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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 15, issue 13 | Copyright
Biogeosciences, 15, 4233-4243, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 12 Jul 2018

Research article | 12 Jul 2018

Grazing increases litter decomposition rate but decreases nitrogen release rate in an alpine meadow

Yi Sun1,3, Xiong Z. He2, Fujiang Hou1, Zhaofeng Wang1, and Shenghua Chang1 Yi Sun et al.
  • 1State Key Laboratory of Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730000, Gansu, China
  • 2School of Agriculture and Environment, College of Science, Massey University, Private Bag 11-222, Palmerston North, New Zealand
  • 3State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 320 Donggang West Road, Lanzhou 730000, China

Abstract. Litter decomposition and N release are the key processes that strongly determine the nutrient cycling at the soil–plant interface; however, how these processes are affected by grazing or grazing exclusion in the alpine grassland ecosystems on the Qinghai-Tibetan Plateau (QTP) is poorly understood. So far few studies have simultaneously investigated the influence of both litter quality and incubation site on litter decomposition and N release. Moreover, previous studies on the QTP investigating how grazing exclusion influences plant abundance and biodiversity usually lasted for many years, and the short-term effects have rarely been reported. This work studied the short-term (6 months) effects of grazing and grazing exclusion on plant community composition (i.e., plant species presented) and litter quality and long-term (27–33 months) effects on soil chemical characteristics and mixed litter decomposition and N release on the QTP. Our results demonstrate that (1) shorter-term grazing exclusion had no effect on plant community composition but increased plant palatability and total litter biomass; (2) grazing resulted in higher N and C content in litter; and (3) grazing accelerated litter decomposition, while grazing exclusion promoted N release from litter and increased soil organic carbon. In addition, incubation site had significantly more impact than litter quality on litter decomposition and N release, while litter quality affected decomposition in the early stages. This study provides insights into the mechanisms behind the nutrient cycling in alpine ecosystems. We suggest that periodic grazing and grazing exclusion is beneficial in grassland management on the QTP.

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Short summary
To investigate how grazing alters litter composition, quality and decomposition, we collected litter from grazing (GP) and grazing exclusion paddocks (GEP) and incubated them in situ and across sites. Grazing increased litter N and grazing exclusion increased litter mass of palatable species and promoted SOC. Litter decomposed faster in GP and N was opposite. Site environment had more impact on litter decomposition. Results may be helpful in developing strategies to restore degraded grasslands.
To investigate how grazing alters litter composition, quality and decomposition, we collected...