626
and various urban developments. These have led
to hydrological perturbations, pollutions and
their effects. Unsustainable levels of grazing and
fi shing activities have also resulted in degradation of wetlands.
The current wetland loss rates in India could
lead to serious consequences, where c 74 % of
the human population is rural. Many of these
people are resource dependent. Most problems
pertaining to India’s wetlands are related to
human population. India contains c 16 % of the
world’s population and, yet, constitutes only c
2.42 % of the earth’s surface. The Indian landscapes have contained fewer and fewer natural
wetlands over time. Restoration of these converted wetlands is quite diffi cult once these
sites are occupied for non-wetland uses. Hence,
the demand for wetland products (e.g. water,
fi sh, wood, fi bre, medicinal plants) will increase
with increase in population. Wetland loss refers
to physical loss in the spatial extent or loss in
the wetland functions. The loss of 1 km
2 of wetlands in India will have much greater impact
than the loss of 1 km
2 of wetlands in low population areas with abundant wetlands. The wetland loss in India could be divided into two
broad groups, namely, (a) acute loss and (b)
chronic loss. The fi lling up of wet areas with
soil constitutes acute loss, while the gradual
elimination of forest cover with subsequent
erosion and sedimentation of the wetlands over
many decades is termed as chronic loss.
29.2.3.5 Introduced Species and
Extinction of Native Biota
Wetlands in India support around 2,400 species
and subspecies of birds. But losses in habitat
have threatened the diversity of the birds
(Mitchell and Gopal 1990 ). Introduced exotic
species like water hyacinth ( Eichhornia
crassipes ) and salvinia ( Salvinia molesta ) have
threatened the wetlands and clogged the waterways, competing with the native vegetation. In
a recent attempt at prioritisation of wetlands
for conservation, Samant noted that as many as
700 potential wetlands do not have any data
to prioritise. Many of these wetlands are
threatened.
29.2.4 Problems of Social Nature
These include the problems which arise out of
use of the wetland by the society, like deforestation and encroachment.
29.2.4.1 Problems with Regard
to Direct Deforestation
in Wetlands
Mangrove vegetation is fl ood and salt tolerant and
grows along the coasts and is valued for fi sh and
shellfi sh, livestock fodder, fuelwood, building
materials, local medicine, honey and bees wax
and for extracting chemicals for tanning leather
(Ahmad 1980 ). Alternative farming methods and
fi sheries production have replaced many mangrove areas and continue to pose threats. c 80 %
of India’s 4,240 km
2 of mangrove forests occur in
the Sunderbans and the Andaman and Nicobar
Islands (Government of India, 1991). But most of
the coastal mangroves are under severe pressure
due to the economic demand for shrimps.
Important ecosystem functions such as buffer
zones against storm surges, nursery grounds and
escape cover for commercially important fi sheries
are lost. The shrimp farms also cause excessive
withdrawal of freshwater and increased pollution
load on water, like increased lime, organic wastes,
pesticides, chemicals and disease-causing organisms. The greatest impacts were on the people
directly dependent on the mangroves for natural
materials, fi sh proteins and revenue. The ability of
wetlands to trap sediments and slow the fl ow of
water is reduced.
29.2.4.2 Problems with Regard
to Encroachment
Big portion of many wetlands have been
encroached by inhabitants today, thereby causing
diminution of the water spread area and other
detrimental effects.
29.2.4.3 Threats and Loss of Wetlands
Wetlands represent dynamic natural environments that are subjected to both human and natural forces. Natural events infl uencing wetlands
include rising sea level, natural succession,
hydrologic cycle, erosion and sedimentation.
29 Potentials and Problems of Wetlands
and various urban developments. These have led
to hydrological perturbations, pollutions and
their effects. Unsustainable levels of grazing and
fi shing activities have also resulted in degradation of wetlands.
The current wetland loss rates in India could
lead to serious consequences, where c 74 % of
the human population is rural. Many of these
people are resource dependent. Most problems
pertaining to India’s wetlands are related to
human population. India contains c 16 % of the
world’s population and, yet, constitutes only c
2.42 % of the earth’s surface. The Indian landscapes have contained fewer and fewer natural
wetlands over time. Restoration of these converted wetlands is quite diffi cult once these
sites are occupied for non-wetland uses. Hence,
the demand for wetland products (e.g. water,
fi sh, wood, fi bre, medicinal plants) will increase
with increase in population. Wetland loss refers
to physical loss in the spatial extent or loss in
the wetland functions. The loss of 1 km
2 of wetlands in India will have much greater impact
than the loss of 1 km
2 of wetlands in low population areas with abundant wetlands. The wetland loss in India could be divided into two
broad groups, namely, (a) acute loss and (b)
chronic loss. The fi lling up of wet areas with
soil constitutes acute loss, while the gradual
elimination of forest cover with subsequent
erosion and sedimentation of the wetlands over
many decades is termed as chronic loss.
29.2.3.5 Introduced Species and
Extinction of Native Biota
Wetlands in India support around 2,400 species
and subspecies of birds. But losses in habitat
have threatened the diversity of the birds
(Mitchell and Gopal 1990 ). Introduced exotic
species like water hyacinth ( Eichhornia
crassipes ) and salvinia ( Salvinia molesta ) have
threatened the wetlands and clogged the waterways, competing with the native vegetation. In
a recent attempt at prioritisation of wetlands
for conservation, Samant noted that as many as
700 potential wetlands do not have any data
to prioritise. Many of these wetlands are
threatened.
29.2.4 Problems of Social Nature
These include the problems which arise out of
use of the wetland by the society, like deforestation and encroachment.
29.2.4.1 Problems with Regard
to Direct Deforestation
in Wetlands
Mangrove vegetation is fl ood and salt tolerant and
grows along the coasts and is valued for fi sh and
shellfi sh, livestock fodder, fuelwood, building
materials, local medicine, honey and bees wax
and for extracting chemicals for tanning leather
(Ahmad 1980 ). Alternative farming methods and
fi sheries production have replaced many mangrove areas and continue to pose threats. c 80 %
of India’s 4,240 km
2 of mangrove forests occur in
the Sunderbans and the Andaman and Nicobar
Islands (Government of India, 1991). But most of
the coastal mangroves are under severe pressure
due to the economic demand for shrimps.
Important ecosystem functions such as buffer
zones against storm surges, nursery grounds and
escape cover for commercially important fi sheries
are lost. The shrimp farms also cause excessive
withdrawal of freshwater and increased pollution
load on water, like increased lime, organic wastes,
pesticides, chemicals and disease-causing organisms. The greatest impacts were on the people
directly dependent on the mangroves for natural
materials, fi sh proteins and revenue. The ability of
wetlands to trap sediments and slow the fl ow of
water is reduced.
29.2.4.2 Problems with Regard
to Encroachment
Big portion of many wetlands have been
encroached by inhabitants today, thereby causing
diminution of the water spread area and other
detrimental effects.
29.2.4.3 Threats and Loss of Wetlands
Wetlands represent dynamic natural environments that are subjected to both human and natural forces. Natural events infl uencing wetlands
include rising sea level, natural succession,
hydrologic cycle, erosion and sedimentation.
29 Potentials and Problems of Wetlands