Organisation

The major vegetation types of the NBR are presently are given below.

Evergreen forests

Low Elevation Evergreen Forests

These forests are found along the western slopes and valleys of the NBR usually inareas where the annual rainfall is not less than 2000 mm. These forests are further distinguished by altitude and thus we have low elevation evergreen forests (0 - 600 m).
These Evergreen forests are characterized by dominant trees in the genera Dipterocarpus, Mesua and Palaquium.
Remnants of these forests are found in New Amarambalam and Muthikulam-Palghat Hills.

Medium Elevation Evergreen Forests

Higher up are the medium elevation evergreen forests (600 - 1400 m)
These Evergreen forests are characterized by dominants such as Cullenia, Mesua and Palaquium.
These forests occur in Silent Valley, New Amarambalam, Attapadi and Nilambur.

High Elevation Evergreen Forests

A third altitudinal category of evergreen forests viz.,the high elevation forest (1400 - 1800 m) is often recognised. This type is however not very distinct in floristic composition as the former two.

Shola Forests

The last category is the montane or shola forests which appear in patches above 1800 m.
These are characterized by their low stature and montane species such as ScheMera
Shola forests are found on the slopes of almost all the higher hills especially within the Nilgiris district. Secondary stages of evergreen forests and mixed forests are often classified as semi- evergreen forests.

Montane grasslands

This vegetation type is found on the higher hills of the southern Western Ghats and is a common feature of the NBR too. Extensive cover of short grass all over the slopes dotted with occasional Rhododendron trees is a characteristic. Grasslands surround most sholas and the ecotones thus created are important habitats for a variety of organisms especially plants.

Deciduous forests

Deciduous forests are the most prevalent of vegetation types in the NBR. Moist deciduous forests cover areas where the rainfall is around 1500 mm. However over most of the NBR where rainfall is around 1000 mm, dry deciduous forests dominate, often thinned down to form tree savanas by human interference. Climax moist deciduous forests may be seen in the Rajiv Gandhi National Park (Nagarhole) and the western parts of Mudumalai. Much of the Bandipur Tiger Reserve shows a typical stand of dry deciduous forests.

Scrub

The eastern margin of the NBR and all along the Moyar River dense scrub jungles occur. These forests are characterized by stunted and thorny trees such as Hardwickia binata and Cassia. Rainfall is usually less than 1000 mm.

Plantations

A variety of exotic and native tree plantations cover the landscape of the NBR.