北温带干旱地区土壤剖面CO_2通量的变化特征

采用开放式样杆方法,对干旱土纲的4种土壤类型(栗钙土、灰钙土、粗骨土、山地灰褐土)进行土壤剖面CO2通量的观测研究,结果表明:1)在0～60cm深度范围内土壤剖面CO2通量随土壤深度的增加而增加,60cm为转折点,之后,随土壤深度的增加而减小。2)土壤剖面CO2通量平均值为660μmol/(m2·h),在-9076～16988μmol/(m2·h)范围内变化,如果土地利用/土地覆盖发生改变(0～70cm深度),将可能有254.6t/(km2·a)CO2从土壤向大气释放。3)土壤种类不同,CO2通量明显不同,森林土壤释放量大于草原土壤。4)在通量-深度曲线中,各土壤类型均出现1～2个拐点,变化原因与土壤剖面结构和根系分布有关,钙积层的有无、厚度起决定作用。5)存在季节变化,植物生长季节的CO2通量远大于其他季节,其他季节可能存在土壤吸收CO2现象。因此,应避免在植物生长季节施工动土,以减少土壤CO2向大气中释放。

Characteristics of carbon dioxide flux in soil profiles of arid areas in north temperate regions,China

By an in situ approach of open-sample pole,we studied carbon dioxide flux in the profiles of 4 types of soil,i.e.,chestnut soil,sierozem soil,fragmental soil and gray-cinnamon soil.The results were that 1) CO_2 flux increased with soil depth at 0-60 am,and then decreased at greater soil depths.2) Mean soil CO_2 flux at 0-70 am depth was 660 μmol/ (m~2·h) ,ranging from-9076 to 16988 μmol/ (m~2·h) .A total of 254.6 t/ (km~2·a) CO_2 gas may be released from the soil into the atmosphere if the soil at 0-70 cm depth was exposed to the air because of a change in land use/land cover.3) Soil CO_2 flux differed greatly in the soil types,and the amount of CO_2 released from forest soils (gray-cinnamon soil and fragment soil) was larger than that from grassland soils (sierozem soil and chestnut soil) .4) In the flux-depth curve of each soil type,there was 1-2 turning points which are correlated with soil structure,root distribution and calcium accumulation layer.5) Soil CO_2 flux changed as a function of season,which was greater during growing season than other seasons,demonstrating a phenomenon of the soil absorbing CO_2 in other seasons.Our results suggest that soils should be treated carefully when breaking the ground,to reduce the release of soil CO_2 into atmosphere.