CONTENTS
Flora index
Fauna index
guide to the mangroves of singapore
The Ecosystem: Biotic components
Peter K L Ng and N Sivasothi (editors)
  Zonation
In relatively undisturbed mangrove forests in Southeast Asia, single-species zonation is common in zones parallel to the coastline and river banks. This can be detected by moving inland from the seaward edge: broad tidal mudbanks or shallow sand banks in the seaward edge are occupied by Avicennia and Sonneratia. Rhizophora is found further inland, and finally Bruguiera, Ceriops, Xylocarpus and Heritiera forming the back mangrove. Mangrove Ecosystem
Abiotic components
Soil
pH
Oxygen
Nutrients
Winds and currents
Light, temperature, humidity
Tides
Salinity

Biotic components
Vegetation
Zonation
In suitable areas, e.g. where a sand/loam substrate is available, Nypa fruticans may develop as the main river bank or lagoon-fringing plant.

The causes of this zonation is still subject to debate but it is probably determined by a combination of factors such as salinity, soil conditions, tidal inundation levels, size of propagules, and interspecific competition.

In Singapore, such zonation is not as clear, possibly because the mangroves are badly disturbed. For example, there were several hectares of Nypa fruticans along the Sungei Tampines in the last decade but they are now gone. Indistinct zonation could also be due to the narrow strip along the coastline that mangroves occupy, varying from 30 to 300 metres.

map of three common zones in Singapore mangroves
Colour map by D. H. Murphy of the mangrove
east of Sungei Buloh Besar. The three zones indicated
are common of mangroves in Singapore.

However, zonation is evident in terms of the topography (map at right): the main forest canopy is frequently delimited by two topographically significant features: a seaward-edge sandbank and a landward-edge Thalassina anomala (mud lobster) mound system, dividing the forest into the following three zones:
  1. The sandbar bearing the seaward tree line composed mainly of Sonneratia ovata and Avicennia alba;
  2. The main forest canopy dominated by A. rumphiana, A. officials, Bruguiera cylindrica, Bruguiera gymnorhiza and Rhizophora apiculata; and
  3. The mud lobster mound and pool complex, bearing mainly Excoecaria agallocha, Bruguiera cylindrica, Bruguiera. gymnorhiza and Rhizophora apiculata. The mounds consist of compacted mud and the pinnacles are between 1.0 to 1.8 metres tall, with the highest peaks above HHWST (supralittoral).
Environmental conditions in each zone are distinct enough that some organisms are restricted to a specific zone, but the more adaptable species are able to exploit a larger area. Within each of these zones are further sub-divisions, but these are less easily defined and will not be discussed here.
aerual view of mangrove mudbank
Avicennia pioneers establishing
on a relatively young mudbank
in Sungei Mandai Besar
What is mangrove?
Introduction

The Ecosystem
Abiotic
Biotic

Value
Intro
Products
Indirect uses
Potential uses

About Mangroves
in Singapore
History
Mangroves to visit
Conservation
 
From "A Guide to Mangroves of Singapore", Peter K. L. Ng and N. Sivasothi (editors)
Volume 1: The Ecosystem and Plant Diversity and Volume 2: Animal Diversity
Authors: Kelvin K. P. Lim, Dennis H. Murphy, T. Morgany, N. Sivasothi, Peter K. L. Ng,
B. C. Soong, Hugh T. W. Tan, K. S. Tan & T. K. Tan
BP Guide to Nature Series published by the Singapore Science Centre, sponsored by British Petroleum
© 2001 Raffles Museum of Biodiversity Research, The National University of Singapore & The Singapore Science Centre