Browsing by Author "Isabirye, Moses"
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Item Economics of Grass Strips Used as Sediment Filters in the Riparian Zones of Lake Victoria, Uganda(Agroecology and Sustainable Food Systems, 2012) Mugonola, Basil; Kimaro, Didas; Isabirye, Moses; Deckers, Jozef; Poesen, Jean; Wanyama, Joshua; Mathijs, ErikLand-use change in the riparian zones has lead to flow of sediments and nutrients into Lake Victoria. Using net present value (NPV) and sensitivity analysis techniques, economic viability of Paspalum, lemon, and elephant grasses as sediment filters under maize production are determined. Findings reveal that grass strips in maize production generates NPVs of 1,620 Cha−1, 1,736 Cha−1, and 1,766 Cha−1 for maize + Paspalum, maize + lemon and maize + elephant grass, respectively, at 5% discount rate. Sensitivity analyses show, NPVs are stable to varying discount rates but not to yield declines in maize and grasses. Overall, integrated land use to reduce sediment and nutrient fluxes is a more acceptable solution to land-constrained farmers.Item Factors influencing the distribution and abundance of small rodent pest species in agricultural landscapes in Eastern Uganda(Journal of Vertebrate Biology, 2020) Mayamba, Alex; Byamungu, Robert M.; Vanden Broecke, Bram; Leirs, Herwig; Hieronimo, Proches; Nakiyemba, Alice; Isabirye, Moses; Kifumba, David; Kimaro, Didas N.; Mdangi, Mshaka E.; Mulungu, Loth S.Small rodents are increasingly gaining importance as agricultural pests, with their distribution and abundance known to vary across landscapes. This study aimed at identifying ecological factors in the landscape that may influence small rodent distribution and abundance across agricultural landscapes in Uganda. This information may be used to inform the development of adaptive control measures for small rodent pests. Small rodent trapping surveys were conducted in three agro-ecosystem landscapes: Butaleja, Mayuge and Bulambuli districts in Eastern Uganda between November 2017 to June 2018 covering both dry and wet seasons. Data on small rodent abundance and richness, vegetation characteristics, land use/cover characteristics, farm management practices and soil characteristics were collected from quadrats. Additionally, Geographic Information System and remote sensing were used to determine vegetation characteristics (Normalized Difference Vegetation Index – NDVI) and land use/cover from satellite images. Our results showed that crop field state (including hygiene, crop type and growth stage) is the most important variable with an overall relative importance of 34.4% prediction value for the abundance of Mastomys natalensis across the landscape studied. In terms of number of species encountered (species richness), results showed field crop status scoring highest with an overall relative importance of 39.8% at predicting small rodent species richness. Second in importance for overall rodent abundance was percentage composition soil silt particles with 15.6% and 18.1% for species richness and abundance respectively. Our findings have important implications for small rodent management, where land use characteristics, especially field crop state, is a critical factor as different conditions tend to affect rodent abundances differently. The study thus recommends that control efforts should be planned to consider field crop state; i.e. field hygiene where fields should be kept free of weeds to eliminate potential rodent breeding/habitation sites thus lowering rates of reproduction and population increase.Item Fitness of the Pestiferous Small Rodent Mastomys Natalensis in an Agroecosystem in Mayuge District, Lake Victoria Crescent, Uganda(Mammalia, 2020) Mayamba, Alex; Isabirye, Brian E.; Byamungu, Robert M.; Nakiyemba, Alice; Isabirye, MosesA 2.5-year study was conducted to understand the fitness of Mastomys natalensis in an agroecosystem in relationship with environmental predictors. The study was conducted in Mayuge district, in the Lake Victoria Crescent zone in Eastern Uganda. Fitness was measured in terms of survival, maturation and capture probability and estimated using multi-event capture-recapture models. Survival rates were higher after high rainfall in the previous month and increased with increasing population density of the animals. Maturation rate, on the other hand, showed no significant association with any predictor variables, while capture probability was significantly associated with sex of the animals, with higher capture probability for males. The results demonstrate that the fitness of M. natalensis in an agroecosystem is dependent on rainfall, sex and current population density. The aforementioned results were associated with increasing vegetation which provides cover for animal nesting and abundant