Pakistan‘s Coastal area is an arid- Sub-tropical desert. (1). the mangrove forest lies between 240 10’ and 250 37’ latitude north and 610 38’ and 680 10’ longitude east. (2).The mangroves thrive at the mouth of Indus- the sixth largest river and the Indus Delta- the fifth largest Delta. The Indus Delta is spread over 600,000 hectares along the southern Arabian Sea Coast in Sindh. Out of these 260,000 hectares are covered with mangroves mainly in the Indus Delta swamps. (1).
Sindh Coastal region is located in the southeastern part of the country between the Indus border along the Sir creek on the east, and the Hub River along the Baluchistan Coast on the west. The Coastal region is about 350 Km long and can be divided into Indus delta/creek and Karachi Coast (3).
Ahmed (1951) divides the Coastal area of Pakistan into two regions. Lower Sindh Coast and Makran-Lasbella Coast. Annual rainfall decrease from 220 mm to around 25 mm from west to east. The eastern part of the Coast receives summer rain while the western part receives winter rain .The mean annual temperature range from 32-40 C0, while extreme maximum values reaching as high as 50 C0 .(5)Wind travel 7.5 to 20.5 Km/h during summer but in June it goes up to 130 Km/h (2).
A study conducted by National Institute of Oceanography (NIO) pointed out that sea-level along the Coast of Pakistan has been rising approximately 1.2 mm per year (6).Its soil is alluvium with plenty of clay. Soil contains sodium chloride, sodium carbonate, and nitrate, some calcium, which comes from shell fragments. The sub soil water table to the sea, which is from 1.5 to 3.0 m deep with the water being completely brackish. The estuary plains cover about two-third of the surface area. (2). Estuary is a partly enclosed Coastal body of brackish water with one or more rivers or streams flow into it, and with a free connection to the open sea (7). Saline estuary soil has a pH. 8.0-8.2 and the organic matter content is less than one percent.
Mangroves vegetation is characteristically present in river estuaries and along the coast, where the land meets the sea. They are salt tolerant trees (2). About 80 species of mangrove tree/shrubs are recognized, of which around 50-60 species make a significant contribution to the structure of forests. Diversity of species is much higher in the Southeast Asian region, where approximately two-third of all species are found.
According to Flora of Pakistan (1972) eight species of mangroves have been reported from Pakistan.
At present there are four mangroves species found in Indus delta. These are as under:
1. Avicennia marina. - About 90%.
2. Rhizophora mucronata- about 08%.
3. Aegiceras Corniculatum- about 1.5%.
4. Ceriops tagal- about 0.5%.
Today Indus Delta mangrove forest has become monoculture. According to Flora of Pakistan eight species of plants have been reported along the Coast of Pakistan, out of which four species have completely disappeared, three species are at the verge of extinction and only one specie Avicennia marina is survived in Indus delta (8).
Avicennia marina occupies about 99.9% of total forest area (Qureshi, 1991, 1995), the dominance is due to its resistance against adverse environmental conditions (including habit, hydrology and climate) .(2). Currently three sub-species of Avivennia are recognized. These are as under.
• Avicennia marina sub-sp. Australasica.
• Avicennia marina sub-sp. Eucalyptifolia
• Avicennia marina sub-sp. Marina.
Avicennia marina commonly known as grey mangrove or white mangrove .Is specie of mangrove tree classified in the plant family Acanthaceae (formally in the Verbenaceae or Avicenniaceae). It occurs in the intertidal zone of the estuarine area. It distributed along Africa’s east Coast, South and South east Asia and Australia. It has aerial roots (pneumatophores), which grow to a height of 20 centimeters and diameter of one centimeter. This allows the plant to absorb oxygen, which is deficient in its habitat. These roots also anchor the plant during the frequent inundation of seawater in the soft substrate of tidal system. (9).
It thrives to achieve its full height in water, where both salt and fresh water are present. The species can tolerate high salinity by excreting salts through its leaves (10).It can found in a soil pH. 6.5-8.0. The mangroves play a major role in the coastal eco-system. These are as under:
• As a pod of diversity they support diverse form of plants and animal life.
• Provide food, shelter and breeding ground for prawns, shrimps, fish, crabs and other marine life. Annual export earning of US $4 billions.
• Reduce wave action and helps stabilizing Coastal line.
• Assimilate swage water waste and heavy metals from industrial plants.
• Protect sea-port from cyclone and reduce the intensity of cyclone.
• Provide livelihood to local population living along the Coast line.
• Source of wood for heating, cooking and fodder for livestock.
