Phytosociology of woody vegetation on the eastern slopes of Nilgiris

Abstract

For proper assessment of biodiversity, its rate of extinction and driving forces leading to extinction,information on the vegetation type, floristic composition and their habitats, human interventions andultimately impact on landscape changes vis-a-vis biological richness characteristics are required.Nilgiris, the blue mountains of the Southern India, is one of the magnificent and oldest mountainranges in the world, lying at the junction of Eastern and Western Ghats of the Indian peninsula.Basically. Ni1giris is a hilly area forming part of the environmentally fragile Western Ghats with extremelyrich. abundant and wide array offlora and fauna. Botanically, as well as zoologically and ethnologically,the N iIgiris forms a distinct ecological realm of its own and possesses enigmatic affinities to Himalayanflora and fauna. An attempt has been made in this study to analyse the vegetation of eastern slopes ofNilgiris forming part of the famous NBR for its floristic composition and phytosociological aspectsduring the year 2002-03.

Results revealed that the vegetation of the entire study area was composed of 166 species distributedamong 51 taxonomic families. Among the different vegetation types under study semi-evergreenvegetation was found to be the richest in species composition (117 species), followed by riverinevegetation (89 species) and least species richness was registered in deciduous vegetation (85 species).Phytosociological studies revealed that Dendrocalamus-Anogeissus-Naringi in deciduous vegetation,Karadisalc-Nothopegia-Pamburus in riverine vegetation and Olea-Ligustrum-Anogeissus in caseof semi-evergreen vegetation were the dominant plant communities. Semi-evergreen vegetation wasfound to be dense with nearly 540 individuals per ha and dominant with BA of 41.85 m? ha' followedby riverine vegetation (520 individuals per ha and 25.07 rn-' ha') and deciduous vegetation (317individuals per ha and 19.17 m ' ha'). Among the vegetation types under study contiguous distributionwas recorded for majority of species followed by random pattern of distribution. None of the speciesshowed regular distribution pattern. Thus, it can be concluded that all the vegetation types underinvestigation registered comparatively rich floristic composition. This valuable resource needs to beprotected and managed sustainably.