The Steering Committee of Project Tiger granted approval in principle to inclusion of Indira Gandhi WLS and NP under Project Tiger in 2005. IGWS was declared a Project Tiger sanctuary in 2008. Continuance of Project Tiger’ in Anamalai Tiger Reserve for FY 2010/11, at the cost of Rs. 235.47 Lakhs, was approved by the National Tiger Conservation Authority on 31 August 2010.
The park is home to a wide variety of flora and fauna typical of the South Western Ghats. There are over 2000 species plants of which about 400 species are of prime medicinal value. The diverse topography and rainfall gradient allow a wide variety of vegetation comprising a mix of natural and man-made habitats. The former includes wet evergreen forest and semi-evergreen forest, montane shola-grassland, moist deciduous, dry deciduous, thorn forests and marshes. Tropical wet evergreen forest is found at an altitude of 600m to 1,600m.
Tropical montane forests occur at higher elevations and are interspersed with montane grasslands, forming the shola-grassland complex. Much of the original evergreen forest now contains introduced teak plantations. Bamboo stands and reeds occur in the natural forests. Tree cover is provided by Hopea parviflora, Mesua ferrea, Calophyllum tomentosum, Vateria indica, Cullenia excelsa and Mangifera indica, Machilus macrantha, Alstonia scholaris, Evodia meliaefolia, Ailanthus and Malabaricum and Eucalyptus grandis. The area is home to Podocarpus wallichianus, a rare South Indian species of conifer.