Silent Valley National Park (സൈലന്റ് വാലീ നാഷണല് പാര്ക്ക്), is located in the Nilgiri Hills, Palakkad District in Kerala, South India. The area in this national park was historically explored in 1847 by the botanist Robert Wight, and is associated with Hindu legend. The park is one of the last undisturbed tracts of South Western Ghats montane rain forests and tropical moist evergreen forest in India. Contiguous with the proposed Karimpuzha National Park (225 km²) to the north and Mukurthi National Park (78.46 km²) to the north-east, it is the core of the Nilgiri International Biosphere Reserve (1,455.4 km²), and is part of The Western Ghats World Heritage Site, Nilgiri Sub-Cluster (6,000+ km²) THUNDER consideration by UNESCO.
Silent Valley is rectangular, 7 km (east-west) X 12 km (north-south) and it is separated from the eastern and northern high altitude plateaus of the (Nilgiris Mountains) by high continuous ridges including Sispara Peak (2,206 m) at the north end of the park. The park gradually slopes southward down to the Palakkad plains and to the west it is bounded by irregular ridges. The altitude of the park ranges from 658 m to 2328 m at Anginda Peak, but most of the park lies within the altitude range of 880 m to 1200 m. Soils are blackish and slightly acidic in evergreen forests where there is good accumulation of organic matter. The underlying rock in the area is granite with schists and gneiss, which give rise to the loamy laterite soils on slopes.
Silent Valley gets copious amounts of rainfall during the monsoons, but the actual amount varies within the region due the varied topography. In general the rainfall is higher at higher altitude and decreases from the west to east due to the rain shadow effect. Eighty per cent of the rainfall occurs during the south-west monsoon between June and September. It also receives significant amount of rainfall during the north-east monsoon between October and November. The park being completely enclosed within a ring of hills, has its own micro-climate and probably receives some convectional rainfall, in addition to rain from two monsoons.
In the remaining months, condensation on vegetation of mist shrouding the valley is estimated to yield 15 per cent of the total water generated in the rainforest. The mean annual temperature is 20.2°C. The hottest months are April and May when the mean temperature is 23°C and the coolest months are January and February when the mean temperature is 18°C. Because of the high rainfall, the relative humidity is consistently high (above 95%) between June and December.
There is no record the valley has ever been settled, but the Mudugar and Irula tribal people are indigenous to the area and do live in the adjacent valley of Attappady Reserved Forest. Also, the Kurumbar people occupy the highest range outside the park bordering on the Nilgiris. Many of the Mudugar and Irula and kurumbar now work as day laborers and porters. Some work for the Forest Department in the park as forest guards and visitor guides. 16 out of 21 tribal colonies in the Attappady range are notorious for ganja cultivation. Many Mudugar are in abject poverty and easily recruited by the so-called ganja mafia, There is a plan to employ 50 additional men from these 21 tribal settlements as forest guards for Rs.500/man/month.
Fauna And Flora:
Valley areas of the park are in a Tropical and subtropical moist broadleaf forests Ecoregion. Hilly areas above 1,000 m are in a South Western Ghats montane rain forests region. Above 1,500 m, the evergreen forests begin to give way to stunted forests, called sholas, interspersed with open grassland. Both are very important to naturalists, biologists and other researchers because the rich biodiversity here has never been disturbed by human settlements. Several threatened species are endemic here. New plant and animal species are often discovered here.
- Forest Fire: Fire is one of the major threats facing the forests of Kerala. People engaged in grazing livestock often burn an area to get fresh grass shoots for their cattle, especially during dry season when fire danger is greatest. Also, illicit activities like ganja cultivation, poaching, tree felling, non timber forest products (NTFP) collection and very often careless tourists and pilgrims are responsible for big forest fires. Some extent of the Mesua - Calophyllum tree association areas in the higher reaches are degraded due to previous fire and the area is now fast regenerating.
- Cannabis Cultivation: The cannabis mafia has cut hundreds of acres of evergreen tropical forest in the Attappady Hills, including Silent Valley buffer zones, for illegal cultivation of the cash crop. The Forest Department had an ambitious plan to root out ganja cultivation from the Attappady forests by April 2006.