food for the animals during rainfall periods and thus increased survival, high mobility in males in search for mates thus exposing animals to high chances of being captured and increased prey saturation at high population density resulting in high animal survival. These results have important implications for the timing of management strategies, i.e. control efforts should be enforced during the rainfall seasons to prevent high population buildup in the succeeding seasons.Item The impact of papyrus wetland encroachment on the spatial and temporal variability of stream flow and sediment export in the upper Rwizi catchment, Southwest Uganda(EGU General Assembly, 2014) Ryken, Nick; Vanmaercke, Matthias; Wanyama, Joshua; Deckers, Jozef; Isabirye, Moses; Poesen, JeanDuring the past 30 years, human activities in the Lake Victoria basin are responsible for eutrophication of Lake Victoria via sediment-bound nutrients. This affects food security for millions on people. Addressing this problem in this densely populated region will require adequate catchment management strategies. However, sediment yield and runoff data to develop such a strategy are currently unavailable. Also in general, sediment yields for catchments in tropical environments are very scarce, especially in East-Africa. Therefore, runoff discharge and sediment export measurements were conducted in the upper Rwizi, a representative catchment for the Lake Victoria basin which is located in Southwest Uganda. Land use in this catchment is characterized by grazing area on the high plateaus, banana cropping on the slopes and Cyperus papyrus L. wetlands in the river valleys. These papyrus wetlands are currently encroached and transformed into cropland. Eight subcatchments (99 km2 - 2120 km2), with different degrees of wetland encroachment, were monitored during the hydrological year June 2009 - May 2010.Item Population and Breeding Patterns of the Pest Rodent: Mastomys Natalensis in a Maize Dominated Agroecosystem in Lake Victoria Crescent Zone, Eastern Uganda(African Zoology, 2021) Mayamba, Alex; Byamungu, Robert Modest; Isabirye, Moses; Makundi, Rhodes H.; Kimaro, Didas N .; Massawe, Apia W.; Kifumba, David; Nakiyemba, Alice; Mdangi, Mshaka E.; Isabirye, Brian E.; Mulungu, Loth S.Multimammate mice (Mastomys natalensis) are a key rodent pest species to cereal crop production in Sub-Saharan Africa. This study aimed at generating information on the population fluctuation and breeding patterns of M. natalensis in a maize dominated agro-ecosystem in the Mayuge district, Eastern Uganda. The area is characterised by a bimodal rainfall pattern with rains in the periods March to May and August to November. A Capture–Mark–Recapture study was established in cultivated and fallow field habitats with, in each habitat, two plots of 60 m by 60 m with 49 evenly spaced trapping points. Trapping was conducted monthly for three consecutive nights, and the study extended from January 2016 to June 2018. A Generalised Linear Mixed Model analysis showed significantly higher population density estimates (β = 0.69, p<0.0001) in fallow land compared to cultivated fields, and also significantly higher density estimates( β = 0.75, p = 0.006) in the first wet season and lowest in the first dry season. The percentage breeding females differed significantly across months (χ 2 = 27.05, df = 11, p = 0.003) and seasons (χ 2 = 17.64, p = 0.0003). Breeding females occurred throughout all the months of trapping, but with significantly higher percentages in the months of March to July (i.e. first wet season extending to second dry season) and generally lowest in the first dry months (i.e. January and February in 2017, and February 2018). The results of this study have important consequences for the timing of control efforts, and recommends that control should be initiated during the dry seasons prior to wet seasons to counteract potential damaging population build up in later wet seasons when crop planting is expected.Item Soil and Water Conservation Technologies in the Upper Rwizi Microcatchment of Southwestern Uganda(Water-Smart Agriculture in East Africa, 2015) Mugonola, Basil; Mathijs, Erik; Poesen, Jean; Deckers, Josef; Wanyama, Joshua; Isabirye, MosesThe continuing decline of agricultural productivity in many areas in Uganda, particularly in the Lake Victoria Basin (LVB), has been attributed to land degradation and, as a consequence, farmers encroach on forests, wetlands, and marginal steep slopes (NEMA, 2009; Mugonola, 2013c). Cultivation of these areas using unsustainable agricultural production methods contributes to increased soil erosion, loss of buffering capacity, sediment deposition, and pollution of water bodies. Degradation of farm and rangeland has on-farm and off-farm effects. On-farm, it leads to reduced current