华西雨屏区苦竹人工林土壤呼吸各组分特征及其温度敏感性

通过在华西雨屏区苦竹(Pleioblastus amarus)人工林内建立固定样地、定期监测等方法,研究该人工林生态系统土壤呼吸各组分特征及其温度敏感性.结果表明:2010年2月-2011年1月,苦竹林平均土壤呼吸速率为1.13 μmol·m-2·s-1,仲夏最高,深冬最低;凋落物层、无根土壤和植物根系对苦竹林土壤呼吸的贡献率分别为30.9％、20.8％和48.3％,各呼吸组分的季节动态均与土壤总呼吸类似,并与温度和凋落量等因素相关;苦竹林土壤总呼吸(RST)、凋落物层CO2排放(RSL)、无根土壤CO2排放(RSS)和植物根系呼吸(RSR)的年碳排放量分别为4.27、1.32、0.87和2.08 MgC· hm-2 ·a-1;土壤总呼吸及其各组分与凋落量呈显著正线性相关,与土壤10 cm温度和气温均呈显著正指数相关;基于土壤温度计算的RST、RSL、RSS和RSR的Q10值分别为2.90、2.28、3.09和3.19,凋落物层CO2排放的温度敏感性显著低于总呼吸和其他各组分.

Characteristics of soil respiration components and their temperature sensitivity in a Pleioblastus amarus plantation in rainy area of West China

To understand the characteristics of soil respiration components and their temperature sensitivity in a Pleioblastus amarus plantation in the Rainy Area of West China, a one-year periodic monitoring was conducted in a fixed plot of the plantation from February 2010 to January 2011. In the plantation, the mean annual soil respiration rate was 1.13 micromol x m(-2) x s(-1), and the soil respiration presented a clear seasonal pattern, with the maximum rate in mid-summer and the minimum rate in late winter. The contribution rates of the respiration of litter layer, root-free soil, and root to the total soil respiration of the plantation accounted for 30.9%, 20.8% and 48.3%, respectively, and the respiration of the components had a similar seasonal pattern to the total soil respiration, being related to temperature and litterfall. The annual CO2 efflux from the total soil respiration, litter layer CO2 release, root-free soil CO2 release, and root respiration was 4.27, 1.32, 0.87 and 2.08 Mg C x hm(-2) x a(-1), respectively. The total soil respiration and its components had significant positive linear correlations with litterfall, and significant positive exponential correlations with air temperature and the soil temperature at depth 10 cm. The Q10 values of total soil respiration, litter layer CO2 release, root-free soil CO2 release, and root respiration calculated based on the soil temperature were 2.90, 2.28, 3.09 and 3.19, respectively, suggesting that the temperature sensitivity of litter layer CO2 release was significantly lower than that of the total soil respiration and of its other components.