapted to local conditions. Naturalized wild fruit trees may have evolved drought resistance in this increasingly dry savanna climate; such genes might usefully be incorporated in crop strains elsewhere as climate change proceeds.
The role of fallowing in the restoration of woody species in the Woodlands of Northern Uganda
(African Journal of Ecology, 2021) Byakagaba, Patrick; Okullo, John Bosco L.; Eilu, Gerald; Mwavu, Edward N.
The study sought to determine the extent to which fallowing can lead to recovery towards an historic woody vegetation of Sudanian woodlands in northern Uganda. Fallow sites of three distinct ages were assessed. Plots were established in crop fields that had been under cultivation for over 10 years, sites that had been under fallow for 3–6 years (young fallow) and fallow sites of at least 9 years (old fallow) in three districts. In each plot, all woody plants were enumerated and species composition, diversity and richness assessed. Young fallow plots were dominated by pioneer species such as Piliostigma thonningii and Annona senegalensis, while old fallow by a mix of late and early successional species such as Vachellia hockii (formerly Acacia hockii) and Combretum collinum. Vitellaria paradoxa (Shea butter tree) was the most abundant in all fallow categories. Species composition in crop field was different from young and old fallow. Species richness increased significantly from abandoned Crop field to Young fallow and then to Old fallow. Simpson's Diversity Index showed similar trends. V. paradoxa contributed most to overall similarity among the fallow categories. Fallowing can facilitate restoration of characteristic species of Sudanian woodlands.
Seedling regeneration, environment and management in a semi-deciduous African tropical rain forest
(Journal of Vegetation science, 2009) Mwavu, Edward N.; Witkowski, Edward T.F.
How is seedling regeneration of woody species of semi-deciduous rain forests affected by (a) historical management for combinations of logging, arboricide treatment or no treatment, (b) forest community type and (c) environmental gradients of topography, light and soil nutrients? Location: Budongo Forest Reserve, Uganda. Methods: Seedling regeneration patterns of trees and shrubs in relation to environmental factors and historical management types were studied using 32 0.5-ha plots laid out in transects along a topographic gradient. We compared seedling species diversity, composition and distribution patterns along topographic gradients and within types of historical management regimes and forest communities to test whether environmental factors contributed to differences in species composition of seedlings. Results: A total of 85 624 woody seedlings representing 237 species and 46 families were recorded in this rain forest. Cynometra alexandri C.H. Wright and Lasiodiscus mildbraedii Engl. had high seedling densities and were widely distributed throughout the plots. The most speciesrich families were Euphorbiaceae, Fabaceae, Rubiaceae, Meliaceae, Moraceae and Rutaceae. Only total seedling density was significantly different between sites with different historical management, with densities highest in logged, intermediate in logged/arboricided and lowest in the nature reserve. Forest communities differed significantly in terms of seedling diversity and density. Seedling composition differed significantly between transects and forest communities, but not between topographic positions or historical management types. Both Chao-Jaccard and Chao-S rensen abundance-based similarity estimators were relatively high in the plot, forest community and in terms of historical management levels, corroborating the lack of significant differences in species richness within these groups. The measured environmental variables explained 59.4% of variance in seedling species distributions, with the three most important being soil organic matter, total soil titanium and leaf area index (LAI). Total seedling density was positively correlated with LAI. Differences in diversity of 42.0 cm dbh plants (juveniles and adults) also explained variations in seedling species diversity. Conclusions: The seedling bank is the major route for regeneration in this semi-deciduous tropical rain forest, with the wide distribution of many species suggesting that these species regenerate continuously. Seedling diversity, density and distribution are largely a function of adult diversity, historical management type and environmental gradients in factors such as soil nutrient content and LAI. The species richness of seedlings was higher in soils both rich in titanium and with low exchangeable cations, as well as in logged areas that were more open and had a low LAI.
Sprouting of woody species following cutting and tree-fall in a lowland semi-deciduous tropical rainforest, North-Western Uganda
(Forest Ecology and Management, 2008) Mwavu, Edward N.; Witkowski, T.F.
