Afforestation: Cultivating plants (mangroves) in an area where no plants (mangroves) grew previously
Air layering: A form of vegetative propagation where a branch is stimulated to form roots while still on the parent plant by removing part of the bark and keeping the area moist
Cotyledon: Leaf forming part of embryo or newly emerged seedling
Ecosystem: Part of the environment that can be recognized with geographical margins due to the characteristic plants and animals that live in them and perform functions as a result of the interactions among its components, both biotic and abiotic
Habitat: Physical space in which an animal or a plant lives
Hypocotyl: The prominent green or greenish brown part of the germinating seed (viviparous) that will give rise to roots at its pointed end.
Inter-tidal zone: Area between land and sea that is flooded during high tide and exposes during low tide
Mangrove associates: Plant species that are found to occur in mangrove as well as in other wetlands, particularly in freshwater marshes
Propagules: Partially germinated seeds with characteristic presence of the hypocotyls, any seed, fruit or other portion of a plant which is able to produce a new plant
Pneumatophores: Roots that grow out of the soil and maintain air passage with the underground root during high tide or breathing roots
Reforestation: Cultivation of mangroves in a deforested mangrove area
Sapling: A young tree
Seedling: A very young plant grown from a seed
Stem cutting: A cut branch of a tree, 12 - 15 cm long with 3 -5 or more nodes, used for vegetative propagation
Stomata: Pores on a plant leaf surface through which water is lost through transpiration
Supra-tidal: Areas that lie immediately above the highest tidal flood level
Transpiration: Water loss through stomata in a plant
True mangrove species: Mangrove species that occur exclusively in the inter-tidal areas or typical mangrove areas
Viviparity: Germination of seeds while it is attached on to the parent tree
Wildlings: A transplanted seedling/ sapling
What are mangroves?
Mangroves are a salt-tolerant group of tropical plants that occupy the inter-tidal zones of the sheltered coasts such as estuaries and lagoons. They are variously adapted to cope with the unfavourable environmental conditions for growth and reproduction resultant by inundation with salt water, unstable soils due to tidal flow and lack of freshwater
Why are they unique?
Breathing roots: Most mangroves have unusual structures to provide them with air during the high tide that they get flooded with salt water. Roots are usually developed towards earth but some mangroves have roots coming out of soil and grow into air to remain above the tide levels so that the connection between the submerged part of the root system and the atmosphere is maintained and a continuous supply of air is received by them even when flooded. These abnormal breathing roots are adaptations characteristic to mangroves.
Salt glands: Some other mangroves have devices to exclude salt from their leaves so that salt will not affect their health. Some can exclude salt in water from their roots while some others store them in their leaves (vacuoles) and shed them periodically
Storage of water: Freshwater is precious in a saline environment and it is stored in mangrove leaves and hence they are fleshy. Freshwater in the plant is lost through pores (stomata) in the leaves and some have relatively a few pores and some others have them covers with hairs so that less water is lost through them. Most leaves have shiny, waxy surfaces to reflect sun rays so that the leaf temperature is kept low and the water loss is reduced. This layer also protects water in the leaf through reducing transpiration
Viviparity: Inter-tidal areas are not at all favourable for seed germination as there is no freshwater and a suitable place to anchor themselves. This problem is evaded by having an unusual method of seed germination called viviparity, where seeds start germinating while they are still attached to the parent plant, a condition that allows the seeds to obtain freshwater from the parent plant and evade saline environment that is unsuitable for seed germination.
Prop/ stilt roots: The problem of unstable soils in the mangrove areas that makes standing the plants upright is difficult is overcome by having prop and stilt roots that give extra support to the trees to be erect.