Bio SBA
Adaptation of mangrove plants to the habitat
Introduction
Mangroves are the habitat that the saline coastal habitats grow
with tree and shrubs. They are most common found in the tropics and
subtropics and also marks the transition between the sea , the estuary
and the land. Therefore most of the mangroves are in the brackish
water region and the salinity is relatively higher than the inland. The
tides in mangroves not only give a gentle gradient to the mangroves
but also affect the humidity of the soils periodically. Furthermore the
aerobic and anaerobic condition of the soil are also affected.
Unique abiotic factors
Mangroves are usually found in sheltered embayments. The trees must be able to withstand being submerged twice a day by tidal saltwater. Evaporation during the inter tidal period can cause the salinity of the water to rise well above that of seawater. During periods of rain the mangroves at low tide are exposed to salinity levels approaching that of freshwater. The soil that the mangroves grow in may be sand but is often a rich mud high in nutrients but lacking in oxygen (anaerobic).
This mud is responsible for the smell often associated with mangrove swamps. Mangroves have specially adapted aerial and salt filtering roots and salt excreting leaves that enable them to occupy the fluctuating wetlands that other plants cannot occupy.
The Term Paper on Different Types of Soils in India
1. Black soils The principal region of black soils is the Deccan plateau and its periphery extending from 8°45’to 26o north latitude and 68o to 83o45′ east longitude. They are formed from Deccan basalt trap rocks and occur in areas under the monsoon climate, mostly of semi-arid and sub-humid types. The overall climate of black soil region may be described as hot and dry summer, 40-100 ...
Soils
Mangrove vegetation can establish and grow on a variety of soil types. Soils are made up of sand, silt and clay in different combinations rich in organic matter. These soils are usually saline, poorly drained and anoxic.
Wave Energy
Mangrove vegetation cannot develop on exposed coasts where excessive wave energy or current action constantly moves sediment which precludes the establishment of seedlings. Protected bays, lagoons and estuaries are the most suitable localities.
Salinity
Mangroves grow best when the water is saline. Although mangroves exist in a saline environment, they depend on fresh water to maintain an optimum salinity balance and for the supply of additional inorganic nutrients that are present in terrestrial run-off.
Soil Type
Fertility and texture of the soil must be of sufficient quality to allow for the growth of vegetation communities and adequate soil drainage respectively.
Soil Drainage
Natural water movement through the mangrove wetland, whether tidal or rainwater run-off, has a great effect on modifying soil salinity, temperature and aeration.
Adaptive features
The muddy shore consists of the very unstable soft substratum with high salinity and anaerobic soil brought by the tidal action
Due to this situation, mangroves have different adaptive features to compromise it
Many mangrove plants have salt glands on their leaves to remove the excess salts and the waxy cuticle to prevent excessive water loss
As the soil is usually waterlogged and under the anaerobic conditions many mangrove plants have aerial roots called Pneumatophores growing out of water from the cable roots for gas exchange with air
The Essay on Mangroves Fresh Water
... mangroves also face common problems of water-logged, unstable and oxygen deficient soils. Despite belonging to many different families mangrove plants ... emerged mud banks, putting up its distinctive peg roots. Mangrove apple Sonneratia alba often grows in this zone ... water. Apart from suddenly altering the salinity levels, these fluctuations in water can alter temperatures as well. Different mangrove ...
Some mangrove plants have prop plants and buttress roots to give better support on the soft mud and give additional surface to get oxygen from air for the roots
The cable root runs horizontally under the soil surface to give better anchorage to the plant
Unique reproductive method
In order to enhance success in seedling development, Kandlia
Obovata produce seeds that germinate inside the fruits. The fruits are
called Droppers. When the droppers detach from the plants, the roots
are already in the early stage of development, and can establish
themselves rapidly in the substratum. The droppers have fleshy
structures called Hypocotyls, which help them to float and disperse.
They are carried by water until they reach a position where the water
is shallow enough for the roots to come in contact with the substratum
Ecological significance
Mangrove forests are among the productive terrestrial ecosystem and natural and are a renewable resource. Mangroves are not a marvel just for their adaptations but also for the significant role they play in our environment.
Mangroves are a source of a vast range of wood and non-wood forest products including fuel wood, charcoal, fodder, honey, medicine etc.
The ecosystem has a very large unexplored potential for natural products useful for medicinal purposes and also for salt production , fisheries products fuel and fodder, etc
Mangroves protect the coast against erosion due to wind, waves, water currents and protect coral reefs, sea-grass bed and shipping lanes against siltation. They are also known to absorb pollutants.
Mangroves host a number of threatened or endangered species, different animal species- mammals ,reptiles, amphibian and bird- offer nutrients to the marine food web and provide spawning grounds to a variety of fish and shellfish, including several commercial species
