不同退耕模式细根(草根)分解过程中C动态及土壤活性有机碳的变化  

Carbon dynamics of fine root(grass root) decomposition and active soil organic carbon in various models of land use conversion from agricultural lands into forest lands

作　　者：荣丽[1,2] 李守剑[3] 李贤伟[1] 张健[1] 王鹏[1] 

机构地区：[1]四川农业大学长江上游生态林业工程四川省重点实验室,四川雅安625014 [2]云南大学亚洲国际河流中心,昆明650091 [3]四川省林业勘察设计研究院,成都610081

出　　处：《生态学报》2011年第1期137-144,共8页Acta Ecologica Sinica

基　　金：国家自然科学基金项目(30771717);国家"十一五"科技支撑项目(2006BAC01A11);四川农业大学长江上游植被恢复与重建创新项目共同资助

摘　　要：由于土壤活性有机碳可以在土壤全碳变化之前反映土壤因管理措施和环境引起的微小的变化,又直接参与土壤微生物化学转化过程,对土壤碳平衡和土壤化学、土壤肥力保持具有重要意义。因此,采用原状土芯(intact core)法,探讨了4种退耕还林模式———光皮桦(Betula luminifera)与扁穗牛鞭草(Hemarthria compressa)复合模式、扁穗牛鞭草草地、柳杉(Cryptameriafortunei)人工林、光皮桦人工林细根(草根)分解过程中的C动态以及土壤活性有机碳变化。研究结果表明,各模式细根(草根)中的C表现为净释放,其质量残留率符合单指数模型(P<0.01)。光皮桦与扁穗牛鞭草复合模式下的土壤微生物量碳(SMBC)、水溶性有机碳(WSOC)、易氧化碳(ROC)、总有机碳(TOC)都大于其他3种模式。4种模式下的SMBC对土壤TOC的贡献分别是1.2%—3.3%、0.7%—1.5%、0.8%—2.2%、0.5%—0.8%;光皮桦与扁穗牛鞭草复合模式的ROC/TOC大于其他3种模式模式;各模式土壤ROC含量与土壤TOC呈极显著正相关关系(P<0.05)。以上结果显示,与其他人工林相比,光皮桦与扁穗牛鞭草复合模式土壤有机碳活性大、易转化,土壤总有机碳的高低决定了易氧化碳的丰缺。Active soil organic carbon,derived from the decomposition of litter,root exudates,soil organic matter hydrolyzation,soil microbe per se and its metabolite is the active fraction of soil organic matter.Despite of the lower percent of the active soil organic carbon to the total soil organic matter,it was a more sensitive indicator of the soil effects caused by management and environmental changes.Therefore,active soil organic carbon was a critical component in maintaining the balance of soil organic carbon and soil fertility.The production,turnover and decomposition of fine roots are major process in the carbon and nutrient dynamics.The input of nutrients and organic matter to the soil by fine roots contributes to the soil fertility and carbon sequestration.Most previous studies focused on the soil organic carbon in plantations converted from agricultural lands,however,little information was available on the active soil organic carbon during the process decomposition process of fine root（grass root）.The carbon dynamic of fine roots（grass roots） decomposition and soil microbial biomass carbon（SMBC）,water soluble organic carbon（WSOC）,readily oxidizable carbon（ROC） and total organic carbon（TOC） in land use conversion from agricultural lands into forest lands were evaluated by the intact core methods in the present study.560 intact soil cores were sampled from the plots of four models viz.Betula luminifera-Hemarthria compressa mixed pattern,Betula luminifera plantation,Hemarthria compressa grassland and Cryptomeria fortunei plantation for one year.After being placed in nylon bags,these intact soil cores were put back to the soil and collected again after 30,90,180,270 and 365 d.Soil microbial biomass carbon（SMBC）,water soluble organic carbon（WSOC）,readily oxidizable carbon（ROC）,total organic carbon（TOC） were then measured for each sample.The results showed that fine roots（grass roots） released net carbon during the decomposition in four models.Carbon loss of decomposing roots

关 键 词：退耕还林 细根(草根) C动态 土壤活性有机碳 分解 

分 类 号：S154[农业科学—土壤学]