改变凋落物输入对喀斯特森林主要演替群落土壤呼吸的影响

以贵州茂兰国家级自然保护区内的喀斯特原生乔木林和次生林为研究对象,利用LI-Cor-6400-09(土壤呼吸叶室)连接LI-6400便携式CO2/H2O分析系统,通过改变凋落物输入,研究了2种群落类型添加和去除凋落物对其土壤呼吸速率以及5 cm深度土壤温度的影响。结果表明:改变凋落物输入对2种群落类型5 cm深度土壤温度产生的差异不显著(P0.05),但均表现为:添加凋落物对照去除凋落物。喀斯特原生乔木林和次生林添加凋落物的年均土壤呼吸速率分别为2.98和3.31 mol/(m2s),分别比对照的年均增加了32.21%和26.20%;去除凋落物的年均土壤呼吸速率分别为2.07和2.14 mol/(m2s),比对照的年均分别降低了17.41%和22.36%;可见,凋落物是影响森林CO2通量的一个重要因子。不同凋落物处理下2种群落类型的土壤呼吸速率与其5 cm深度土壤温度均呈显著的指数相关关系(P0.001),能解释土壤呼吸速率变化的85%以上(R2在0.877 0～0.957 7之间)。原生乔木林和次生林添加、去除凋落物和对照的土壤呼吸的温度敏感系数Q10值分别为2.97、3.89、3.82和2.74、3.29、2.87,均表现为去除凋落物对照添加凋落物。 

Effects of litter exclusion and addition on soil respiration of major forest communities at two successional stages in Maolan karst forest of southwestern China

With communities at two successional stages, i. e. , primary forest ( PF ) and secondary forest ( SF) , in karst region of Maolan National Nature Reserve as the research object, and using the portable system of infrared gas exchange analyzer ( LI-Cor-6400-09 ) , we studied the effect of litter exclusion and addition on soil respiration rate and soil temperature at the depth of 5 cm by changing the litter input. The results showed that there was no significant difference in soil temperature ( P >0. 05 ) between two successional stages when changing the litter input, both following the order of litter addition>control>litter exclusion. In the litter addition experiment, the annual soil respiration rate was 2. 98μmol/( m2·s) in PF and 3. 31μmol/( m2·s) in SF, which was 32. 21% and 26. 20% higher than that of control. In the litter exclusion treatment, the annual soil respiration rate was 2. 07 μmol/( m2·s) in PF and 2. 14μmol/(m2·s) in SF, which was 17. 41% and 22. 36% lower than control, respectively. The results demonstrated that forest litter was an important factor affecting forest CO2 flux. At both successional stages, there was a significantly exponential correlation between soil respiration rate and soil temperature at 5 cm depth (P<0. 001), which could explain more than 85% of variation in soil respiration rate (R2 ranged from 0. 877 0 -0. 957 7 ) . The temperature sensitivity coefficient of soil respiration Q10 of litter exclusion, litter addition and control treatment were 2. 97, 3. 89, 3. 82 in PF and 2. 74, 3. 29, 2. 87 in SF, respectively, and they all presented the order of litter exclusion>control>litter addition.