Journal of Plant Ecology ›› 2021, Vol. 14 ›› Issue (5): 816-828.DOI: 10.1093/jpe/rtab034

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  • 收稿日期:2020-10-31 修回日期:2020-12-15 接受日期:2021-03-16 出版日期:2021-10-01 发布日期:2021-05-31

Nitrogen addition amplified water effects on species composition shift and productivity increase

Xiaolin Zhang1,2,†, Muqier Hasi1,3,†, Ang Li1, *, Yulian Tan1, Stefani Daryanto4, Lixin Wang4, Xueyao Zhang1, Shiping Chen1 and Jianhui Huang1,3, *   

  1. 1 State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093, China, 2 College of Grassland Science, Shanxi Agricultural University, Taigu 030801, China, 3 College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China, 4 Department of Earth Sciences, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA

    *Corresponding author. E-mail: lyons@ibcas.ac.cn (A.L.); jhhuang@ibcas.ac.cn (J.H.)
    †These authors contributed equally to this work.
  • Received:2020-10-31 Revised:2020-12-15 Accepted:2021-03-16 Online:2021-10-01 Published:2021-05-31

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摘要： 增加氮素放大了水分对物种组成变化和生产力提高的影响
水分和氮素是旱地生态系统中的重要资源，二者对群落结构和生态系统功能的影响存在着复杂的交互作用。未来降水(降雨与降雪)变化将如何影响地上净初级生产力(ANPP)尚未研究清楚，尤其是当降水变化与氮沉降引起的氮有效性增加相互结合时。在本研究中，我们探讨了半干旱温带典型草原对增加降水(降雨与降雪)和氮素的响应，包括群落生产力、两种主要植物功能群、多年生根茎禾草(PR)和多年生丛生禾草(PB)的多度和地上生物量的变化。研究结果发现，夏季增雨略微增加了群落的ANPP，显著增加了PR的多度和地上生物量，而对PB的多度和地上生物量没有影响。夏季增雨提高了PR生物量在ANPP中的占比，降低了PB生物量的占比。春季增雪对上述两个植物功能群地上生物量均无显著影响，尽管它对群落ANPP有一定的提高。在夏季增雨条件下，氮素添加显著增加了群落ANPP，主要是由于增加了PR的生物量，说明氮和水分添加对群落ANPP存在较强的交互作用，并在很大程度上通过提高PR生物量来实现。我们发现随着降水量的增加，施氮对生产力的正效应呈非线性增加。上述结果表明，在未来大气氮沉降增加的情景下，降水增加对草地生产力的影响将得到进一步放大。

关键词: 地上净初级生产力, 群落结构, 温带草原, 氮素添加, 雨雪添加

Abstract:

Aims

Water and nitrogen (N) are two key resources in dryland ecosystems, but they may have complex interactive effects on the community structure and ecosystem functions. How future precipitation (rainfall vs snowfall) change will impact aboveground net primary production (ANPP) is far from clear, especially when combined with increasing N availability.

Methods

In this study, we investigated changes in community productivity, abundance and aboveground biomass of two dominant plant functional groups (PFGs), i.e. perennial rhizome grasses (PR) and perennial bunchgrasses (PB) under the impacts of increased precipitation (rainfall vs snowfall) combined with N addition in a semiarid temperate steppe.

Important Findings

Summer rainfall augmentation marginally increased community ANPP, whereas it significantly increased the abundance and aboveground biomass of PR, but not those of PB. Summer rainfall addition increased the fraction of PR biomass (fPR) while decreased that of PB (fPB). Spring snow addition had no effect on aboveground biomass of either compositional PFG although it marginally increased community ANPP. Nitrogen addition significantly increased community ANPP with greater increase in PR under summer rainfall addition, indicating strong interactive effects on community ANPP largely by enhancing PR biomass. We also found a nonlinear increase in the positive effect of nitrogen addition on productivity with the increased precipitation amount. These findings indicate an amplified impact of precipitation increase on grassland productivity under the accelerated atmospheric N deposition in the future.

Key words: aboveground net primary production, community structure, temperate steppe, nitrogen addition, snow and water addition

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