Land degradation in BD

1. Land Degradation
Degradation of land refers to loss of its potential production capability as a result of degradation
of soil quality and also its loss for effective use. In Bangladesh, the topsoil degrades due to
natural processes and human activities. The functional capabilities of soil deteriorate from
activities related to agriculture, forestry, and industry. Natural events such as cyclones and floods
cause land loss, and can also deteriorate functional capabilities of soil.
In 45% of Net Cultivable Area (NCA) in Bangladesh the presence of organic metal is less than
1.1% & in 17% land organic metal contents are 3.5% which can be called High Quality Land in
1999. Based on agricultural sustainability Degraded lands are categorized as Light, Moderate,
High.
Light
The terrain has somewhat reduced agricultural suitability, but is suitable for use in local farming
systems. Restoration to full productivity is possible through modification of the management
system. Original biotic functions are still largely intact. Production loss is 5-10%
Moderate
The terrain has greatly reduced agricultural productivity, but is still suitable for use in local
farming systems. Major improvements are required to restore productivity. Original biotic
functions are partially destroyed. Production loss is 20-25%.
High
When the production loss is more than the percentage of moderate level these are highly
degraded land. Major equipments are required for terrain restoration. Original biotic functions
are largely destroyed. Specialists can find a remedy for this problem.
Process of land degradation
1. Human interference
Improper Cultivation in Hill Slopes, Terrace Land and Piedmont Plains
Jhum cultivation in the greater Chittagong Hill Tracts is a slash-and-burn process where a certain
area is cleared and cultivated for 1-2 years, and then abandoned for 5-12 years until the natural
fertility of the soil is regained to a useful economic level. Due to increase in the number of
population in the CHT region there is a demand on agricultural production, which is putting
pressure on cultivable land and the soil is loosing its fertility. Clearing of natural vegetation for
cultivation of pineapple, ginger and turmeric along the slopes increases soil erosion in Sylhet and
in the hilly areas of Chittagong. These lands after 5-7 years of cultivation totally degrade to an
almost irreversible state and become practically unfit for further generations. Rubber plantations
on more than 70 per cent of the slopes of Sylhet and Chittagong hills, leads to severe landslides
during the heavy monsoon period.
Faulty Irrigation
As a result of continuous irrigation, the land remains inundated in most of the seasons, which
keeps an adverse effect on soils because of continued oxygen deprivation in the sub-soils.

2. Chemical changes of soil material forming toxic compounds for plants and constant percolation
loss of essential nutrient elements including micronutrients and organic matter.
Unplanned Rural Infrastructure (Road, Embankment, FCD/I)
The rural roadways of the country have been constructed under Upazila or District programs
through Upazila or Union Parishads (local level government). Therefore, the road alignment was
subject to the influence of local politicians and influential people. A noteworthy feature of this
alignment is that it follows the boundaries separating agricultural lands, rather than cutting
through them. As a result, the actual length of the roads is often much longer than needed.
Urbanization
The present process of urbanization in Bangladesh invariably reduces the amount of good
agricultural land. Dhaka city has been growing at the expense of what were dense jackfruit and
mango orchards in Savar, Gulshan, Banani and Uttara areas. The expansion of Khulna is
reducing the coconut plantations of Phultala and Abhayanagar. These lands were not only good
for horticulture, but also for Aus, Transplanted Aman, ugarcane and all kinds of dry land crops.
The rapid urban growth of the past two decades has mainly affected potentially triple croppable
highlands.
Improper Use of Pesticides
Although pesticides are used at low levels still they are a cause of land degradation. Insecticide
accounts for about 90 per cent of the total consumed pesticide, and are used most for cultivating
vegetables and Rabi crops. The pesticides sprayed over standing crops ultimately contaminate
the surrounding soil. Research findings show that pesticides applied at the rate of about one
kilogram per hectare contaminates the topsoil to a depth of about 30 cm. The pesticides not only
destroy harmful insects, but also destroy useful topsoil microbes, which eventually reduce the
biological nutrient replenishment of the soil.
Brickfields and Biomass Use
Brick kilns are mostly situated on good agricultural land as brick manufacture needs silty clay
loam to silty clay soils with good drainage conditions, which is turning good agricultural land
into unproductive lands. Over 50 per cent of the energy used for firing bricks comes from
biomass.
Unplanned Industrial Development
Unplanned industrial development is of concern because it often encroaches on fertile land, and
industrial effluents not only deteriorate the quality of soils but also affect fisheries & cause
serious harm to crops. The rivers Sitalakhya, Buriganga, Karnaphuli and their banks are some of
the many examples. Vast effluent discharge by ships has been identified as a major cause of

