4.0  ECOLOGICAL ASSESSMENT

                                                     

4.1       GENERAL FEATURES OF THE STUDY AREA

            The major portion of the area is represented by agricultural land.  The area generally is a flat terrain traversed by some important meandering rivers.  On the eastern side of the study area flows the river Aie in the south east direction.  The western boundaries of the study area have major tributaries of the river Brahmaputra. The entire study area is well drained by these rivers and their smaller tributaries - Tunia and Kujia.  A few offshoots of the Assam ranges stand out as conspicuous hillocks above the alluvium.  Nakkatti, Bhumeshwar and Kakoijana are important hillocks within the 20km radial zone.  These hillocks generally range in height from 122m to 212m above mean sea level.  A very small part of the study area (less than 5 percent of land) represent the Reserved Forest area.

 

4.2       FORESTS OF THE STUDY AREA

            Forest within the study area are represented by the Reserved Forests patches.  The details of the different Reserved Forests patches which fall within the study area are provided in Table 5 below.

 

Table 5.         Reserved Forest areas represented in 10km radial zone.

S.No.	Reserved Forests within 10km radial zone	Total area of RF (km2)	Area within the study zone (km2)	% area within   the study zone
1	Bhumeshwar Reserved Forest (proposed )	3.07	0.87	28.4%
2	Nakatti Reserved Forest	7.46	0.87	11.71%
3	Kakoijana Reserved Forest	3.22	0.35	10.78%

  

            All the Reserved Forests listed above are the part of Aie Valley Forest Division and are the part of sub mountain tract known as the Bhabhar area.  The soil over most of the Bhabhar area is dry sandy loam superimposed on beds of pebbles with very thin layer of humus.

 

4.2.1   Vegetation

            Vegetation of the study area is categorised as Eastern Terai Sal type 3C/C_1c as per the classification of Champion & Seth (1968).  As the name suggests, it is a Sal bearing zone in the Terai belt.  The floristics of the zone as per Champion & Seth (1968) is briefly described below.

 

i.      Shorea robusta, Terminalia bellerica, Stereospurmum personatum, Schima wallichi, Albizzia spp., Cedrela toona, Syzygium cumini.

ii.     Dillenia pentagyna, Careya arborea, Callicarpa arborea, Premna spp., Spondias spp.

iii.    Murraya exotica, Trema orientalis, Leea aculeata, Coffea bengalensis, Clerodendrum infortunatum, Morinda augustifolia, Solanum indicum.

iv. a. Alpinia allughas, Flemingia strobilifera, Laportea crenulate, Culesume montana.

iv. b. Microstegium ciliatum.

v.      Spatholobus roxburghii, Acacia pennata.

 

4.3       TERRESTRIAL HABITATS

            Aie Valley Forest Division supports diverse wildlife species and an equally diverse habitat.  The list of faunal species of Aie Valley Division is appended as Appendix - II.  It is evident from Appendix - II that the Division has been a home for large number of faunal species including highly endangered species represented from several faunal groups.  The Reserved forest area within the study area has some of the representative habitats for animals listed in the Appendix - II.  During the course of survey however not many species of terrestrial wild animals could be sighted.  Heavy biotic interference, incidences of fire and political insurgency in the area have had widespread implications on the overall integrity of the ecosystem.  Poor regeneration of sal and associate species and grazing pressure have led to the decline of the habitat potential of these Reserved Forest patch in general.  Extremely low siting of the animals during the field work could also be attributed to very small areas of forest actually falling within the study area that has been surveyed during the course of study.

            Moist deciduous forest make up ideal habitat for many wildlife species.  Reserved Forests of Kakoijana, Nakatti hills and Bhumeshwar hills form important habitats for many forest dwelling species including Golden langur (Trachypithecus geei), Pangolin (Manis crassicaudata), Python (Python molurus molurus), Barking deer (Muntiacus muntjak), Hog deer (Axis porcinus), Wild boar (Sus scrofa) and species of primates, tortoise and turtles.  The Kakoijana Reserved Forest has a special significance as a wildlife habitat as it has been the only forest patch within the study zone to harbour troops of Golden langur (Trachypithecus geei) (Plate 1).  At least 5 troops of Golden langur (Trachypithecus geei) are reported from this area (Srivastava, 1996).  The state of Assam has 10 of the 15 species of primates found in India.  Golden langur (Trachypithecus geei) is one of the nine primates that are endangered.  This Reserved Forest is the only habitat for this species outside its range of reported distribution in Manas Tiger Reserve and Reserved Forests of Kokrajhar district (Choudhary, 1989 and Srivastava, 1996).  The potential of this small patch of isolated Reserved Forests to provide the habitat requisites for Golden langur (Trachypithecus geei) has fairly enhanced the ecological significance of this area.

 

Plate 1. Golden Langur (Trachypithecus geei) in Kalkaijana Reserved Forest

 

4.4       STATUS OF WETLAND HABITATS

            The wetlands within the study zone support a fairly diverse aquatic fauna.  Aie river is the only major water body and occupies most of the northern part of the study area.  The river is an ideal habitat for varied avifaunal species.  Some of the species reported from the river during Asian water fowl census in the year 1996 are Indian shag, Little cormorant, Rudy shelduck, Spot billed duck, Goosander, Little tinged plover, Common sand piper and Temmincks stint and Osprey.  The riverine habitat of the Aie river has been greatly threatened by fishing and hunting.

 

            Several large and small waterbodies (lakes and ponds) locally known as beels within the study support diverse species of migratory water fowl.  Species of birds sighted during the survey are listed in Table 6.

 

Table 6.         Bird species sighted during the field visit.

 

S.No.	Name of the wetland	Bird species sighted
1	Aie river	Rudy shelduck, Little cormorant, Great grebe, Spot billed duck, White heron, Cattle egret, Lesser whistling teal, Small blue kingfisher, Indian shag, Skylark, Goosander, Yellow headed wagtail, Mallard.
2	Tunia river	Common shelduck, Dove spp., Cattle egret.
3	Kujia river	Little cormorant, Cattle egret, Pond heron.
4	Naodora lake	Little adjutant stork, Dove spp., Common shelduck.
5	Kasorani lake	Little cormorant, White breasted kingfisher, Cattle egret, Lesser whistling teal.
6	Paropota lake	Cattle egret, Little cormorant.
7	Bhosamari lake	Brown winged jacana, Pond heron, Open billed stork, Little cormorant, Lesser whistling teal, Cattle egret, White breasted kingfisher, Small blue kingfisher.

           

            Nature's Foster, a local NGO based at Bongaigaon has reported 156 species of birds from different wetlands in the Bongaigaon district (Appendix - III).  This exhaustive list of species is a reflection of richness of bird life in this area.  Our own observations during February, 1996 provide convincing evidences of the areas rich avian diversity.