内蒙古羊草草原不同物候期CH_4通量日变化特征与日通量比较

The comparison of the CH 4 flux diurnal variation characteristics and diurnal uptake flux in different phenologies in Leymus Chinense grassland in Inner Mongolia,China

利用静态暗箱法对内蒙古半干旱羊草草原不同物候期原状群落与土壤CH4 通量的日变化进行了野外定位试验研究 ,结果表明 :羊草草原土壤为大气CH4 的吸收汇 ,不同观测日CH4 通量的日变化特征存在较大差异 ;气温及表层地温与CH4 吸收通量除果后营养期呈显著或极显著正相关外 ,其余观测日两者的相关性不明显 ;原状群落与土壤CH4 吸收通量间除2 0 0 2年果后营养期以及 2 0 0 3年开花期两者差异分别达到 0 10与 0 0 5的显著性水平外 ,两者在其余观测日差异均不显著 ;不同物候期间CH4 日平均通量除原状群落开花期与结实后期间 ,开花期与 2 0 0 1年果后营养期以及结实后期与 2 0 0 2年果后营养期间差异显著外 ,其它不同物候期之间CH4

Using the static chamber method, the diurnal variation of CH 4 fluxes of the undisturbed community and soil were studied through the experiment in situ at different phenologies of Leymus Chinense grassland in Xilin river basin of Inner Mongolia. According to the results of field experiment, we analyzed the characteristics of diurnal variation of undisturbed community and soil CH 4 flux and the statistic relationship between CH 4 fluxes and environmental factors (e.g. air temperature, surface soil temperature, soil moisture) together with the ecological factors(e.g. aboveground biomass, underground biomass, litter biomass)by correlation analysis and multiple stepwise regression method. The main research results were as follows: The fluxes of undisturbed community and soil CH 4 were all negative and the Leymus Chinense grassland was the sink of air CH 4. There was great difference among diurnal variation patterns of CH 4 flux in different phenologies and the effect of temperature condition on diurnal variation of CH 4 flux wasn't remarkable except the post-fruiting vegetative stage. The difference between undisturbed community CH 4 fluxes and corresponding soil CH 4 fluxes wasn't significant except in post-fruit vegetative stage of 2002 and in flowering stage. And for the difference of undisturbed community CH 4 flux among different phenologies, the difference between flowering stage and post grain-filling stage, flowering stage and post-fruiting vegetative stage of 2001, post grain-filling stage and post-fruiting vegetative stage of 2002 reached the significance of 0.01 or 0.05, but the differences of undisturbed community CH 4 flux between any other two phenologies and the differences of soil CH 4 flux between any two phenologies were all not significant. The results of multiple regression analysis indicated that the changes of underground biomass at 0-20cm depth could account for 95.0% of the variance of the community CH 4 flux and 99.0% of the change of soil CH 4 flux of different phenologies. The change of the ratio of soil CH 4 diurnal uptake flux and the total community diurnal uptake flux was affected markedly by the change of litterfall biomass.