Diversity, distribution and habitat characteristics of dragonflies in Nee Soon freshwater swamp forest, Singapore

Abstract

ABSTRACT. Biodiversity baselines were established for dragonflies of Nee Soon freshwater swamp forest based on quantitative sampling across the eight sub-catchments. Surveys were conducted from December 2014 to April 2016. Hydrological, physiochemical parameters and habitats were analysed to identify the main drivers structuring the dragonfly community. A total of 1706 odonate specimens were recorded, comprising 49 species of 34 genera in 11 families. The species diversity in each sub-catchment was compared using the Shannon- Wiener Index (H’). Hierarchical clustering and Detrended Correspondence Analysis (DCA) indicated that three main groupings of sites existed, each with a distinct community of associated species. Further analysis by Canonical Correspondence Analysis (CCA) with 12 significant environmental variables showed that these groups were significantly associated with respective environmental variables. Principal Components Analysis (PCA) was performed to analyse the full 23 environmental variables. The first four principal components of the PCA explained 63% of the variation in all the environmental variables. These four axes were input as independent variables into an Ordinary Least Square (OLS) model to test the significance of the link between habitat characteristics and diversity of the dragonfly community. Threats to the odonate fauna of the freshwater swamp forest are identified and conservation management measures are discussed. Keywords.