• Provide shelter to migratory birds during winter (11)
The following information’s are extracted from prof.K.Kathiresan research paper:
• Mangroves have high calorific value, hence more energy one ton of mangrove firewood can provide energy equivalent to five tons of Indian charcoal.
• The high amounts of tannin in mangrove wood make its timber more durable for furniture market.
• The mangrove leaves are used in mats, baskets and roof making.
• Mangroves attract honey bees and helps in apiculture activities.
• Mangroves especially Avicennia form cheap and nutritive feed for buffalos, sheep, goats and camels.
• Mangroves extracts are used in indigenous medicine for example Brugiera species (leaves) are used for reducing Excoecaria agallaocha for the treatment of leprosy and epilepsy.
• Avicennia marina (Avicenniaceae) is a species of mangroves tree used for treatment of small pox lesions in Persian folk medicine (12).
• Mangroves helps in protecting the Coast from solar UV-B radiation “green house” effect, and fury of cyclone, flood, sea level rise, wave action and Coastal erosion.
• Mangrove swamps act as a trap for sediments and sink for nutrients. The root system of the plant keeps the substrate firm and thus contributes to a lasting stability of the Coast.
• The mangrove systems minimize the action of waves and thus prevent the Coast from erosion.
• Mangrove ecosystem produces large amounts of litter in the form of falling leaves, branches and other debris decomposition of the litter contribute to the production of dissolve organic matter (DOM) and the recycling of nutrients this helps in catalyzing agricultural activity.
But the rate of erosion of mangrove forest found near KetiBander was about 1.5 feet per day and from 1960’s to 1980’s the mangrove cover area has reduced from 604,870 hectare to 104,000 hectares (13).Coastal area are vulnerable for two reasons: firstly rise in sea level and secondly increased frequency and intensity of cyclones(6).
Reductions in inflow of fresh water from Indus on account of diversion of water for other purposes, inflow of pollutants from industries, navigational activities and intermix of industrial effluents.
Human and livestock population pressure for fuel wood and fodder collection have exposed this complex ecosystem to serve environmental and social stress in the form of loss of habitat and biodiversity, decline in fish productivity these brings social and economic problems for the Coastal communities (11).
Conclusion
Mangroves are the backbone of the Coastal communities. The economy and livelihood of these communities can be improved by imitating more schemes of rehabilitations of ecological system along the Coastline through plantations of mangroves, and start various schemes for training them in income generation activities, health care, environmental management skill, organizational leadership’s and skill development.
We can improve infrastructure by opening new schools, roads, drinking water supply, flood protection structure and water harvesting structures also provide safety against flood. This way we can control the further degradation of the Coastal area and manage its biological diversity (14).
References
1. Pkissan-news channel- The species that survive in mangroves. Monday. December 12,2005 by Dr.S.M.Alam
2. wateerinfo.net.pk- Mangroves of Pakistan, status and management IUCN.Pakistan.2005
3. Foreverindus.org. Indus Eco region Programme. Coastal area.
4. Salt tolerant plants of Costal. Sabkhat of Pakistan by M. Ajmal Khan and Bilquces Gul; Department of botany, university of Karachi.75270. Pakistan
5. Ahmed, K.S.1951. Climate region of Pakistan, Geography. Review. 6:1-35.
6. Risk to coastal communities by climate change highlighted by Faiza Ilyas. Date.11.4.2014. DAWN Newspaper.
7. Wikipedia. Google dictionary.
8. Official website Forest department government of Sindh.
9. Wikipedia.org-Avicennia marina.
10. Rippey, Elizabeth; Rowland (Reinette), Barbara (2004), 1995. Coastal plants; Perth and South. west region ( 2nd edition).Perth, UWA Press. ISBN. 1-920694-05-6.
11. Degradation of Indus delta mangroves in Pakistan by Amjad. A.Shah; Kasawani, I, and Kamaruzaman, J. Forest Geospatial Information and Survey Lab.Lebuh Silikon; Faculty of Forestry, university of Putra. Malaysia. UPM-43400, Serdang, Selangor. Malaysia.
12. Inhibitory activity of Avicennia marina, a medicinal plant in Persian folk medicine against HIV and HS by Rahele Namzi, Revan Zabiholahi, Mandana Behahani and Abbas Rezaei.
13. Mangrove Forest in Sindh (Kumailcraft.blog.spot.com). A national conference on mangrove eco-system, some fact.
14. Tribune.com.pk. Sindh coastal community: ADB full of praise for US$ 33m development project by Shahbaz Rana published 9th April 2014.