不同林龄闽楠林土壤呼吸与碳储量研究

Study on the soil respiration and carbon reserve in different age stands of Phoebe bournei

本研究采用Li-8100土壤碳通量观测系统,对成熟林(38 a)、中龄林(22 a)和幼龄林(7 a) 3种闽楠人工林土壤呼吸进行1 a的定位观测,并测定各林龄闽楠林分土壤有机碳含量。结果表明:不同林分年龄闽楠林土壤呼吸速率的季节变化表现出明显的单峰曲线格局;土壤温度与土壤呼吸呈极显著的指数相关(P<0.01),土壤含水率对土壤呼吸的影响不显著(P>0.05)。随着林龄的增加,土壤呼吸年通量也相应增大,7、22和38 a的闽楠林土壤呼吸年通量依次是1 117、1 370和1 686 g·hm^(-2)·a^(-1);温度敏感性指数Q_(10)值也随林分年龄增加而增大,但三者间无显著差异;土壤有机碳储量随林分年龄的增加而增大,成熟林显著高于中龄林与幼龄林(P<0.05); Pearson相关分析表明,土壤呼吸年通量与表层土壤有机碳密度呈极显著相关(P<0.01),表层土壤有机碳含量的差异是引起3种林龄闽楠人工林土壤呼吸年通量产生变化的重要因素。

Soil respiration and soil organic C content were investigated along a stand development sequence of Phoebe bournei plantations(7,22,38 a).The results showed that soil respiration rates of P.bournei plantations with different stand ages are characterized by a similar unimodal humpbacked trend,which peaked in summer.A significant exponential relationship between soil temperature and respiration rate was observed in the P.bournei plantations(P<0.01),while soil respiration rate showed a weak relationship with soil water content(P>0.05).With stand age development,the annual fluxes of soil respiration increased,being 1 117,1 370 and 1 686 g·hm-2·a-1 at 7,22 and 38 a stand,respectively.The Q 10 value(i.e.,temperature sensitivity index of soil respiration)also slightly increased with stand age.Soil organic carbon storage increased with stand development,and the mature forest is significantly higher than the middle and young forest(P<0.05).Pearson correlation analysis showed that the annual flux of soil respiration were significantly correlated with the density of surface soil organic C(P<0.01),and the organic C content of surface soil is an important determinant of the annual flux of soil respiration in these forests.