Dragonflies of Nee Soon swamp forest 
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2 and Mid 3 sub-catchments. The statistical clustering results indicated that the site’s 
odonate community was grouped into group 1, together with most of the sites located 
at the Nee Soon outskirts, rather than with those of Mid 2 and Mid 3 sub-catchments. 
Close examination shows that the Lower 3D site is right alongside a pipeline service 
trail which, although it is near the middle of the freshwater swamp forest, has created 
an approximately 10-15 m width gap in the canopy, creating a significant access path 
for many heliothermic species penetrating the forest to colonise the site and disturb the 
overall RCC distribution pattern. The changes in community assemblage suggest that 
the shift in habitats and its long term impact will need to be monitored closely. 
There may be more threats posed by the pipeline service trail to the odonate 
fauna in Nee Soon. Results from the recent hydrological baseline study of Nee Soon 
freshwater swamp forest show that water quality in the stream parallel to the pipeline 
has high calcium concentrations (A. D. Ziegler, pers. comm.; Nguyen et al., 2018) as 
compared to other sub-catchments. This is probably linked to the construction and 
material used for the pipeline. Soil erosion along the pipeline has also been observed to 
wash down sediment to the stream during heavy rainfall and occasionally pipe leakage 
events. Whether such anthropogenic impacts on water quality have negative effects 
on the odonate fauna in Mid 3 sub-catchment (which happened to have low species 
richness and low species diversity H’ in our study) should be determined. Additionally, 
with the opening of the forest canopy as well as the creation of ephemeral water bodies 
along the pipeline, exotic species of odonates may find suitable pathways into the 
freshwater swamp forest. 
Evaluation of sampling protocol 
An updated species list indicated 67 species of odonate have been recorded in the Nee 
Soon freshwater swamp forest (Appendix 1), and many species reported previously 
were not captured by the current study. These include the majority of rare and 
nationally Critically Endangered species so far found in Singapore only within Nee 
Soon freshwater swamp forest. 
The main focus of the study was on adult odonates, as larvae were collected 
as a secondary sampling during the aquatic insect surveys which took place 
simultaneously (Su, 2016). When larvae are factored in, the data show the possible 
presence of odonates of which the adults were not observed. For example, although 
only one adult Tetracanthagyna plagiata was spotted at site 1C, the larvae of this 
species (identified as Anisoptera sp.) were found at sites Low 1C, Low 2B, Low 3D, 
Mid 2A, and Up 1C. With the combined records, the biodiversity of the survey sites 
may be assessed more accurately. Patten et al. (2015), in their study of USA odonates, 
pointed out that ecological models for adults were broader geographically and had 
a wider, more equitable (higher evenness) balance of contributing environmental 
variables (niche dimensions) than did models for larvae, which tended to be more 
ecologically specialised. They suggested that surveys of adult dragonflies, which are 
relatively easy to conduct because of organised efforts to encourage observations by 
citizen scientists, can paint a misleadingly broad picture of a species’ ecological niche. 
They recommended that evidence of breeding, especially the presence of tenerals or 
