植物生态学报 ›› 2020, Vol. 44 ›› Issue (8): 791-806.DOI: 10.17521/cjpe.2020.0126

• 研究论文 •    下一篇

凋落物输入变化和氮添加对半干旱草原群落生产力及功能群组成的影响

嘎玛达尔基1,2, 杨泽1,2, 谭星儒1,2, 王珊珊1,2, 李伟晶1,2, 游翠海1,2, 王彦兵1,2, 张兵伟1,3, 任婷婷1,2, 陈世苹1,2,*()   

  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, 北京 100049
    3中山大学有害生物控制与资源利用国家重点实验室, 中山大学生命科学学院, 广州 510275
  • 收稿日期:2020-04-30 接受日期:2020-07-01 出版日期:2020-08-20 发布日期:2020-07-09
  • 通讯作者: 陈世苹
  • 作者简介:* spchen@ibcas.ac.cn
  • 基金资助:
    国家自然科学基金(41773084);国家重点研发计划(2017YFA0604801);国家重点研发计划(2016YFC0500103)

Effect of altered litter input and nitrogen addition on ecosystem aboveground primary productivity and plant functional group composition in a semiarid grassland

GAMADAERJI 1,2, YANG Ze1,2, TAN Xing-Ru1,2, WANG Shan-Shan1,2, LI Wei-Jing1,2, YOU Cui-Hai1,2, WANG Yan-Bing1,2, ZHANG Bing-Wei1,3, REN Ting-Ting1,2, CHEN Shi-Ping1,2,*()   

  1. 1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    2University of Chinese Academy of Sciences, Beijing 100049, China
    3State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
  • Received:2020-04-30 Accepted:2020-07-01 Online:2020-08-20 Published:2020-07-09
  • Contact: CHEN Shi-Ping
  • Supported by:
    National Natural Science Foundation of China(41773084);National Key R&D Program of China(2017YFA0604801);National Key R&D Program of China(2016YFC0500103)

摘要:

不同的草原利用方式(围封、放牧和割草等)随着大气氮沉降的不断加剧, 改变了凋落物输入量。凋落物作为连接地上-地下碳循环过程的关键环节, 对草原生态系统生产力和碳循环过程影响显著。氮是草原生产力的主要限制因子, 凋落物输入量的变化对草原生态系统结构和功能的影响仍缺乏长期实验证据支持。该研究在内蒙古半干旱典型草原建立一个凋落物输入变化和氮添加控制实验平台, 通过连续6年对群落生产力和功能群组成的监测, 研究了凋落物添加与去除和氮添加对半干旱草原群落生产力和功能群组成的影响。研究发现: 1)凋落物输入量增加和氮添加均显著提高了群落生产力, 在对照和氮添加处理下, 凋落物去除处理导致生产力分别降低了8.4%和7.6%, 而凋落物添加处理使生产力分别提高了10.7%和6.3%; 2)不同植物功能群对凋落物输入变化和氮添加的响应存在差异, 导致群落功能群结构发生变化。随着凋落物输入量增加和氮添加, 群落优势功能群多年生禾草(包括多年生丛生禾草和多年生根茎禾草)的生物量显著提高, 对群落生产力的贡献增加, 在群落中的优势地位增强; 而另一优势功能群多年生杂类草生物量对凋落物和氮添加处理均无显著响应, 进而导致在氮添加处理下其对群落生物量的贡献比例显著降低; 3)凋落物输入主要改善土壤水分状况, 而氮添加则主要通过提高土壤养分含量, 促进群落生产力, 并通过影响主要功能群生物量, 导致群落结构发生变化。以上结果表明, 适当的草原管理方式如围封禁牧和降低放牧强度等都能通过增加凋落物的输入来提高草原生产力, 维持生态系统稳定性。而适量的氮等养分添加管理也有助于提高草原生产力, 促进其恢复。

关键词: 地上净初级生产力, 植物功能群, 凋落物输入变化, 氮添加, 半干旱草原

Abstract:

Aims Litter is the major input source of soil organic carbon and nutrients in natural ecosystems and considered as a key link between above- and belowground carbon cycles. Changes in litter input amount have been proven to exert significant impacts on plant productivity, community structure, and therefore ecosystem function. In Nei Mongol semiarid grasslands, different grassland management practices such as grazing, clipping, and fencing have caused dramatic changes in litter production and input. In addition, as a nitrogen-limited ecosystem, Nei Mongol semiarid grasslands also experienced increasing nitrogen deposition. However, how do changes in litter input and nitrogen addition impact the community productivity and composition of plant functional groups are still unclear in the semiarid grasslands. In this study, our objectives are: 1) to investigate the effects of altered litter input and nitrogen addition on community productivity; 2) to study the changes in aboveground biomass of different plant functional groups and their contribution to community productivity under different litter input and N addition treatments.
Methods We established a manipulative experiment with altered litter input and nitrogen addition treatments in a semiarid typical grassland in West Ujimqin Banner, Nei Mongol. A randomized block split-plot design was applied with five blocks. Three litter input treatments, including litter removal (C0), control (C1) and litter addition (C2), were assigned randomly in each block. Each plot (6 m × 7 m) of litter input treatment was separated into two subplots. One of the subplots was assigned as the N addition treatment (N1) and another subplot was considered as the control treatment without N addition (N0). In N addition treatment, 15 g N·m-2·a-1 N fertilizer (as NH4NO3) was applied every year since 2013. Aboveground net primary productivity (ANPP) in community and plant functional group levels of each treatment were determined during the peak season from 2013 to 2018.
Important findings Based on 6-year measurements, we found the following results. 1) Litter input increase and nitrogen addition increased community ANPP. Compared with the control, litter removal treatment significantly decreased ANPP by 8.4% and 7.6% in plots without and with N addition, respectively. Litter addition increased ANPP by 10.7% and 6.3% in plots without and with N addition, respectively. 2) Different responses of plant functional groups to altered litter input and N addition led to a change in plant functional group composition. The biomass of perennial bunch grass (PB) and perennial rhizome grass (PR) increased significantly with the increment of litter and nitrogen, which enhanced their dominant status in the community. 3) Improved soil water condition by litter input and nutrient supply by N addition are the major pathways that enhanced ANPP and changed the functional group composition. These results show that proper management, such as grazing exclusion and reducing grazing intensity, can promote productivity by increasing inputs of litter in semiarid grasslands, which leads to the maintenance of ecosystem stability. Suitable nutrients management, like nitrogen addition, is also helpful for productivity improvement and the recovery of degraded grasslands.

Key words: aboveground net primary productivity (ANPP), plant functional group, altered litter input, nitrogen addition, semiarid grassland