3. pollution in the Passur river downstream of Mongla port. This has affected both forest and
coastal lands in the Sunderbans.
Mining of Sand and Gravels from Agricultural Land
Mining of sand from agricultural land is common along the eastern side of the Dhaka-Chittagong
road, from Comilla to near Sitakunda, and in the northern piedmont areas of northern Netrokona
District. Farmers tend to enjoy the immediate monetary benefit and lease out their land for
extracting sand, which is used in glass manufacturing industries or as building material. 2-3 feet
of topsoil are removed from the land and dumped anywhere available near the site. The damage
is two fold - the land purchased for dumping topsoil is used unproductively, and the land from
where sand is extracted remains unutilized for many years.
2. Water borne activities
Riverbank Erosion and Sedimentation
The active floodplains of the Ganges, the Brahmaputra- Jamuna, the Tista and the Meghna
rivers are most susceptible to riverbank erosion. The unique geographic setting, the behavior of
an alluvial channel, together with characteristics of the tropical monsoon climate, is mainly
responsible for these ravages. An enormous volume of water comes from the melting of ice in
the Himalayan range. Besides Human activities both irrational use of forest and other natural
resources, cause further deterioration of the situation & producing devastating floods, which
cause bank erosion and sedimentation.
Deposition of Sandy Over-wash on Agricultural Land
Deposition of sandy materials on agricultural land is frequent in the lower part of the piedmont
areas of greater Mymensingh and valleys of Sylhet and Chittagong Hill Tracts. During the
monsoon season, when heavy rainfall occurs in the upper hill areas, it causes flash floods in the
lower plains. With the runoff, the water carries sandy sediments that spread over agricultural
lands. Deposits of sandy materials go up to even a few meters, which compels farmers to
abandon such land for agriculture purposes.
Salinity
Salinity in the coastal areas developed due to continuous accumulation of salt from tidal flooding
and salt removal by leaching or washing by rain or inadequate freshwater flushing. Total salt
affected area of the coastal area is 0.83 million hectares.
Biodiversity

4. Biological diversity is the diversity of all life forms on earth including the various graces and
species of all microbes, plants and animals, the genetic differences i.e, the gene pool of each
species.
Biological Diversity means the variability among living organisms from all sources including,
inter alia, terrestrial, marine and other aquatic ecosystems, and the ecological complexes of
which they are part; it includes diversity within species between species, and of ecosystems.
Bangladesh is a transitional zone of flora and fauna, because of its geographical settings and
climatic characteristics. Bangladesh’s inland water bodies are known to be the habitat of 266
species of indigenous fish, 13 exotic fish, 56 prawns, about 26 freshwater molluscs, and 150
birds. The marine water bodies (200 nautical miles along the coast) are also remarkable for being
habitat of 442 species of fish. According to the Red List of IUCN, there are 54 species of inland
fishes, 8 amphibians, 58 reptiles, 41 resident birds, and 40 mammals, which are threatened
throughout the country.
Under the management of the Forest Department, the three main types of forest are hill forest,
plain-land forest, and mangrove forest.
Hill forest biodiversity
The total area of hill forest is 670,000 hectares, which is 4.54 per cent of total land area of the
country. The hill forests have been broadly classified as tropical wet-evergreen forest, and
tropical semi-evergreen forest. Under hill forests the following types of forests are found:
Reserved Forests (RF)
Unclassified State Forests (USF)
The most important commercial timber species of the CHT are Jarul, Gamari (Gmelina arborea),
Garjan, Chaplaish, Toon (Cedrella microcarpa), Koroi (Albizia procera), Civit, Champa
(Michelia champaca), Shimul (Salmalia insignis) & Chandul.
Types of Forest
1. Hill Forest
Reserved Forest
Unclassified State Forest
2. Plain-land Forest
Deciduous Forest
Village Forest
3 Mangrove Forest
Sundarban Natural Forest
Coastal Afforestation
4. Social Forest
5. Tea Gardens
Table 3.4.6 Types of Forest in Bangladesh
Source: Department of Forest, Bangladesh

