【摘要】 研究土壤有机碳垂直分布特征规律对精确测算土壤有机碳储量具有重要意义。通过野外调查实地挖取北京市平原区40个典型土壤剖面共169个样品数据,研究土壤有机碳垂直分布特征。结果表明:1)北京市平原区0—150 cm土壤平均有机碳含量为(5.98±2.62) g/kg,垂直分布上,随剖面深度增加土壤有机碳含量逐渐降低,且在浅层(≤60 cm)下降速度显著快于深层(>60 cm); 2)各发生层次不同土壤质地的有机碳含量差异整体上均表现为粉粒及黏粒含量比例越高,即质地越黏重,土壤有机碳含量越高; 3)不同土体构型的平均土壤有机碳含量大小关系为通体砂<通体壤<上壤下黏<夹黏,通体砂型土壤有机碳含量垂直变化相对平缓,上壤下黏型土壤有机碳含量在垂直方向呈"降-升-降"趋势,通体壤及夹黏型则均呈先快速下降后缓慢下降趋势; 4)耕地和园地土壤平均有机碳含量高于荒草地,耕地在整个剖面中土壤有机碳含量均居于三种土地利用类型之首,耕地和园地的土壤有机碳含量在0—20 cm和40—60 cm之间下降速度高达40.10%和55.92%,剖面深度超过60 cm后下降速度显著放缓,受人类活动直接影响相对较少的荒草地在垂直方向上变化相对平缓。更多还原

【Abstract】 Understanding the vertical distribution of soil organic carbon(SOC) is of great significance for precisely assessing SOC storage. In this paper,data from 169 samples of 40 typical soil profiles in the plains areas of Beijing were excavated in the field and analyzed to investigate the vertical distribution characteristics of SOC. The results showed: 1) The average SOC content in the 0—150 cm depth in the plains areas of Beijing was 5.98 ± 2.62 g/kg. SOC content gradually decreased with depth,and the rate of decrease in the shallow(≤60 cm) SOC was significantly faster than that in deep(>60 cm) SOC. The average SOC contents in the depths of 0—20,20—40,40—60,60—80,80—100 cm and 100—150cm were 8.49,6.47,4.78,4.94,4.61 g/kg and 3.87 g/kg,respectively. 2) The differences in the SOC of different soil textures at different profile layers generally showed that the higher the proportion of powder and clay content,namely,the more viscous the texture,the higher the content of SOC. 3) The trend of average SOC contents along different soil profile configuration patterns was sand-sand-sand < loam-loam-loam < loam-loam-clay < loam-clay-loam. The average SOC of sandsand-sand was significantly lower than that of the other soil profile configurations,and its vertical variation was relatively gentle. The SOC content of loam-loam-clay showed a vertical trend of "decline-rise-decline",while the SOC content of loam-loam-loam and loam-clay-loam showed a trend of rapid decrease and then slight decrease. 4) The average SOC contents of cultivated land and orchard land were higher than that of grassland,and the cultivated land in each profile levelranked the first among the three kinds of land use types. The SOC content of cultivated land and orchard land decreased by40.10% and 55.92%,respectively,between the depths of 0—20 cm and 40—60 cm,and the rate of decrease slowed down significantly in the profile depths deeper than 60 cm. Compared with the cultivated land and orchard land,which were more directly affected by human activities,the SOC contents of grassland changed relatively gently in the vertical direction.更多还原