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2016-12-24T18:13:07

We assessed tree species density and diversity in 12 1-ha plots in four forests of the Albertine rift, western Uganda. There were 5747 trees of diameter ≥ 10 cm in 53 families, 159 genera, and 212 species. Density ranged between 344 and 557 trees ha −1 (average 479 trees ha −1 ). Tree species diversity was highest in the Bwindi and Budongo forests. The Euphorbiaceae family was the most species rich (25 species) followed by Rubiaceae and Meliaceae with 16 species each. Canonical Correspondence Analysis (CCA) showed that major gradients in environmental variables influenced tree species distribution. Sample scores on ordination axes 1 and 2 were strongly correlated with pH and altitude, respectively. Correlated with rainfall and other soil factors, pH and altitude are presumed to be among the most important in influencing the distribution of tree species in the Albertine rift forests. Strategies that take account of variations in pH and elevation are required to conserve tree species in forests of the Albertine rift.

Before Bwindi Impenetrable forest, Uganda, became a national park in 1991, there was a high level of human activity in much of the forest, especially cutting of large trees for timber by pitsawyers. This created extensive gaps in this tropical Afromontane rain forest. We quantified and compared tree regeneration in three sites that were logged at different intensities. Gap sizes in Bwindi, even under fairly natural conditions are very large (mean ¼ 4460.1 m 2 ). Logging further enlarged the gap sizes and had a negative impact on tree regeneration. The study shows the strong role of logging disturbance in promoting an alternative successional pathway, where the large gaps created by logging are in a low-canopy state dominated by a dense tangle of herbs, shrubs, and herbaceous or semiwoody climbers. We recommend periodic monitoring of gap size and tree regeneration in the gaps to ascertain the trend of recovery from past logging disturbance.

The classical aim of the application of super absorbent polyacrylate (SAPs) hydrogels is the prolonging of plant survival under water stress. Their effect on plant growth during non-water stress conditions is not known. This study examined the root and shoot biomass of seedlings of nine tree species; Eucalyptus grandis, Eucalyptus citriodora, Pinus caribaea, Araucaria cunninghamii, Melia volkensii, Grevillea robusta, Azadirachta indica, Maesopsis eminii and Terminalia superba. The seedlings were potted in five soil types; sand, sandy loam, loam, silt loam and clay. These were amended at two hydrogel levels: 0.2 and 0.4% w/w and grown under controlled conditions in a green house. Root and shoot growth responses of the seedlings were determined by measuring the dry weight of the roots, stems, leaves and twigs. The addition of either 0.2 or 0.4% hydrogel to the five soil types resulted in a significant increase of the root dry weight (p a 0.001) in eight tree species compared to the controls after 8 wk of routine watering. Also, the dry weight of stems and leaves and twigs were significantly (p a 0.001) higher in the nine tree species potted in hydrogel amended soil types than in the hydrogel free controls. These results suggested that hydrogel amendment enhances the efficiency of water uptake and utilization of photosynthates of plants grown in soils which have water contents close to field capacity.

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Mineral composition of dry Tamarindus indica LINN pulp and seeds was evaluated on samples collected from three different agro‐ecological zones of Uganda (Lake Victoria Crescent, and Eastern and West Nile). The objective of the study was to evaluate the mineral composition of T. indica pulp and seed samples from across Uganda's different agro‐ecological zones and land use types. Separately grounded samples of T. indica pulp and seeds were analyzed for Zn, Fe, Mg, P, Na, K, and Ca. The univariate analysis of variance in the General Linear Model was used to compare differences in mineral composition. Treatment means were separated using Least Significant Difference (LSD) in Post Hoc Tests. The results showed that there were significant differences (p ≤ 0.005) in mineral composition levels of T. indica pulp and seed samples between the different agro‐ecological zones with the exception of P and Na (for pulp). The T. indica pulp and seeds samples from the Lake Victoria Crescent zone and wild land use type had generally higher mineral levels than T. indica samples from other agro‐ecological zones and different land use types. As mineral composition levels were generally higher in the seed than the pulp samples, consumption of T. indica seeds should be promoted. There is also need to conserve individual species both on‐farm and in the wild population, but T. indica mineral concentrations (both pulp and seeds) were higher in the samples from the wild population, making them good for human and animal diets.

Traditional practices are universally recognised as a basis for conservation of biodiversity. However, such practices are often not included in natural resource conservation policies. This study assessed local conservation practices of shea trees (Vitellaria paradoxa) within different farming systems in Uganda and developed conservation guidelines for the species. The assessment involved 300 respondents, 15 focus groups and 41 key informants. Content analysis was used to identify the most important management and conservation practices. Local uses were categorised on the basis of shea tree products while differences in conservation practices were analysed using the Friedman test. The results show that eight shea tree products are used for 36 different purposes. Respondents' age significantly influenced their knowledge about the shea tree. Traditional conservation practices include on-farm retention during cultivation and the use of folklore (mainly Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue. taboos), customs and rituals. Traditional management practices include weeding, bush burning, pollarding and pruning. Based on the current management and traditional conservation practices, a framework for the conservation of shea trees is proposed for integration into conservation policy decisions.