基于发生层的均腐土理化性质和元素生态化学计量特征分析

Characteristics of physicochemical properties and element ecological stoichiometry in Isohumosols from soil genetic horizons

为明确土壤剖面理化性状及元素生态化学计量的变化规律,从而为认识土壤形成机制和保护土壤资源提供科学依据,本研究以黑龙江省干润和湿润均腐土亚纲为研究对象,基于发生层采集土壤剖面样品,对其理化性状及元素生态化学计量进行了比较分析。结果表明,从A层到C层,均腐土的有机碳(SOC)、全氮(TN)、全磷(TP)、铵态氮(NH4+-N)、速效磷(AP)和砂粒含量以及土壤颗粒表面积和体积平均径(SMD和VMD)逐渐降低;相反,土壤pH、黏粒和粉粒含量则明显升高。研究发现不同土系均腐土C层(母质层)显示出了比Ah层(腐殖质层)更大的土壤异质性,并且湿润均腐土理化性质沿着剖面的垂直变化程度比干润均腐土更大。此外,元素生态化学计量分析发现,均腐土C∶N、C∶P和N∶P随着发生层深度的增加而明显降低,说明深层土壤养分循环过程受到碳和氮限制增强。

To clarify the change patterns of physicochemical properties and element ecological stoichiometry of soil profiles,and thus provide a scientific basis for understanding soil formation mechanisms and protecting soil resources,this study collected soil samples from Ustic and Udic Isohumosols in Heilongjiang Province of China based on the genetic horizons,and their physicochemical properties and element ecological stoichiometry were comparatively examined.The results showed that from A-horizon to Chorizon,the soil organic carbon(SOC),total nitrogen(TN),total phosphorus(TP),ammonia nitrogen(NH4+-N),available phosphorus(AP)and sand contents,as well as the surface mean diameter(SMD)and volume mean diameter(VMD)of soil particles decrease gradually;while the soil pH,clay and silt contents increase significantly.Notably,greater soil heterogeneities are observed in Chorizons(parent material horizons)than in Ah-horizons(humus horizons),and the variations of the physicochemical properties along soil profiles are greater in Udic Isohumosols compared to Ustic Isohumosols.In addition,the element ecological stoichiometric analysis found that soil C∶N,C∶P and N∶P decrease significantly with increasing soil depth in both Ustic and Udic Isohumosols,suggesting that the nutrient cycling processes in deeper soil horizons are more strongly constrained by carbon and nitrogen.