Browsing by Author "Mugerwa, Badru"

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    Annual Cycles are the Most Common Reproductive Strategy in African Tropical Tree Communities
    (Biotropica, 2018) Adamescu, Gabriela S.; Plumptre, Andrew J.; Ndangalasi, Henry J.; Mugerwa, Badru; Gilagiza, Baraka; Bitariho, Robert
    We present the first cross-continental comparison of the flowering and fruiting phenology of tropical forests across Africa. Flowering events of 5446 trees from 196 species across 12 sites and fruiting events of 4595 trees from 191 species across 11 sites were monitored over periods of 6 to 29 years and analyzed to describe phenology at the continental level. To study phenology, we used Fourier analysis to identify the dominant cycles of flowering and fruiting for each individual tree and we identified the time of year African trees bloom and bear fruit and their relationship to local seasonality. Reproductive strategies were diverse, and no single regular cycle was found in >50% of individuals across all 12 sites. Additionally, we found annual flowering and fruiting cycles to be the most common. Sub-annual cycles were the next most common for flowering, whereas supra-annual patterns were the next most common for fruiting. We also identify variation in different subsets of species, with species exhibiting mainly annual cycles most common in West and West Central African tropical forests, while more species at sites in East Central and East African forests showed cycles ranging from sub-annual to supra-annual. Despite many trees showing strong seasonality, at most sites some flowering and fruiting occurred all year round. Environmental factors with annual cycles are likely to be important drivers of seasonal periodicity in trees across Africa, but proximate triggers are unlikely to be constant across the continent.
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    Grafting Success of Pinus caribaea under Varying Shade Intensities at National Tree Seed Center, Namanve, Uganda
    (The African Journal of Plant Science and Biotechnology, 2010) Mugerwa, Badru; Okullo, John B. L.
    The effect of shade intensity and grafting methods on grafting success and growth rate of Pinus caribaea was assessed in Uganda by subjecting grafts to different shade intensities. Scion growth and number of new leaves produced were counted and recorded for a period of 16 weeks. One-way ANOVA was used to statistically analyze the results. Shade intensity had a significant effect on height growth (P=0.000) and leaf production (P=0.027) but not on scion diameter growth (P=0.401). Different grafting methods showed a significant effect on scion height growth (P=0.000). Higher mean graft survival was observed with the top wedge method (49%). 95% shade intensity had the highest mean survival with a 38% graft survival. The mean scion height growth rate per week was 0.30 and 0.21 cm for top wedge and splice method, respectively. The mean scion diameter growth rate was higher with the splice method (0.032 cm) than with the top wedge method (0.017 cm). Shade intensity had a significant effect on mean height and diameter growth of scions for 0, 50 and 95% shade intensities, respectively. Although P. caribaea grafts’ survival and scion growth rate are highly influenced by both grafting method and shade intensity, a more extended study is still needed to elucidate the survival and growth rate of grafts in the field.