植物学报 ›› 2018, Vol. 53 ›› Issue (1): 27-41.DOI: 10.11983/CBB17041

• 研究论文 • 上一篇    下一篇

氮素添加对内蒙古草甸草原生态系统CO2交换的影响

哈斯木其尔1,2, 张学耀1,2, 牛国祥1,2, 王银柳1,2, 黄建辉1,*()   

  1. 1中国科学院植物研究所, 植被与环境变化国家重点实验室, 北京 100093
    2中国科学院大学生命科学学院, 北京 100049
  • 收稿日期:2017-03-09 接受日期:2017-05-08 出版日期:2018-01-01 发布日期:2018-08-10
  • 通讯作者: 黄建辉
  • 基金资助:
    国家自然科学基金(No.31670483)和科技部生态修复专项(No.2016YFC0500706)

Effects of Nitrogen Addition on Ecosystem CO2 Exchange in a Meadow Steppe, Inner Mongolia

Muqier Hasi1,2, Xueyao Zhang1,2, Guoxiang Niu1,2, Yinliu Wang1,2, Jianhui Huang1,*()   

  1. 1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    2College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2017-03-09 Accepted:2017-05-08 Online:2018-01-01 Published:2018-08-10
  • Contact: Jianhui Huang

摘要:

氮沉降增加将影响草原生态系统固碳, 但如何影响草原生态系统CO2交换目前为止还没有定论。同时, 不同类型和剂量氮素对生态系统CO2交换影响的差异也不明确。选取内蒙古额尔古纳草甸草原, 开展了不同类型氮肥和不同剂量氮素添加条件下生态系统CO2交换的野外测定。实验设置尿素和缓释尿素2种类型氮肥各5个剂量水平(0、5.0、10.0、20.0和50.0 g N·m-2·a-1)。结果显示, 生长季初期及中期降雨量低时, 氮素添加抑制生态系统CO2交换; 而生长季末期降雨量较高时促进生态系统CO2交换。随着氮素添加水平的提高, NEE和GEP均显著增加, 当氮素添加量达到10 g N·m-2·a-1时, NEE和GEP的响应趋于饱和。2种氮肥(尿素和缓释尿素)仅在施氮量为5 g N·m-2·a-1时, 缓释尿素对生态系统CO2交换的促进作用显著大于尿素, 在其它添加剂量时差异不显著。研究结果表明: 氮素是该草甸草原生态系统的重要限制因子, 但氮沉降增加对生态系统CO2交换的影响强烈地受降雨量与降雨季节分配的限制, 不同氮肥(尿素和缓释尿素)对生态系统CO2交换作用存在差异。

关键词: 氮素添加, 生态系统净CO2交换, 生态系统呼吸, 草原生态系统总光合, 草甸草原

Abstract:

Increasing nitrogen deposition influences carbon sequestration in grassland ecosystems, but we have no consistent results on how it impacts the exchange of CO2 at the ecosystem level. As well, the impact of different types of N fertilizers and rates of N increase are not clear yet. This study aimed to evaluate the effect of N addition on ecosystem CO2 exchange and was performed in a meadow steppe in Erguna, Inner Mongolia. A field experiment compared two types of N fertilizers (urea and slow-release urea) with five N addition rates (0, 5.0, 10.0, 20.0 and 50.0 g N·m-2·a-1). At the start and middle stage of the growing season, N addition had weak and inhibitive effects on ecosystem CO2 exchange when precipitation was low, and significantly increased ecosystem CO2 exchange in the late growing season when precipitation was high. Both net ecosystem CO2 exchange and gross ecosystem photosynthesis increased significantly with N addition rate but showed a tendency of saturation when the N addition rate reached 10 g N·m-2·a-1. The two types of N fertilizers resulted in slightly different responses of ecosystem CO2 exchange: slow-release urea had a stronger positive effect at 5 g N·m-2·a-1 with no significant difference at other addition rates. Our study suggests that increasing N deposition has significant effects on carbon assimilation in this semi-arid grassland, but the direction and magnitude of effects are strongly affected by seasonal pattern and amount of precipitation. The effects of different types of N fertilizers (i.e., urea and slow-release urea) on ecosystem CO2 exchange may differ.

Key words: nitrogen addition, net ecosystem CO2 exchange, ecosystem respiration, gross ecosystem photosynthesis, meadow steppe