This paper reports on the findings of an ecological survey conducted in Ngumburuni Forest Reserve, a biodiversity rich forest reserve within the coastal forests of Tanzania. The main goal of this study was to determine the influence of uncontrolled anthropogenic activities on tree species diversity and composition within the forest ecosystem. It was revealed that economic activities including logging, charcoaling, and shifting cultivation were the most important disturbing activities affecting ecological functioning and biodiversity integrity of the forest. Further to this, we noted that the values of species diversity, composition, and regeneration potential within the undisturbed forest areas were significantly different from those in heavily disturbed areas. These observations confirm that the ongoing human activities have already caused size quality degradation of useful plants, enhanced species diversification impacts to the forest ecosystem, and possibly negatively affected the livelihoods of the adjacent local communities. Despite these disturbances, Ngumburuni forest reserve still holds important proportions of both endemic and threatened animal and plant species. The study suggests urgent implementation of several conservation measures in order to limit accessibility to the forest resources so as to safeguard the richness and abundance of useful biodiversity stocks in the reserve.

The increase in livestock grazing in African drylands such as miombo woodlands threatens land productivity and ecosystem functioning. Trees have positive effects on soil hydraulic properties, but few studies have looked at grazing intensity and hydrological functioning in different land uses. Therefore, we conducted a biophysical survey in Morogoro Rural District, Tanzania, where we identified four main land uses and land cover types, that is, Forest reserve, open-access forest, cropland under fallow, and active cropland. We assessed grazing intensity, measured infiltration capacity, and conducted dye tracer experiments to assess the degree of preferential flow in 64 plots. We also tested the effect of grazing exclusion on infiltration capacity in 12-year-old fenced plots. Our results show that irrespective of land use or cover type, soil bulk density increased by 10% from low to high grazing intensity, whereas infiltration capacity and soil organic carbon decreased by 55% and 28%, respectively.We found a positive relationship between infiltration capacity and tree basal area in plots with lowest grazing intensities. However, at higher grazing, the infiltration capacity remained low independently of the basal area. Preferential flow in deeper soils was six-times higher in areas with no grazing, indicating higher deep soil and groundwater recharge potential at low grazing intensities. We conclude that the negative impacts on soil hydrological functioning of excessive livestock grazing override the positive effect of trees, but restricting grazing can reverse the impact.

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SYNOPSISPropagation of African sandalwood (Osyris lanceolata) by air layering (marcotting) was investigated at Sao Hill, Tanzania, aiming at providing an alternative propagation technique to the use of seeds or cuttings that germinate or root poorly. Air layers were initiated on the young shoots (1 -2 years old) of mature O. lanceolata trees growing at Sao Hill catchment Forest. After root initiation, which took 8 weeks, they were detached from the parents, potted in polyethylene tubes and reared at the nursery for a further three months. The factors assessed in this experiment were the effect of time at which air layers were initiated (i.e. February, June, September and December); and the influence of IBA as rooting promoter at three concentrations (50, 100 and 150 ppm). From the data collected it was observed that rooting success of up to 80% can be achieved from air layers, making this propagation technique a viable alternative to seedlings or cutting propagation. Rooting success was influenced by both the season and application of rooting hormone with optimal rooting being achieved during June and September with the addition of IBA at a rate of 50 ppm. The significance increase in rootability of air layers during June and September may be linked to the advantage of the dry season in Tanzania where reduction of plant development activities such as budding, leafing and flowering in the dormant dry season might have reduced resource competition and thus promoting the observed rooting.

SYNOPSISIdentification of the host plants of the hemi-parasitic African sandalwood (Osyris lanceolata) and the influence of some on its early growth performance was investigated at Image, Nundu, Sao Hill and Iringa in the southern highlands of Tanzania. The aim was to identify host plants that support the growth of O. lanceolata, and to evaluate the potential of some in promoting its early growth under artificial establishment. The results revealed that O. lanceolata parasitises a wide range of hosts although some were preferred. The preferred hosts were Rhus natalensis, Dodonaea viscosa, Tecomaria capensis, Catha edulis, Apodytes dimidiata, Brachystegia spiciformis, Maytenus acuminatus and Aphloia theiformis. Of the preferred hosts, Brachytegia spiciformis, Rhus natalensis and Casuarina equisetifolia promoted most effectively the early growth of O. lanceolata in terms of height, diameter and overall root and shoot biomass. Possibly the light crown of these host species and the nitrogen fixing ability of C. equisetifolia played a significant role in conferring this advantage. The species are thus recommended as appropriate host plants when raising O. lanceolata seedlings for planting. However, a decision on whether these hosts will support the growth of O. lanceolata at a later stage is subject to further experimentation as they may only be serving as initial or intermediate hosts as reported in a related species Santalum album.