桂林市尧山桉树及马尾松林春、夏两季土壤碳通量特征

目的]以广西壮族自治区桂林市尧山地区的4年生桉树林、20年生桉树林和22年生马尾松林为研究对象,旨在研究由森林类型、林龄及其它因子驱动的森林土壤呼吸动态变化特征,并为桉树、马尾松人工林生态系统碳动态模拟提供基础数据。方法]采用Li-8100土壤碳通量测量系统于2013年3—8月(春、夏两季),分别对这3种林分的土壤呼吸及其组分、土壤温度、土壤湿度进行了6个月的观测。结果](1)3种林分的土壤总呼吸速率无显著差异。(2)4年生桉树林的自养呼吸速率显著大于20年生桉树林及22年生马尾松林。20年生桉树林的异养呼吸速率显著大于4年生桉树林及22年生马尾松林。(3)土壤温度是影响土壤呼吸及其组分的主要环境因子,3种林分土壤呼吸及其组分与土壤温度均呈显著的指数关系;(4)4年生桉树林的土壤呼吸与土壤含水量的相关性不显著,20年生桉树林的土壤呼吸与土壤含水量呈显著正相关关系,22年生马尾松林的土壤呼吸与土壤含水量呈显著负相关关系。(5)对温度敏感性系数Q10值的分析表明,4年生桉树林的温度敏感性较大,20年生桉树林和22年生马尾松林较小。

Characteristics of Soil Carbon Flux of Eucalyptus sp. and Pinus Massoniana Forest During Spring and Summer in Yaoshan Mountain of Guilin City

Objective] Based on the 4 years old, 20 years old Eucalyptus sp. plantations and 22 years old Pinus massoniana plantations in Yaoshan Mountain in Guilin City of Guangxi Zhuang Autonomous Region, this study conducted the characteristics of forest soil respiration which droved by forest types, forest age and other factors, so that to provide basic data with carbon dynamic simulation on Eucalyptus and Pinus massoniana plantations ecosystem.Methods] From March to August in 2013(during Spring and Summer), the soil respiration and its components(soil autotrophic respiration and soil heterotrophic respiration), soil temperature and the soil water content of the three forests were observed monthly with the Li-8100 automated soil CO₂ flux system respectively.Results] (1) There was no significant difference in the soil respiration rate among the three forests; (2) The autotrophic respiration rate of the 4 years old Eucalyptus sp. forest was higher than that of the 20 years old Eucalyptus sp. forest and 22 years old Pinus massoniana forest. The heterotrophic respiration rate of the 20 years old Eucalyptus sp. forest was higher than the 4 years old Eucalyptus sp. forest and the 22 years old Pinus massoniana forest; (3) According to the correlation coefficient analysis, soil temperature was the main environmental factor influencing the soil respiration rate and its components. There existed exponential relationships between soil temperature and soil respiration rate and its components; (4) In the 4 years old Eucalyptus sp. forest, the correlation between soil moisture content and soil respiration rate was indistinctive, there were significant positive correlations between soil respiration rate and soil moisture content in the 20 years old Eucalyptus sp. forest, and significant negative correlations between soil respiration rate and soil moisture content in the 22 years old Pinus massoniana forest; (5) the Q₁₀ value analysis of the temperature sensibility coefficient of the three forests indicated that the value of the 4 years old Eucalyptus sp. forest was higher, the 20 years old Eucalyptus sp. forest and the 22 years old Pinus massoniana forest were lower.