GEOGRAPHIC LOCATION
Corbett Tiger Reserve (CTR), the ecosystem under study, is situated in the foothills of the Himalayas i.e. the Shiwalik range and falls within Nainital and Pauri Garhwal districts of the state of Uttarakhand. Corbett National Park (CNP), 520.82 km2, and 301.18 km2 of adjoining Sonanadi Wildlife Sanctuary along with 466.32 sq.km of buffer zone together forms 1288.32 km2 of the tiger reserve (Barthari 12). CTR lies between 290 25’ N to 290 40’ N latitudes and 78 05’E to 790 5’E longitudes (see Fig. 1).
Figure 1: Location map of Corbett Tiger Reserve.
CLIMATE
The climate of the area is characterized by distinct winter, summer and rainy season. In general it is subtropical. The annual temperature varies from a maximum of 40°C in summer to a minimum of 0°C in winter. The 95% of the rainfall is received in the rainy season extending from June to September. Long term data suggest the annual rainfall to range from 1025 mm to 1585mm. sometimes there is erratic rainfall in the winter months ranging from 0.2 mm to 425 mm. the summer months of March to May is very hot and dry (Gupta and Kumar 78). The place of the Siwalik Hills and the lesser Himalayas to the North of the Siwalik play an important role in the amount of rainfall that the region gets. They capture the moisture content from both the Arabian Sea and Bay of Bengal branch of the North-West Monsoon winds. The North-West Monsoon winds is responsible for bringing rains to the Indian subcontinent. Hot summers a result of hot winds that blow in the western part of India, from the states of Punjab, Haryana and Rajasthan which are characterized by arid and semi-arid climates.
Extreme weather events exist in this area in the form of droughts and heavy rainfall followed by floods. In the year 2013 a cloud burst high up in the Himalayas caused a high amount of discharge in the river which caused a lot of destruction in the area. Lot of areas by the rivers caved in because of river side erosion. According to Koeppen’s climatic classification this region falls under Cwg category, which signifies Mesothermal Climate (Gangetic Plain Type). It is characterized by dry cold winters and hot and dry summers. Most of Northern India is covered under this zone.
LANDFORMS AND THE LAND FORMING PROCESSES
CTR is characterized by hilly, undulating terrain with ridges and valleys and dry river beds with coarse boulders. The topography is considerably varied with hilly and riverine areas, plateaus, + marshy depressions, and ravines. A series of more or less parallel ridges (The Siwalik Hills) run from the North West to the South East decreasing in height on approaching the plains along the southern boundary. Conglomerates, sand rock, sand stone and Bhabar (a porous rock formation) deposits together contribute to the geological aspect of the park. The river Ramganga and its tributaries form the drainage pattern and are the primary source of water for the area. The reservoir formed due to the construction of the dam is 80 km2. The reservoir also proves to be a perennial source of water to the park. Kosi River flows along the eastern boundary of the park.
The Siwaliks Hills are soft and friable. The depositional composition of these hills are alluvial detritus, being mainly composed clay sand, sand rocks, poorly bedded sandstones and conglomerates, carried down by various rivers and deposited at these foothills (Wadia 101). These are mainly alluvial in character, with respect to their composition, only that they are more compact and have faced folding and faulting during the Post-Tertiary orogenic movements. This was the when the Indian landmass collided with the Asian landmass and the Himalayas were formed. Almost all of the tectonic activities in this region belong to that time.
The Siwalik Hills are highly dissected by ephemeral streams and give rise to a badland topography. Erosion coupled with deforestation under anthropogenic pressures have formed various erosional landforms like hogbacks, cuestas, rills, gullies, scarps, spurs, sharp ridges etc. (Singh 25). Longitudinal and transverse folds can be seen in the area, and constitute the main structural characteristics of the region. Towards the south these erode away into rolling plains called piedmont plains. These are human dominated and mainly constitute agricultural areas.
