Matter dynamics with respect to influences of C3 and C4 plants in four subtropical grasslands of Nilgiri Biosphere Reserve, the Western Ghats, India

Abstract

Biomass changes, net primary production and transfer dynamics of dry matter in four subtropical humid montane grasslands at Ebbenadu, Korakundah, Thiashola and Wenlockdown in Nilgiri Biosphere Reserve (NBR), the Western Ghats, India, were investigated. Despite the early report of a higher density and dominance of C4 species over C3 species in these grasslands, no functional study of matter production had previously been carried out. Therefore, in order to determine the roles played by these two groups of species, the present study was attempted. The study revealed that the dry matter and net primary production contributed by C4 species were much greater than those of its C3 counterpart in all the grasslands. The turnover rate of aboveground dry matter for both C3 and C4 species was generally rapid, whereas it was slow for belowground parts, and litter components of C3 and C4 species together. In all grasslands, generally about 60% and 10% of the input were channeled to aboveground and belowground parts, respectively, by the C4 species, whereas the C3 species transferred only about 22% and 8% of dry matter to aboveground and belowground parts, respectively. The total disappearance of dry matter was 2.73, 2.10, 3.19, and 1.96 g m-2 day-1 in Ebbenadu, Korakundah, Thiashola and Wenlockdown grasslands, which was 48.83%, 44.30%, 54.81%, and 41.09% of the total input, respectively, in these grasslands. This resulted in a considerable surplus dry matter production in all the grasslands studied. This balance sheet of dry matter in community function indicates that all the four studied grasslands were supporting the existing wild animals adequately in terms of pasture supply. The study further revealed that the stronger establishment of C4 species rather than their C3 counterparts, in terms of higher density and dominance, has driven them to play major roles in matter dynamics and system transfer functions in all the four grasslands studied. This fact evidenced that pasture from C4 species for wild animals was determined to be higher in comparison to that of C3 species. © The Ecological Society of Korea.