Seasonal Variation in Composition, Plant Biomass, and Net Primary Productivity of a Tropical Grassland at Kurukshetra, India

The variation in composition, plant biomass, and net primary productivity was analyzed in a tropical grassland situated within the campus of the Kurukshetra University, India, at 29° 58' N latitude and 76° 51' E longitude. A study of life forms indicated a therocryptophytic flora. Detailed phytosociological values of constituent species of the vegetation were studied at monthly intervals (May 1970 to May 1971) through tiller analysis. Most of the species were found to be contagiously distributed. The changes throughout the year in the aboveground plant biomass, standing dead, litter, and belowground biomass showed a maximum aboveground biomass in September (1,974 g/m 2 ) and maximum belowground biomass in November (1,167 g/m 2 ). Examination of vertical distribution of the aboveground biomass of total vegetation as well as of the individual species indicated that different layers of vegetation are dominated by different species in different months. The aboveground net primary production was maximum during the rainy season (1,706 g/m 2 ), and the belowground maximum occurred during the winter season (785 g/m 2 ). Total annual net primary production is estimated to be 3,538 g/m 2 . The system transfer functions revealed that productivity was more aboveground—directed during the wet period and more belowground—directed during the dry period. Annual efficiency of energy capture by the primary producers was calculated to be 1.66% on the basis of half total incident solar radiation.