黔东南3种林型土壤碳氮磷生态化学计量特征

Stoichiometry characteristics of soil carbon,nitrogen and phosphorus of three forest types in southeast of Guizhou Province

【目的】探究黔东南不同林型土壤碳氮磷生态化学计量特征,为揭示森林土壤养分分布规律及养分管理提供理论依据。【方法】以马尾松林、杉木林和灌丛林3种林型为研究对象,分别采集0~20 cm、20~40 cm和40~60 cm土层土壤样品,测定不同土层土壤碳(SOC)、氮(TN)、磷(TP)含量并分析其化学计量比。【结果】3种林型在0~60 cm土层土壤SOC、TN和TP含量的变化范围为10.24~25.72 g/kg、0.49~1.23 g/kg和0.10~0.40 g/kg,整体均表现为灌丛林>马尾松林>杉木林;随土层深度的增加,3种林型土壤SOC、TN和TP含量均呈下降趋势,其中土壤SOC和TN含量在各土层间均存在显著差异(P<0.05,下同)。3种林型在0~60 cm土层土壤C∶N、C∶P和N∶P的变化范围为21.94~30.16、65.72~154.81和2.80~10.55,不同林型土壤C:N表现为杉木林>灌丛林>马尾松林,土壤C∶P和N∶P均表现为马尾松林>杉木林>灌丛林;随土层深度的增加,3种林型的土壤C∶N和C∶P均呈先增后减趋势,其中杉木林土壤C∶P在各土层间存在显著差异,土壤N∶P在马尾松林和杉木林中均呈上升趋势,在灌丛林中呈下降趋势,且均无显著差异(P>0.05,下同)。冗余分析表明,坡度是影响土壤C、N、P化学计量特征的主导因子,解释量达到18.7%,电导率也对其有显著影响,解释量达10.0%,而土壤温度对其影响不显著,解释量为3.1%。【结论】研究区土壤有机质矿化快,C含量高,在养分供应方面受N和P元素限制,坡度是主要限制土壤N和P供给的主要因素。

【Objective】Exploring the contents of carbon,nitrogen,phosphorus and ecological stoichiometry characteristics of soil in different forest types in southeast of Guizhou Province,to reveal the nutrient distribution law of forest soil and provide a theoretical basis for nutrient management.【Method】Three forest types(Pinus massoniana forest,Cunninghamia lanceolata forest and shrubs forest)were selected as the research objects. Soil samples were taken at depth intervals of 0-20 cm,20-40 cm and 40-60 cm,the contents of soil carbon(SOC),nitrogen(TN),phosphorus(TP)were measured in different soil layers and their stoichiometric ratios were analyzed.【Result】The contents of SOC,TN and TP in 0-60 cm soil layer of the three forest types ranged from 10.24-25.72 g/kg,0.49-1.23 g/kg and 0.10-0.40 g/kg,respectively,and the contents of SOC,TN and TP in soil showed as shrubs forest>C. lanceolata forest>P. massoniana forest. With the increase of soil depth,the contents of SOC,TN and TP in the three forests showed a decreasing tendency,among which the contents of SOC and TN in the soils were significantly different(P<0.05,the same below). The soil C∶N,C∶P and N∶P in 0-60 cm soil layers of the three forest types ranged from 21.94-30.16,65.72-154.81 and 2.80-10.55,respectively. The soil C∶N showed as P. massoniana forest>shrubs forest>C. lanceolata forest in different forest types,and soil C∶P,N∶P showed as C. lanceolata forest>P. massoniana forest>shrubs forest. With the increase of soil depth,the contents of soil C∶N,C∶P in the three forests increased at first and then decreased,among which the soil C:P of C. lanceolata forest in the soils was significantly different. And the soil N∶P showed an increasing tendency in P. massoniana forest and C. lanceolata forest,and a decreasing tendency in shrubs forest,and there was no significant difference(P>0.05,the same below). Redundant analysis showed that slope was the dominant factor affecting the stoichiometric characteristics of soil C,N and P,and the explanatory rate reached 18.7%. Electrical conductivity also had a significant impact on it,and the explanatory rate reached 10.0%,while soil temperature had no significant impact on it,and the explanatory rate reached 3.1%.【Conclusion】Soil organic matter mineralization is fast,C content is high,and nutrient supply is limited by N and P in the study area,and slope is the main factor restricting soil N and P supply.