Bangladesh has lost her last stadium size forest’- this may be a newspaper headline after few decades. The forces of over-population are invading the natural habitats, hastening the demise of the forests. During the past 40 years, close to 70 percent of the forest coverage has been cut down — more than in the whole of previous 250 years since the British colonization began. Due to high population density and sharply skewed distribution of land, the forest resources are overexploited.
Per capita forestland in the country is around 0.02 ha and the existing natural forests are decreasing at a rate varying from 2.1% /yr to 3.3% /yr. The recurrent anthropogenic disturbances in the natural forests have rendered the system inhospitable for the regeneration and growth of wild plant associates, causing a net loss of biodiversity. Like many others, the writer fears that an additional 20 percent of the trees will be lost over the next decade. If that happens, the forest ecology will begin to simply unravel.
In our country, the events set in motion by logging are almost always more destructive than the logging itself. The land sharks follow the roads deep into previously impenetrable forest, and then destroy tracts to make it look as if they own them. Encroachment, illegal logging, regeneration destruction, looping, litter sweeping, animal grazing, shifting cultivation, agroforestation, soil disturbances, over-exploitation of natural resources, people living inside the forests and the recreational activities like picnic are the main causes of massive erosion of the Sal forests. The hydro-electricity project, ethnic conflict, encroachment, jhum cultivation, land sliding, hill cutting and illegal logging are the main factors involved in the degradation of hill forests. Poverty, profit-making, over-exploitation of forest products, illegal logging, natural disaster, salinity and sedimentation cause deforestation of coastal forests.
Different studies show that all our natural forests have become critically fragmented to the point where they are considered unlikely to maintain minimum level of green biomass. On the other hand, the cities of Bangladesh have been becoming urban mayhem and losing living ambiance. The single storied residential buildings with open green spaces are fast disappearing and multistoried buildings are replacing them. With disappearing plant habitats Bangladesh is losing its ecological balance. Ensuring the long term healthy environment by using green development is a crying need for the future generations.
At least 25% forest cover is essential for maintaining biodiversity and ensuring ecological goods and services, such as clean air, clean water, carbon sequestration, and flood control. An increase in forest cover can happen through afforestation, reforestation and natural expansion of forests. Afforestation occurs when trees are planted on land that was not previously forested. Natural expansion of forests refers to an expansion of forest through natural succession onto previously non-forested lands, usually abandoned agricultural land. Reforestation occurs when trees are planted or regenerated on the sites that were previously forested. Where part of a forest is cut down but replanted (reforestation), or where the forest grows back on its own within a relatively short period (natural regeneration), there is no change in forest area. Green Bangladesh can be brought back in the following ways:
Natural succession in the denuded core zone: Following the human disturbances pioneer species like Sal, Sundori and Garjans will become established in the open areas under full sunlight. Eventually, in the absence of further disturbance, these pioneer species will be replaced by seral species that will occupy the site through a series of successional stages, leading ultimately to a plant community comprised of climax species. The denuded areas belonging to core zone of our natural forests can be reforested through natural succession. However, during the early successional stage, the natural regeneration requires protection from further anthropogenic disturbances.
Natural regeneration in the natural habitat: Natural regeneration is an effective means of regenerating the forest when conditions are right. It is usually favourable for the trees suited to the site. Effective natural regeneration from seed depends on the seed productivity and dispersal. Alternatively, some species like Sal can regenerate from suckers and shoots. Sal can be effectively regenerated naturally from shoots growing from stumps after a clearcut harvest. With natural regeneration, there is a higher probability of developing mixed stands. This may occur even when the original stand is pure. In the core and buffer zones of each forest natural regeneration should be facilitated to maintain the ecological balance and to ensure continuous forest coverage.
Direct (artificial) seeding in the peripheral zone: Direct (artificial) seeding is usually carried out from the ground on sites that have been prepared for seed germination. While it is a more expensive procedure than natural regeneration, there is a greater likelihood of establishing the desired species. Large volumes of seed (5-10 seeds for each seedling) are required for successful regeneration. Direct seeding can be applied in the buffer zone and totally degraded forest areas.
Gap filling by rare species: In forests where small-scale disturbances exist, stand dynamics are controlled by the creation of gaps due to single or multiple overstory-tree mortality. Sometimes openings are created due to illegal logging in small scale. Newly established seedlings or advance regeneration of rare or endangered species should be recruited in these openings. This will protect the rare and very rare species from extinction as well.
Woodlot plantation in the encroached forest lands: Plantation of hardwood trees to harvest for profits and environmental carbon offset is called woodlot plantation. Invasive species should be avoided for woodlot plantation as they disrupt native biodiversity. Teak, Mahogany, Jackfruit, Sissoo, Rain tree, Koroi, Rajkoroi and Chapalish can be planted in the encroached areas under the forest restoration programme.
Riparian plantation: Riparian forests are typically composed of overstorey, understorey and macrophyte species. Deep-rooted species (overstorey) are more capable of reinforcing riverbanks against mass failure than shallow rooted groundcover. Trees should be planted around potential slump-block failure planes. However, understorey and groundcover species provide mid- and upper-bank sections with greater protection from scour. Lower bank sections that tend to remain wet throughout the year are best protected by macrophyte species where they can be established. Hogla, Hanthol and Golpata can be used for the reparation plantation.
Building greenbelt in the coastal areas: The coastal areas of Bangladesh are prone to severe damage from cyclones. It has been proved that dense forest cover along the coastline is an effective protection against the impacts of cyclones. Coconut, betel nut, palm, babla and jhau tree can be planted in the entire coastal area to build up a green belt.
Embankment, roadside, and railside plantations: Rail-side land, sides of national highways and feeder roads, and river embankments should be planted native timbering and fuel wood tree species. The roadside trees are pruned twice a year and the branches are used for firewood.
Homestead and institution plantations: Old and unproductive trees in the homesteads should be replaced by new and high yielding multipurpose, fruit trees and medicinal plants. The open spaces of schools, colleges, mosques, temples, other institutions, local government offices and cyclone shelters need plantations by multipurpose trees.
Sand dune plantation: Accredited foreshore and offshore islands need to be planted for dune stabililising. Screw pine (Pandanus) can grow on sand dune and has thick ‘prop roots’ to anchor itself in the loose sand. Keora, Kakra, Gewa, Hargoza, Khalisha and Bain are the suitable species for such type of plantation as they have fast growing roots.
Tanguya plantation: It consists of growing annual agricultural crops along with forest trees during the early establishment of forest plantations on the hills. This is a method of establishing agricultural crops in temporary combination with forestation. Agricultural cropping ends with the casting of dense lateral shade or closing of the forest canopy. This system can be applied for the afforestation and reforeation programme in the hilly areas.
Urban forestation: Urban forests play an important role in maintaining congenial human habitat in many ways: they filter air, water, and sunlight, and provide shelter and recreational area for people. They are critical in cooling the urban heat island in peak summer months. In a wider sense it may include any kind of woody plant vegetation growing in and around human settlements.
This article is written by Dr. Md. Mizanur Rahman , a biodiversity specialist, is Assistant Commissioner, Jhalakathi Collectorate. E-mail: mizan_peroj @yahoo.com
The article was first published in The Daily Star, Bangladesh, the original article published on 2010.10.09.
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