桂林尧山桉树及马尾松林冬季土壤碳通量特征

Characteristics on Soil Carbon Flux of Eucalyptus spp.and Pinus massoniana Forest in Winter in Yaoshan Mountain of Guilin,China

本研究以桂林尧山的4年生桉树幼龄林、20年生桉树老龄林和22年生马尾松林为研究对象,于冬季(2012年12月至2013年2月)分别对这3种林分的土壤呼吸及其组分、土壤温度、土壤湿度进行3个月的观测,结果表明:①4年生桉树幼龄林的土壤呼吸速率与20年生桉树老龄林差异不显著,但显著大于22年生马尾松林,20年生桉树老龄林与22年生马尾松林也无显著差异。总体来看,3种林分的土壤呼吸都处在较低水平。②3种林分异养呼吸速率差异不显著,自养呼吸速率差异显著,其大小顺序为:4年生桉树幼龄林>20年生桉树老龄林>22年生马尾松林。4年生桉树幼龄林的自养呼吸贡献率明显大于20年生桉树老龄林和22年生马尾松林。③相关性分析表明,土壤温度是影响土壤呼吸及其组分的主要环境因子,温度与土壤呼吸呈显著的指数关系,土壤含水量对土壤呼吸的影响不显著。④对温度敏感性系数Q10值的分析表明,3种林分中20年生桉树老龄林的温度敏感性最大,4年生桉树幼龄林对温度敏感性最小。

The experiment was conducted on the young-growth Eucalyptus spp. forest （4 a）,old-growth Eucalyptus spp. forest （20 a） and the Pinus massoniana forest （22 a） from December 2012 to February 2013 in Yaoshan Mountain of Guilin, and the soil respiration and its components, the soil temperature and the soil water content of the three stands had been observed. The results are as follows： （1）The soil respiration rate of the young-growth Eucalyptus spp. forest was higher than the Pinus massoniana forest significantly,but with no significant difference between the young-growth Eucalyptus spp. forest and the old-growth one, and between the old-growth Eucalyptus spp. forest and the Pinus massoniana forest. In general, the soil respiration rates of the three stands were at low level. （2）There was no significant difference on the heterotrophic respiration rate among the three stands,however, the reverse results occurred on the autotrophic respiration rate with the following order, the young-growth Eucalyptus spp. forest^the old-growth Eucalyptus spp. forest~＇〉the Pinus massoniana forest. The rate of contribution of autotrophic respiration of the young-growth Eucalyptus spp. forest was significantly greater than the old-growth one and the Pinus massoniana forest. （3）According to correlation analysis, the soil temperature was the main environmental factor influencing the soil respiration rate and its components. There existed exponential relationship between the soil temperature and the soil respiration rate and its components. However, soil moisture content didn＇t have a significant influence on the soil respiration rate. （4）As for the three stands, the Q10 value analysis of the temperature sensibility coefficient indicated that the value of the old-growth Eucalyptus spp. forest was the highest and the young-growth Eucalyptus spp. forest was the lowest.