Chin J Plant Ecol ›› 2020, Vol. 44 ›› Issue (1): 80-92.DOI: 10.17521/cjpe.2018.0177

• Research Articles • Previous Articles    

Effects of nitrogen and water addition on soil respiration in a Nei Mongol desert steppe with different intensities of grazing history

WEN Chao1,2,*(),SHAN Yu-Mei1,2,YE Ru-Han1,2,ZHANG Pu-Jin1,2,MU Lan1,2,CHANG Hong1,2,REN Ting-Ting3,4,CHEN Shi-Ping3,4,BAI Yong-Fei3,4,HUANG Jian-Hui3,4,SUN Hai-Lian1,2   

  1. 1Inner Mongolia Research Center for Prataculture, Chinese Academy of Sciences, Hohhot 010031, China
    2Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences, Hohhot 010031, China
    3State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    4Inner Mongolia Research Center for Prataculture, Chinese Academy of Sciences, Beijing 100093, China
  • Received:2018-07-30 Revised:2019-07-22 Online:2020-01-20 Published:2020-03-26
  • Contact: WEN Chao
  • Supported by:
    National Natural Science Foundation of China(31860138);Natural Science Foundation of Nei Mongol of China(2019MS03029);National Key R&D Program of China(2016YFC0500705);Science and Technology Innovation Foundation of Nei Mongol Agriculture and Animal Husbandry(2017CXJJM07)


Aims Soil respiration is an important indicator for evaluation of ecosystem health in the grazing grasslands of arid regions, and thus can be used to assess dynamics of ecosystem functioning during the restoration of degraded grasslands from enduring intensive grazing.
Methods This study was carried out in a Nei Mongol desert grassland with four grazing intensity treatments, i.e., control, light, moderate, and heavy grazing intensity designated as CK, LG, MG, and HG, respectively. Our objectives of this study were to explore the responses of soil respiration in these treatments with additional nitrogen (N) and water (W) addition. The plant community was dominated by a grass species, Stipa breviflora.
Important findings Our results showed that: (1) previous grazing intensity had significant impacts on soil respiration in 2016 and 2017, but not in 2015. Grazing increased soil respiration. Moreover, both nitrogen and water addition significantly enhanced soil respiration in MG plots, while only combined addition of nitrogen and water significantly increased soil respiration in HG plots. (2) Neither grazing intensity nor addition of nitrogen and water changed the seasonal dynamics of growing season soil respiration in this desert grassland. Soil respiration showed a single-peak curve model, and the peak occurred in July with both rain and heat. (3) The effects of nitrogen and water addition varied in different growing seasons. Nitrogen addition had no significant effects in the first two years (2015 and 2016), while showed significant effects in the third year (2017). Water addition had significant effects in years with normal precipitation (2015 and 2017), while had insignificant effect in the year with high precipitation (2016). Combined addition of nitrogen and water showed stronger effects than only addition of water in CK, LG, and HG plots, indicating that the synergistic effects of nitrogen and water addition on soil respiration. (4) The sensitivity of soil respiration to soil temperature at 10 cm depth (i.e., the Q10 value) ranged between 1.13 and 2.41, with an average value of 1.71. Without addition of nitrogen and water, Q10 values in grazing plots were all lower than in CK plots, with the lowest value occurring in HG plots. With the addition of water and combined addition of water and nitrogen, the Q10 value increased significantly by 100%. Taken together, our results indicated that soil moisture was the leading environmental factor affecting soil respiration in this desert grassland, while nitrogen played an effective role only after the minimum requirement of water availability was met. Results from this study will provide important helpful information for the restoration and rational utilization of the degraded desert steppe.

Key words: desert steppe, grazing intensity, soil respiration, precipitation increase, nitrogen addition