5. Mangrove forest biodiversity
The mangrove forests serve as a natural fence against cyclonic storms and tidal surges, stabilize
coastlines, enhance land accretion, and enrich soil near the aquatic environment. The mangrove
forest of Sundarban is very rich in biodiversity and supports 334 species of plants, 400 fish, and
42 species of mammals. It is also the largest honey-producing habitat in the country & the best
tree for producing honey in the Sundarbans is Khulshi. The Sunderbans is the only remaining
habitat of the famous Royal Bengal Tiger (Panthera tigris), and estuarine crocodiles (Crocodylus
porosus) occur extensively in the rivers. Out of 26 species of mangroves, the two dominant ones
are the Sundari (Heritiera fomes) and Gewa (Excoecaria agallocha). Another mangrove forest at
Chokoria Mangroves in Cox’s Bazar has been destroyed mainly due to uncontrolled logging,
agricultural expansion, and shrimp culture.
Wetland biodiversity in the Haor Basin
About 50 per cent or more of the land surface of Bangladesh is wetland, consisting of about 700
rivers, creeks, streams, and other water bodies known locally as haor, baor, beel and khal. The
northeast region of Bangladesh, comprising the flood plains of the Meghna tributaries known as
the Haor Basin. This basin comprises an area of about 17.5 per cent of the area of Bangladesh.
The haors are depressions located between two or more rivers, and function as small internal
drainage basins. The Haor Basin alone produces a remarkable quantity of freshwater fish, and
each haor acts as a fish sanctuary for several indigenous fish species.
Coastal biodiversity
Bangladesh has the world’s longest beach (710 km) along the Bay of Bengal, filled with a rich
and unique coastal biodiversity. It has a great natural ecosystem value in terms of scientific
interest, and because of its outstanding aesthetic value.
 St. Martin’s Island
The southern-most offshore island, St. Martin’s is a small and beautiful coral island located in
the Bay of Bengal. The coastal area of St. Martin's is fringed with intertidal rocks that support a
diverse coral community. About 66 species of corals from 22 genera have been identified at St.
Martin’s Island.
 Nijhum Dweep
Nijhum Dweep is located at the confluence of Meghna estuary on the Bay of Bengal is the
habitat for waterfowl, migratory shore birds, and a large number of reptiles and mammals.
Causes of loss of biodiversity
 Destruction of habitat
 Overexploitation of flora and fauna
 Indiscriminate use of agro-chemicals

6.  Industrial waste disposal.
 Oil spills
 Encroachment into the natural forests
 Change in land use pattern and land use conflict.
 Water pollution
 Air pollution
 Both flora and fauna are threatened by the loss of habitat resulting from increasing human
populations, and unwise bio-resource utilization.
 Increasing demand for timber and fuel-wood, encroachment for other purposes, and Jhum
(shifting) cultivation in the hilly districts, might be the aggravating factors in the annual
rate of deforestation and degradation.
 The unplanned rapid urbanization and industrialization are leading to waste and pollution
problems that affect natural ecosystems. As the land and water-based ecosystems are
environmentally compromised, the flora and fauna populations are being seriously
affected.
 Wildlife species have become extinct in Bangladesh, and many more are threatened.
Most of the economically important local plants, medicinal plants, etc., are also under
equally great pressure, and are likely to be lost due to habitat destruction, and
unsustainable harvesting.