藏东南折拉山不同林分类型土壤有机碳及其组分分布特征

Characteristics of Soil Organic Carbon and Its Component Distribution in Different Forest Stand Types on Mount Zola in Southeastern Tibet

了解藏东南折拉山森林土壤有机碳及其组分分布特征,对区域内森林可持续发展和管理保护具有重要意义。在研究区折拉山选取川滇高山栎(Quercus aquifolioides)、察隅冷杉(Abies chayuensis)、密枝圆柏(Juniperus convallium)、大果红杉(Larix potaninii)等4种森林,采集林下0-20、20-40 cm土壤样品,探究森林类型和不同深度土壤有机碳(SOC)、微生物量碳(MBC)、水溶解性土壤有机碳(WSOC)、土壤易氧化有机碳(ROC)、土壤颗粒有机碳(POC)、矿质结合态有机碳(MAOC)、稳定态有机碳(NOC)的分布情况,阐明SOC及其组分与土壤理化性质的相关性和主要影响因子。结果表明:4种森林类型土壤SOC及其组分(MBC除外)含量随土层深度的增加而减小,且不同土层间差异显著(p<0.05);各层土壤中密枝圆柏的各项碳组分在不同森林类型间均为最高。0-40 cm土层,土壤ROC、NOC、POC含量均表现为:密枝圆柏林>察隅冷杉林>大果红杉林>川滇高山栎林。相关性分析表明:土壤SOC与ROC和NOC、ROC与POC呈极显著正相关(p<0.01);WSOC与POC和ROC、NOC与POC呈极显著正相关(p<0.01);土壤酸碱性(pH)与SOC、WSOC、ROC、POC呈极显著正相关(p<0.01);土壤全钾(TK)与WSOC、POC和MOAC呈极显著负相关(p<0.01)。冗余分析表明:土壤硝态氮(NO_(3)^(-)-N)、全氮(TN)、土壤含水率(SWC)、电导率(EC)是影响4种森林类型土壤SOC及其组分的主要影响因子。综上,折拉山4种森林类型间土壤SOC及其组分的含量存在差异性,且受到土层深度的影响呈现出表聚性;土壤SOC及其组分的含量受土壤理化指标影响较大,其他因子对其影响较小。

Understanding the distribution characteristics of soil organic carbon(SOC)and its components in the forests of the Mt.ZheLa in southeastern Tibet is highly important for the sustainable development,management,and conservation of forests in the region.In the study area of the Mt.ZheLa,four forest types were selected:Quercus aquifolioides,Abies chayuensis,Juniperus convallium,and Larix potaninii.Soil samples were collected from depths of 0-20 cm and 20-40 cm to investigate the distributions of SOC and its components,including microbial biomass carbon(MBC),water-soluble organic carbon(WSOC),readily oxidizable organic carbon(ROC),particulate organic carbon(POC),mineral-associated organic carbon(MAOC),and non-oxidizable organic carbon(NOC),as well as to elucidate the correlations between SOC and its components with soil physicochemical properties and the main influencing factors.The results showed that the contents of SOC and its components(excluding MBC)in the soils of the four forest types decreased with increasing soil depth,with significant differences between the different soil layers(p<0.05).Among the various forest types,Juniperus convallium had the highest content of all carbon components in each soil layer.In the 0-40 cm soil layer,the contents of ROC,NOC,POC followed the order:Juniperus convallium forest>Abies chayuensis forest>Larix potaninii forest>Quercus aquifolioides forest.Correlation analysis showed that soil SOC was highly significantly and positively correlated with ROC and NOC,and ROC with POC(p<0.01);WSOC was highly significantly and positively correlated with POC and ROC,and NOC with POC(p<0.01);and soil acidity and alkalinity(pH)was highly significantly and positively correlated with SOC,WSOC,ROC,and POC(p<0.01);soil total potassium(TK)was highly significantly negatively correlated with WSOC,POC and MOAC(p<0.01).Redundancy analysis indicated that soil nitrate nitrogen(NO_(3)^(-)-N),total nitrogen(TN),soil water content(SWC),electrical conductivity(EC)were the primary factors influencing SOC and its components across the four forest types.In summary,there were differences in the content of SOC and its components among the four forest types on Mt.ZheLa,with a tendency for accumulation in the surface soil layers as influenced by soil depth.The content of SOC and its components was significantly affected by soil physicochemical properties,while other factors had a lesser impact.