Gardens’ Bulletin Singapore 70 (Suppl. 1): 123-153. 2018 
doi: 10.26492/gbs70(suppl.l).2018-07 
123 
Diversity, distribution and habitat characteristics 
of dragonflies in Nee Soon freshwater 
swamp forest, Singapore 
Y. Cai 1 , C. Y. Ng 1 & R.W.J. Ngiam 2 
National Biodiversity Centre, National Parks Board, 
1 Cluny Road, 259569 Singapore 
cai_yixiong @ nparks. go v. sg 
2 Central Nature Reserves, National Parks Board, 
1 Cluny Road, 259569 Singapore 
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. Community structure, ecology, Odonata, statistical analysis 
Introduction 
Nee Soon freshwater swamp forest (Fig. 1) is the only primary freshwater swamp 
forest left in Singapore and is a critical refuge for a large number of Red Listed plant 
and animal species threatened with national extirpation (Ng & Lim, 1992; Clews et al., 
2018). It represents the remaining section of a larger freshwater swamp forest that once 
existed between Upper Seletar Reservoir and Mandai Road (Corner, 1978; Turner, 
1996) and may now be threatened by anthropogenic activities in the surrounding 
areas. The streams in Nee Soon catchment are shaded and have shallow waters flowing 
over clay, sand, or mud. Their pH is more acidic than other forest streams due to 
the decomposition of accumulated leaf litter and woody debris (Ng & Lim, 1992). 
