植物生态学报 ›› 2019, Vol. 43 ›› Issue (7): 624-634.doi: 10.17521/cjpe.2019.0028

• 研究论文 • 上一篇    

长期不同植被覆盖对黑土团聚体内有机碳组分的影响

李娜,张一鹤,韩晓增,尤孟阳,郝翔翔   

  1. 中国科学院东北地理与农业生态研究所
  • 收稿日期:2019-01-30 修回日期:2019-07-26 出版日期:2019-07-20 发布日期:2019-12-12
  • 通讯作者: 韩晓增 E-mail:xzhan@iga.ac.cn
  • 基金资助:
    国家重点研发计划项目;中国科学院前沿科学研究重点计划项目;中国科学院青年创新促进会项目;中国科学院东北地理与农业生态研究所优秀青年人才项目

The effects of long-term vegetation cover changes on the carbon fractions in soil aggregates of Mollisols

1,Zhang Yihe2,Han Xiaozeng2,You Mengyang2,Hao Xiangxiang2   

  1. 1. Northeast Institute of Geography and Agroecology, CAS
    2. Northeast institute of Geography and Agroecology, Chinese Academy of Sciences
  • Received:2019-01-30 Revised:2019-07-26 Online:2019-07-20 Published:2019-12-12
  • Contact: Han Xiaozeng E-mail:xzhan@iga.ac.cn

摘要: 土壤团聚体是土壤有机质分解转化和形成的主要场所, 是制约土壤固碳效应的关键, 不同粒径团聚体中土壤有机碳(SOC)组分的稳定机制存在差异。为探究黑土团聚体内SOC的“分馏”特征, 揭示不同植被覆盖下土壤团聚体的固碳机制, 该文以中国科学院海伦站内不同植被覆盖(草地、农田和裸地)长期定位实验的土样为研究对象, 利用团聚体湿筛分组、有机碳物理和化学分组相结合的方法, 研究了黑土团聚体及其内部的碳密度和腐殖质组分的碳分配特征。研究发现, 黑土经过31年不同植被覆盖后, 长期草地覆盖使土壤表层SOC、全氮(TN)含量显著增加, 农田和无植被覆盖的裸地SOC含量减少, 且在裸地显著降低。3种处理中, 2–0.25 mm粒级团聚体均为优粒级。土壤团聚体的稳定性顺序为草地>农田>裸地。草地覆盖使土壤大团聚体的比例和有机碳库增加, 微团聚体和粉黏粒所占比例和碳库均减少, 说明草地覆盖促进了土壤大团聚体形成, 土壤固碳能力显著增强。而农田和裸地因外源碳投入少, 有机碳含量均是微团聚体>大团聚体>粉黏粒, SOC主要分布在微团聚体中。不同植被覆盖处理对土壤团聚体内密度组分和腐殖质各组分碳的富集“分馏”作用很明显, 与农田和裸地相比, 长期草地植被覆盖处理>2 mm和2–0.25 mm粒级团聚体中轻组碳含量富集的较多, 2–0.25 mm粒级团聚体中富里酸、胡敏酸和胡敏素的碳富集均最高, 而农田和裸地促进了微团聚体内腐殖质碳的富集。说明草地覆盖显著增加了大团聚体内活性有机碳组分, 来源于植物的碳首先进入到大粒径的团聚体中, 使土壤团聚结构显著改善, 农田和无植被覆盖的裸地土壤中轻组碳含量显著降低, 团聚体内有机碳以重组碳和胡敏素为主, 稳定化程度更高。该研究结果揭示了不同植被覆盖下黑土团聚体的固碳特征及其内组分碳的“分馏”特征, 为土壤团聚体固碳机制的研究提供了理论依据, 也对优化黑土利用方式提供指导意义。

关键词: 植被覆盖, 水稳性团聚体, 土壤有机碳, 密度组分, 腐殖酸

Abstract:
Aims Soil aggregate is the main habitat for decomposition and transformation of soil organic carbon (SOC). It’s the key to regulate SOC sequestration. The stability mechanisms of SOC fractions may vary among different aggregate sizes. The aims of this study are to explore the SOC “fractionation” characteristics of aggregates, and to reveal the C sequestration mechanisms within soil aggregates after 31-year different vegetation cover in Mollisols. Methods A long-term field vegetation cover experiment (grassland, farmland and bare land) was established in Hailun Station of Chinese Academy of Sciences. Soil aggregate fractionation, further density and humus fractionation within different aggregate sizes were carried out. Important findings The results showed that after 31 years of grassland (GL), farmland (FL) and bareland (BL) treatments, the surface SOC and total nitrogen (TN) contents in GL with higher C inputs increased significantly, while the SOC and TN contents decreased in FL and BL, and significance were found in BL. The 2–0.25 mm aggregates was the excellent fraction in all three treatments. The stability of soil aggregate fell in the order of: GL > FL > BL. The mass proportion of soil aggregate and its associated content significantly improved in GL, and the proportion of microaggregate and its carbon allocation rate decreased. However, due to the lower C inputs in FL and BL, the distribution of aggregates was microaggregate > macroaggregate > silt-clay fraction, and OC content was higher in microaggregates. Different vegetation cover caused the C “fractionation” of density and humus fractions in aggregates. Compared with FL and BL soils, OC contents in light fractions in >2 mm and 2–0.25 mm aggregates were higher in GL, and the OC contents in FA, HA and HU were highest in 2–0.25 mm aggregates, while the humus OC in microaggregates were accumulated in FL and BL. Our results indicated that the plant-derived C entered into macroaggregates firstly, long-term grassland enhanced free and light C fractions in macroaggregate, which consequently improved the stability of soil aggregates and enhanced the “fractionation” effects of large aggregates on the humus fractions. Our results revealed that the carbon sequestration characteristics of soil aggregates under different vegetation cover in mollisol. The C “fractionation” characteristics in aggregates can provide theoretical basis and significant guidance for the study of soil carbon sequestration mechanism and optimization of black soil utilization.

Key words: vegetation cover, water-stable aggregates, soil organic carbon, density fraction, humus