中亚热带米槠天然林土壤甲烷吸收速率季节变化

Seasonal variations of soil CH_4 uptake rate in Castanopsis carlesii forest in mid-subtropical China

以福建省建瓯市万木林自然保护区米槠天然林为对象,定位观测了土壤甲烷吸收速率(VCH4)的季节变化.结果表明:米槠天然林土壤VCH4的季节变化表现出夏秋季高于冬春季的趋势,最大值(95.13μg·m-2·h-1)出现在初秋(9月),最小值(9.13μg·m-2·h-1)出现在初春(3月).土壤全年均为甲烷汇.随土壤温度和含水量的增加,VCH4分别呈增加和降低趋势,但VCH4与土壤温度和土壤含水量的相关性均不显著.米槠天然林土壤甲烷年通量为3.93kg·hm-2·a-1,高于全球天然林土壤甲烷年通量的平均水平(2.4kg·hm-2·a-1)和亚洲地区热带天然林土壤甲烷年通量(2.07kg·hm-2·a-1),低于亚洲地区温带天然林的土壤甲烷年通量(8.12kg·hm-2·a-1).

A monthly measurement of soil CH4 uptake rate （VCH4） in a natural Castanopsis carlesii forest in Wanmulin Natural Reserve of Fujian Province, East China was conducted from March 2010 to February 2011. The VCH4 showed a pronounced seasonal fluctuation, being higher in summer-autumn than in winter-spring, with the maximum value （95.13 μg·m-2·h-1） in September and the minimum value （9.13 μg·m-2·h-1） in March. With the increase of soil temperature and moisture, the VCH4 showed an increasing and a decreasing trend, respectively, but the correlations of the VCH4 with soil temperature and moisture were not significant. The annual soil CH4 flux of the forest （3.93 kg·hm-2·a-1） was higher than the average value of global natural forests （2.4 kg·hm-2·a-1） and of Asian tropical natural forests （2.07 kg·hm-2·a-1）, but lower than that of Asian temperate natural forests （8.12 kg·hm-2·a-1）.