Browsing by Author "Soka, G. E."

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Land use and vegetation cover dynamics in and around Kagoma Forest Reserve in Tanzania
(Selectedworks, 2013) Nzunda, N. G.; Munishi, P.K.T.; Kashaigil, J. J.; Soka, G. E.; Monjare, J. F.
Kagoma Forest Reserve (KFR) is found in Kagera Region, Tanzania and is comprised of a large area of Miombo woodland. The extent of land use and vegetation cover changes in and around Kagoma Forest Reserve was investigated. Remote sensing and GIS techniques were used to analyze land use and vegetation cover changes over the past 23 years which revealed the occurrence of significant land use and vegetation cover transformation from one land use class to another. During the first period of 12 years under observations (1988-1999), woodlands increased by 5.8%, cultivated lands increased by 5.9%, settlements increased by 0.52% and forests decreased by 5.64%. During the next 11 years period under observations (1999-2010), woodlands decreased by 22.97%, cultivated lands increased by 6.07%, settlements increased by 9.14% when year 1999 was used as a common baseline data year for both periods and forests which decreased by 2.5%. There was a slight increase in settlements from 1998 to 1999 but there was a rapid increase thereafter. It was estimated that vegetation cover was decreasing at the rate of 45.08 ha (0.27%) per year. The study concludes that, there have been significant changes in land use pattern and forest cover in and around KFR in Tanzania which require concerted actions to reverse the changes. The establishment and enforcement of different laws and regulations relating to natural resources and land use planning could improve land tenure and resource use in villages bordering the forest.
Modeling black rhinoceros (Diceros bicornis) population performance in East Africa: the case of Lake Nakuru National Park, Kenya
(2014-03-06) Rija, A. A.; Soka, G. E.; Owino, A.
The black rhinoceros have declined across Africa both in numbers and range distribution, making long-term population persistence of this iconic species uncertain. We conducted simulation models to predict population performance of black rhinoceros in Lake Nakuru National Park under different scenarios of environmental variation and translocation regimes. A decade-long (1987-1997) demographic data were used to construct stochastic simulation models using VORTEX computer program. In addition, we assessed extinction risks and patterns of heterozygosity among the modelled populations (reported every five years) to characterize the dynamics of this population over a hundred years. The population of black rhinoceros showed varying patterns of fluctuations under different scenarios. The best-case scenario showed a considerable increase in the modelled population with the population attaining the highest growth (population growth (λ)= 1.04) after 40 years. The mean final population size for the successful cases was 70.85±2.0 animals, which was relatively close to the carrying capacity used in the simulation. The expected heterozygosity was 0.912±0.02 suggesting that the remaining population may be genetically viable. Further, environmental variation of 1-2% magnitude across the various age categories, and without translocation, had no significant effect on the deterministic growth rate of the population. Maintaining the translocation of 2 males and 2 females on yearly basis would significantly boost and sustain the population of black rhinoceros in the study area.