Tanzania Forestry Research Institute TAFORI

Kibaha, Tanzania

Tanzania Forestry Research Institute TAFORI

Kibaha, Tanzania
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Wagner F.H.,National Institute for Space Research | Herault B.,CIRAD | Bonal D.,French National Institute for Agricultural Research | Stahl C.,French National Institute for Agricultural Research | And 107 more authors.
Biogeosciences | Year: 2016

The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is < 2000ĝ€-mmĝ€-yrĝ'1 (water-limited forests) and to radiation otherwise (light-limited forests). On the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest productivity in a drier climate in water-limited forest, and in current light-limited forest with future rainfall < 2000ĝ€-mmĝ€-yrĝ'1. Author(s) 2016.

Kadu C.A.C.,Federal Research and Training Center for Forests | Kadu C.A.C.,Kenyatta University | Konrad H.,Federal Research and Training Center for Forests | Schueler S.,Federal Research and Training Center for Forests | And 11 more authors.
Annals of Botany | Year: 2013

Background and AimsAfromontane forest ecosystems share a high similarity of plant and animal biodiversity, although they occur mainly on isolated mountain massifs throughout the continent. This resemblance has long provoked questions on former wider distribution of Afromontane forests. In this study Prunus africana (one of the character trees of Afromontane forests) is used as a model for understanding the biogeography of this vegetation zone.MethodsThirty natural populations from nine African countries covering a large part of Afromontane regions were analysed using six nuclear microsatellites. Standard population genetic analysis as well as Bayesian and maximum likelihood models were used to infer genetic diversity, population differentiation, barriers to gene flow, and recent and all migration among populations.Key ResultsPrunus africana exhibits strong divergence among five main Afromontane regions: West Africa, East Africa west of the Eastern Rift Valley (ERV), East Africa east of the ERV, southern Africa and Madagascar. The strongest divergence was evident between Madagascar and continental Africa. Populations from West Africa showed high similarity with East African populations west of the ERV, whereas populations east of the ERV are closely related to populations of southern Africa, respectively. ConclusionsThe observed patterns indicate divergent population history across the continent most likely associated to Pleistocene changes in climatic conditions. The high genetic similarity between populations of West Africa with population of East Africa west of the ERV is in agreement with faunistic and floristic patterns and provides further evidence for a historical migration route. Contrasting estimates of recent and historical gene flow indicate a shift of the main barrier to gene flow from the Lake Victoria basin to the ERV, highlighting the dynamic environmental and evolutionary history of the region. © 2012 The Author. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.

Kadu C.A.C.,Federal Research Center for Forests | Schueler S.,Federal Research Center for Forests | Konrad H.,Federal Research Center for Forests | Muluvi G.M.M.,Kenyatta University | And 10 more authors.
Molecular Ecology | Year: 2011

Scattered populations of the same tree species in montane forests through Africa have led to speculations on the origins of distributions. Here, we inferred the colonization history of the Afromontane tree Prunus africana using seven chloroplast DNA loci to study 582 individuals from 32 populations sampled in a range-wide survey from across Africa, revealing 22 haplotypes. The predominant haplotype, HT1a, occurred in 13 populations of eastern and southern Africa, while a second common haplotype, HT1m, occurred in populations of western Uganda and western Africa. The high differentiation observed between populations in East Africa was unexpected, with stands in western Uganda belonging with the western African lineage. High genetic differentiation among populations revealed using ordered alleles (NST = 0.840) compared with unordered alleles (GST = 0.735), indicated a clear phylogeographic pattern. Bayesian coalescence modelling suggested that 'east' and 'west' African types likely split early during southward migration of the species, while further more recent splitting events occurred among populations in the East of the continent. The high genetic similarity found between western Uganda and west African populations indicates that a former Afromontane migration corridor may have existed through Equatorial Africa. © 2010 Blackwell Publishing Ltd.

