Faculty of Engineering, Design and Technology

Permanent URI for this collectionhttps://hdl.handle.net/20.500.11951/927

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Browsing Faculty of Engineering, Design and Technology by Subject "Anthropogenic disturbance"

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    Communities of Trees Along a Tropical Forest Restoration Gradient
    (2016-01) Owiny, Arthur A.
    Increasing rates of deforestation in tropical forests have been linked to agriculturalists. A critical concern generating debate is how well communities of trees recover into a more species rich ecosystem after restoration planting. The aim of the study was to evaluate the pattern of recovery of communities of tree, assess the influence of Acanthus pubescens, Lantana camara and Pennisetum purpureum, on the recovery as well as how restoration planting facilitates recruitment of other native tree seedlings along a gradient of forest restoration in Kibale National Park, Uganda after evictions of illegal settlers. We studied six restoration forests ranging in age from 3 to 16 years, naturally regenerating and three primary forests. Our results showed that recovery with natural regeneration was more effective than restoration planting although the latter enhanced recruitment of other native tree seedling. Tree recovery was generally correlated with age so that species density and diversity increased although at different rates. A reverse pattern was found for dominance but no clear pattern was found for tree density (individual/ha). Communities of tree showed directional patterns of change however community composition were still distinct among the different forests. A. pubescens, L. camara and P. purpureum negatively correlated with species density, tree density and diversity but a positive correlation was found for dominance. Restoration planting can reestablish forests with high species density, tree density and diversity, but this is dependent on age and the extent of the herbs, grasses and shrubs cover in tropical forests.
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    Tree communities of different aged logged areas in an Afrotropical rainforest
    (2016-03-09) Owiny, Arthur A; Valtonen, Anu; Nyeko, Philip; Malinga, Geoffrey M.; Roininen, Heikki
    Predicting the recovery processes in tree communities after logging is critical when developing conservation strategies. We assessed the patterns in tree communities in logged and primary forests in Kibale National Park, Uganda, representing 9- to 19-year-old clear-cuts of former conifer plantations, 42- to 43-year-old logged forests and primary forests. Species density and diversity were lower and dominance higher in the 9- to 19-year-old forests compared to the 42- to 43-year-old forests or primary forests. The tree species density, diversity and dominance of 42- to 43-year-old forests did not differ significantly from primary forests. However, they had a lower stem density, and higher cover of Acanthus pubescens, a shrub known to arrest the succession in Kibale. The tree community compositions of 9- to 19-year-old, 42- to 43-year-old and primary forests differed from each other. A large group of tree species (21) were primary forest indicators, that is, they were either missing or relatively rare in logged forests. The results of this study show that even after four decades of natural recovery, logged Afrotropical forests can still be distinguished from primary forests in their tree community compositions, emphasizing the slow community recovery and the important role of primary forests when preserving the tree communities in tropical rainforests.