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Other causes for enhanced erosion rates are the presence of trails and traffic of 
trekkers, bikers, and hunters who damage tracks and bridges. The clearing of vegetation 
and increased activity along this area increases the soil mobility and transport of 
sediments. Further restricting visitors to the catchment and repairing damage to the 
tracks and bridges would help serve to stabilise these processes. Forest recovery and 
replanting of endemic floral families would aid in not only the ecological resurgence 
of the reserve, but also the retention of water, sediments, and nutrients in the system. 
The excavation of a soil pit in the upper catchment uncovered ancient charcoal 
remains, indicating clear evidence of past fires (Nguyen et al., 2018). Fires along 
the hillslopes and dryland forests are not only capable of removing large swathes of 
primary and old secondary forest, but may expose the slopes to significant erosion 
during subsequent precipitation and inundation. The apparently increasing severity of 
El Nino effects (Sun et al., 2018), the spread of development and human activities close 
to the edges of Nee Soon freshwater swamp forest, and other human pressures within 
the nature reserve may all increase the likelihood of fires. Therefore, the catchment 
must be readily accessible for fire fighters appropriately trained for operation in a 
nature reserve. The specialised techniques required would differ significantly from fire 
fighting in non-forested areas. It is unlikely but conceivable that some plant species 
require fire for germination and the relative importance of hillslope stability and 
ecological succession must be considered. 
The construction of the firing range, golf course, and expressway within or close 
to the Nee Soon freshwater swamp forest may be affecting the water and soil quality of 
the stream channels (Nguyen et al., 2018; Sun et al., 2018). Analysis of soils for heavy 
metals throughout the reserve found that soils in the lower catchment are significantly 
more enriched than those in the upper catchment. Due to the compositional homogeneity 
of soils in the enriched and normal zones, it has been concluded that some components 
of the heavy metal enrichments may be a result of such nearby developments (Nguyen 
et al., 2018). 
It has been reported that the water supply pipeline cutting across the catchment 
from the Upper Seletar Reservoir to the Lower Pierce Reservoir did experience 
early problems with line breakages due to defective operation of the pump pipeline 
and contributed to significant erosion in the lower catchment (Murphy, 1997). It is 
important to ensure that the pipeline does not leak significantly and that the bund along 
its side does not erode into the swamp. 
Finally, the dam at the mouth of the Upper Seletar outlet when opened has 
been observed causing regular back-flooding into the swamp flushing the system with 
reservoir water, and facilitating the influx of alien aquatic vertebrates and invertebrates. 
Strategies to prevent back-flooding need to be investigated. 
Friess et al. (2015) estimated the entire island of Singapore had an average of 60 
Mg C , which is more than the mean stocks held by 100 other cities around the world 
(Dobbs et al., 2014). Considering the urbanised state of the island, the natural areas 
disproportionately hold the majority of the carbon stocks. Sites like the Nee Soon 
freshwater swamp forest should thus continue to be protected and managed carefully 
in order to maximise its carbon sequestration potential. 
