秦岭小陇山锐齿栎林皆伐迹地土壤呼吸特征

Soil respiration characteristics in the clear-cutting site of Quercus aliena var. acuteserrata forest in Xiaolong Mountain in Qinling Mountains

2011年5月—2012年4月，利用Li-6400系统测定秦岭小陇山锐齿栎林皆伐迹地的土壤呼吸速率，研究锐齿栎林皆伐迹地土壤呼吸速率日动态、月动态和土壤温湿度以及土壤理化性质对土壤呼吸的影响.结果表明： 皆伐迹地和锐齿栎对照林地的土壤呼吸日动态和月动态均表现为单峰曲线，与土壤温度变化趋势相似；皆伐迹地和对照林地土壤呼吸速率的月均最大值均出现在7月，分别为4.63和4.01 μmol·m-2·s-1，月均最小值均出现在2月，分别为0.10和0.30 μmol·m-2·s-1；皆伐后4～6个月，皆伐迹地土壤呼吸速率月均值大于对照林地，此后则小于对照林地；土壤温度、湿度及二者交互作用的多元回归模型能够解释皆伐迹地土壤呼吸速率变化的89.6%～90.8%，解释对照林地的94.7%～95.5%；利用指数方程计算两样地土壤呼吸的Q10值，皆伐迹地和对照林地土壤呼吸的Q10值分别为3.47～4.22和3.54～3.96；皆伐迹地和对照林地年土壤碳释放量分别为344.8和512.9 g·m-2，冬季土壤碳释放量分别为24.2和40.9 g·m-2，占全年的7.0%和8.0%.

By using Li-6400 portable photosynthesis system with soil chamber, the soil respiration rates （Rs） of Quercus aliena var. acuteserrata forest land （control site） and their clear-cutting site were measured in Xiaolong Mountain of Qinling Mountains from May 2011 to April 2012 to understand the diurnal and monthly dynamics of soil respiration rate and the influences from soil temperature, soil moisture, soil physical and chemical properties. The results showed that both diurnal and monthly dynamics of soil respiration rate presented a single-peak curve, similar to the variation of soil temperature at the clear-cutting and control sites. During the study period, the maximum monthly mean values of soil respiration rate at the clearcutting and control sites occurred in July （4.63 and 4.01 μmol·m-2·s-1, respectively） and the minimum values presented in February （0.10 and 0.30 μmol·m-2·s-1, respectively）. Soil respiration rate in 4-6 months after clear-cutting was higher than at the control site, and became lower afterwards. 89.6%-90.8% of soil respiration rate variation was interpreted by the multiple regression models of soil temperature, soil moisture and their interaction at the clear-cutting site, and 94.7%-95.5% at the control site. The Q10 values computed by exponential equations were 3.47-4.22 and 3.54-3.96 at the clear-cutting and control sites, respectively. The C fluxes at the clear-cutting and control sites were 344.8 and 512.9 g·m-2 annually, and 24.2 and 40.9 g·m-2 in winter, respectively.