The Palni Hills are an eastward spur of the Western Ghats with a maximum East-West length of 65km., and a North-South width of 40km. (area 2064sq.km.). These hills may be simply divided into four distinct zones,
1. The foothills to 800m. consisting of thorn forest at the lower range and then dry deciduous forest typical of Peninsular India. There are also some very good stretches of evergreen riverine forest at these altitudes.

 

 

2. Sub-montane evergreen forest accompanied by shrub savannah to 1600m. although most has been converted to plantations.
3. From 1600m. to 2000m., the outer montane slopes characterised by grassland savannah and Shola.
The undulating plateau interspersed with occasional peaks rising to c. 2,500m. (area 385sq. km, average altitude 2,200m.) largely consisting of grasslands with bracken, interspersed with Sholas. The grassland component is now largely dominated by forest plantation.
The Western Ghats are themselves renowned as one of the World's great bio-diversity hot-spots. This great chain of hills effectively operates as a string of islands, each with their own distinctive eco-systems and varying plant communities. Hotspots are identified by two main criteria; first plant endemism and then degree of threat. Endemism is the main criteria because endemic species are dependent on a single area for survival, hence the island metaphor. The Palnis are one such "island".
The Palnis differ greatly from much of the Western Ghats in that it lies in the rain shadow of the backbone of the range, i.e. it receives only light rainfall during the June-September S.W. monsoon.The bulk of the rain falls on the Annamalais in the West in Kerala. The dense luxuriant tropical rainforests of the Western lowlands are absent. Moist areas though exist along the ravines and in the sheltered pockets of Shola forest c.2000m.
Here are often found endemic hotspots within a hotspot, most notably Pambar Shola. These hotspots are also notable for their relic populations such as Arenga wightii, Artocarpus hirsutus, Mesua ferrea var. coramandeliana, Bentinckia condapanna and Pittosporum tetraspermum, where only a few individuals of each species may be found.

 

The Palnis have c. 15 endemic species, but share many more species that are limited to just a few other neighbouring hills such as the Nilgiris and the Annamalais. Fr. K.M. Matthew listed 1758 species as native in 1999, (since then the list has grown). Of these Fr. Matthew rated 46 species as vulnerable and 14 (amalgamated) as probably extinct locally.
The threat status of many of these species has lessened due to our cultivation and distribution since 1989. Of the 14 extincts, 6 have been relocated and raised, 2 of them being reintroductions from the neighbouring Nilgiris. Nevertheless we feel a fresh survey would indicate a growing number of species that should be listed as vulnerable due to the ever diminishing grassland habitat over the last 20 years.

© 2006Vattakanal Conservation Trust. All rights reserved