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P. K. Dash , P. P. Mohapatra , Y. Giri Rao

Abstract

The Niyamgiri hills in the South-Eastern parts of Orissa are a unique forest ecosystem harbouring rich floristic composition and vast natural resources. As there is absolutely no published record on flora of the hill till date, the phytosociological characteristics, diversity and distribution of tree species at three proposed reserve forests of the hill ranges between elevations from 400-1,306 m were studied. A total of 152 tree species were recorded from the study sites belonging to 114 genera and 41 families. Species diversity was found to be maximum at Khambesi Reserve Forest and minimum at Niyamgiri Reserve Forest. Significant correlation of species diversity with species evenness and species richness were observed while significant negative correlations were marked between species diversity, concentration of dominance, beta diversity and maturity index. At present the biodiversity of the hill is under threat due to the ongoing and upcoming mining activities. The results of this study might render a helping hand to the forest managers in preparing a conservation plan for the highly species diverse and threatened ecosystem of the hill ranges.

Keywords

Trees, Distribution, Diversity, Niyamgiri Hills, Tamil Nadu

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Pramod Singh ¹, M. G. Yadava ², Malik Z. Ahmad ¹, P. P. Mohapatra ¹, A. H. Laskar ², S. Doradla ¹, J. Saravanavel ³, C. J. Kumanan ³

Affiliations
1 Department of Earth Sciences, School of Physical, Chemical and Applied Sciences, Pondicherry University, R.V. Nagar, Kalapet, Puducherry 605 014, IN
2 Geoscience Division, Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, IN
3 Centre for Remote Sensing, Bharathidasan University, Khajamalai Campus, Tiruchirappalli 620 023, IN

Abstract

The Cauvery delta encompasses legendary farmlands for at least over the last ~2300 years BP that had supported the growth of the famous Chola and Pandya kingdoms. The chrono-stratigraphic study from six sediment cores taken from the Cauvery basin indicates Holocene evolution of the present delta in response to the past sea-level changes. It is found that at the time of lower sea level during the Last Glacial Maximum, older sediments from the present delta plain, were removed and the extent of removal in different parts was observed to have been controlled by the variation in shelf morphology. Subsequent sealevel rise during the deglaciation after the Last Glacial Maximum, led to filling of the incised valleys with the younger sediments of the Holocene. Nilgiri- Kodaikanal-Palani-Biligirirangan hills granulites and Brahmagiri regions constitute the upper catchment. Geochemistry of the sediments indicates presence of plagioclase and dominance of 2:1 clay, suggesting weathering-limited provenance of southern granulitetype rocks, the source of which is perhaps the high relief and tectonically more active Nilgiri-Kodaikanal- Palani-Biligirirangan hills mountain region rather than the Brahmagiri region. A continuous deposition since the beginning of the Holocene has resulted in the formation of fertile farmlands in the Cauvery delta region.

Keywords

Cauvery, Delta, Farmlands, Holocene Evolution, Sea-Level Change.

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