Pedada – marching seaward

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Pedada’s breathing roots enable the tree to breathe in anaerobic, oxygen-deprived conditions.

Fruits are seen on the Pedada tree

MANGROVE Forests are frequently spoken of as simply mangroves, as if all Mangrove Forests are the same with few species.

Botanist Dr Paul Chai has actually identified nine individual subtypes of Mangrove Forest and named each subtype after the dominant species. He has identified 49 mangrove tree and shrub species.

The species composition changes as the forests move from the seaward side to the landward side along with the decreasing frequency of inundation of salt water.

Compared to other forest types, for example Mixed Dipterocarp Forests, there is little species diversity, but these plants are able to colonise harsh, changing tidal landscapes; during tides they are inundated with salt water, at low tide they are exposed to the strong tropical sun.

They can withstand drought and have adapted to oxygen-deprived environments. In this harsh environment, natural beauty survives with the survival of the fittest.

On the seaward side, almost pure forests of Pedada (Sonneratia alba) march towards the sea stabilising exposed mudflats with their wide spreading horizontal roots; creating niches for other creatures including nurseries of commercially important fish and prawn species.

This species has adapted to surviving in situations with wide ranging salinity conditions. These Pedada stands serve as barriers to rising tides and storms. Lumber is harvested from these forests for firewood, building posts and piles. Although probably due to the salt concentration, its wood erodes metal.

Pedada are members of the genus Sonneratia, which contains six members, and the family Lythraceae. It is a common tropical Mangrove Forest species with worldwide distribution from East Africa, to the Indian subcontinent, Southeast Asia and the Pacific Islands.

Survival in a harsh environment

Pedada or aptly mangrove in English has evolved to survive in the harsh tidal zone area with wide-ranging salinity and is frequently submerged by the tides.

The wide-ranging horizontal roots, which anchor the tree in place, have vertical thick cone-shaped pneumatophores. These breathing roots — that can slowly grow to three metres, but are normally about 50 centimetres — emerge from the water at least part of the day. They enable the tree to breathe in anaerobic, oxygen-deprived conditions.

Another tactic used to protect this ultrafiltrator is to absorb only some ions. It is possible that extra salt is deposited in the dead leaves that will be shed.

The bark of the seedlings is coated with a waxy substance protecting the tree from salt water and insects.

Appearance

The rounded, leathery Pedada leaves prevent evaporation of water. Its green four-centimetre fruits, which contain 100 to 150 seeds, are also leathery, protecting the approximate 15-metre tree from water loss. Its creamy or grey coloured bark has slight vertical cracks.

Role in the habitat

Pedada serves as host trees for fireflies that produce spectacular synchronised flashing displays. The highly-endangered Proboscis Monkey (Nasalis larvatus) and insects eat their leaves.

It provides favourable conditions for other creatures to survive in, including as previously mentioned, larvae from commercially valuable prawn and fish species.

Without Mangrove Forests and Pedada, there would likely be no durians.  Durian flowers are pollinated by fruit bats, members of the Pteropodidae family, such as the Lesser Short-nosed Fruit Bat (Cynopeterus brachyotis) and the Flying Fox (Pteropus sp).

These bats feed on Pedada flowers and other commercially important fruits such as banana and papaya.

This shows the connection between land and sea; plant and animal; between ecosystems that which at first glance do not look connected.

A missing link in the chain might cause the disruption of connected systems. What would happen if the Pedada pure stands become the missing link?

For information on Mangrove Forests or Pedada visit mangrove.nus.edu.sg or www.naturia.sg/buloh. Information can also be found in ‘National Parks of Sarawak’ by Han Hazebroek and Abang Kashim Abang Morshidi.

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