重庆缙云山3种林型土壤呼吸及其影响因子

2011年1～12月,采用LI-Cor 8100开路式土壤碳通量测量系统对重庆缙云山保护区3种主要林分类型(针阔混交林、常绿阔叶林和毛竹林)的土壤呼吸速率和林内气温、土壤温度和湿度进行了野外观测。结果表明:针阔混交林、常绿阔叶林和毛竹林的土壤呼吸碳通量分别为654.70、1008.37和910.64 g C m-2a-1;3种林型土壤呼吸速率均呈现显著的季节性变化,且夏季>秋季>春季>冬季,最大值出现在7月,最小值出现在1月;3种林型土壤呼吸速率全年平均值分别为1.73、2.66和2.40μmol m-2s-1;3种林型土壤呼吸速率均与林内气温存在显著正相关关系(P<0.05),且与5 cm土壤温度均存在极显著的指数正相关(P<0.05);与5 cm土壤含水量的相关性不显著(P>0.05),但土壤含水量较低而温度较高时,较低的土壤含水量对呼吸速率具有一定抑制作用;3种林型的土壤呼吸对温度的敏感系数(Q10值)存在差异,全年表现为毛竹林(2.44)>针阔混交林(1.76)>常绿阔叶林(1.72),同时均表现显著的季节差异。

Soil Respiration and Impact Factors of 3 Forest Types in Jinyun Mountain of Chongqing

By using Li-Cor 8100 open soil carbon flux system,an in situ measurement on soil respiration rates,soil temperature,air temperature inside the forests and soil moisture content in three forest types mixed conifer and broadleaf,evergreen broadleaved and Phyllostachys pubescens forest in Jinyun Mountain Nature Reserve of Chongqing from January to December in 2011.The results indicated that the C flux of soil respiration in mixed conifer and broadleaf,evergreen broadleaved and Phyllostachys pubescens forest was 654.70,1008.37 and 910.64 g C/(m2 a).There were distinct seasonal changes in soil respiration rates of the three forest types,and they were summer,autumn,spring and winter in decreasing order,while maximum appears in July,minimum in January.The average annual of soil respiration rates of the three forest types was 1.73,2.66 and 2.40 μmol/(m2 s).There were significant positive correlations between soil respiration rates and the air temperature inside the forests(P<0.05),and with considerably high exponential positive correlations between soil respiration rates and soil temperature in 5 cm soil depth(P<0.05).Soil respiration rates are not significantly correlated with soil volumetric water content(P>0.05),but when soil volumetric water content is lower with higher temperatures,lower soil volumetric water content had a certain inhibitory effect on soil respiration rates.The different sensitivity coefficients to temperature,Q10,were Phyllostachys pubescens forest(2.44),mixed conifer and broadleaf(1.76),evergreen broadleaf(1.72).There were distinct seasonal changes in Q10 of the three forest type.