Diversity and distribution of Odonata (Insecta) in Kalinzu Central Forest Reserve in South-Western Uganda

Abstract

Odonates have gained importance in the field of environmental management and biodiversity research as bioindicators of pollution and habitat changes of both aquatic and terrestrial ecosystems. Odonates diversity and abundance in an ecosystem is an indication of the general diversity of the ecosystem, owing to their position in the food chain as predators of both aquatic and terrestrial insects and probably other invertebrates. Larval community are predators in aquatic ecosystem, while adults prey on flying insects. In Uganda, most studies have focused on other insect groups especially those that are pests, vectors or those for food/feeds. For ecological insects, most studies are limited to the charismatic lepidopteran taxon, with only a few studies focusing on odonates. This study, conducted in Kalinzu CFR in south-western Uganda aimed to establish a baseline of Odonata in the forest with the objectives of: i) determining the diversity of Odonata species in Kalinzu CFR, ii) assessing distribution and assemblage of Odonata fauna in the different biotopes of Kalinzu CFR, and iii) evaluating environmental variables that influence the pattern of distribution of odonates in Kalinzu CFR. Adult odonates were collected using a standard sweep net along eight water courses; two from each of the four management zones of the forest reserve. Selected environmental variables were also assessed in the different sites. Species diversity in each zone was analysed using different diversity indices. PCA and Hierarchical clustering using PAST software were used to evaluate species distribution and relationship between different variables with odonates. A total of 1019 individuals belonging to 25 species, 16 genera, and seven families were recorded. Results showed that the forest had high diversity of odonates with the strict Nature reserve being the most diverse, while the Buffer zone was the least diverse. Umma saphirina was found to be the most dominant species and distributed throughout the forest reserve. Majority of species were localised and some such as Allocnemis superba were found restricted to the Research zone. Width of the water channels, water flow rate, canopy cover, vegetation density at ground level near water courses and presence of lentic or lotic system significantly influenced the distribution, richness and abundance of Odonata fauna in the forest reserve. The Strict nature reserve holds the highest conservation value and should be protected. Sustainable use of forest products in the Production zone should be practiced to conserve Odonata fauna and biodiversity