Effective management, conservation and restoration of tropical forests require an understanding of plant responses (e.g. sprouting) to natural and anthropogenic disturbance events. Sprouting among woody plants within Budongo Forest Reserve (BFR) in response to harvesting for poles and saplings, and tree and branch fall disturbances was examined. A total of 835 woody stumps representing 122 species were recorded. Human harvesting accounted for 83% of 835 damaged stumps. Both canopy and sub-canopy trees sprouted prolifically. Of the 122 affected species, 119 (97.5%) from 31 families sprouted from stem stumps, with only Caloncoba crepiniana exhibiting stem and root sprouting. Only Maesopsis eminii, Cordia milleni and Raphia farinifera did not resprout. Sprouts/stump ranged from 16.3 1.8 (S.E.) for Rawsonia lucida, to 1 for 10 species. Number of sprouts/stump differed significantly among families (Kruskal–Wallis H = 182.63, P < 0.0001), species (H = 256.26, P < 0.0001) and stump size-classes (H = 73.18, P < 0.0001). Mean sprouts/stump was significantly higher for intermediate sized stems of basal diameter (BD) 5.1– 20.0 cm. Dead sprouts occurred on 26 species. There were species-specific significant differences in height (H = 39.92, P = 0.0297) and BD (H = 52.34, P = 0.0011) of the leading sprout. Stump BD (x21 ¼ 6:62, P = 0.0101), height (x21 ¼ 38:52, P < 0.0001), bark-thickness (x21 ¼ 14:56, P < 0.0001) and height of stump above ground at which the first sprout emerged (x21 ¼ 74:42, P < 0.0001) were significant predictors of sprouting ability among individuals. Hence, this semi-deciduous tropical rainforest has a high proportion of sprouting species and incidence of sprouting stems. Sprouting of small and relatively large stumps, and the survival and growth of sprouts, suggests that sprouting plays an important role in forest resilience to selective timber, pole and sapling harvesting.
Woody Species Alpha-diversity and Species Abundance Distributions in an African Semi-deciduous Tropical Rain Forest
(Biotropica, 2015) Mwavu, Edward N.; Witkowski, T. F.
Understanding plant species diversity patterns and distributions is critical for conserving and sustainably managing tropical rain forests of high conservation value. We analyzed the alpha-diversity, species abundance distributions, and relative ecological importance of woody species in the Budongo Forest, a remnant forest of the Albertine Rift in Uganda. In 32 0.5-ha plots, we recorded 269 species in 171 genera and 51 families with stems of ≥2.0 cm in diameter at breast height (dbh). There were 53 more species with stems of ≥2.0 cm dbh than with stems of ≥10 cm dbh, of which 33 were treelets and 20 were multi-stemmed shrubs. For both minimum stem diameter cut-offs (i.e., ≥2 cm dbh vs. ≥10 cm dbh), the Fabaceae, Euphorbiaceae, Ulmaceae, and Meliaceae families and the species Cynometra alexandri, Lasiodiscus mildbraedii, and Celtis mildbraedii had the highest relative ecological importance. The relative ecological importance of some species and families changed greatly with the minimum stem diameter measured. Alpha-diversity, species richness, and species abundance distributions varied across historical management practice types, forest community types, and as a function of minimum stem diameter. Species richness and Shannon–Weiner diversity index were greater for species with stems of ≥2.0 cm dbh than of ≥10 cm dbh. The decrease in species evenness with an increasing number of plots was accompanied by an increase in species richness for trees of both minimum diameters. This forest is characterized by a small number of abundant species and a relatively large proportion of infrequent species, many of which are sparsely distributed and with restricted habitats. We recommend lowering the minimum stem diameter measured for woody species diversity studies in tropical forests from 10 cm dbh to 2 cm dbh to include a larger proportion of the species pool.

Browsing by Author "Mwavu, Edward N."

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