Vegetation Types of Mangrove Ecosystems
The development of mangrove swamps is a result of substrate, topography and freshwater hydrology as well as tidal action. One can expect several different types of mangroves developing under different sets of these conditions. Five types of mangals are generally recognized in the world: they are;
- Fringing Mangroves,
- Over wash Mangroves,
- Riverrine Mangroves,
- Basin Mangroves,
- Dwarf Mangroves .
Fringing mangroves are common along protected shorelines adjacent to land higher than mean high tide but are exposed to daily tides. It can be seen as relatively thin fringe along the waterways. Because of more prop roots and low energy tides the fringing mangrove can collect more organic matters as they face open wind directly (De Silva & De Silva, 2006).
Overwash mangroves exist as islands frequently washed by tides every day during the high tides. They are dominated by Rhizophora species because of their strong stilt root system that withstands the daily tidal flow and strong waves during periods of heavy seas (De Silva & De Silva, 2006).
These mangroves are found in estuaries and estuarine creeks, sometime it may extend several miles inland from the river mouth. In riverine mangroves the nutrient status is very high because it can accumulate organic matters from both upland and estuary. Trees grow tall and broad in the riverine mangroves.
They annually add a large amount of organic matter to the environment because of their high productivity. In the riverine mangals the salinity always varies because of the freshwater from rains and seasonal flooding during the wet season (De Silva & De Silva, 2006).
Basin mangroves develop in inland depressions, or basins, often behind fringe mangroves. They are often isolated from all but the highest tides. Flooded water can remain for a long period of time due to the topography of the area. The salinity of the soil is comparatively high and the dominant mangrove species in the basin mangroves are Avicennnia sp. (De Silva, & De Silva, 2006).
These are found in comparatively higher elevations of the coastal fringe. The plant species which constitute the dwarf mangroves are relatively small. The reason being lack of nutrients in the soil so the productivity of the plants also is very low (De Silva & De Silva, 2006). See figure 1.3
Information on mangrove species has been obtained from “Hand book of mangroves in Indonesia” (Ministry of Forestry in Indonesia, MCA, ISME,1997) and the Botany of mangroves (Tomlinson, 1994)
Description of true mangroves species are in page 14 to 55. Photographs of mangrove associates from page 57 to 63 and beach plants from 65 to 69.
Sourced from published literature