北江中下游不同林分类型土壤C、N、P生态化学计量特征

Soil C,N and P stoichiometry in different forest stand types in the middle and lower reaches of the Beijiang River,China

选取北江中下游阔叶林、针叶林、针阔混交林3种类型林分为对象,研究0~80 cm土层土壤的有机碳(C)、全氮(N)、全磷(P)含量及其生态化学计量比的垂直分布特征。结果表明:3种林分类型的土壤C、N、P含量分别为12.17~14.25、1.14~1.31、0.27~0.30 g·kg^(-1),C、N含量随土层深度增加呈降低的趋势。各土层土壤C、N含量表现为针阔混交林>针叶林>阔叶林;P含量在3种林分类型间差异不显著,在垂直剖面上无明显的规律性变化。3种林分类型土壤C/N、C/P、N/P分别为11.2~11.3、49.0~60.3、4.5~5.7,土壤C/N在3种林分类型间差异不显著,土壤C/P、N/P均以针阔混交林最高,且显著高于阔叶林和针叶林。土壤深度和林分类型对土壤C、N、P含量及其化学计量比无显著的交互作用,但C与N、N与C/P在各林分类型和土层中均呈显著正相关。土壤C/P和N/P对林分类型的生态指示作用更明显,针阔混交林受P限制较强。

We examined the vertical distribution characteristics of soil organic carbon(C),total nitrogen(N),total phosphorus(P)and their ecological stoichiometric ratios in 0-80 cm soil profile under three forest stand types in the middle and lower reaches of the Beijiang River,including broad-leaved forest,coniferous forest,and mixed coniferous and broad-leaved forest.The results showed that soil C,N and P contents of the three forest stand types were 12.17-14.25,1.14-1.31,and 0.27-0.30 g·kg^(-1),respectively.The contents of C and N decreased with the increases of soil depth.The content of C and N in each soil layer showed that coniferous and broad-leaved mixed forest>coniferous forest>broad-leaved forest.There was no significant difference in P content among the three stand types,and there was no obvious variation in the vertical profile.The soil C/N,C/P,and N/P of the three forest types were 11.2-11.3,49.0-60.3,and 4.5-5.7,respectively.There was no significant difference in soil C/N among the three stand types.The highest soil C/P and N/P were found in the mixed forest.There was no interaction between soil depth and stand type in affecting soil C,N,P contents and their stoichiometric ratios.There was significant positive correlation between C and N,and between N and C/P in each stand type and soil layer.Soil C/P and N/P had stronger ecological indicating effects on stand types.The coniferous and broad-leaved mixed forest was strongly limited by P availability.