两种亚热带森林土壤甲烷氧化活性的垂直分布特征

Vertical Distribution of Methane Oxidation Activity in two Sub-tropic Forest Soils

为明确亚热带森林土壤甲烷(CH_4)氧化活性的垂直分布特征,对福建省万亩林保护区的天然林和杉木(Cunninghamia lanceolata)人工林0~60 cm土层CH_4氧化速率进行了测定与分析。结果发现,天然林和杉木林土壤CH_4氧化活性都主要分布在0~40 cm土层(92.8~94.9%)。0~6 cm土层,杉木林CH_4氧化速率(0.33 ug CH_4g^(-1)d^(-1))显著小于天然林(0.57ug CH_4g^(-1)d^(-1),P<0.05),6~60 cm土层,两者无显著差别。杉木林和天然林CH_4氧化速率垂直分布趋势在样品之间存在着很大变化,表层土(0~3 cm)与亚表层土(3~6 cm)氧化速率差异是垂直分布趋势变化的主要原因。表层土CH_4氧化速率变异程度高(天然林和杉木林的变异系数分别为54.0%和86.4%),且与下面相邻层不相关,表明,相对于亚表层及其以下土层,表层土CH_4氧化可能受更多环境因子调控。

To characterize the vertical distribution of methane （ CH4 ） oxidation activity for the sub-tropic forest soils, the CH4 oxidation rates were measured at the 0~60 cm soils from a natural forest and a fir （ Cunninghamia lanceolata） plantation in the Wanmulin Nature Reserve of Fujian Province. Results showed that CH4 oxidation were mainly located in the 0~40 cm soils in both forests （ 92. 8~94. 9%） . The CH4 oxidation rates were significantly lower in the fir plantation soils （0. 33 ugCH4 g-1 d-1 ） than in the natural forest （0. 57 ugCH4 g-1 d-1 ） from 0 to 6 cm, but not significantly different throughout the depth of 6 ~60 cm. The vertical distribution of CH4 oxidation rates varied among the samples due to the difference between the top （0~3 cm） and sub-top （3~6 cm） soils. The variabili-ty of CH4 oxidation rates was high in the top 3cm soils, with the coefficients of variation of 54. 0% for fir plantation and 84. 6% for natural forest, respectively. The CH4 oxidation rates in the top soils showed no correlations with those of the underlying layers. Therefore, the methane oxidation rates in the top soils were likely to be regulated by more environmental factors than the soils underlying it.