木麻黄沿海防护林土壤呼吸动态及其关键影响因子

Soil respiration dynamics and major controlling factors in a coastal protective forest

以中国亚热带木麻黄沿海防护林为研究对象,利用LI-8100土壤呼吸自动观测系统,对木麻黄人工林生态系统的土壤呼吸特征进行了监测.结果表明,不同林龄木麻黄林地土壤呼吸日动态均呈双峰变化曲线,8：00-10：00和14：00-16：00出现峰值,最小值出现在20：00-22：00;季节动态均呈单峰曲线,最大值出现在6-7月份,最小值则出现在12-1月份.土壤温度和水分对土壤呼吸的季节变化存在显著影响,并有明显的交互作用,进行单因素方差分析发现,土壤呼吸季节变化与5cm土温存在着较好的指数相关关系（P〈0.01）,与土壤表层含水量存在较好的线性相关关系（P〈0.01）.利用双因素模型模拟发现,5cm土温和土壤表层含水量能够共同解释土壤呼吸变异的69.0%-91.9%（P〈0.05）.不同林龄的土壤呼吸速率差异显著（P〈0.05）,其平均土壤呼吸速率呈现中林〉成林〉幼林;随着林龄的增大,土壤呼吸对土壤温度和土壤水分的敏感性增强.

The soil respiration in 3 Casuarina equisetifolia plantations with different ages in a coastal sub-tropical ecosystem was monitored with an LI-8100 Automated Soil CO2 Flux System from May 2006 to April 2007. Diurnal dynamic of soil respiration featured two peaks, with the maximums at 8：00-10：00 and 14：00-16：00, and with the minimum at 20：00-22：00. Seasonal dynamic of soil respiration featured a single peak, with the maximum at June or July and the minimum at December or January. Soil respiration had a highly exponent relation to soil temperature at 5 cm depth, and a highly linear relation to soil water content of the upper 20 cm. In addition, regression equation--R=a×e^bT×W^c could better predict soil respiration than using respective independent variable, and the R2 values were 0.69, 0.92 and 0.90 for the 3 plantations, respectively. Soil respiration rates were the highest in middle-age plantation, followed by the mature plantation, and the lowest was young-age plantation. With the increase of plantation age, the variation of soil respiration was more sensitive to the change in soil temperature and soil moisture.