Chin J Plant Ecol ›› 2020, Vol. 44 ›› Issue (8): 791-806.DOI: 10.17521/cjpe.2020.0126

• Research Articles •     Next Articles

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)


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