Salim Ali School of Ecology and Environmental Sciences, Pondicherry University, Pondicherry 605 014, INDIA.
Tropical forests represent the greatest storehouse of biological diversity in the world and are a mosaic of communities, which are dynamic in space and time. Dry tropical forests account for 46 % of the total forest cover of India (Singh and Singh, 1988). Studies on dry tropical forests are inadequate and merit a thorough investigation because the factors governing the dynamics of these forests may be very different from those of rain forests due to variations in climatic factors. size, shape and seasonal timing of canopy gaps which influence the regeneration of woody species (Sukumar et al., 1992).
Local species extinction rates appear to be very high for tropical species (Stehli et al., 1969: Farnworth and Golley, 1974) and therefore much more caution is needed for these dry forests compared to rain forests which are fairly well protected that too in the recent past by the establishment of Biosphere reserves, National parks etc.. but there are no proper documentation of species extinction and related changes in the dry tropical forests. Further forest department may pay more attention to forests that are productive in terms of potential timber yield, and protection to these thorn forests may be overlooked.
Quantitative studies on structure and functioning of forests in India are extremely limited although some data are available on selected sites in the Himalayas and in the Western Ghats. But no research work is available on these aspects in the Coromandel Coast of India. Therefore, considering this large lacuna existing in the understanding of forest ecosystem functioning, the present study was undertaken to investigate some aspects of vegetation structure and nutrient cycling process in two tropical dry evergreen forests namely Marakkanam Reserve Forest (MRF) and Puthupet Sacred Grove (PSG) in the Coromandel Coast of Tamil Nadu, India.
The species diversity and the structural aspects of vegetation were investigated. Seasonal changes in soil fertility status, fine root production, standing crop of fine roots, endomycorrhizal colonization and spore population of the belowground system were studied. Since soil fertility in tropical forest ecosystem is maintained through tight cycling of nutrients in soil - vegetation - litter components by rapid decomposition, nutrient concentration of the aboveground vegetation was analysed; litter production and the standing crop of litter was quantified to understand a dry forest functioning.