The wood of which tree found in Mangrove forests is used for making boats ?
Answers
Answer:
Mangroves are defined as assemblages of salt tolerant trees and shrubs that grow in the intertidal regions of the tropical and subtropical coastlines. They grow luxuriantly in the places where freshwater mixes with seawater and where sediment is composed of accumulated deposits of mud. Mangrove wetlands are normally classified into six types on the basis of the geophysical, geomorphological and biological factors. They are (a) river dominated, (b) tide dominated, (c) wave dominated, (d) composite river and wave dominated, (e) drowned bedrock valley mangroves and (f) mangroves in carbonate settings (Thom, 1984). The first five types of mangrove wetlands can be seen on coasts dominated by terrigenous sediments (shallow marine sediment consisting of material derived from the land surface) whereas the last one can be seen in oceanic islands, coral reefs and carbonate banks.
Mangroves of the Maldives belongs to carbonate setting type and within this broad category mangroves of the Maldives are found in four different environmental conditions: i) in the fringe area of some of the islands, where wave energy and wind speed is less and brackish water is present due to mixing of seawater with the margin of the freshwater lens, ii) in between two islands, where the water is shallow and there is accumulated deposits of sediments, iii) along the borders of lagoon that is connected to the sea, iv) along the borders of lagoon that has lost connection to the sea but receives seawater periodically through seepage and v) in shallow depressions, where rain water accumulates. Freshwater enters into all these types of mangroves through surface runoff and underground seepage. These areas normally receive limited amount of terrestrial sediment but they are rich in calcareous sediment or lime mud (marl).
Flora
Plants of mangroves are generally divided into two groups, namely, i) true or exclusive mangroves species and ii) associated mangrove species. True mangrove species grow only in mangrove environment and do not extend into terrestrial plant community and are morphologically, physiologically and reproductively adapted to saline, waterlogged and anaerobic condition. A total number of 69 species in 27 genera, belonging to 20 families are considered as true mangrove species (Duke, 1992; Bringham and Kathiresan, 2001; Selvam et al., 2004). In Maldives, a total number of 13 true mangrove species are present and fact sheet for each of these species is given in this book. Some of the plants that grow in the terrestrial environment and pure halophytes (plants that grow only in saline environment) are also found within or in the peripheral area of mangrove wetlands. These species are considered as mangrove associates.
Adaptation
Mangrove environment is highly dynamic and harsh and mangrove species are variously adapted to cope with these environmental conditions.
Breathing roots: Underground tissue of any plant requires oxygen for respiration and in mangrove environment, oxygen in soil is very limited or nil. This necessitates mangrove root system to take up oxygen from the atmosphere. For this purpose, mangrove species have specialized above ground roots called breathing roots or pneumatophores. In some species, these roots are pencil sized and peg like whereas in some other species they look like a knee. These roots have numerous pores through which oxygen enters into the underground tissues. In some plants buttress roots function as breathing roots and also provide mechanical support to the tree.
Silt roots: In some mangrove species, roots diverge from stems and branches and penetrate the soil some distance away from the main stem as in the case of banyan trees. Because of their appearance and because they provide the main physical support to these they are called as stilt roots. These roots also have many pores through which atmospheric oxygen enters into the roots.
Vivipary: Saline water, unconsolidated saline soil with little or no oxygen is not a conducive environment for seeds to germinate and establish. To overcome this, mangrove species have unique way of reproduction, which is generally known as vivipary. In this method of reproduction, seeds germinate and develop into seedlings while the seeds are still attached to the parent tree. These seedlings are normally called as propagules and they photosynthesize while still attached to the mother tree. The parent tree supplies water and necessary nutrients. They are buoyant and float in the water for sometime before rooting themselves on
Answer:
Keel and frames are traditionally made of hardwoods such as oak while planking can be oak but is more often softwood such as pine, larch or cedar. Plywood is especially popular for amateur construction but only marine ply using waterproof glues and even laminates should be used.
The Nicobarese are said to be the best boat builders. They use a variety of woods for boat building. This includes Artocarpus chaplasha, Diploknema butyracea, Lanea cormandahca, etc.