2011 International Year of the forests – wet forests

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Detail of the stilt roots of the red mangrove

Mangroves

At the mention of the name “wet” forest most people will instantly think of rain forests. Large areas lushly irrigated forest where the leaves glisten with moisture, the ground a muddy mass of soil, and where the smell of rotting leaves dominates the senses. It is certainly true that many rain forests, including the Pantanal in Brazil, are inundated much of the year. This creates a complex system of relationships between the moisture, the trees and other plants and animals that live there. Most forests, however, are also influenced by seasonal dry periods, when there is very little or no rain. The most striking “wet” forests in the world, but still somewhat the “underdogs”, are the mangroves, the only forests that grow near and within salt water.

Coastal Protection

Forgotten by many, despite major campaigns by environmental organizations, these forests became suddenly “hot” when a devastating tsunami destroyed large coastal areas of countries in Asia in 2006. The large scale human induced destruction of the mangrove forests along the coast was held responsible for the enormous magnitude of the disaster.

Coastal development for tourism, but also for urban development and construction of agricultural land, was responsible for the removal of the natural protection of the coast – the mangroves-, thereby paving the way for the flooding wave and allowing it to reach much further inland than what it likely would have done when the forests would have been left in place.

Red mangroves adjacent to a seagrass bed

Mangroves do not protect the coast all by themselves. Together with a healthy coral reef and well developed seagrass beds the coastal areas are optimally protected.
This system of coastal protection is also found in Curaçao, and especially in the inland bays. The word ‘mangroves’ triggers most Curacaoans to think about the trees at Koredor or surrounding the Holiday Beach Hotel. However, mangroves do also occur in the inland bays of St. Joris, Spanish Water, Schottegat, Piscadera, Hermanus, St. Martha and St. Cruz and also along the saliñas (former inland bays) of Daaibooi, San Juan, Knip etc.

Oxygen production and waste water filtering

A mangrove forest is not just a coast guard against possible storm surges, but also produces large amounts of oxygen that people and animals make good use of. In between the so called stilt roots young fish and other sea creatures can and will hide. The canopies are the place where reptiles, birds and insects find shelter. The complex root systems filters sand and mud (and other contaminants) from rainwater that flows towards the sea through the gully systems. This is a good thing, because one of the archenemies of corals is sediment.

The stilt roots are a vital habitat for young reef fish - the nursery of the reef

Species of mangrove

Typically, a mangrove area will harbor 4 different types of mangroves: the red, black, white and false mangrove.
When you approach the coast from the sea the first kind you will encounter is the red mangrove, Rhizophora mangle. This species is very recognizable by its long stilt roots as if it stands on its “feet” in the water. The name comes from the reddish color of the wood beneath the bark. The next zone is inhabited by the black mangrove, Avicennia germinans, which is identified by the myriad “snorkels” sticking up from its subsurface roots. The third is the white mangrove, Laguncularia racemosa, a tree with no characteristic adaptations to the roots, since it occurs on the dry part of the mangrove forest. The last zone is occupied by the so-called Buttonwood, Conocarpus erectus, which is not a member of the mangrove family but salt-loving nonetheless. The blue-gray cousin of this species is regularly used on the island for landscaping purposes. The roots of the latter two species do not directly penetrate salt water, but the trees do have special adaptations to survive in saline soils at the water’s edge. They will store salt within their thick leaves, for example, that will fall off when saturated.

These are not beans! - The seeds of the red mangrove sprout while still attached to the tree, an essential survival strategy for a tree growing in the water

Essential coastal ecosystems

Although all mangrove forests appear to look the same to the untrained eye there certainly are differences between the mangrove forests in the world. The small patches and ribbons of mangroves on Curacao cannot be compared with the large expanses of mangrove forest in Suriname, inhabited by large groups of red and white ibises, herons and other waterfowl. The difference in size makes the Island version not less valuable, though. Especially because of the limited areas we need to treat the mangroves with care, at least if we want to continue to reap all the benefits they offer us. Without mangroves the natural systems of tropical coasts are in danger of perishing!

 

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