川西高原泥炭沼泽土壤有机碳分布特征及其影响因素

Distribution characteristics of soil organic carbon and its influencing factors in the peatlands of Western Sichuan Plateau,China

川西高原是中国高海拔泥炭地集中分布区,有机碳资源丰富,但由于方法学差异及数据缺乏,其有机碳分布研究存在一定程度的不确定性,探究其分布特征对于补充该地区泥炭资源数据具有重要意义.通过大量野外调查,收集了川西高原阿坝州和甘孜州共87个样点的0-30 cm深度泥炭沼泽土壤样品,分析其有机碳含量及有机碳密度分布特征,并讨论环境因子对有机碳分布的影响.结果表明,在垂直分布上,川西高原泥炭沼泽表层(0-10 cm)土壤有机碳含量显著高于亚表层(10-30 cm)土壤,与土壤pH、土壤容重显著负相关(P<0.01).在空间分布上,土壤有机碳含量及有机碳密度均随纬度增加而显著降低,有机碳含量分布主要受土壤容重及年均温影响,有机碳密度分布主要由年均温及纬度决定.此外,本研究区域泥炭沼泽0-30 cm土壤平均有机碳密度(20.04 kg/m^(2))是整个中国陆地生态系统0-30 cm土壤有机碳密度(3.70 kg/m^(2))的约5.4倍.总体而言,川西高原泥炭沼泽土壤有机碳资源丰富,有机碳含量及密度在空间分布上表现为“北低南高”,这种分布格局主要由年均温决定,结果可为更深入理解气候变化下的高海拔泥炭沼泽生态系统碳循环提供一定理论和数据支撑.(图4表7参82)

China’s Western Sichuan Plateau contains an abundance of peatlands,with abundant soil organic carbon resources.However,methodological differences and lack of data from previous studies have led to uncertainty about the carbon resources of these peatlands.In this study,87 sampling sites were selected to investigate soil organic carbon content(SOC)and soil organic carbon density(SOCD)distribution patterns in the uppermost 30 cm soil layer in peatlands near the cities of Aba and Ganzi in the Western Sichuan Plateau.In addition,the effects of environmental factors on SOC and SOCD are also discussed.Our results indicated that SOC in the soil surface layer(0-10 cm)was significantly higher than in the subsurface layer(10-30 cm),and was strongly negatively related to pH and bulk density(BD)(P<0.01).In terms of spatial distribution,SOC and SOCD were found to decrease significantly with increasing latitude.Mean annual temperature(MAT)and soil BD were the primary factors influencing SOC distribution,whereas SOCD distribution was regulated by MAT and latitude.Moreover,mean SOCD to a depth of 30 cm was approximately five times greater in Western Sichuan Plateau peatlands(20.04 kg/m^(2))than in terrestrial ecosystem soils in China(3.70 kg/m^(2)).The results of our analysis show that the Western Sichuan Plateau peatlands are an important soil carbon pool,and that SOC and SOCD patterns were more variable in the south than in the north and mainly determined by MAT.The findings presented here provide potential reference values for projecting how carbon cycling in high-altitude peatland ecosystems will respond under future climate change scenarios.