杉木人工林皆伐火烧后土壤呼吸研究

Soil Respiration of Chinese Fir Plantation Subjected to Clear-cutting and Burning in the Mid-subtropical Zone,China

通过静态碱吸收法对福建三明27年生杉木人工林皆伐火烧后土壤呼吸进行为期1年多的定位研究．研究发现，林地皆伐火烧后土壤呼吸速率季节变化呈单峰曲线，对照地和皆伐地最大值均出现在6月，火烧地最大值出现在4月和5月之间，3块样地最小值均出现在12月．1年中对照地、皆伐地和火烧地土壤呼吸速率（释放CO2）变化范围分别在86．1～367．9mg m^-2h^-1、62．2～211．7mg m^-2h^-1和42．6～150mg m^-2h^-1之间．用指数模型和双因素模型对土壤呼吸进行拟合显示，温度和湿度是对照地的主要影响因子，但温度和湿度不能很好地解释皆伐地和火烧地土壤呼吸速率的变化．双因素模型中，土壤呼吸温度敏感性因子Q10对照地为2．1，皆伐地和火烧地分别为1．3和1．1，小于已报道范围．

A number of studies have been conducted to compare soil CO2 efflux under different kinds of forest management practice, including clearfelling. However, the pattern of soil CO2 efflux reported after clearfelling is not consistent across these studies. The primary purpose of this stucly was to determine seasonal dynamics, controlling factors of soil respiration of Chinese fir after clear-cutting and burning. The rates of soil respiration were determined in situ utilizing the alkali sorption method. The soil respiration rates on the three contrasting sites （i. e. control, clear-cutting and burning） showed a similar seasonal pattern with one single peak occurring during summer and a minimum during the winter, and varied from 86.1 to 367.9 mg m^-2h^-1 on the control, from 62.2 to 211.7 mg m^-2h^-1 on the clear-cutting site and from 42.6 to 150 mg m^-2h^-1 on the burning site. The soil respiration on the control site was mainly controlled by soil temperature at 5 cm depth （R^2 =0.93）, and soil temperature and soil water content at 0410 cm depth together could explain 98% of the variation. However, soil temperature and soil water content together only explained 5%-33% of the variation in soil respiration of clear-cutting and burned field sites. Soil respiration rate on the control site had the greatest value of Q10 at 2.1, followed hy the clear-cutting site at 1.3 and the hurned field site at 1. 1.