Chin J Plant Ecol ›› 2020, Vol. 44 ›› Issue (1): 70-79.DOI: 10.17521/cjpe.2019.0270

• Research Articles • Previous Articles     Next Articles

Response of soil respiration to addition of different forms of nitrogen and mowing in a saline-alkali grassland in the northern agro-pastoral ecotone

HU Shu-Ya1,2,DIAO Hua-Jie1,3,WANG Hui-Ling3,BO Yuan-Chao3,SHEN Yan1,SUN Wei4,DONG Kuan-Hu3,HUANG Jian-Hui1,2,WANG Chang-Hui1,*()   

  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
    3College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Jinzhong, Shanxi 030801, China
    4Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun 130024, China
  • Received:2019-10-15 Revised:2020-01-05 Online:2020-01-20 Published:2020-03-26
  • Contact: WANG Chang-Hui
  • Supported by:
    National Natural Science Foundation of China(31770526);National Natural Science Foundation of China(31872406);National Key R&D Program of China(2017YFA0604802);National Key R&D Program of China(2016YFC0500703)

Abstract:

Aims The agro-pastoral ecotone is considered as fragile ecosystems which are strongly affected by agriculture and animal husbandry. The saline-alkali grassland is a unique grassland type in the agro-pastoral ecotone. A large amount of fertilizers are used to increase productivity in this area, which also promotes the emission of reactive nitrogen (N) gases and leads to the changes in soil carbon and N cycles. Mowing is a primary management practice in the agro-pastoral grassland in northern China. In order to explore the impact of N addition and mowing on carbon dynamic in this saline-alkali grassland located in the agro-pastoral ecotone, we determined the response of soil respiration to N addition and mowing.
Methods This study area is located in Youyu County, an agro-pastoral grassland ecosystem in northern China. The field experiment was set up in May, 2017. The treatments included: control (without mowing and mowing), addition of urea, addition of slow release urea, addition of urea + mowing, addition of slow release urea + mowing. Each treatment included 6 replicates. Therefore, there were totally 36 plots in this experiment. Soil respiration rate, soil temperature, soil moisture content, microbial biomass, inorganic N content, above-ground and below-ground biomass were measured under different treatments, and the cumulative carbon emissions and CO2 fluxes were calculated.
Important findings Our results showed that: (1) Short-term (2017-2018) N addition significantly increased soil respiration rates and soil cumulative carbon emissions. Meanwhile, soil respiration rates and cumulative carbon emissions were significantly higher under urea treatment than those under slow release urea addition. (2) Mowing significantly reduced soil respiration rates and cumulative carbon emissions. (3) The interaction of short-term N addition and mowing had no significant effect on soil respiration rate. Therefore, short-term N addition can promote soil carbon release from the saline-alkali grassland in the agro-pastoral ecotone of northern China. Mowing can reduce soil respiration and decrease cumulative of carbon emissions. This may be because that mowing reduced the input of litter and further reduced soil substrate for microbes, which led to a decrease in soil microbial activity. However, long-term effect of N addition and mowing on soil carbon dynamics in saline-alkaline grasslands in the agro-pastoral ecotone still needs to be further explored.

Key words: mowing, nitrogen forms, soil respiration, agro-pastoral ecotone, saline-alkali grassland