Abstract

                                The herbage yield in the form of aboveground net primary production is getting paramount importance for herbivores and hence ecosystem management. To compare the herbage yield (aboveground net primary production) and to determine the influence of certain environmental factors, six grassland communities (community near Kongunadu Arts and Science College Site I; community near Bharathiar University Site II; community at Burliar Site III; community at Coonoor Site IV; community at Ooty site V; community . at Nadugani Site VI) located at different climatic zones (Sites I and II tropical; Sites III and VI subtropical and Sites IV and V temperate) were selected. The study revealed that the tropical sites registered higher annual net primary production along with higher energy potential in biomass and it is followed by subtropical and temperate sites. When all the sites are considered together, the physical factor, temperature and the intrinsic factor, higher proportion of C, plants were directly correlated with aboveground net primary production. Contrary to this, the factors viz. the rainfall and the proportion of C, plants have inverse relationship with aboveground net production. Since there was no limiting physical factors in the studied temperate sites (Sites IV and V), the population of C, plants alone largely determines the community production. Hence, planting tree species randomly in the studied temperate sites, where the C, plants are more, can enhance the primary production owing to their higher efficiency of production in shade condition.

Key words : Herbage yields, Environmental factors, Photosynthetic pathway, Grasslands.