亚热带次生林土壤自养和异养呼吸研究

Investigation of Heterotrophic and Autotrophic Components of Soil Respiration in a Secondary Forest in Subtropical China

以南京市郊北亚热带次生林为研究对象,于2010年设置挖沟断根和不断根处理小区,观测了土壤呼吸、异养呼吸的季节变异规律,并以此计算了自养呼吸速率,同时,观测了土壤温度、湿度等环境因子.结果表明,土壤呼吸、异养呼吸具有相似的季节变化规律,季节平均土壤呼吸、异养呼吸和自养呼吸速率分别为3.42、2.36和1.06μmol.(m2.s)-1.回归分析表明,异养呼吸随土壤呼吸增大而增加,异养呼吸(y)与土壤呼吸(x)之间的关系可用对数回归方程描述,该方程可解释异养呼吸90.5%(R2=0.905)的季节变异.进一步的分析表明,土壤呼吸不同组分与温度间均存在指数回归关系,描述土壤呼吸、异养呼吸、自养呼吸与温度间关系的指数回归方程可分别解释78.4%、76.4%和65.6%的变异,P值均达到极显著水平(P<0.01).根据回归方程估算的土壤呼吸、异养呼吸和自养呼吸温度系数Q10值分别为1.97、1.76和3.31.本研究表明,在树木生长的3～10月,土壤呼吸自养和异养组分的比例分别为69%和31%,且异养呼吸的温度敏感性显著小于自养呼吸的温度敏感性.

Trenched plots were set up in 2010 in a secondary forest in subtropical China,in order to investigate the seasonal variations of soil respiration（Rs） and heterotrophic respiration（Rh）.Autotrophic respiration（Ra） was estimated to be the difference between Rs and Rh.Soil temperature and moisture were simultaneously measured during respiration measurements.Results indicated that Rs and Rh showed the similar seasonal variations.Seasonal mean rates for Rs,Rh and Ra were 3.42,2.36 and 1.06 μmol·（m2·s）-1,respectively.Regression analysis indicated that Rh increased with the increase of Rs;an natural logistic equation could be employed to explained the relationship between Rh（y） and Rs（x）.Approximately 90.5%（R2=0.905） variations in Rh could be explained by the equation.Apparent exponential relationships of Rh and Ra with soil temperature existed,but differed from each other and from the relationship for Rs.The exponential equations explained about 78.4%,76.4% and 65.6% variations in Rs,Rh and Ra,respectively,with the P values less than 0.01.The Q10 values for Rs,Rh and Ra were 1.97,1.76 and 3.31,respectively.It was indicated that,seasonally,Rh and Ra represented 69% and 31% of Rs.Ra showed significantly higher temperature sensitivity than Rh.