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Ganl. Bull. Singapore 70 (Suppl. 1) 2018 
deforestation continued unabated in the decades that followed, almost to completion. 
A wealth of research has been written and published about the Amazonian wetland 
forests (e.g. Junk et al., 2010), but in comparison, few studies have been made since 
Corner’s seminal work to update our knowledge of tropical freshwater swamp forests 
in this part of the world (Turner et al., 1996a) where they are no less special. The 
recent literature on freshwater swamp forests in insular Southeast Asia is focused 
predominantly on peat swamp forests (swamp forests with a deep layer of ombrogenous 
peat) because of interests in preserving the massive below ground carbon stocks and 
avoiding transboundary air pollution arising from the burning of this particular swamp 
forest type (Yule, 2010; Posa et al., 2011). There is no historical evidence of true peat 
swamp forests in Singapore (see also Nguyen et al., 2018), therefore in this article we 
exclude peat swamps in our use of the term ‘freshwater swamp forest’. 
Freshwater swamp forest was suggested by Corlett (1991) to have once 
constituted 5% of the vegetation of Singapore prior to modern human settlement. The 
swamp forests at Mandai Road and Jurong were among the main study sites of Corner 
(1978). Most of the Mandai swamp was flooded to become part of the Upper Seletar 
Reservoir, while the Jurong swamp was in-filled to be used as industrial land. Today, 
the freshwater swamp forest at Nee Soon is the country’s last substantial remnant of this 
forest type (Turner et al., 1996a). This paper presents a portion of our research focusing 
on the vegetation and plant communities in the Nee Soon catchment, conducted as part 
of a larger project (Davison et al., 2018) to understand the biodiversity and hydrology 
of the Nee Soon freshwater swamp forest that is within this catchment. 
Prior to our study, 16 vascular plant species that were presumed Nationally 
Extinct in Singapore in the most recent edition of the Singapore Red Data Book 
(ferns and fern allies: B.C. Tan et al., 2008; seed plants: H.T.W. Tan et al., 2008) 
were rediscovered in the Nee Soon catchment and published in various sources (Table 
1). One new species record, Hoy a caudata Hook.f. (Apocynaceae), was reported by 
Rodda & Ang (2012). Therefore, the Nee Soon catchment was already a known prime 
spot for new records and rediscoveries leading Chong et al. (2012) and the authors of 
many of the references listed in Table 1 to call for more botanical exploration of the 
patch of freshwater swamp forest in this catchment. 
Turner et al. (1996a) compiled a list of freshwater swamp vascular plant species 
in Singapore from three of the clusters of plots studied by Wong et al. (1994) for trees, 
and Turner et al. (1996b) for herbs, that were in the freshwater swamp forest areas 
of Nee Soon, and supplemented this with the species recorded by Corner (1978) at 
Mandai and Jurong, as well as with past herbarium specimens. Wong et al. (2013) 
produced a preliminary checklist of all the land plant species (i.e., including mosses 
and liverworts) of the Nee Soon catchment by adding data from newly surveyed plots, 
including ten 15 x 15 m plots established in the earlier Phase 1 of this project, and 
recently collected herbarium specimens. During Phase 2 of this project, we were able 
to re-assess the vascular plant species in Wong et al. (2013) and correct some of the 
nomenclature and identifications (for details, see Chong et al., 2016; Lim et al., 2016; 
Neo et al., 2016; Tan et al., 2016). The physical, climatic and ecological context of the 
Nee Soon freshwater swamp forest is described by Clews et al. (2018). 
