Broadly his research is concerned with the structure, function and dynamics of tropical ecosystems, especially on trees. Increasing anthropogenic pressures on environment have been resulting in habitat loss, fragmentation and loss of biodiversity in the tropics. As the steady decline of forests progresses, more accurate information on the biodiversity (species, structural and functional composition) across spatio-temporal scales is necessary to understand the pattern and processes that shape and influence biodiversity of the region. The main objectives of his current research to biodiversity characterization and dynamics of tropical forest diversity with reference to disturbance and climate:

Biodiversity characterization at forest stand to regional scale. 1) The specific objectives of the project are: (i) to characterize biodiversity and develop community level maps, (ii) to assess decadal changes of the regional forest landscapes, (iii) to describe vegetation structure using both high resolution multispectral satellite data and field inventory, (iv) to evaluate the utility of stand level canopy heterogeneity and height as a predictor of biodiversity and (v) to identify Earth observations and variables that are relevant to monitoring biodiversity at the community level. Two sites viz., Ranganathaswamy Temple tiger reserve and Shettihalli Wildlife sanctuary in the Western Ghats has been selected and are under investigation in the project.

Dynamics of forest diversity: The lack of annual growth rings in most of tropical trees and the mechanisms that allow coexistence of so many canopy species in relatively homogenous areas are poorly understood. Spatio-temporal scale analysis in the permanent plots of tropical forest would yield life-history strategies to structures, growth, regeneration, dynamics and also information related to conservation of species in the changing world’s climate. The Uppangala permanent sampling plots in the logged and unlogged forests are under investigation for phenology and forest dynamics with the climate in the project.

1. Old Publications: Ayyappan, N. and Parthasarathy. N.1999. Biodiversity inventory of trees in a large-scale permanent plot of tropical evergreen forest at Varagalaiar, Anamalaias, Western Ghats, India. Biodiversity and Conservation 8:1533-1554.
2. Ayyappan, N. and Parthasarathy, N. 2001. Composition, population structure and distribution of dipterocarps in a tropical evergreen forest at Varagalaiar, Anamalais, Western Ghats, south India. Journal of Tropical Forest Science 13:311-321.
3. Ayyappan, N. and Parthasarathy. N. 2001. Drypetes subsessilis (Kurz) Pax and Hoffman- a new record to southern Peninsular India. Phytotaxonomy 1:132-133.
4. Ayyappan, N. and Parthasarathy, N. 2001. Patterns of tree diversity within a large-scale permanent plot of tropical evergreen forest, Western Ghats, India. Ecotropica 7: 61-76.
5. Ayyappan, N. and Parthasarathy, N. 2004. Short-term changes in tree populations in a tropical evergreen forest at Varagalaiar, Western Ghats, India. Biodiversity and Conservation13: 1843-1851.
6. Ayyappan, N. and Parthasarathy. N. 2005. Prismatomeris tetrandra (Roxb.) K.Schum. subsp. malayana (Ridley) J.T. Johansson- a new record to Indian tree flora. Journal of Economic and Taxonomic Botany 29:802-804.
7. Muthuramkumar, S., Ayyappan, N., Parthasarathy, N., Divya Muddappa, Shankar Raman, T.R., Arthur Selwyn and Arul Pragasam, L. 2006. Plant community structure in tropical rainforest fragments of the Western Ghats, India. Biotropica 38: 143-160.