SEPARATING ROOT AND SOIL MICROBIAL CONTRIBUTIONS TO TOTAL SOIL RESPIRATION IN A GRAZED GRASSLAND IN THE XILIN RIVER BASIN

The contribution of root respiration to total soil respiration was examined in a grazed steppe grassland in Inner Mongolia. From respiration data based on CO 2 uptake by NaOH and corresponding root biomass values for each of 10 plots, a linear regression of CO 2 rates on root dry weights was calculated for every ten days. By extrapolating the regressive line to zero root biomass, the proportion of the total soil respiration flux that is attributable to live root respiration was estimated to be 24% on average, ranging from 15% to 37% in the growing season. The larger proportional values appeared in the same period of the season as that of the peak values of root growth, both of which occurred in mid_June and early_August respectively.