海拔对杉木人工林土壤活性有机碳组分的影响

Effects of altitude on soil active organic carbon components in Cunninghamia lanceolata plantations

【目的】探究杉木(Cunninghamia lanceolata)林地土壤活性有机碳组分在不同海拔上的分布特征和影响因素,为土壤碳循环及杉木人工林的可持续发展提供科学依据。【方法】在安徽省金寨县马鬃岭自然保护区,以不同海拔高度(750,850,1000,1150 m)的杉木人工林为研究对象,分析不同海拔杉木林下0~10,10~20,20~30 cm土层土壤中的活性有机碳组分微生物量碳(MBC)、易氧化有机碳(EOC)、可溶性有机碳(DOC)、颗粒有机碳(POC)、稳定性碳同位素(δ13C)和土壤理化性质有机碳(SOC)、全氮(TN)、含水率、pH、电导率(EC)的变化特征,并分析土壤活性有机碳组分与理化性质之间的相关性。【结果】同一土层下,POC、EOC、DOC、MBC含量随着海拔的升高均呈现先降低后升高的趋势。同一海拔下,随着土层深度的增加,MBC含量呈现出递减规律,其他组分无明显变化。土壤理化性质中,随着海拔升高,土壤SOC、TN、含水率总体呈先下降后升高的趋势,pH总体呈先上升后下降趋势,δ13C含量总体呈增加趋势,EC则无明显变化规律。在同一海拔下,随着土层深度的增加,SOC、TN、EC、含水率总体呈下降趋势,土壤pH无显著变化,土壤δ13C含量呈增加趋势。相关性分析显示,4种活性有机碳组分之间及其与TN、SOC之间均存在极显著正相关关系(P<0.01),与δ13C之间存在极显著负相关关系(P<0.01)。【结论】海拔和土壤理化性质的差异可能是导致土壤活性有机碳组分变化的重要影响因素,土壤POC、EOC、MBC、DOC含量可作为衡量森林土壤碳、氮动态变化的敏感性指标。

【Objective】This study revealed distribution characteristics and influencing factors of soil active organic carbon components at different altitudes to provide basis for soil carbon cycle and sustainable development of Cunninghamia lanceolata plantations.【Method】The Cunninghamia lanceolata plantations at different altitudes(750,850,1000 and 1150 m)were selected and soil microbial biomass carbon(MBC),easily oxidizable carbon(EOC),soluble organic carbon(DOC),particulate organic carbon(POC),stable carbon isotope(δ13C)and other physical and chemical properties(SOC,TN,moisture,pH,EC)at different soil layers(0-10,10-20 and 20-30 cm)in the Mazongling Nature Reserve in Jinzhai,Anhui were analyzed.The correlations between soil active organic carbon components and physicochemical properties were also analyzed.【Result】POC,EOC,DOC and MBC at same soil layer decreased first and then increased with increase of altitude.With the increase of soil layer at same altitude,MBC showed a decreasing trend,while other components had no obvious changes.With the increase of altitude,SOC,TN and moisture contents generally decreased first followed by increase,pH increased first followed by decrease,δ13C generally increased,while EC had no changes.At same altitude,SOC,TN,EC and soil moisture decreased with the increase of soil depth,pH had no significant changes,whileδ13C in soil increased.Correlation analysis showed that there were significant positive correlations among the four active organic carbon components(P<0.01).They also had very significant and positive correlations with TN and SOC(P<0.01),and very significant and negative correlation withδ13C(P<0.01).【Conclusion】Altitude and soil physical and chemical properties may be important factors in changes of active organic carbon.Contents of soil POC,EOC,MBC and DOC can be used as sensitive indices to measure dynamic changes of forest soil carbon and nitrogen.