06-bioresourcesstatu.. - M. S. Swaminathan Research Foundation

Bhitarkanika
headquarters of mangrove forest division.
Rajnagar is at a distance of 130 km from
Bhubaneshwar, the state capital.The sanctuary is
interspersed with numerous rivers, creeks and
nallahs which are the distributary system of
Baitarani and Brahmani rivers.
ii. Climate
The climate is hot and humid most of the year. In
winter the temperature comes down to 10° C
minimum and in summer the maximum
temperature reaches upto 45° C. Due to the
coastal environment, humidity is also high
throughout the year, varying between 75-95%.
The variation in annual rainfall is dependent on
the monsoon. The main monsoon months are
August and September. The average annual
rainfall is 1300 mm, based on the data collected at
Dangmal Crocodile Research Centre during last 26
years. The area is prone to severe cyclonic storms
during April-June and October-November almost
every year and also there are occasional tidal
bores. During the monsoon the entire area gets
flooded with excess water from the river and
becomes a freshwater wetland. And as the water
subsides the area becomes brackish water again.
This phenomenon gives rise to luxuriant mangrove
wetlands.
iii. Soils and Topography
The deltaic mangrove swamps of Bhitarkanika
Wildlife Sanctuary area, are subjected to regular
tidal inundation, and are extremely low lying.
Mean elevation above mean sea level is between 1-
2 meters. Higher ground extends to about 3-4
meters.
The core area of the Bhitarkanika Wildlife
sanctuary is mostly formed by the alluvial filling of
the littoral zones. There is a continuous land, built
up through sedimentation and subsidence, forming
a prograding delta. The deltaic region is covered
by sediments of the flood plain deposits of subrecent
origin and Pleistocene forms.
The area is influenced by heavy alluvial silt
brought down by the rivers and deposited in
deltaic areas due to regular tidal inundation.
Chadha and Kar (1999) report eight newly
surfaced islands due to heavy siltation in the river
mouths. On northern end of the coastal section are
flat sand spits with a number of small sand dunes
about 0.5-1.0 m in height covered with the beach
vegetation typical of the area. At points, as a
178
result of the prevailing wind action the dunes are
very high, sometimes exceeding 20 m.
Due to the regular inundation through tidal action
the soil is mostly clayey loam and highly slushy.
The surface soil is composed of silt loam and
clayey loam and is about 3-4 m in depth. The soil
though well aerated, is saline, in the elevated
areas, away from the creeks and channels the soil
is more sandy and comparatively less moist and
saline. The soil pH varies from 6.3 to 7.1 . The
water is alkaline with a pH of 7.4-8.0. Table 1.
describes the soil characteristics of the
Bhitarkanika Wildlife Sanctuary (Kanvinde and
Das 1995).
Table 1 : Soil characteristics
Areas
Outer estuaries
pH Organic matter % EC IAllhos cm'
6.8
Inner estuaries
Creeks at lower elevations 6.9
Creeks at higher elevations 7.1
Transitional! hinterlands 6.3
EC:Eleclrlcal conductivity
30--12
24--9
15--6
5--1
iv. Short Summary on vegetation and animal life
The mangrove vegetation is locally known as
"Hental Jungle" as the hen tal plants (Phoenix
paludosa) predominate in many areas of the
sanctuary and are very useful plant species for
the local inhabitants. The sanctuary covers an
area of 762 sq.km. and 130 sq.km of this is
mangrove forests.
The mangroves of this sanctuary are similar to
those of the Sunderbans and are a part of the
Indo-Pacific mangal elements. The mangroves of
Bhitarkanika are the only surviving, relatively
undisturbed examples of this vegetation on the
Orissa coast.
The vegetation 'of Bhitarkanika contains the
maximum number of mangrove species in India but
2.5
3.0
3.5
4.8
Figure 1: Jlfap of Bh/larkanlka