DRAINAGE PATTERNS AND STREAM SYSTEMS
The drainage pattern in the area in dendritic. “Dendrites” in Greek mean tree like. So the dendritic drainage pattern is like branches of a tree. They are characterized by irregular branching in various directions and at all possible angles of the tributary streams. They develop on rocks that are uniform in resistance. So there is no structural control. They commonly form on horizontal sedimentary rocks. Same is the case here in the Siwalik Hills.
The young V shaped valleys and even the wide river channels laid with boulders are mostly dry throughout the year and filled up to the brim during torrential rain or during the rainy season. This is when most of the erosion takes place. There are often floods during the rainy season, which inundates the adjoin flood plains.
BIOME
The study area includes 2 of the 14 ecological land classification developed by World Wide Fund for Nature (Olson et al. 935). The hilly tract comes under “tropical and subtropical moist broadleaf forests ecoregion”, and the plains come under “Tropical and subtropical grasslands, savannas, and shrublands”, more specifically “Terai-Duar savanna and grasslands”.
The hilly tracts are dominated by Sal (Shorea robusta) and teak (Tectona grandis) forests and the plains are dominated by river side grasslands with very tall grasses. Both regions are characterized by the presence of the Asian elephant, the Bengal Tiger and various species of deer.
ECOSYSTEM CHARACTERISTICS
The diverse topography and geology of the area has given rise to a varied communities in this forest. Such communities with their respective flora and fauna form separate ecosystems in CTR. The rugged and dissected hills have an unusual variation in slope and aspect and the amount of rainfall and sunlight varies accordingly. This has given rise to a good diversity of plants and animal in this ecosystem, which is very delicate and fragile. With altitude it shows a variation floral and faunal composition. The Sal forests in the foothills and the lower elevation zones forms a very important wildlife habitat in CTR. It grows to a height of 200-1200m. Khair (Acacia catechu) and Shisham (Dalbergia sissoo) forests which grows on freshly deposited alluvium on the flood plains forms another important part of this ecosystem. They form climax vegetation towards Sal forests. They add nitrogen to the soil and enriches them. They are good habitats for Sambar deer and leopards. Chaurs, the local name for savannah grasslands, is one of the most unique habitats in CTR. Various species of grasses grow on it and they attach deer and elephant, who graze on this grass species. The rivers of CTR are teaming with life as well. They harbor different species of fish, crocodiles and otters. These water attract various birds of prey like the rare Tawny Fish-owl and Pallas’ Fish Eagle.
HABITATS
The forests of CTR are classified into three major forest habitat types viz. Northern moist deciduous (3C), Northern tropical dry deciduous (5B) and Himalayan sub-tropical pine forest (9) (Champion and Seth 195).
PLANT AND ANIMAL COMMUNITIES
Sal Shorea robusta is the most dominant tree species gregariously growing in the park area. Evergreen species like Mallotus philippinensis and Syzygium cuminii are also commonly seen. The main grass species found in these grasslands are Saccharum bengalenses, Themeda arundinacea, Arundo donax, Vetiveria ziznoides, Apluda mutica, Heteropogon contortus, Eragrostis spp. and Cynodon dactylon. Eulaliopsis binata and Thysanolena maxima can be seen growing on cliffs and moist shady places.
This area harbors one of the highest densities of the Bengal tiger (Panthera tigris tigris) in the world. It also has a good population of the Asian elephant (Elephas maximus) and various deer species like the spotted deer (Axis axis), Sambar deer (Rusa unicolor) etc.
FOOD WEB AND FOOD CHAINS
CTR harbors so many species of wild animals and complex food web and chain. The food web starts from micro-organisms in the rivers and lakes which are fed upon by the birds of prey, otters and crocodiles. Sometimes the crocodiles may feed on the otters. The crocodiles also occasionally prey on deer and elephant who come for a drink of water. Luxuriant growth of grasses occur in flood plains where different species of deer graze and they form the prey of carnivores like tiger and leopards. Kill remains of large predators are scavenged by jackals and vultures. The jackals may occasionally predate on small prey like rodents and hares. The tiger is the apex predator of this ecosystem. It maintain the ecological balance of the whole ecosystem, by regulating herbivore prey species, and in turn other carnivore species.
