Browsing by Author "Mbilinyi, Boniface P."
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Item Agronomic management strategies for adaptation to the current climate variability: the case of North-Eastern Tanzania(2014) Tumbo, Siza D.; Rwehumbiza, Filbert B.; Kahimba, Frederick C.; Enfors, Elin; Mahoo, Henry F.; Mbilinyi, Boniface P.; Mkoga, Zacharia; Churi, AyubuRainfed agriculture in semi-arid areas of sub-Saharan Africa faces a great challenge due to increasingly high variability and unreliability of rainfall. Two of the effective adaptive responses to reduce the vulnerability to the changing climate are through use of soil and water conservation technologies and employment of improved agronomic practices. A study was conducted to quantify the risk and profitability of agronomic management strategies for maize using long-term climatic data and a crop simulation model. APSIM model was used to perform long-term simulations of different management strategies. Simulated maize grain yield for different cultivars and sets of management strategies were evaluated to establish the associated risks and benefits. Results indicate that planting Situka or SC401 during Masika season instead of Kito or other cultivars, gives a yield of more than 1 ton/ha under conventional methods. Maize yield increases to 2t/ha or even higher with the use of fertilizers and recommended management practices. The cost benefit analysis indicated that income greater than USD 700 per ha could be obtained when recommended practices are applied, with Situka and SC401 as the maize varieties planted. Based on the results of the study, it is recommended that farmers should employ improved agronomic management practices only when the seasonal forecast indicates above normal rainfall. The early availability of seasonal rainfall forecast is thus vital. Alternatively, farmers are much safer if they continue to employ their conventional approaches of farming because these have lower risks.Item Deforestation in an African biodiversity hotspot: extent, variation and the effectiveness of protected areas(Elsevier, 2013-06) Green, Jonathan M.H.; Larrosa, Cecilia; Burgess, Neil D.; Balmford, Andrew; Johnston, Alison; Mbilinyi, Boniface P.; Platts, Philip J.; Coad, LaurenThe Eastern Arc Mountains of Tanzania show exceptional endemism that is threatened by high anthro- pogenic pressure leading to the loss of natural habitat. Using a novel habitat conversion model, we pres- ent a spatially explicit analysis of the predictors of forest and woodland conversion in the Eastern Arc over 25 years. Our results show that 5% (210 km 2 ) of evergreen forest and 43% (2060 km 2 ) of miombo woodland was lost in the Eastern Arc Mountains between 1975 and 2000. Important predictors of habitat conversion included distance to natural habitat edge, topography and measures of remoteness. The main conservation strategy in these mountains for the past 100 years has been to develop a network of pro- tected areas. These appear to have reduced rates of habitat loss and most remaining evergreen forest is now within protected areas. However, the majority of miombo woodland, an important source of eco- system services, lies outside formal protected areas, where additional conservation strategies may be needed.Item Dynamics of Usangu plains wetlands: use of remote sensing and GIS as management decision tools(Elsevier, 2006) Kashaigili, Japhet J.; Mbilinyi, Boniface P.; Mccartney, Matthew; Mwanuzi, Fredrick L.Wetlands are resources of paramount importance with many values and functions that need proper management for their continued functioning and the delivery of benefits to the community. Sustained functioning of wetlands requires proper use of land and management of water. It is commonly said that increased human activities have had negative impacts on the Usangu Plains wetlands and that these wetlands are on the verge of total collapse due to altered flows. Nevertheless, these beliefs are little supported by quantitative data. A study on the dynamics of Usangu Plains wetlands therefore investigated long-term and seasonal changes that have occurred as a result of human and developmental activities in the study area for the periods between 1973 and 1984, and between 1984 and 2000. Landsat- MSS and Landsat-TM images were used to locate and quantify the changes. The study revealed a 14% increase in area covered by veg- etated swamp between 1973 and 1984, and a decline by 77% and 70% in area covered by closed and open woodlands respectively. Between 1984 and 2000, the vegetated swamp cover declined by 67%, while the closed woodland and open woodlands declined by 83% and 77% respectively. It has also been revealed that the differences in spatial resolution could impair the detection of change. The continued decline in wetland covers has the potential to cause irreversible changes in these wetlands. Remote sensing and GIS tech- nologies have proved to be useful tools for assisting decision-makers to locate and quantify changes in land resources, and hence to iden- tify appropriate solutions for sustainable management of wetlands. 2006 Elsevier Ltd. All rights reserved.Item Prediction of soil moisture-holding capacity with support vector machines in dry subhumid tropics(Hindawi, 2018-07) Kaingo, Jacob; Tumbo, Siza D.; Kihupi, Nganga I.; Mbilinyi, Boniface P.Soil moisture-holding capacity data are required in modelling agrohydrological functions of dry subhumid environments for sustainable crop yields. However, they are hardly sufficient and costly to measure. Mathematical models called pedotransfer functions (PTFs) that use soil physicochemical properties as inputs to estimate soil moisture-holding capacity are an attractive alternative but limited by specificity to pedoenvironments and regression methods. This study explored the support vector machines method in the development of PTFs (SVR-PTFs) for dry subhumid tropics. Comparison with the multiple linear regression method (MLR-PTFs) was done using a soil dataset containing 296 samples of measured moisture content and soil physicochemical properties. Developed SVR-PTFs have a tendency to underestimate moisture content with the root-mean-square error between 0.037 and 0.042 cm 3 ·cm −3 and coefficients of determination (R 2 ) between 56.2% and 67.9%. The SVR-PTFs were marginally better than MLR-PTFs and had better accuracy than published SVR-PTFs. It is held that the adoption of the linear kernel in the calibration process of SVR-PTFs influenced their performance.Item Use of a hydrological model for environmental management of the usangu wetlands, Tanzania(IWMI Research, 2016-05) Kashaigili, Japhet J.; McCartney, Matthew P.; Mahoo, Henry F.; Lankford, Bruce A.; Mbilinyi, Boniface P.; Yawson, Daniel K.; Tumbo, Siza D.This report presents the findings of a study to assess changes to flows into, and downstream of, the Usangu Wetlands, located in the headwaters of the Great Ruaha River, Tanzania. Hydrological data, in conjunction with remote sensing techniques, were used to provide insights into changes that have occurred to the Eastern Wetland. Results indicate that, between 1958 and 2004, inflows to the wetland declined by about 70 percent in the dry season months (July to November) as a consequence of increased human withdrawals, primarily for irrigation. This resulted in a decrease in the dry season area of the wetland of approximately 40 percent (i.e., from 160 km 2 to 93 km 2 ). In the last decade, outflows from the wetland have ceased for extended periods. An environmentalflow model indicates that a minimum dry season outflow of approximately 0.6 m 3 s -1 is essential to sustain the basic ecological condition of the river. To maintain this outflow from the wetland, a minimum average dry season inflow of approximately 7 m 3 s -1 (i.e., approximately double current dry season flows) is required. To achieve this, dry season flows in the perennial rivers discharging into the wetland would have to be apportioned so that 20 percent is used for anthropogenic purposes and the remaining 80 percent discharges into the wetland. There issignificant potential for improving water use efficiency. However, to ensure minimum downstream flow requirements, consideration should also be given to active water management within the wetland itself.