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in the environmental data) were retained and analysed. The four axes were then 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 odonate 
community, represented by Shannon-Weaver Index (IT) and Species Richness (R). 
Spatial autocorrelation and homoscedasticity of the residuals were investigated with 
a Durbin-Watson test and Breusch-Pagan test respectively. The significant PCA 
axes were then further examined to understand the major environmental variables 
influencing the community diversity. 
Results 
Abundance and diversity of odonates in Nee Soon 
A total of 1706 odonate specimens were sampled, comprising 49 species of 34 genera 
in 11 families. The suborder Zygotera was represented by 1014 individuals, distributed 
in seven families (Argiolestidae, Calopterygidae, Chlorocyphidae Coenagrionidae, 
Euphaeidae, Platycnemididae, and Platystictidae), 14 genera and 22 species. Suborder 
Anisoptera contributed 702 individuals, distributed in four families (Aeshnidae, 
Gomphidae, Libellulidae and Macromiidae), 20 genera and 27 species. Prodasineura 
was the most abundant Zygopteran genus (n=552 specimens) followed by Pseudagrion 
(n=lll). Neurothemis was the most abundant Anisopteran genus (n=334) followed by 
Orthetrum (n=138). Relative species richness per survey site varied from two to 13, 
mean abundance of individuals recorded per survey site varied from three to 106. An 
updated species list of Nee Soon freshwater swamp forest odonates, with 68 species of 
47 genera in 11 families could be found in appendix 1. 
1. Distribution of odonates within Nee Soon freshwater swamp forest 
The species found in each of the sub-catchments are summarised in Table 1. The most 
widely distributed species was Prodasineura notostigma which was present at 21 
of the 32 sites, distributed across all the eight sub-catchment regions. Prodasineura 
interrupta and Orthetrum chrysis were found at seven of the eight sub-catchments in 
Nee Soon. Fourteen species were only found from one sub-catchment viz, Libellago 
lineata (LP), Podolestes orientalis (L2), Argiocnemis rubescens (L2), Pseudagrion 
australasiae (L2), Pseudagrion pruinosum (LI), Anax guttatus (LP), Macrogomphus 
quadratus (Ml), Acisoma panorpoides (LI), Crocothemis servilia (LI), Nannophya 
pygmaea (L3), Orchithemis pulcherrima (LI), Pseudothemis jorina (L2) Rhyothemis 
obsolescens (L2), and Trithemis festiva (LI). 
2. Spatial variation in odonate abundance, species richness and diversity 
The species richness and abundance of odonates in each sub-catchment were summed 
up from the four sampling stations and the total results are presented in Fig. 2. Species 
richness is further analysed by the average value of the four sampling sites within 
each sub-catchment (Fig. 3). Among the eight sub-catchments, the three middle sub¬ 
catchments all showed low abundance and species richness whereas the three lower 
