南京林业大学学报(自然科学版) ›› 2020, Vol. 44 ›› Issue (4): 167-175.doi: 10.3969/j.issn.1000-2006.202001021

• 研究论文 • 上一篇    下一篇

滨海滩涂不同土地利用类型土壤活性有机碳含量与垂直分布

许梦璐1(), 吴炜1, 颜铮明1, 曹国华2, 沈彩芹2, 阮宏华1()   

  1. 1.南京林业大学生物与环境学院, 南方现代林业协同创新中心,江苏 南京 210037
    2.江苏省东台市林场,江苏 东台 224200
  • 收稿日期:2020-01-08 修回日期:2020-03-16 出版日期:2020-07-22 发布日期:2020-08-13
  • 通讯作者: 阮宏华
  • 作者简介:许梦璐(xml@njfu.edu.cn),ORCID(0000-0003-0991-1663)
  • 基金资助:
    国家重点研发计划(2016YFD0600204);江苏高校优势学科建设工程资助项目

Content and vertical distribution of soil labile organic carbons in different land use types in the tidal flat area

XU Menglu1(), WU Wei1, YAN Zhengming1, CAO Guohua2, SHEN Caiqin2, RUAN Honghua1()   

  1. 1.Co -Innovation Center for the Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China
    2.Dongtai City Forest Farm of Jiangsu Province, Dongtai 224200, China
  • Received:2020-01-08 Revised:2020-03-16 Online:2020-07-22 Published:2020-08-13
  • Contact: RUAN Honghua

摘要: 目的

近年来,滨海滩涂已成为人类围垦开发的主要区域。围垦,一方面改变了土壤基本的理化性质,另一方面也加速了土壤有机碳库的变化,特别是对围垦活动比较敏感的活性有机碳,因此研究围垦区不同土地利用类型下土壤有机碳及其活性组分的含量与差异,能够为合理开发利用滨海湿地,了解围垦区的土壤碳循环特征提供参考。

方法

选择江苏东台沿海滩涂围垦区林地、旱地及水田土壤作为研究对象,并以光滩土壤作为对照,分层采集不同剖面的土壤样品,分析不同土地利用类型下可溶性有机碳(dissolved organic carbon, DOC)、微生物生物量碳(microbial biomass carbon, MBC)和易氧化碳(easily oxidized carbon, EOC)含量的变化特征及与土壤基本理化指标间的相关性。

结果

①随着土层深度的增加,各土地利用类型土壤DOC含量呈先增(0~40 cm)后减(≥40 ~100 cm)的趋势;土壤MBC和EOC含量均随土层深度呈现显著阶梯式下降。不同土地利用类型同一土层,除了DOC含量表现为光滩显著大于林地、旱地和水田外, MBC和EOC 的含量由大到小顺序依次为林地、水田、旱地、光滩。②随土层深度的增加,DOC和MBC分配比例的变化趋势一致,即光滩中无明显变化规律,林地、旱地和水田均先增后减,EOC分配比例随着土层深度的增加则没有表现出一致的变化趋势。0~40 cm土层,林地、旱地和水田的有机碳活性组分分配比例均显著低于光滩,40cm以下,各分配比例没有呈现一致的规律。③土壤MBC和EOC含量之间存在极显著相关关系,且二者均与土壤总有机碳(soil organic carbon, SOC)、总氮(total nitrogen, TN)含量呈极显著正相关,与pH呈极显著负相关,但与电导率(electric conductivity, EC)和总磷(total phosphorus, TP)含量之间不存在相关关系。而土壤DOC含量则与各指标间均不存在相关性。

结论

人为的农业耕种措施显著增加了土壤有机碳及其活性组分的含量,提高了土壤有机碳的稳定性,其中,林地和水田土壤活性有机碳含量较多,尤其林地更有利于土壤有机碳的积累,可能发挥更大的碳汇功能。水田降低pH效果最佳,故在围垦初期,人类耕作活动以水田为主可快速脱盐脱钙,进而有利于有机碳的积累。滨海滩涂的开发利用可能显著改变原有湿地碳循环的路径与模式,故应该充分考虑滩涂围垦对土壤碳循环的影响。

关键词: 可溶性有机碳, 微生物生物量碳, 易氧化碳, 土地利用类型, 滩涂围垦

Abstract: Objective

Coastal tidal flats have a high carbon sequestration potential, which may contribute to alleviating the global greenhouse effect.However, they are being reclaimed at an increasing rate because they provide important land for relieving population pressure, promoting regional economic growth, and ensuring food safety. With the largest area of tidal flats in China, a long history of coastal reclamation activities has been existed in Jiangsu Province. Tidal flat reclamation practices change the basic physical and chemical properties of soil, and accelerate changes in the soil organic carbon pool, especially the active organic carbon, which is sensitive to reclamation activities. Meanwhile, the active organic carbon components can be used to characterize the short term changes in the soil organic carbon pool. As such, studying the differences in soil organic carbon and its active components under different land use types in reclamation areas may provide a reference for the rational development and utilization of coastal wetlands. It is also important to elucidate the role of soil carbon in coastal reclamation areas.

Method

A bare tidal flat, paddy field, and area of upland and forest land in the reclamation area in Dongtai, Jiangsu were selected as research sites.At each site, soil samples were collected from different soil depth layers in order to analyze the variations in dissolved organic carbon (DOC), microbial biomass carbon (MBC) and easily oxidized carbon (EOC) under the different land use types.

Result

①With the increase of soil depth, the DOC content increased in soil depths of 0—40 cm soils, but decreased in soil depths of 40—100 cm.Furthermore, the MBC and EOC content decreased significantly in soil depths of 0—100 cm across the four land use types. When tested in the same soil layer, the DOC content of the bared tidal flat soil was significantly larger than that of the soil in the other three land use types. However, the MBC and EOC content descended in the following order: forest land, paddy field, upland,bared tidal flat soil.②With the increase of soil depth, the ratio of DOC to SOC and the ratio of MBC to SOC content followed the same trend in the forest land, the upland and the paddy field; first they increased in soil of 0—40 cm depth, then decreased in soil of 40—100 cm depth. However, there were no obvious changes in the bare tidal flat soil,and the ratio of EOC to SOC content did not show the same trend with the increase of soil depth. Furthermore, in soil depths of 0—40 cm, the ratios of DOC to SOC, MBC to SOC content, and EOC to SOC content in the forest land, upland and paddy field were significantly lower than those in the bared tidal flat. ③The MBC and EOC contents were significantly correlated, and were both significantly correlated with SOC, TN content and pH. However, the correlations with EC and TP content were not significant, and DOC content was not correlated with any of the indices.

Conclusion

Our results indicate that agricultural cultivation measures significantly increased the content of soil organic carbon and its active components, and improved the stability of the soil organic carbon.The forest land and paddy field had more soil active organic carbon than the other sites tested. The forest land in particular had accumulated the most soil organic carbon, indicating that the types of land may play an important role as carbon sinks in the coastal area of Jiangsu, southeastern China.Reclamation had the best effect on decreasing soil pH at the paddy field site, and as the main farming activity which is practiced at the early stages of reclaiming land fromtidal flats, this could quickly lead to desalination and decalcification of the land. In conclusion, the development and utilization of tidal flats can significantly change the natural pathway and models of the carbon cycles in the coastal wet lands, and the impacts of land use designation on the soil carbon cycle during reclamation should be fully considered in future research.

Key words: dissolved organic carbon, microbial biomass carbon, easily oxidized carbon, land use type, reclamation

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