Warburgia ugandensis is an important medicinal tree species whose bark is widely harvested for its valuable anti-bacterial and anti-fungal properties. Consequently, this tree species is considered threatened. Therefore, this species is ranked as one of the priority species for management and conservation. This study investigated an appropriate technique for propagation of W. ugandensis using stem cuttings. Three types of stem cutting (hardwood, semi-hardwood and softwood) were obtained from Mabira Forest Reserve, Uganda and propagated in a factorial experiment using non-misting tunnels. Data on callusing root and shoot formation, number and length of roots and shoots were collected over a period of 93 days. Data manipulation was done by employing general linear model analysis of variance and Chi-square tests. There was significant variation (p < 0.05) in callus formation, root and shoot development, number and length of roots and shoots for different stem cutting types. The highest percentage of callusing, rooting and shoot regeneration (46, 49 and 57%) was recorded in softwood cuttings which also produced the highest number and longest roots and shoots. Successful propagation of W. ugandensis can therefore be appropriately achieved through softwood stem cuttings rather than either hardwood or semi-hardwood cuttings.

The impacts of invasive alien plant species on native plants are generally well documented, but little is known about the mechanisms underlying their impacts on crop growth. A better understanding of immediate as well as legacy effects and of direct and indirect impacts of invasive alien plant species is essential for an improved management of invaded cropland. We investigated how Lantana camara impacts the growth of two subsistence crops (maize and cassava) through competition for resources, allelopathy and the indirect plant–plant interactions. We carried out two pot experiments using soils from invaded abandoned, invaded cultivated and non‐invaded cultivated crop fields. In the first experiment maize and cassava were grown alone or together with L. camara and half of the pots were treated with activated carbon to suppress allelochemicals. The effect of the soil microbial community on L. camara—crop interactions was assessed in a second experiment using autoclaved soil with 5% of soil from the three soil types. We found that L. camara reduced the growth of maize by 29%, but cassava was not affected. We did not find evidence of allelopathic effects of L. camara. Inoculation of autoclaved soil with microorganisms from all soil types increased biomass of cassava and reduced the growth of maize. Because L. camara only caused impacts when growing simultaneously with maize, the results suggest that removal of L. camara will immediately mitigate its negative impacts on maize.

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There is insufficient information regarding the factors affecting the environmental impacts of alien species. In particular, little is known about whether there is any relationship between the invasiveness (establishment and spread) of an introduced species and its per capita impact. We experimentally assessed the relationship between the extent of spread of up to 29 alien plant species and their impact on recruitment of native tree species in Amani Botanical Garden, Tanzania. We also studied the effects of allelochemicals of selected alien on native plant species to assess potential mechanisms of impact. We found no relationship between the extent of spread of an alien tree species and their impact on seed germination, seedling survival, and seedling communities of native trees in their understory, and no indication that allelochemicals consistently explain their effects on recruitment of the studied species. These results suggest that extent of spread cannot be used as a proxy for impact. Hence, managers should continue assessing both the spread and the impact of alien species when prioritizing alien species for management.

The recent heightened attention on mushrooms has not considered shortening the production time and increasing nutritional value using substrates from agroforestry trees in addition to traditionally used agro-industrial residues. This study therefore, examined harvesting time, protein and essential minerals of Pleurotus floridanus grown on rice straw amended with Gliricidia sepium foliage in Morogoro, Tanzania. Mushrooms were cultivated in 30 x 40 cm 4 kg dry weight polythene bags in randomized complete block design (RCBD) experiment. Results showed that the addition of 5% G. sepium into rice straw reduced total time between spawning and first harvest of P. floridanus. Gliricidia sepium increased significantly (P < 0.05) protein contents of the mushrooms by up to 40%. The addition of 5–10% G. sepium into rice straw increased significantly (P < 0.05) manganese, copper and zinc in the mushrooms. The decrease in production time and high increase in protein and mineral contents indicate that agroforestry trees have the potential to increase production cycles and nutritional value of P. floridanus. Therefore, use of foliage from agroforestry trees in combination with traditional substrates for mushroom production could help fight malnutrition, improve food security and enhance income. Keywords: Food security; Gliricidia sepium; Income; Mushrooms; Smallholder farmers