Mangrove
soils in Sungei Buloh are recent marine alluvium. These soils are
transported as sediment and deposited by rivers and the ocean. The
soils in the reserve are classified as the 'Kranji series'. Different
regions of the park have soils made up of different combinations of
sand, silt and clay. The 'mud' associated with mangrove is a mixture of
silt and clay rich in organic matter (detritus). Generally
the surface topsoil is sandy or clayey. The sandy topsoils are lighter-coloured
and porous. These soils encourage water
percolation and soil aeration at low tide. The clayey topsoils,
however, are darker-coloured
and less aerated. Subsoils
of the 'A' and 'B' horizons are usually waterlogged and have increasing
levels of anoxia correlated with depth. These
horizons contain a high percentage of organic matter which is
decomposing very slowley.
These
soils are generally dark grey or black and produce a strong odour when
disturbed. This indicates that anaerobic, sulphur-reducing bacteria are
present and are generating hydrogen sulphide. The bedrock in the area
is granite.
Sandy
topsoil both picture from: http://mangrove.nus.edu.sg/guidebooks/text/1010.htm |
Clayey
topsoil |