海拔变化对黄山松阔叶混交林土壤有机碳组分的影响

Effects of altitude change on soil organic carbon fractions in Pinus taiwanensis and broad-leaved mixed forest

【目的】明确海拔变化对黄山松阔叶混交林土壤有机碳化学组分含量的影响及初步影响机理,了解全球气候变暖后,典型林分土壤有机碳稳定性的变化。【方法】以黄山松在凤阳山的主要分布海拔范围1 000～1 800 m为准,选取1 200、1 500、1 800 m 3个海拔梯度,在每个海拔梯度的阳坡选取3个标准样地(20 m×20 m),用蛇形法于每块样地取样,带回测定其土壤理化性质及有机碳化学组分含量。【结果】随着海拔升高,土壤养分含量呈先升高后降低的变化趋势,土壤水溶性碳及有效磷含量在各海拔间差异性显著(P <0. 05);随海拔升高,烷基碳、N-烷氧碳含量先增大后减小;芳香碳、酚基碳及羰基碳含量则先减小后增大;烷氧碳和缩醛碳含量则随海拔升高而降低;海拔1 200 m处羰基碳含量与其他两个海拔存在显著差异(P <0. 05)。非度量多维标度(NMDS)排序显示不同海拔梯度土壤有机碳组分含量之间有显著差异,这些差异主要是由于羰基碳、烷基碳含量及Z烷基碳/Z烷氧碳的变化引起的。冗余分析(RDA)显示,土壤总磷含量及土壤容重对有机碳分子结构复杂程度影响较强;土壤总氮含量与有机碳稳定性则呈极显著正相关关系。【结论】海拔变化所引起的土壤理化性质的改变,是影响土壤有机碳稳定性的重要因素;高海拔处温度过低会对土壤有机碳的分解产生影响,从而影响土壤有机碳稳定性。

[Objective]This study was performed to understand the effects of altitude on soil organic carbon chemical composition in a Pinus taiwanensis broad-leaved mixed forest and its preliminary influencing mechanism and changes in soil organic carbon stability in typical stands after global warming.[Method]On the basis of the distribution range of Pinus taiwanensis on Fengyang Mountain,1 200,1 500,and 1 800 m were selected as the three altitudinal gradients,and three standard plots(20 m×20 m)were set at each elevation gradient and sampled in August 2016.Solid-state nuclear magnetic resonance spectros copy was used to determine the chemical composition of soil organic carbon.[Result]With an increase in elevation,the soil nutrient content increased and then decreased,and soil soluble carbon and phosphorus content at each elevation between significant difference(P<0.05).With an increase in altitude,the N-alkyl carbon and alkyl carbon content initially increased and then decreased,and the aromatic carbon,phenolic carbon and carbonyl carbon content initially decreased and then increased.O-alkyl carbon and a cetal carbon content decreased with the in crease in altitude at 1 200 m above sea level;at 1 200 m,the carbonyl carbon content was significantly different from those at the other two elevations(P<0.05).Non-metric multidimensional scaling ordination showed significant differences in soil organic carbon fractions at different elevations,mainly because of changes in carbonyl carbon,alkyl carbon,and Zalkyl carbon /ZO-alkyl carbon .Redundancy analysis showed that the soil total phosphorus content and soil bulk density have a great influence on the molecular structure complexity of organic carbon,soil total nitrogen content and organic carbon stability are significantly positively related.[Conclusion]The physicochemical properties of altitude changes caused by the change of soil are important factors that affect the stability of soil organic carbon.Soil organic carbon has the lowest stability at 1 800 m,and low temperature can affect the decomposition of soil organic carbon,thus affecting the stability of soil organic carbon.