The biological, ecological and conservation significance of freshwater swamp forest in Singapore

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ABSTRACT. This paper presents initial findings from research on the hydro-geomorphic status of Nee Soon freshwater swamp forest catchment in Singapore. The hydrological system of Nee Soon contains a swamp that is best described as an organic-rich wetland, with organic matter content as high as 40% near the surface (too low to be classified as peat). Total longterm denudation rate in the catchment is an estimated 23.4 ± 2.08 Mg km -2 yr -1 , with physical erosion (5.6 ± 0.5 Mg km -2 yr -1 ) and chemical weathering (17.8 ± 1.58 Mg km -2 yr -1 ) accounting for 24% and 76% of the totals, respectively. Age dating of a 1.95-m sediment core from the lower swamp indicates several distinct periods of variable sediment deposition (0.04 to 0.009 cm y -1 ) since 15,000 BCE, across a variety of climate regimes. A missing layer, representing more than a 7000 year period, verifies substantial channel erosion in the swamp occurring since 1950. Accelerated erosion associated with forest conversion to agriculture in the upper catchment could not be verified through examination of sediment cores. High concentrations of several heavy metals (e.g. As, Cr, Mn, Ni, Sr, V) in the lower catchment, compared with the upper catchment, appear to be natural (e.g. related to differences in the underlying bedrock), rather than contamination. The very high concentrations of lead, copper, and zinc associated with firing activities in the military range in the lower catchment are spatially isolated (e.g. shooting berms), and currently not posing a threat to the swamp environment. Other hydrogeomorphic degradation processes/activities now include disruption to hillslope soils and streams by trampling and mountain biking, back-flow of reservoir release water into the lower swamp area, and atmospheric deposition of contaminants.

Section: Introductionmentioning

confidence: 99%

The hydro-geomorphic status of Nee Soon freshwater swamp forest catchment of Singapore

Nguyen¹,

Wasson²,

Ziegler³

2018

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“…Nee Soon freshwater swamp forest is one of the most important conservation sites in Singapore and contains a significant number of native, endemic and nationally threatened flora and fauna (Ng & Lim, 1992;Ng, 1997;Clews et al, 2018). The forest is located within the Central Catchment Nature Reserve, bordered by the Upper Seletar Reservoir to the north, Seletar Expressway and Old Upper Thomson Road to the east, Upper and Lower Peirce Reservoirs to the south, and the southwestern tributary of the Upper Seletar Reservoir and the northern-most tributary of the Upper Peirce Reservoir to the west (Yeo & Lim, 2011).…”

Section: Introductionmentioning

confidence: 99%

Diversity of terrestrial snails and slugs in Nee Soon freshwater swamp forest, Singapore

Lim¹,

Li²,

Yongshou³

2018

ABSTRACT. Nee Soon freshwater swamp forest is the last remaining primary freshwater swamp forest left in Singapore and it contains a rich diversity of native and locally threatened fauna. As native terrestrial snails and slugs are poorly studied and understood in Nee Soon freshwater swamp forest, an extensive survey was conducted to establish their current status. A total of 19 species was recorded, of which one was recorded for Singapore for the first time. Amphidromus atricallosus temasek, a recently described subspecies endemic to Singapore, was found to be more commonly distributed than previously known from the swamp forest. Results also indicate that despite low overall abundance, Nee Soon freshwater swamp forest harbours a rich diversity of land snails and slugs. Any future long term changes in climate or topography, or short term changes in hydrology, might affect their distribution and diversity.

“…The catchment is also a hotspot of new plant records and rediscoveries of species that have previously been presumed to be extinct in Singapore. The Nee Soon freshwater swamp forest is therefore of high floristic conservation value locally (Chong et al, 2018;Clews et al, 2018).…”

Section: Vegetation Ecologymentioning

confidence: 99%

“…Another eight papers have been accepted for publication Chong et al, 2018;Clews et al, 2018;Ho et al, 2018;Kutty et al, 2018;Lim et al, 2018;Nguyen et al, 2018;Sun et al, 2018). used for editing and data management.…”

Section: # Aims Achievementsmentioning

confidence: 99%

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Conservation outputs and recommendations for Nee Soon freshwater swamp forest, Singapore

CAI¹,

Davison²,

Chan³

et al. 2018

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ABSTRACT. The current paper acts as a summary to the "Nee Soon Swamp Forest biodiversity and hydrology baseline studies project", including results published previously and the results from papers of the current volume. Overall, flora and fauna surveys indicate healthy and diverse plant, fish and aquatic macroinvertebrate communities in Nee Soon freshwater swamp forest. There are some concerns over terrestrial and aquatic alien invasive species, loss of big emergent trees, small population sizes and viability of various native species, and the uncertain outcomes of changes in water quality and quantity. The findings inform management that Nee Soon freshwater swamp forest is especially vulnerable to changes in hydrology and there is much dependency on precipitation for its water budget. Projected climate change effects on precipitation and statistical analyses of biotic responses to hydrology clearly define drought as a major, perhaps the foremost, source of vulnerability to the ecosystem functioning of Nee Soon freshwater swamp forest. Potential management solutions are suggested to address five issues of concern for the forest: hydrological integrity, erosion and sedimentation, ecological integrity, the impact of the spillway, and impacts of construction and development.