Forest Types
1. The Southern thorn Forests 6A/C1
This forest type occurs on shallow and bouldary soils and on the outcrops of lime stones, kankar and Gneissic rocks upto an elevation of 1,100 meters, annual rainfall being 60 to 70 cm a year, the climatic condition are extremely dry. The floristic overwood composition of this type of forest includes Acacia ferruginea, Albezzia amara, Azardirachta indica, Canthium diccoccum, Zizyphus species, etc.The under story tree species includes Randia dumetorium, Carissa carandas, Atlantia monophylla, Gmelina asiatica, etc. The undergrowth vegetation includes Cassia auriculata, Mundulea sericea, Capparis zeylanica, etc. Ground flora consists of Pavania zeylanica, Aerva lantana, etc.
This forest type occurs all along the lower slopes of the limb of the horse shoe shaped three valleys upto an elevation of 1,100 meters in Periyanaickanpalayam Range, Coimbatore Range, Anaikatty South, Anaikatty South Extention, Gopinari Reserves, eastern end of Bolampatty Reserves in Ayyasamy South block, Ettimadai, Konnamalai, Ichikudi and Marudamalai block. In Mettupalayam and Sirumugai Range these thorn forests occurs all over the scattered plain forests of the region, as also along the foot hills and slopes upto an elevation of 600 meters. It generally believed that the sandal in these areas originally spread from Nilgiris hill slopes and plateau region of Sathyamangalam Forest Division.
2. The Southern Dry Mixed Deciduous Forests 5A/C3
This is the most important type of the Forests occurring in this division, as economically valuable species grow here. This forest type found in Bolambatty Reserves, west of the Chunnambu Odai, Walayar Valley ad also in the slopes of Coimbatore and Periyanaickenpalayam forest ranges upto 1060 to 1210 meters elevations. This type also found in interior areas of Anaikatty South, Anaikatty South Extension, Gopinari reserves, east of Kodungaraipallam, and hill slopes upto 600 to 1200 meters elevation of the Mettupalayam and Sirumugai forest ranges. The important over wood tree species found in this forest includes Albizzia lebbeck, Dalbergia paniculata, Terminalia bellerica, Santalaum album, Hardwickia binata, Tectona grandis, etc. The under storey consists of Sterblus asper, Morinda tinctoria, Bauhinia malabarica, Acacia intsia, etc. The under growth includes Solanum trilobatum, Pavetta indica, Vitex negunda, Cassia Montana, etc.
Sandal (Sandalum album)
The sandal trees found growing almost an every type of soil, on stony red soil along the higher reaches of the Moyar Valley, and alluvial soil along the Hallur hallah, on rich loam in Hulical, Kallar, Jaccanare Reserves and on shallow gravelly soil of the Melur and Pillur slopes. Sandal is found not only in plenty in the comparatively dry thorn forests, but it also extends to the sub-tropical evergreen forests in the Sandal wood Reserve forests.
Teak (Tectona grandis)
In Bolampatty Range, Teak occurs in the waterfall block and Poondi areas, but it is not frequently seen in the natural state in other areas.
Bamboo
The bamboo species Bambusa bamboo and Dendrocalamus strictus occurs scarcely in the forest type. The later species found in the plains of the Walayar Valley and higher ranges of Bolambatty Range. Also bamboo found in the Anaikatty south Extention Reserve forests, a small portion of Thadagam Block IV RF and its Western end. In Mettupalayam and Sirumugai Range bamboo occurs in Hulical Durg, jaccanare and Nilgiris Eastern Slopes RF.
3. The Phoenix savannah 5/E3
This forest type occurs as a fire climax in patches on mid-slopes at the head of both Thadagam and Velliangadu Valleys in Periyanaickenpalayam and Karamadai Ranges and along the upper reaches of Nilgiris Eastern Slopes RF in Sirumugai Range. The tree species consists of Bauhinia longan, Diospyros melonoxylon, Cochlospermum religiosum, Phoenix sylvestris, etc. The undergrowth consists of coarse grasses such as Cymbopogan mardus, Heteropogon contortus, etc found in this forest type.This forest type more fire prone areas mainly by the graziers.
4. The West Coast Semi-evergreen Forests 2A/C2
The upper storey tree species of this forest type consists of Machilus macarantha, Bischofia javanica, Syzygium sp., Garcinia cambogia, Cinnamomum supharatum, Calophyllum elatum, Actinodaphne hooker, etc.The tree species are small and often festonned with Lichens, mosses and herbaceous epiphytes. The Kurunchi plants forms extensive thickets in this type of forests. This vegetation found in patches of Thadagam Valley over 1200 meters. One such patch is seen in Perumalmudi peak and Melmudy Rangasamy Koil. In Mettupalayam Range this forest found above 1200 meters along the Nilgiri Slopes and few patches occur in Aduthurai Extension Reserves, in the Sholas above Kodampakombai in Pillur Slopes RF, in Sirumugai, Kullankoraimalai in the Nilgiri Eastern Slopes RF. In Bolambatty Range it occurs above 1500 meters in small patches on the Periakunjiramalai, Vellingiri, Koppudukamalai and Varadamudy areas
5. The West Coast Tropical Evergreen Forests 1A/C4
The typical evergreen or “Rain Forests” is characterised by its luxuriance of vegetation consisting of several tiers, the highest containing tall trees and the lower containing dense shrubby undergrowth. A heavy rainfall, high humidity, and a short dry season are characteristic of this forest type. This forest type found over 1200 to 1500 meters. The upper storey tree species consists of Vateria macrocarpa, Acrocarpus fraxinifolius, Palaquium ellipticum, Mesua ferrea, cullenia resavrana, Syzygium sp., Cedrela toona, etc. The middle storey tree consists of Euphorbia longana, Macaranga peltata, Plovathia coffecides, Agrostistachys longifolia, etc. The undergrowth includes Laportea orenulata, Strobilanthus sp. Leea indica, etc. The climbers found in this type forest are Smilax zeylanica, Derrris sp., etc. This type of forest found in small patches of Bolampatty upper slopes of Block II RF, on the Vada Varadimalai Plateau and along the Valleys of Walmukkiar, the Kanavaraiar, the Noyilar, the Arear, the Chinnar and Mundanthoraiar areas.