and future land productivity and land values, while off-farm, soil erosion results in environmental degradation, desertification, siltation of waterways, and flooding, among others.Item Species Composition and Community Structure of Small Pest Rodents (Muridae) in Cultivated and Fallow Fields in Maize‐ Growing Areas in Mayuge District, Eastern Uganda(Ecology and evolution,, 2019) Mayamba, Alex; Byamungu, Robert M.; Makundi, Rhodes H.; Kimaro, Didas N.; Isabirye, Moses; Massawe, Apia W.; Kifumba, David; Nakiyemba, Alice; Isabirye, Brian E.; Mulungu, Loth S.Pest rodents remain key biotic constraints to cereal crops production in the East African region where they occur, especially in seasons of outbreaks. Despite that, Uganda has scant information on rodents as crop pests to guide effective management strategies. A capture–mark–recapture (CMR) technique was employed to study the ecology of small rodents, specifically to establish the species composition and community structure in a maize-based agro ecosystem. Trapping of small rodents was conducted in permanent fallow land and cultivated fields, with each category replicated twice making four study grids. At each field, a 60 × 60 m grid was measured and marked with permanent trapping points spaced at 10 × 10 m, making a total of 49 trapping points/grids. Trapping was conducted monthly at 4-week interval for three consecutive days for two and half years using Sherman live traps. Eleven identified small rodent species and one insectivorous small mammal were recorded with Mastomys natalensis being the most dominant species (over 60.7%). Other species were Mus triton (16.1%), Aethomys hendei (6.7%), Lemniscomys zebra (5.2%), Lophuromys sikapusi (4.8%), Arvicanthis niloticus (0.9%), Gerbilliscus kempi (0.1%), Graphiurus murinus (0.1%), Steatomys parvus (0.1%), Dasymys incomtus (0.1%), and Grammomys dolichurus (0.1%). Spatially, species richness differed significantly (p = 0.0001) between the studied field habitats with significantly higher richness in fallow land compared with cultivated fields. Temporally, total species richness and abundance showed a significant interaction effect over the months, years, and fields of trapping with significantly (p = 0.001) higher abundances during months of wet seasons and in the first and third year of trapping. In terms of community structure, higher species diversity associated more with fallow field habitats but also with certain rare species found only in cultivated fields. Synthesis and applications. Based on these findings, management strategies can be designed to target the key pest species and the most vulnerable habitats thus reducing the impact they can inflict on field crops.Item Stakeholders’ Perceptions of the Problem of Wetland Degradation in the Ugandan Lake Victoria Basin Uganda(Natural Resources, 2020) Were Nakiyemba, Alice; Isabirye, Moses; Poesen, Jean; Deckers, Jozef; Mathijs, ErikWetlands are one of the most essential resources of Uganda. They are key components of the riparian areas filtering sediments from run-off thereby reducing water pollution. However, they are increasingly threatened by the expansion of agricultural activities. This condition prompted the study of stakeholder’s perspective on the governance of Lake Victoria natural resources in Uganda. The purpose of the study was to analyse relevant stakeholders with a stake in wetland resource, their socio-economic characteristics, motives and perceptions on wetland degradation in the Lake Victoria Basin. We aimed at understanding how stakeholders influence decisions of managing wetlands in the Upper River Rwizi and Iguluibi micro catchments in light of the current farming systems and practices and their implications to the Lake Victoria Basin. A mixed method approach that includes both qualitative and quantitative surveying techniques was applied. We used a semi-structured questionnaire, focus group discussions, key informant interviews, ethnographic observations and secondary data. A stakeholder analysis framework was used to identify the relevant actors with a stake in wetland use and management. It further analyses their characteristics and perceptions of the problem of wetland degradation. Results reveal that around the 1950s, wetlands were intact ecosystems without any disturbances from human activities. Land use changes started around the 1990s when farmers started diversifying from subsistence-based economy to market-oriented. The interests, benefits and conflicts over use and management of wetland resources vary from one stakeholder group to another and their influence and power relations are quite distinct. These all combined with governance systems and perceptions influence the process of wetland degradation. the Upper River Rwizi and Iguluibi micro catchments in light of