The potential of farmed ecosystems to conserve avian and woody plant species biodiversity in Buhaguzi County, Hoima District, Uganda

Abstract

This study assessed the potential of farmed ecosystems in Buhaguzi County, Hoima District, Uganda to conserve biodiversity. In order to achieve this, comparisons of floristic structure of woody species and bird species diversity in the different land use types of farmland, bush fallow and forests were made. The influence of floristic structure on bird distribution and abundance was also determined. The study was carried out on twelve randomly selected transects. Importance Value Index (IVI) was used to highlight ten species of conservation significance in each land use type while woody species population structure was used to assess their regeneration potential. Differences in woody species and bird species diversity indices between land use types were tested using a Solow's randomisation test in community structure. Furthermore Analysis Of Similarity (ANOSIM) was used to test for variations in woody species and bird species composition between land use types. Density differences of floristic structure variables, bird species habitat categories and feeding guilds were analysed using one way analysis of variance (ANOVA), followed by Tukey's Post hoc tests. Canonical correspondence analysis (CCA) was used to explore the variations in bird species distributions explained by floristic variables.

Analysis of similarity revealed that woody species and bird species composition differed significantly among the three land use types. Overall woody species diversity index was significantly higher in forest than farmland and bush fallow. Ficus species were common to all the land use types and had a high IVI but appeared to be generally threatened by extinction. Woody species with low IVI are threatened, and some of them are IUCN red-listed species. Farmland was found to harbour Afrotropical migrants and regionally near-threatened bird species. Bird species diversity index showed two trends: one, it was significantly higher in farmland than all other land use types for all pooled data of bird species habitat categories; two, it was significantly higher in forests than farmland and bush fallow when analysed on basis of forest specialist bird species. Granivores and faunivore frungivores were more abundant in farmland, an indication of severe disturbance resulting from the conversion of forest to farmland; while arboreal insectivore frugivores, sallying insectivore and terrestrial insectivores were abundant in forests. CCA analysis revealed that the most important floristic variables significantly associated with the distribution of bird species were canopy cover and litter. Despite woody species richness and diversity being significantly higher in forest land use types than farmland and bush fallow, farmland has the potential to conserve a diversity of woody species and forest specialist (FF) bird species. However forest land use type was the most important habitat type for the existence of forest understory birds and for these the disappearance of forests may threaten their existence. This confirms the need to maintain the diversity of woody species floristic structure among all land use types if bird diversity is to be maintained.