雷州半岛尾巨桉人工林土壤呼吸动态变化及其对气象因子的响应

Soil Respiration of Eucalyptus urophylla×E. grandis Plantation and Its Response to Meteorological Factors in Leizhou Peninsula

摘要:

为探讨桉树（Eucalyptus spp.）人工林土壤呼吸及其对气象因子的响应，采用LI-8100A土壤碳通量自动测量系统，对雷州半岛北部尾巨桉（E. urophylla×E. grandis）人工林的土壤呼吸速率进行监测。结果表明，尾巨桉人工林土壤呼吸速率具有明显的时间变化特征，表现为单峰曲线型变化趋势，2016年5月和翌年2月分别达到最高值[（3.17±0.12） μmol m^-2s^-1]和最低值[（1.18±0.16） μmol m^-2s^-1]，年均值为（2.34±0.70） μmol m^-2s^-1。根据相关系数，土壤呼吸速率的影响因子以土壤温度 > 气温 > 气压 > 光合有效辐射 > 饱和水汽压差 > 土壤湿度。主成分分析表明，温度、光合有效辐射等引起的热能量变异和土壤湿度等引起的水分变异是土壤呼吸速率的主要影响因子。回归分析表明，气象因子综合模型能解释土壤呼吸速率94.0%的变异情况，模型可靠性较高。尾巨桉林土壤表面全年CO₂通量为893.31 g C m^-2a^-1。气象因子的综合作用能更全面地解释土壤呼吸的时间变异情况。

Abstract:

In order to understand the dynamic change of soil respiration rate and it’s response to meteorological factors, soil respiration rate of Eucalyptus urophylla×E. grandis plantation in Leizhou Peninsula was measured by using LI-8100A Soil carbon flux automatic measurement system. The results indicated that soil respiration rate of E. urophylla×E. grandis plantation changed distinctly from March 2016 to February 2017, showing single peak curve with the maximum at May, 2016 and minimum at February, 2017, respectively. The mean soil respiration rate was (2.34±0.70) μmol m^-2s^-1. According to the correlation coefficient, the influencing factors on soil respiration rate was ordered as soil temperature > air temperature > atmospheric pressure > photosynthetical active radiation > vapor pressure deficit > soil moisture. Furthermore, the principal component analysis showed that the variation of heat energy caused by temperature and photosynthetical active radiation and that of moisture caused by soil moisture were the main effect factors on soil respiration rate. The meteorological factors model was reliable due to 94.0% variation of soil respiration rate can be explained by regression analysis. The cumulative annual CO₂ flux of soil surface in E. urophylla×E. grandis plantation was estimated as 893.31 g C m^-2a^-1. The temporal variation of soil respiration could be fully explained by coupling effect of meteorological factors.