中文关键词红壤丘陵区水田旱地林地土壤有机碳(SOC)有机碳组分 英文关键词hilly red soil regionspaddyuplandwoodlandsoil organic carbon (SOC)soil organic carbon fractions

作者	单位	E-mail
章晓芳	中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 中国科学院大学, 北京 100049	zhangxiaofang17@mails.ucas.ac.cn
郑生猛	中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 中国科学院大学, 北京 100049
夏银行	中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 中国科学院大学, 北京 100049
胡亚军	中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125
苏以荣	中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125
陈香碧	中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125	xbchen@isa.ac.cn

中文摘要 土地利用方式影响土壤有机碳（SOC）及其组分，进而决定了碳库的稳定性.以林地为参照，分析我国红壤丘陵区农田（水田和旱地）SOC及其活性组分［可溶性有机碳（DOC）、微生物生物量碳（MBC）和颗粒有机碳（POC）］和惰性组分［矿物结合态有机碳（MAOC）］含量，探讨土壤有机碳组分对土地利用方式的响应特征.结果表明，与旱地和林地相比，水田SOC、MBC、POC和MAOC含量均为最高.DOC含量以林地显著高于旱地和水田（P<0.001）.SOC各组分占SOC的比例，即DOC/SOC、MBC/SOC、POC/SOC和MAOC/SOC范围分别为0.22%~0.93%、1.62%~2.70%、31.08%~40.00%和43.22%~56.82%.活性组分（MBC和POC）含量与占比趋势一致，均以水田 > 林地 > 旱地.MAOC含量以水田最高、旱地最低，MAOC/SOC则以旱地最高、水田最低.相关分析表明，水田、旱地和林地中MBC、POC和MAOC分别与SOC呈极显著正相关（P<0.001），而DOC与SOC及其它组分均无显著相关性（P>0.05）；旱地、林地中POC与MBC呈极显著正相关（P<0.001）；水田、旱地MAOC与MBC呈极显著正相关（P<0.001）；3种土地利用方式下POC与MAOC呈极显著正相关（P<0.001），POC/MAOC以水田最大，旱地最低.因而，与旱地和林地相比，水田SOC的活性组分比例高、惰性组分比例低，且其活性组分POC与微生物生物量关系不紧密，而惰性组分与微生物生物量显著相关.综上，农业利用显著改变红壤丘陵区土壤有机碳及其组成，水田虽有利于SOC固持，但其不稳定性组分占比较高，可能容易因不当耕作管理而丢失. 英文摘要 Land use type exerts important influences on soil organic carbon (SOC) and its fractions, and determines the stability of the carbon pool. Taking woodland as a reference, the content of SOC and its labile fractions[dissolved organic carbon (DOC), microbial biomass carbon (MBC), and particulate organic carbon (POC)] and non-labile fractions[mineral-associated organic carbon (MAOC)] in upland and paddy surface soils in hilly red soil regions were determined to explore the responses of SOC fractions to land use type. The results showed that the contents of SOC, MBC, POC, and MAOC ranked highest in paddy compared with upland and woodland. DOC content in woodland was significantly higher than in upland and paddy (P<0.001). The proportion of each SOC fraction, i.e. DOC/SOC, MBC/SOC, POC/SOC, and MAOC/SOC, was in the range of 0.22%-0.93%, 1.62%-2.70%, 31.08%-40.00%, and 43.22%-56.82%, respectively. The contents of labile fractions (MBC and POC) and their proportions (MBC/SOC and POC/SOC) were in the order of paddy > woodland > upland. MAOC content ranked the highest in paddy but the lowest in upland, while MAOC/SOC exhibited the opposite trend. The correlation suggested that the labile fractions (MBC and POC) and inert fraction (MAOC) were significantly positively correlated with SOC (P<0.001) in the three land use types, while no significant correlations were found between DOC and SOC and its fractions (P>0.05). There was a significant positive correlation between POC and MBC in upland and woodland (P<0.001). POC was significantly positively correlated with MAOC in the three land use types (P<0.001). MAOC and MBC in paddy and upland were significantly positively correlated (P<0.001). Therefore, compared with upland and woodland, SOC in paddy had a higher proportion of labile SOC fraction, but a lower proportion of inert fraction. Moreover, MBC content in paddy was not related to the accumulation of the labile fraction of POC, but positively related to the accumulation of the inert fraction of MAOC. In summary, agricultural land uses have great influence on SOC and its fractions in hilly red soil regions. Though paddy is beneficial for SOC sequestration, the proportions of labile fractions in its SOC are relatively higher, and thus it is vulnerable to loss due to improper agricultural management.

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