喀斯特石漠化地区土壤温室气体的地气交换特征

The characteristics of greenhouse flux of soil in Karst rocky desertification regions

利用密闭箱-气相色谱法于2006～2007年对黔中喀斯特地区土壤二氧化碳、氧化亚氮和甲烷的释放通量进行原位观测,研究我国南方喀斯特石漠化地区土壤温室气体地气交换特征。结果表明:喀斯特石漠化地区土壤是大气CO_2、N_2O的释放源,CH_4的吸收汇。土壤CO_2的释放通量介于450.8±50.8～1281.3±214.7 mg·m^(-2)·h^(-1)在之间,夏秋季节高于冬春季节;N_2O的释放通量介于-25.4±4.1～105.8±31.2μg·m^(-2)·h^(-1)之间,在夏季最高,在9月、11月和12月出现土壤对大气N_2O的吸收;全年CH_4交换通量介于-0.27±0.18～0.81±0.26 mg·m^(-2)·h^(-1)之间,随季节的变化不明显。气候条件对土壤CO_2和CH_4交换通量的影响较小,土壤水分对N_2O释放通量的影响效应在不同的季节不同。相关分析结果显示,土壤N_2O和CH_4地气交换通量受到土壤硝态氮含量的调控。

CO2, N2O and CH4 fluxes from Karst rocky desertification areas in central Guizhou were measured monthly by using static chamber-GC method from June 2006 to May 2007 to investigate the characteristics of seasonal change of greenhouse gas fluxes from soil in Karst region in South China. The results indicate that the soils are the sources of CO2 and N20, but the sink of CH4. CO2 fluxes change from 450.8±50.8 to 1281.3±214.7 mg·m^-2·h^-1, with higher fluxes in summer and autumn, but lower fluxes in spring and winter. N2o fluxes vary from -25.4±4.1 to 105.8±31.2 μg ·m^-2·h^-1, with the highest fluxes in summer. The soils absorb N2O in the air in September, November and December. CH4 fluxes show no significant changes with the seasons, and they vary from -0.27±0.18 to 0.81±0.26 mg·m^-2·h^-1. The climate conditions have no obvious effects on the fluxes of CO2 and CH4.The effects of soil water on N2O fluxes vary with seasons. The correlation analysis shows that there is significant correlation between soil nitrate content and N2O/CH4 fluxes, suggesting nitrate content in soil is the primary driven factor affecting the seasonal change of N2O and CH4 fluxes.