大兴安岭重度火烧迹地天然次生林土壤温室气体通量及其影响因子

Soil greenhouse gases fluxes and the affecting factors of natural secondary forest from seriou-sly burned area in Greater Khingan Mountains,China

为研究大兴安岭重度火烧迹地自然恢复后的林分土壤温室气体源汇强度及其影响因素,采用静态箱/气相色谱法,对生长季(6—9月)天然次生林土壤温室气体CO_2、CH_4、N_2O通量进行原位观测.结果表明:1)生长季内天然次生林土壤为大气CO_2、N_2O的源,CH_4的汇,平均通量分别为575.81 mg·m^(-2)·h^(-1)、17.81μg·m^(-2)·h^(-1)和-68.69μg·m^(-2)·h^(-1);CO_2与CH_4通量在生长季内表现出明显的双峰变化规律,N_2O通量则呈单峰变化,且均在8月达到观测期的最大值.2)土壤温度是影响该区天然次生林土壤温室气体通量的主控因子,土壤湿度和大气湿度在昼夜与季节尺度上与土壤温室气体通量的相关性不同.3)该区天然次生林9:00—12:00时段观测获得的土壤气体通量值经矫正后可代表当日气体通量.研究补充了大兴安岭火烧迹地森林生态系统温室气体通量数据,为该区土壤温室气体源汇的相关研究提供了依据.

To learn the intensity of greenhouse gases (GHG) fluxes source/sink from soil and the influence factors of a natural secondary forest from seriously burned area in Greater Khingan Mountains, we used static chamber-GC technique to measure soil GHG (CO2, N2O, CH4) in situ during the growing season (from June to September). The results showed that: 1) The soil of natural secondary forest was atmospheric CO2 and N2O source and CH4 sink. The mean fluxes of soil GHG (CO2, N2O, CH4) during the growing season were 575.81 mg·m^-2·h^-1, 17.81 μg·m^-2·h^-1 and -68.69 μg·m^-2·h^-1, respectively. The CO2 and CH4 fluxes showed an obvious double-peak trend and the change of N2O fluxes was a single-peak pattern during the growing season, with all maximum fluxes occurred in August. 2) Soil temperature was the predominant factor controlling the soil GHG fluxes. The correlation of soil/atmospheric humidity and soil GHG fluxes was complicated and differed between diurnal scale and seasonal scale. 3) The soil GHG fluxes measured at 9:00-12:00 am could represent the diurnal average fluxes on the same day after proper correction in this area. The findings supplemented the soil GHG fluxes data of fired forest ecosystem in Greater Khingan Mountains, which could provide a basis for related research of soil GHG source/sink in this area.