广宁红花油茶林与次生林土壤有机碳和养分的垂直分布特征

Vertical Distribution Characteristics of Soil Organic Carbon and Nutrients in Camellia semiserrata Plantation and Secondary Forest

为比较广宁红花油茶Camellia semiserrata与次生林土壤有机碳和养分水平的差异,文章以广东省樟木头林场的广宁红花油茶林和次生林为研究对象,测定两种林分土壤的碳氮磷等指标,分析土壤有机碳的垂直变化规律及其影响因素,结果发现:(1)两种林分土壤容重均随土层深度的增加而增加,而总孔隙度、非毛管孔隙度和通气孔隙度随着土层深度的增加而下降;广宁红花油茶林土壤自然含水量、毛管持水量和毛管孔隙度均显著高于次生林,而非毛管孔隙度和通气孔隙度显著低于次生林;(2)两种林分土壤的总有机碳(TOC)、总氮(TN)、水解氮(HN)、速效磷(AP)、碳氮比(C∶N)、碳磷比(C∶P)和氮磷比(N∶P)均随着土层深度的增加而降低,而土壤pH值和全磷(TP)在各土层间无显著差异;次生林土壤TOC、TN、TP、全钾(TK)、速效钾(AK)和HN含量显著高于红花油茶林;(3)相关性分析表明,广宁红花油茶林表层土壤TOC与容重、TK呈显著负相关,与总孔隙度和通气孔隙度呈显著正相关;次生林表层土壤TOC含量与容重、毛管孔隙度和TK呈显著负相关,与HN、毛管孔隙度、通气孔隙度、TN呈显著正相关;次生林底层土壤TOC含量与HN、AP呈极显著正相关;另外,两种林分土壤的表层和底层土壤TOC均与C∶N和C∶P呈极显著正相关,说明表层土壤TOC更容易受到土壤物理性质的影响,而底层TOC受到C∶N和C∶P的调控。研究结果可知,广宁红花油茶林土壤TOC和N、P和K养分低于次生林,表明广宁红花油茶的生长和产量可能受到土壤氮磷钾养分供应的影响,未来应加强对广宁红花油茶林土壤氮磷钾的养分管理;两种林分土壤表层有机碳受到土壤物理性质的显著影响,表明抚育管理等措施将会改变土壤有机碳的含量。

In this paper,the Camellia semiserrata plantation and secondary forest in Zhangmutou Forest Farm of Guangdong province were selected as the research objects,to determine the soil carbon(C),nitrogen(N),and phosphorus(P)of the two stands,and analyze the vertical changes of soil total organic carbon(TOC)and its influencing factors,which can provide scientific data for forest soil TOC accumulation and nutrient management.The results showed that:(1)Soil bulk density increased with the increase of soil depth,while total porosity,non-capillary porosity,and aerated porosity decreased with the increase of soil depth.The soil water content,capillary water capacity,and capillary porosity of C.semiserrata plantation were significantly higher than those of the secondary forest,while the non-capillary porosity and aerated porosity were significantly lower than those of the secondary forest.(2)The TOC,total N(TN),hydrolyzed N(HN),available P(AP),C∶N,C∶P,and N∶P of the two stands decreased with the increase of soil layer,but the soil pH value and total P(TP)were not significantly different among different soil layers.The contents of TOC,TN,TP,total potassium(TK),available potassium(AK),and HN in secondary forests were significantly higher than those in C.semiserrata plantation.(3)Correlation analysis showed that TOC was negatively correlated with bulk density and TK,and positively correlated with total porosity and aerated porosity.TOC content in secondary forest was negatively correlated with bulk density,capillary porosity,and TK,and positively correlated with HN,capillary porosity,aerated porosity,and TN.TOC content in the topsoil of the secondary forest was positively correlated with HN and AP.In addition,TOC in both topsoil and subsoil soil of the two stands showed a significant positive correlation with C∶N and C∶P,indicating that TOC in topsoil was more susceptible to the influence of soil physical properties,while TOC in subsoil was regulated by C∶N and C∶P.The results showed that TOC and N,P,and K elements in C.semiserrata plantation were lower than those in the secondary forest,indicating that the growth and yield of C.semiserrata were affected by the supply of soil N,P,and K nutrients,and the nutrient management of C.semiserrata plantation should be strengthened in the future.The TOC of topsoil was significantly affected by the soil physical properties,indicating that tending and management would change the contents of soil organic carbon.