摘要
[目的]研究不同树种组成对土壤有机碳含量及其稳定性的影响程度,为北亚热带森林土壤固碳能力的提升提供依据。[方法]以南京市溧水区林场林龄相同、立地条件相近的麻栎(Quercus acutissima Carruth.)纯林和麻栎-马尾松(Pinus massoniana Lamb.)针阔混交林为研究对象,测定0~20 cm和20~40 cm土层的总有机碳及其组分含量、微生物残体碳、细根和凋落物特性、酶活性等,评价土壤有机碳稳定性,并利用结构方程模型明晰土壤有机碳含量和稳定性的主要影响因素。[结果](1)土壤有机碳(SOC)、矿物结合态有机碳(MAOC)、粗颗粒有机碳(cPOC)、细颗粒有机碳(fPOC)含量范围分别为21.90~42.30 g·kg^(-1)、13.34~27.05 g·kg^(-1)、6.75~14.24 g·kg^(-1)和1.72~3.84 g·kg^(-1),混交林SOC含量显著高于纯林(p<0.05),呈现明显“表聚效应”。(2)MAOC、cPOC、fPOC对SOC的贡献分别为53.70%~65.69%、26.12%~37.18%、5.55%~10.00%,混交林MAOC对SOC的贡献高于纯林,其中表层土壤具有显著差异(p<0.05)。(3)土壤微生物残体碳(MNC)含量范围为3.11~7.61 g·kg^(-1),对SOC的贡献为11.70%~19.88%。混交林底层土壤MNC含量显著高于纯林(p<0.05)。(4)结构方程模型表明,颗粒有机碳(POC)和MAOC对土壤有机碳含量均有极显著正效应(p<0.001),POC受土壤基本理化性质影响较大,MAOC受酶活性影响较大。土壤基本理化性质、细根和凋落物特性通过对MNC、酶活性产生极显著正效应(p<0.001),进而影响MAOC/SOC。[结论]相比于麻栎纯林,麻栎马尾松混交林具有较高的酶活性、细根生物量和较低的细根碳氮比,增加了土壤有机碳输入量,推动土壤碳代谢和转化过程,进而提高了土壤有机碳含量、矿物结合态有机碳含量及其在总有机碳中的占比,导致混交林具有较高的有机碳含量和稳定性。
[Objective]This study aims to assess the impact of different tree species compositions on soil organic carbon(SOC)content and its stability,providing insights for enhancing soil carbon sequestration in North Subtropical forests.[Method]Based on the Q.acutissima pure forest and Q.acutissima-P.masso-niana mixed forest with the same age and similar stand conditions in Nanjing Lishui Forest Farm,the or-ganic carbon and its components,microbial residue carbon,fine root and litter characteristics,and en-zyme activities in the soil layers of 0~20 cm and 20~40 cm in the two forests were measured.The SOC stability was evaluated,and a structural equation model(SEM)was used to identify key factors influencing SOC content and stability.[Results](1)The SOC,mineral bound organic carbon(MAOC),coarse particu-late organic carbon(cPOC),and fine particulate organic carbon(fPOC)ranged from 21.90 to 42.30 g·kg^(-1),13.34 to 27.05 g·kg^(-1),6.75 to 14.24 g·kg^(-1),and 1.72 to 3.84 g·kg^(-1),respectively.The SOC content of mixed forests was significantly higher than that of pure forests(p<0.05),and there was an obvious“epimer-ization effect”.(2)The contributions of MAOC,cPOC and fPOC to SOC ranged from 53.70%to 65.69%,26.12%to 37.18%and 5.55%to 10.00%,respectively,and the contributions of MAOC to SOC were higher in mixed forests than in pure forests,with significant differences in the 0~20 cm soil layer(p<0.05).(3)Soil microbial residual carbon(MNC)content ranged from 3.11 to 7.61 g·kg^(-1) and contributed 11.70%to 19.88%to SOC.The MNC content of the 20~40 cm soil layer of the mixed forest was significantly higher than that of the pure forest(p<0.05).(4)Structural equation models showed that both POC and MAOC had highly significant positive effects(p<0.001)on SOC content,POC was strongly influenced by basic soil physicochemical properties,and MAOC was strongly influenced by enzyme activity.Soil physicochemical properties,fine root and litter characteristics had highly significant positive effects(p<0.001)on MNC and enzymatic activity,which in turn influenced the MAOC/SOC ratio.[Conclusion]Compared to the pure Quercus acutissima forest,the mixed Quercus acutissima–Pinus massoniana forest exhibited higher en-zymatic activity,fine root biomass,and a lower fine root C:N ratio,which enhanced SOC input and pro-moted soil carbon metabolism and transformation.This led to higher SOC and MAOC contents,as well as an increased proportion of MAOC in total SOC,resulting in greater SOC content and stability in the mixed forest.
作者
孟董悦
刘大源
关庆伟
张琳婧
张宇恬
史珑燕
MENG Dong-yue;LIU Da-yuan;GUAN Qing-wei;ZHANG Lin-jing;ZHANG Yu-tian;SHI Long-yan(Co-Innovation Center for Sustainable Forestry in Southern China,Nanjing 210037,Jiangsu,China;College of Ecology and Environment,Nanjing Forestry University,Nanjing 210037,Jiangsu,China)
出处
《林业科学研究》
北大核心
2025年第5期49-58,共10页
Forest Research
基金
江苏省林业科技创新与推广项目(LYKJ[2022]04)。
关键词
树种组成
有机碳含量
稳定性
微生物残体碳
影响因素
species composition
organic carbon content
stability
microbial necromass carbon
influencing factor
