[Study on the free-grazed steppes root respiration of growing season in the Xilin River Basin, China].

In order to determine the proportion of the root respiration to the total soil respiration, field experiments were condusted to measured soil respiration in three temperate grassland communities including Leymus chinensis free-grazed steppe, stipa grandis free-grazed steppe and Leymus chinensis degenerated free-grazed steppe using root biomass ratiocination method in the growing season, 2005. At the same time, seasonal variation including root respiration, total soil respiration and proportion of the root respiration to the total soil respiration in different grassland communities were compared, and the influence of root biomass, water and temperature to these processes were expounded. The results indicated that the rule of the root respiration and total soil respiration in the three steps was a one-peak pattern with the season dynamic, the maximum rate was in the late of July, but in Leymus chinensis degenerated free-grazed steppe, the rate was obviously larger than the other two types between July and August; The proportion of the root respiration to the total soil respiration obviously changed in the growing season, and the proportion was varied from 40% - 50 % with the mean value of 40.3 % , but it was very different among three steps because of the regional differentiations.