不同土地利用方式对岩溶区土壤有机碳组分稳定性的影响  

Effect of Land Use on the Stability of Soil Organic Carbon in a Karst Region

作　　者：陈坚淇 贾亚男 贺秋芳 江可 陈畅 叶凯 CHEN Jian-qi;JIA Ya-nan;HE Qiu-fang;JIANG Ke;CHEN Chang;YE Kai(Chongqing Key Laboratory of Karst Environment,School of Geographic Sciences,Southwest University,Chongqing 400715,China)

机构地区：[1]西南大学地理科学学院,岩溶环境重庆市重点实验室,重庆400715

出　　处：《环境科学》2024年第1期335-342,共8页Environmental Science

基　　金：重庆市自然科学基金项目(cstc2020yszx-jcyjX0006,cstc2021yszx-jcyjX0005);岩溶动力学重点实验室开放课题项目(KDL&Guangxi 202007);重庆市教委会创新人才培养计划项目(CY220211)。

摘　　要：土壤有机碳的组分及其稳定机制是深入了解陆地碳汇能力的关键,岩溶生态系统中土壤有机碳稳定性在很大程度上影响土壤固碳能力.为了解人类活动对岩溶区土壤有机碳稳定性的影响,选取重庆市中梁山岩溶槽谷区为例,分层采集了4种典型土地利用方式(混交林、竹林地、荒草地和耕地)的土壤样本,分析不同土地利用方式下总有机碳(TOC)、重组有机碳(HFOC)、轻组有机碳(LFOC)、活性有机碳(LOC)、惰性有机碳(ROC)的分布特征,运用结构方程模型定量分析土地利用方式对土壤有机碳组成的影响及其稳定性的影响,为岩溶区土壤碳汇评估和土壤质量保护提供基础数据.结果表明:岩溶区不同土地利用方式下的各有机碳组分均出现明显的表聚现象,表层有机碳组分含量是底层的1.2倍;应用土壤惰性有机碳指数(ROCI)指示土壤有机碳稳定性,其变化区间为33.9%~64.5%,其中混交林最高为64.5%~66.3%,耕地最低为33.8%~39.6%.岩溶区惰性有机碳含量和ROCI表明,人类农业耕作活动引起土壤有机碳含量减少和土壤物理结构被破坏,导致土壤有机质分解和周转速率加快;影响岩溶区土壤稳定性的最重要因素是土壤pH,耕作活动引起土壤pH降低,减少了土壤微生物活性,不利于土壤中惰性有机碳和土壤有机碳库的积累.The composition of soil organic carbon and its stability mechanism are the key to understanding the terrestrial carbon sink capacity.The stability of soil organic carbon in a karst ecosystem greatly affects the soil carbon fixation capacity.In order to understand the impact of human activities on the stability of soil organic carbon in karst areas,the karst valley area of Zhongliang Mountain in Chongqing was selected as an example,and soil samples of four typical land use modes(mixed forest,bamboo forest,grassland,and cultivated land)were collected in layers to analyze the total organic carbon(TOC)and heavy fraction organic carbon(HFOC).The distribution characteristics of light fraction organic carbon(LFOC),labile organic carbon(LOC),and recalcitrant organic carbon(ROC)were analyzed quantitatively by using a structural equation model to provide basic data for soil carbon sink assessment and soil quality protection in karst areas.The results showed that the organic carbon components under different land use patterns in karst areas had obvious surface accumulation,and the content of organic carbon components in the surface layer was 1.2 times that in the bottom layer.Except for LFOC,the content of other organic carbon components was the highest in the mixed forest,followed by that in the bamboo forest and wasteland,with the lowest in cultivated land.Mixed forestω(TOC)content was the highest,42.5 g·kg^(-1),followed by that of bamboo forest(36.6 g·kg^(-1))and grassland(18.7 g·kg^(-1)),and cultivated land content was the lowest,13.4 g·kg^(-1).The soil organic carbon content of cultivated land was 68.5%,63.5%,and 28.3%lower than that of mixed forest,bamboo forest,and grassland,respectively.Mixed forest had the highest content ofω(HFOC),21 g·kg^(-1),followed by those of bamboo forest(20.9 g·kg^(-1)),grassland(18.2 g·kg^(-1)),and cultivated land(13.5 g·kg^(-1)).The mixed forestω(LOC)content was the highest,16.3 g·kg^(-1),followed by those of bamboo forest(14.9 g·kg^(-1)),grassland(11.5 g·kg^(-1)),and cultiv

关 键 词：岩溶区 土地利用 惰性有机碳 土壤有机碳稳定性 结构方程模型 

分 类 号：X144[环境科学与工程—环境科学]