Effect of power plant emissions on plant community structure.

A field study was conducted around two coal-fired thermal power plants (TPP) to analyse the impact of their emission on the structure of herbaceous communities in a dry tropical area. Phytosociological studies reflected that Cassia tora, Cynodon dactylon and Dichanthium annulatum dominate at heavily polluted sites. Alsycarpus monilifer, Convolvulus pluricaulis, and Desmodium triflorum are uniformly distributed, whereas Paspalidium flavidum, Phyllanthus simplex, and Rungia repens are dominant at less polluted sites. On the basis of Importance Value Index, the species were classified as sensitive, intermediate and resistant to TPP emissions. Shannon-Wiener Index of species diversity, species richness and evenness were inversely related, whereas concentration of dominance was directly related to the pollution load in the area. Significant negative correlation between ambient SO2 concentration and species diversity suggested selective elimination of sensitive species from the heavily polluted sites.