AN EXAMPLE OF AT LEAST ONE ANIMAL AND ITS NICHE
Spotted deer occur in large number in CTR. They contribute to the sustenance of large carnivores like the tiger and leopard. In CTR the bulk of wild ungulates are comprised mostly of Spotted deer (Karanth and Sunquist 30) which plays a critical role of keystone species in most of the Indian forests owing to its high densities and representing substantial proportion of large carnivore diets. They are wide ranging and tolerate high levels of disturbance in their habitat. They are found generally in open forests and forest edges. They undergo “fission-fusion” system of group formation. Group sizes variations in Spotted deer overwhelmingly corresponded to habitat structure and role of predation. A matriarchal family unit in spotted deer, generally comprises of an adult female, her yearling and a fawn. Sometimes chital herds are composed of two or more of these family units. Their monthly herd size varies from 5-38 individuals. They prefer dry deciduous habitat with scrub.
AN EXAMPLE OF SYMBIOTIC RELATIONSHIPS
A nice symbiotic relationship can be seen between the spotted deer and the langur monkey (Presbytis entellus). The monkeys feed on tree tops and drop fruits and foliage which are fed upon by the deer. They monkeys benefit from the vigilant behavior of the deer, who gives alarm calls when a predator is in sight (Newton 100).
HUMAN-LAND RELATIONSHIPS
The CNP is surrounded by human habitation outside its boundary on all sides. The residents of the village benefit a lot from the tourism money that they are able to earn from the park working as tour guides. Some of them also work with forest department. They extract fodder and fuel wood from the forest and even take their cattle inside the park for grazing. They catch fish in the rivers of the forest. Percolating influence of humans inside the forest has in a way causes human animal conflict. Wild ungulates move out of the forest to feed on crops. Carnivores like leopard and tigers predate on livestock and cattle.
ECOSYSTEM STATUS
In the Western Terai Arc Landscape, owing to high anthropogenic pressure or wildlife habitat connectivity loss, there is considerable reduction of tiger density at certain pockets where the population exists well below the carrying capacity resulting in reduction of predation pressure and thereby giving a gradient of predation pressure (High-Medium-Low) across the landscape. Hunting of wild prey depletes the prey base for large carnivores who in turn come out of the forest in search of food and fed on livestock and cattle. There is conflict and this results in the negative mindset of the local people towards conservation. Illegal collection of timber from the forest also degrades the forest and results in habitat loss for various wild species. There is a need to do proper scientific and long term monitoring of the carnivore population and their prey species, along with monitoring their habitat quality, and also to bring local people into the folds of the conservation actions.
Works Cited
Bharthari, R. 1999 “Management plan for Corbett National Park” (Ramnagar Tiger Reserve Division) 1 : 1-11.
Champion, Sir HG, and Shiam Kishore Seth. "A revised survey of the forest types of India." A revised survey of the forest types of India. (1968).
Gupta, S.R., and Ravi Kumar. “Vegetation composition and plant biodiversity in forest ecosystems of Siwaliks in northern Haryana.” Indian Journal of Fundamental and Applied Life Sciences 4.2 (2014): 76–88. Print.
Karanth, K. Ullas, and Melvin E. Sunquist. "Population structure, density and biomass of large herbivores in the tropical forests of Nagarahole, India." Journal of Tropical Ecology 8.01 (1992): 21-35. Print.
Newton, Paul N. "Associations between langur monkeys (Presbytis entellus) and chital deer (Axis axis): Chance encounters or a mutualism?." Ethology 83.2 (1989): 89-120. Print.
Olson, David M., et al. "Terrestrial Ecoregions of the World: A New Map of Life on Earth A new global map of terrestrial ecoregions provides an innovative tool for conserving biodiversity." BioScience 51.11 (2001): 933-938. Print.
Singh, Yadvinder. "Geo-ecology of the Trans Satluj Punjab-Haryana Siwalik Hills, NW India." Himalayan Ecology and Development: Envis Bulletin 9.2 (2001): 15-34.
Wadia, Darashaw Nosherwan. "Geology of India." (1944).
