Variation characteristics of soil respiration and its components in Larix Gmelinii forest

In the present study,we use trenching method to separate heterotrophic and autotrophic respiration in the Larix gmelinii forest and measure soil temperature and soil water content at 10 cm soil layer.The daily and seasonal variation of soil respiration and their composition were investigated in the Larix gmelinii forest.The results are showed as follows: ①Soil respiration,heterotrophic and autotrophic respiration indicated an obvious daily and seasonal variation trend and the diurnal variation of soil total respiration and its components was described as a single-peak curve.Compared with soil respiration and heterotrophic respiration,the daily variation of autotrophic respiration is relatively flat and its maximum appeared hysteresis phenomenon.During the growing season,the ranking for the monthly average soil and heterotrophic respiration rate is July August September June,and for the autotrophic respiration is AugustJuly September June.②The total soil respiration rate and its components were exponentially related to the soil temperature in 10 cm soil layer.The Q10values of total soil respiration,heterotrophic respiration,and autotrophic respiration calculated based on the soil temperature were 1.69,1.97 and 1.24,suggesting that the temperature sensitivity was significantly lower than that of the other regions.However the soil respiration was not significantly influenced by the soil water content.③The contribution rate of heterotrophic respiration and autotrophic respiration to total soil respiration estimated in the growing season were 63% and 37%,indicating that the contribution rate of heterotrophic respiration was twice autotrophic respiration in this area.