Jan

20

If you like flowers in your room you might know the problem: Your favorite flower looks sad and ill although you took care and watered it very often. So maybe you watered it too often and the roots couldn`t breathe any more. That is exactly the problem mangroves suffer from. You can just stop pour so much water into the flowerpot but mangroves can´t run away from where they root.
In waterlogged soils like those in mangrove forests all spaces between soil particles are filled with water and the few oxygen in the soil is soon depleted by the aerobic respiration of soil bacteria. To survive in such unpromising surroundings mangroves adapted various forms of aerial roots called pneumatophores. Roots of mangroves are usually very shallow and to receive oxygen they send up pneumatophores as extensions above the ground. This form of aerial roots is often found at Avicienna mangroves.

Pneumatophores of Sonneratia alba

The aerial prop roots of Rhirophora mangroves diverge 2 m above the ground, elongate and penetrate to soil in some distance. These stilt roots provide the main physical support of the trunk. There are also some other forms of roots but these two are the most outstanding types. Often the aerial roots of the trees within a mangrove cross and form an impenetrable tangle that makes life of mangrove researchers very hard.

Stilt roots of Rhizophora mangle

Jan

13

You can find mangroves throughout the tropical and subtropical shores, as long as these coasts are sheltered from wave action. In addition they appear upstream along the banks of rivers and in valleys in the backcountry that are seldom exposed to tides. (map)

Mangrove forest is among the mayor ecosystems with an area of 146.000km². In Indonesia alone there are 45.000 km² of mangrove forests due to the coral reef protected shore.

As an ecosystem mangroves provide a habitat for a huge number of terrestrial and marine species. Inside a mangrove forest they are protected from strong wind and waves and also from predators. Furthermore the retention of nutrients and the litter from the plants supplies food for the mangroval fauna. Some species especially fish and crabs use the sheltered mangrove forest as nursery ground. Despite the fact that the ecological importance of mangroves has been neglected for a long time, they play an important role for marine and shore ecology as well as in economic aspects such as fisheries. In fact 75% of all tropical commercial fish species pass part of their lives in the mangroves.

Another attribute of mangrove forests is the zonation within the forest because of the different environmental factors. On the seaward area there are species located that need daily wetting and whose seedlings do not grow well in shade or under heavy siltation. Behind this fringe there are species that prefer to be only flooded at high tide. Landward you find species that need to grow on more heavy sediment.

Such as the mangrove species the species of the inhabitants vary within the zones. Terrestrial species such as monkeys or arthropods live in the upper reaches of the trees, whereas marine species such as mollusks and crustaceans live in the water between the roots.

Henceforth I will present a species of the week with a detailed description.

Jan

13

Mangroves are trees or shrubs that grow in the tidal range of the tropical and subtropical wetlands around the equator. Usually they root in muddy, oxygen poor grounds at the coast. That means a mangrove has to cope with high salt concentration, strong tides and wind. There are several species of trees or shrubs that altogether form a mangrove forest. They belong to 70 species of trees, shrubs or ferns in 20 different families. All of them share some characteristics that allow them to withstand the environmental conditions:

  • special roots to stabilize in the mud and breathe above the sediment and water.
  • different mechanisms to deal with the osmotic problem of living in a saline environment
  • adapted reproductive strategies such as vivipary and dispersal by water.

Usually you don´t find a single mangrove tree but here in the backcountry of the Cape Sable area of Everglades National Park is a solid Black Mangrove