黔西南石漠化区不同群落土壤碳氮磷垂直分异及化学计量特征

Vertical Differentiation and Stoichiometry Characteristics of Soil Carbon,Nitrogen and Phosphorus in Different Communities of Southwest Guizhou Desertification Area

【目的】揭示黔西南石漠化区不同群落土壤碳氮磷空间分布及化学计量的垂直分异规律,为黔西南喀斯特石漠化区生态治理和植被恢复提供科学依据。【方法】以5种植物群落下不同深度土壤为研究对象,探讨土壤有机碳(SOC)、全氮(TN)、全磷(TP)含量及生态化学计量的垂直分布特征。【结果】SOC、TN、TP的变幅分别为11.98~32.91、1.98~4.99和0.43~1.69 g/kg,SOC、TN总体随土层加深而降低,TP在各土层间无明显变化;C:N、C:P、N:P的变化范围依次为4.64~7.87、11.49~33.98、1.91~5.28,总体格局呈上高下低变化;C:N低于全国平均水平,C:P总体水平较高,N:P<14,指示N亏缺,植物生长易受N限制。土壤SOC、TN、TP呈两两极显著正相关,C:P与C:N、N:P呈极显著正相关;C:P与TN呈显著负相关;SOC与N:P之间为反向作用效应。【结论】人工恢复植物群落土壤全量养分高于荒地,养分积累能力较强;化学计量比特征SOC分解、矿化率高,P矿化能力弱、有效性低;研究区全量养分之间关系密切,土壤生态系统内养分平衡具有较强的正向调控机制,C、N之间存在互馈效应,C制约着N、P元素的比例关系。

【Objective】The spatial distribution and stoichiometric vertical differentiation rule of soil carbon,nitrogen and phosphorus in different communities of desertification area desertification area are revealed to provide the scientific basis for ecological management and vegetation recovery in Southwest Guizhou karst desertification area.【Method】The vertical distribution and ecosystem stoichiometric characteristics of SOC,TN and TP content in soils with different soil depth of five different communities are discussed.【Result】The variation range of SOC,TN and TP is 11.98-32.91,1.98-4.99 and 0.43-1.69 g/kg respectively.The SOC and TN content decreases with increase of soil depth in general and there is no significance in TP content among different soil layers.The variation range of C∶N,C∶P and N∶P is 4.64-7.87,11.49-33.98 and 1.91-5.28 separately and the vertical direction of their ratios is a high to low pattern with increase of soil depth.The C∶N ratio is lower than national average level and C∶P ratio is higher.The plant growth is easily influenced by N limit when N∶P ratio is less than 14.There are the very significant positive correlations between SOC and TN,SOC and TP,TN and TP.C∶P is very significantly and positively related to C∶N and N∶P.C∶P is significantly and negatively related to TN.There is a reverse effect between SOC and N∶P.【Conclusion】The soil nutrients of the vegetation community recovered by artificial labour are higher than wasteland because the recovered vegetation community has a strong ability of nutrient accumulation.The soil organic carbon is quickly decomposed and efficiently mineralized.The mineralization ability of P element is weak and the effectiveness is low.There are very significant correlations between different nutrients in the research area.The nutrient balance has a strong positive regulatory mechanism in the soil ecosystem.There is a mutual feedback effect between C and N.The proportion of N and P is restricted by C element.