Tree species diversity and abundance in coffee farms adjacent to areas of different disturbance histories in Mabira forest system, central Uganda

Coffee production in Uganda is done on small-scale farms containing a very significant tree component. However, there is little information on how tree species abundance, richness and diversity change in coffee farms as distance from forest changes. The main objectives of this study, therefore, were to assess (a) abundance and (b) diversity of tree species in the coffee production systems in proximity to disturbed and undisturbed forest around Mabira forest, one of Uganda's Robusta coffee-growing areas. Seventy-nine 0.1 ha plots were established in nine villages close to undisturbed and disturbed forest, and over 5 km from the forest. A total of 875 trees belonging to 63 species were recorded. There was significant similarity in species composition among the three study sites (analysis of similarity R = 0.09, p < 0.01; analysis of variance: F3,12 = 0.353, p = 0.79). Non-metric dimensional scaling supported these findings (stress value = 0.224 at k = 2) and showed that tree species composition in the three proximity categories was very similar. These results demonstrate that tree species composition and diversity is similar in coffee farms regardless of their distance from the nearest natural forest and forest exploitation history. (Résumé d'auteur

Effect of Soaking Treatment on Germination of Hard Coated Tropical Forest Tree Seeds

Seed germination and seedling growth performance of Maesopsis eminii and Terminalia catappa under different water soaking treatments were evaluated for 120 days under nursery conditions. A total of 1400 seeds were pre-treated with hot (95oC) and cold water (ambient temperature) by soaking for 12, 24 and 48 hours with a control of no soaking. The seeds were sown directly into polythene pots filled with uniform growth medium (top forest soil, sand and clay soilmixed in a ratio of 5:3:2) to avoid disturbance of the root system after germination. The seeds were sown in a randomized block design with seven treatments and three replicates. Data were analysed using ANOVA in GenStat v18. Results indicated that soaking enhanced seed germination. Soaking of seeds in cold water for 12 hours resulted into higher germination (90% for Terminalia catappa and 85% for Maesopsis eminii) than the control (48%). Soaking period and water temperature significantly influenced seedling vigour (F value = 0.962; p = 0.038). Soaking seeds in cold water for 24 hours enhanced Maesopsis eminii seedling growth by 8.0 cm Terminalia catappa seedlings by 7.4 cm. Seed dormancy, germination percentage and growth performance in hard coated seeds such as Maesopsis eminii and Terminalia catappa can be broken by soaking in cold water for 12-24 hours. Pre-germination treatments significantly influences the germination and seedling growth. Keywords: Maesopsis eminii, Terminalia catappa, seeds, pre-germination, soaking

Variation in seed and seedling traits of the different ethno-varieties of jackfruit, a potential fruit tree species for food security

A key component of the performance of plant seeds is the germination capability as well as seedling survival and vigor. Seed traits from five jackfruit ethno-varieties (infra-specific diversity as understood and managed by farmers) were assessed. A greenhouse experiment was conducted to determine the survival of seeds, emergence and germination rate. Seeds from different ethno-varieties differed in their length (F (4,145) = 6.31, p < 0.001). The difference was highest between seeds from white, orange or yellow ethno-varieties. The width also slightly differed among ethno-varieties (F (4,145) = 3.29, p < 0.05). The average fresh and dry weights tended to be higher in seeds from the soft ethno-variety than the rest of the ethno-varieties. Differences in the survival of seeds and germination rate were also exhibited among ethno-varieties, where the white ethno-variety showed the highest pre-emergence mortality but at the same time the least germination time. Over the six-week period of germination, the soft ethno-variety exhibited the highest root:shoot ratio but also grew faster than all other ethno-varieties. There is potential evidence of phylogenetic constraints on seed size, germination and seedling vigor. Optimum growth for most of the traits was achieved between 6 and 7 weeks after sowing, which can guide on the time seedlings should be left in the pots before being transferred to the field. Further progeny tests should be undertaken on these provenances in the field over a longer period so as to obtain better distinction of the growth traits among the ethno-varieties

Folk Classification of Shea Butter Tree (Vitellaria paradoxa subsp. nilotica) Ethno-varieties in Uganda

researchFolk knowledge has been the basis for selection and improvement of many food crops such as potatoes, sorghum, yams, cassava and rice. In Uganda, there is strong potential to utilize folk knowledge to select and domesticate the shea butter tree (Vitellaria paradoxa C.F. Gaertn. subsp. nilotica (Kotschy) A.N. Henry & Chithra & N.C. Nair), an important economic tree species. Farmers report high variation in fruit yield, tree form and pulp taste. In this study, we documented shea tree folk classification by interviewing 300 respondents, 15 focus groups and 41 key informants across three farming systems of Uganda. Data were analyzed using Kruskall-Wallis and Spearman’s tests, Chi-square, Multivariate, Factor and Discriminant Function Analyses. Folk classification and nomenclature of shea tree ethno-varieties is based on fruit/nut organoleptic (color and taste) and morphological attributes. Interestingly, despite the socio-cultural importance of shea oil, it does not feature as a factor in the folk classification and nomenclature of shea tree ethno-varieties. There was no significant difference in classification knowledge across the three farming systems (Kruskal – Wallis ?2 = 28, df = 28, p > 0.05; Spearman’s R > 0.8, p < 0.0001) although there was significant influence from ethnicity of the respondents (Pillai’s trace = 0.817, p < 0.001). While this study provides a record of shea tree ethno-varieties and associated classification criteria, there is need to validate these ‘ethno-varieties’ using detailed morphological, biochemical and molecular analyses