Anthropogenic Disturbance on the Vegetation in Makurunge Woodland, Bagamoyo District, Tanzania

Makurunge woodland is part of the major vegetation component covering coastal forest landscape in Tanzania that has been severely affected by anthropogenic disturbance. The present study determined the effects of anthropogenic disturbance on biomass, diversity, plant communities and plant species distribution pattern using nested sample plots systematically established along transects. Six major vegetation communities with different biomass were found. Plant species diversity ranged from 2.5 to 3.3 and was high in scrub forests, riverine and thicketed habitats, although the difference among these habitats was not significant (P>0.05). About 61-90% of the woodland was affected and this influenced the plant species distribution pattern with strong disturbance gradients in both the first and the second Canonical Correspondence Analysis (CCA) axes. Although fire disturbance rated the highest among variables, its effect was not significant. Monte Carlo test showed that charcoal making, pole cutting and fuel wood cutting had significant effects on the distribution pattern of plant species. Fragmentation of habitats formed patches that have reduced plant species population sizes, and this reduced biodiversity in the study area. Conservation of woodland habitats is necessary for survival of plant populations in the remaining stands.Keywords: Anthropogenic disturbance, biomass, CCA, communities, distribution, diversityTanz. J. Sci. Vol. 37 2011, 94-10

Southern Forests

Scorodophloeus fischeri (Fabaceae, subfamily Caesalpinoideae) and Manilkara sulcata (Sapotaceae) are examples of tropical African hardwood species and are endemic to East African coastal forests. These plant species are threatened by human activities beyond natural recovery in some forests. This study aimed to assess the effects of anthropogenic disturbance on the natural regeneration potential of S. fischeri and M. sulcata in the selected coastal forests of Tanzania. Transects were established in various vegetation communities and a nested quadrat technique was used to assess the natural regeneration. Scorodophloeus fischeri regenerates best in Zaraninge forest with high density of trees with diameter at breast height (DBH) between 10-50 cm and a higher seedling density than in other forests. Similarly, M. sulcata regenerates best in Pande forest, although many trees had a DBH of 10-30 cm, implying that the trees with size classes above these are missing. It was concluded that the minimum level of human disturbances in Zaraninge favoured high potentials of natural regeneration of S. fischeri. Disturbances through human activities contributed to the variation in the natural regeneration potentials for S. fischeri and M. sulcata in these forests. Conservation attention is likely to improve population structure and natural regeneration patterns of S. fischeri and M. sulcata in East African coastal forests

Impact of research and development in food legumes on production and productivity in the last two deacdes

Food legumes include a suite of legume crops grown for human consumption. These include: chickpea (Cicer arietinum L.). lentil (Lens culinaris Mediks), faba bean (Viciafaba), dry bean (Phaseolus vulgaris L.), pea (Pisum sativum L.). pigeonpea (Cajanus cajan L.), cowpea (Vigna unguiculata L.). mungbean (Vigna radiata) and blackgram (Vigna mungo L.). In addition, there are more than a dozen minor food legumes cultivated in many countries. to meet the local preferences for specialty foods, snacks, etc. For all food legumes together. the global trend from 1985-2004 indicated 7.73% increase in area, 20.12% increase in production and 11.49% increase in productivity. The demand for food legumes has doubled in the last quarter century. mostly due to increased population. especially in many developing here the poor people cannot afford buy meat or poultry to meet the protein needs countries where in the daily diets. A study of the area, production and productivity of food legumes in the selected countries (both developed and peveloping) indicates a mixed trend in tenns of i ncreased production of legumes globally. However, the trend is not consistent across countries. Area has drastically reduced in some countries, while in others there are signs of increase in area. Productivity (yield per ha) of foodJegumes in_generaL ha£ shown an over the last two decades. The impact of research and development (R&D) increasing trend on production and productivity of food legumes in context of regional and global trade is discussed and suggestions have been made for the future R&D efforts to increase the global production

Post fire regeneration of indigenous plant species in the Pugu Forest Reserve, Tanzania

Pugu Forest Reserve is part of the Coastal Forests of Eastern Africa Hotspot, recognized as one among the 34 global biodiversity hotspots. Fire unselectively devastated many favorable habitats and directly killed a substantial number of plant species in 2008 in the northern part of the Pugu Forest Reserve. The aim of the study was to assess natural regeneration of indigenous plant species five years after that fire. Sampling was performed using a nested plot design along three transects established among the topographic positions of hill tops, hill slopes and valley bottom. It documented 116 indigenous plant species from 46 families that had successfully regenerated in the burnt area. The stem densities of woody plant species differed significantly among the three topographic positions. The results of this study indicate higher densities of coppiced trees, sprouts, and seedlings on ridge tops versus hill slopes and valley bottoms. The species Garcinia acutifolia, Fernandoa magnifica, Rothmannia macrosiphon, Baphia puguensis and Uvaria decidua were among the threatened plant species under the International Union for Conservation of Nature (IUCN) Red List that failed to regenerate in the ridge tops. The impacts of the fire modified the natural habitat characteristics of the forest, causing some plant species to shift their normal distribution ranges. This study concludes that the forest recovery observed following the 2008 fire highlights the importance of fire suppression in effective conservation management strategies of the Pugu Forest Reserve. Keywords: 2008 fire impact, Endemism, Natural regeneration, Pugu forest reserve, Topographic, Positions, IUCN red list of threatened specie

Vegetation community structure, composition and distribution pattern in the Zaraninge Forest, Bagamoyo District, Tanzania

Zaraninge Forest, part of the Coastal Forest Biodiversity Hotspot of Tanzania, is threatened by human activities. The effect of such activities on the ecology of the forest is less known. Nested quadrat sampling technique was used along preestablished transect lines. Trees had a stem density of 521 ha-1, the majority falling in Diameter at Breast Height (DBH) size classes 9.5 to 44.9 cm. There was no significant difference in species diversity between sampling areas, which had a Shannon’s diversity index ranging from 1.64 to 2.63. PCA identified two vegetation sample groups with Baphia kirkii, Cynometra webberi, C. brachyrachis, Scorodophloeus fischeri and Tessmannia burttii being abundant in both groups. TWINSPAN revealed three vegetation communities: Community A was fragmented woodlands characterized by the effects of fire and exploitation and having few remaining individuals of the valuable timber trees Afzelia quanzensis and Pterocarpus angolensis; community B was growing in a moist ecologically rich habitat and included rare species (Inhambanella henriquesii), endemic species (T. burttii, C. brachyrachis and S. fischeri); and community C had dry habitats dominated by C. webberi and C. brachyrachis. We conclude that habitat characteristics, fire, past and the present exploitation clearly influence the species diversity, distribution and variation in vegetation communities. The results are discussed in context of current and future management plans for this ecologically important forest.Keywords: Coastal Forest of Tanzania, community structure, diversity, forest managemen