Kadu C.A.C.,Federal Research Center for Forests | Kadu C.A.C.,Kenyatta University | Parich A.,University of Natural Resources and Life Sciences, Vienna | Schueler S.,Federal Research Center for Forests | And 14 more authors.
Phytochemistry | Year: 2012

Prunus africana - an evergreen tree found in Afromontane forests - is used in traditional medicine to cure benign prostate hyperplasia. Different bioactive constituents derived from bark extracts from 20 tree populations sampled throughout the species' natural range in Africa were studied by means of GC-MSD. The average concentration [mg/kg w/w] in increasing order was: lauric acid (18), myristic acid (22), n-docosanol (25), ferulic acid (49), β-sitostenone (198), β-sitosterol (490), and ursolic acid (743). The concentrations of many bark constituents were significantly correlated and concentration of n-docosanol was highly significantly correlated with all other analytes. Estimates of variance components revealed the highest variation among populations for ursolic acid (66%) and the lowest for β-sitosterol (20%). In general, environmental parameters recorded (temperature, precipitation, altitude) for the samples sites were not correlated with the concentration of most constituents; however, concentration of ferulic acid was significantly correlated with annual precipitation. Because the concentration of compounds in bark extracts may be affected by tree size, the diameter of sampled plants at 1.3 m tree height (as proxy of age) was recorded. The only relationship with tree diameter was a negative correlation with ursolic acid. Under the assumption that genetically less variable populations have less variable concentrations of bark compounds, correlations between variation parameters of the concentration and the respective genetic composition based on chloroplast and nuclear DNA markers were assessed. Only variation of β-sitosterol concentration was significantly correlated with haplotypic diversity. The fixation index (F IS) was positively correlated with the variation in concentration of ferulic acid. Principal Components Analysis (PCA) indicated a weak geographic pattern. Mantel tests, however, revealed associations between the geographic patterns of bioactive constituents and the phylogenetic relationship among the populations sampled. This suggests an independent evolution of bark metabolism within different phylogeographical lineages, and the molecular phylogeographic pattern is partly reflected in the variation in concentration of bark constituents. The results have important implications for the design of strategies for the sustainable use and conservation of this important African tree species. © 2012 Elsevier Ltd. All rights reserved.

Kideghesho J.R.,Sokoine University of Agriculture | Msuya T.S.,Tanzania Forestry Research Institute TAFORI
International Journal of Biodiversity Science, Ecosystems Services and Management | Year: 2010

The limited capacity of governments in developing countries to service primary health care has resulted in a rapid increase in use of indigenous medicinal plants. This increase, together with other biological and non-biological factors, has rendered these plants vulnerable to over-use and extirpation. Domestication is a conservation intervention that can relieve pressure on medicinal species. In order to ensure effectiveness and sustainability of an intervention, understanding the influencing factors is imperative. We examined the influence of gender and some socio-economic factors on domestication of medicinal plants in the West Usambara Mountains of northern Tanzania. Participatory wealth ranking, structured and semi-structured interviews, botanical surveys and participant observations were employed in data collection. Results showed that domestication has played a fundamental role in conservation of medicinal plants in the study area. Forty (89%) and twelve (27%) of forty-five indigenous plant species were domesticated on farms and around homesteads, respectively. A total of 89% of respondents (n=173) had domesticated medicinal plants on their farms and around homesteads. Gender was the most important factor that influenced this practice, with more male-headed than female-headed households involved in the domestication effort. This can be attributed to social and cultural factors that, besides dispossessing women of tenure rights over resources and land, also subject them to heavy workloads and therefore diminish the time available for plant domestication. The number of domesticated medicinal plants also depended on age, affluence, farm size, household size and ethnicity. We recommend that agroforestry research should focus not only on integrating forest plants in farmlands, but also on cultural, socio-economic and institutional aspects affecting the whole system of domestication. © 2010 Taylor & Francis.

Msuya T.S.,Tanzania Forestry Research Institute TAFORI | Kideghesho J.R.,Sokoine University of Agriculture | Mosha T.C.E.,Sokoine University of Agriculture
Ecology of Food and Nutrition | Year: 2010

We investigated the availability, preference, and consumption of indigenous forest foods in Uluguru North (UNM) and West Usam-bara Mountains (WUM) of Tanzania. Data collection techniques involved focus group discussion, structured questionnaires, and botanical identification. Results revealed (1) there were 114 indigenous forest food plant species representing 57 families used by communities living adjacent to the two mountains; (2) sixty-seven species supplied edible fruits, nuts and seeds: 24 and 14 species came from WUM and UNM, respectively, while 29 came from both study areas; (3) of the 57 identified vegetable species, 22 were found in WUM only, 13 in UNM only, and 12 in both areas; (4) there were three species of edible mushrooms and five species of roots and tubers; (5) unlike the indigenous roots and tubers, the preference and consumption of indigenous vegetables, nuts, and seeds/oils was higher than exotic species in both study areas; and (6) UNM had more indigenous fruits compared to WUM, although preference and consumption was higher in WUM. We recommend increased research attention on forest foods to quantify their contribution to household food security and ensure their sustainability. © Taylor & Francis Group.

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