黄土高原西段表层土壤有机碳储量及时空变化规律

黄土高原表层土壤有机碳在土壤碳循环中具有重要地位,通过土地质量地球化学调查获得的黄土高原甘肃省境内表层土壤有机碳数据,总结了表层土壤有机碳在不同土壤类型、土地利用方式及地形地貌中的分布特征,分析了研究区土壤有机碳密度与全国其他典型地区的差异,并与全省第二次土壤普查成果进行了比较。结果表明:在不同土壤类型中有机碳密度呈灰褐土>高山草甸土>黑钙土>栗钙土>红黏土>灌漠土>灌淤土>黑麻土>黑垆土>黄绵土>灰钙土>风沙土的分布趋势;在不同土地利用方式下土壤有机碳密度呈林地>建设用地>耕地>园地>草地>未利用地的分布趋势;在不同地形地貌单元间土壤有机碳密度呈塬面>梯田>坡地>沟道的分布规律。黄土高原西段表层土壤有机碳密度在全国各典型地区最低,为1.87 kg/m²;有机碳储量为78.56 Mt,较1990年增幅10.54%,近年来土壤有机碳储量呈不断上升趋势。

Topsoil Organic Carbon Storage and Its Spatial and Temporal Variation in the Western Loess Plateau

Surface soil organic carbon plays an important role in soil carbon cycle in the Loess Plateau. A prelimi-nary study was conducted on the storage and distribution characteristics of soil surface organic carbon (SOC) in Gansu Province in the western part of the Loess Plateau,and the distribution regularity of SOC in different land utilization patterns and soil types was analyzed. Meanwhile,the difference of SOC in different landform was compared with the results of the second soil census in Gansu Province. The results showed that the average organic carbon density,from high to low,was forest land,construction land,cultivated land,orchard,grassland,unutilized land. The highest average organic carbon density,from high to low,in each soil type was as follows: cinnamon soil,alpine meadow soil,chernozem,chestnut soil,red clay,irrigated desert soils,anthropoge-nic-alluvial soil,black gunny soil,black loessial soil,yellow loamy soil,sierozem and sand. And the organic carbon density in different geomorphologic units,from high to low,was tablelands,terraces,hillside fields,gullies. The total organic carbon storage in the western part of the Loess Plateau is 78.56 Mt now,which is 10.54% higher than that in 1990,and the soil organic carbon density is 1.87 kg/m². The storage of topsoil's organic carbon in the western part of the Loess Plateau is on the rise.