Browsing by Author "Nahonyo, Cuthbert"

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Efficacy of land use designation in protecting habitat in the miombo woodlands: Insights from Tanzania
(Cold Spring Harbor Laboratory, 2017-03-17) Lobora, Alex; Nahonyo, Cuthbert; Munishi, Linus; Caro, Tim; Foley, Charles; Beale, Colin
Loss of natural landscapes surrounding major conservation areas compromise their future and threaten long-term conservation. We evaluate the effectiveness of fully and lesser protected areas within Katavi-Rukwa and Ruaha-Rungwa ecosystems in south-western Tanzania to protecting natural landscapes within their boundaries over the past four decades. Using a time series of Landsat satellite imageries of September 1972, July 1990 and September 2015, we assess the extent to which natural habitat has been lost within and around these areas mainly through anthropogenic activities. We also test the viability of the remaining natural habitat to provide connectivity between the two ecosystems. Our analysis reveals that while fully protected areas remained intact over the past four decades, lesser protected areas lost a combined total area of about 5,984 km2 during that period which is about 17.5% of habitat available in 1972. We also find that about 3,380 km2 of natural habitat is still available for connectivity between the two ecosystems through Piti East and Rungwa South Open Areas. We recommend relevant authorities to establish conservation friendly village land use plans in all villages surrounding and between the two ecosystems to ensure long-term conservation of these ecosystems.
Incipient signs of genetic differentiation among African elephant populations in fragmenting miombo ecosystems in south-western Tanzania
(John Wiley & Sons, Inc., 2018-07-12) Lobora, Alex; Nahonyo, Cuthbert; Munishi, Linus; Caro, Tim; Foley, Charles; Prunier, Jérôme; Beale, Colin; Eggert, Lori
Habitat fragmentation can play a major role in the reduction of genetic diversity among wildlife populations. The Ruaha-Rungwa and Katavi-Rukwa ecosystems in south-western Tanzania comprise one of the world's largest remaining African savannah elephant metapopulations but are increasingly threatened by loss of connectivity and poaching for ivory. To investigate the genetic structure of populations, we compared the genotypes for nine microsatellite loci in the western, central and eastern populations. We found evidence of genetic differentiation among the three populations, but the levels were low and mostly concerned the younger cohort, suggesting recent divergence probably resulting from habitat loss between the two ecosystems. We identified weak isolation by distance, suggesting higher gene flow among individuals located less than 50 km apart. In a long-lived species with overlapping generations, it takes a long time to develop genetic substructure even when there are substantial obstacles to migration. Thus, in these recently fragmented populations, inbreeding (and the loss of heterozygosity) may be less of an immediate concern than the loss of adults due to illegal hunting.
Modelling habitat conversion in miombo woodlands: insights from Tanzania
(Taylor & Francis Group, 2017-05-29) Lobora, Alex; Nahonyo, Cuthbert; Munishi, Linus; Caro, Tim; Foley, Charles; Beale, Colin
Understanding the drivers of natural habitat conversion is a major challenge, yet predicting where future losses may occur is crucial to preventing them. Here, we used Bayesian analysis to model spatio-temporal patterns of land-use/cover change in two protected areas designations and unclassified land in Tanzania using time-series satellite images. We further investigated the costs and benefits of preserving fragmenting habitat joining the two ecosystems over the next two decades. We reveal that habitat conversion is driven by human population, existing land-use systems and the road network. We also reveal the probability of habitat conversion to be higher in the least protected area category. Preservation of habitat linking the two ecosystems saving 1640 ha of land from conversion could store between 21,320 and 49,200 t of carbon in the next 20 years, with the potential for generating between US$ 85,280 and 131,200 assuming a REDD+ project is implemented.