Abstract: Indian east coast in West Bengal, Orissa, Andhra Pradesh, Tamil Nadu
and the Andaman and Nicobar islands supports various types of mangrove
formations such as deltaic, estuarine, backwater and sheltered, insular bay
types. The present study is an effort to collect ecological information on
zonation of mangrove species based on phytosociological methods at four forest
sites in Mangrove Ecosystems of Orissa coast. A total of 16 species were
recorded at Thakurdia site, 20 tree species at Dangmal site, 24 tree species at
the Bhitarkanika forest site and 17 tree species at Kakranasi forest site. The
Bhitarkanika site has the highest number of species among all the four study
sites. This block along with Dangmal is in the core area of the Bhitarkanika
wildlife sanctuary. Availability of fresh water through Bhitarkanika (Maipura)
and Brahmani rivers and saline water from sea help wide range of niches for
different species to occur and, thus, species diversity is the highest in this
mangrove ecosystem. A clear zonation pattern so characteristically reported by
authors from different mangrove forests of world is absent in the study area.
The mangrove species in study area occur as 'ecological
mosaics' scattered over the forest blocks. Such mosaic formations
could be linked to the very dynamic nature of the forest blocks in the study
area with ecological functions such as tidal inundation, seed/propagule
dispersal etc. operating equally throughout the area. Rhizophora and Kandelia
species which are characteristic of the riverbank vegetation were seen deep
inside the forest blocks, thus adapting to different type of niches. The
riverbank-like niche is provided by innumerable creeks that criss cross the
forest blocks and thus favouring these species that grow on the banks. Based on
these habitat types a new classification of mangrove forest types of
Bhitarkanika forest ecosystem has been proposed through present study.
