Plant composition change mediates climate drought, nitrogen addition, and grazing effects on soil net nitrogen mineralization in a semi-arid grassland in North China

Peng Lv; Shanshan Sun; Yuqiang Li; Shenglong Zhao; Jing Zhang; Ya Hu; Ping Yue; Xiaoan Zuo

doi:10.1016/j.scitotenv.2023.168282

Plant composition change mediates climate drought, nitrogen addition, and grazing effects on soil net nitrogen mineralization in a semi-arid grassland in North China

Sci Total Environ. 2024 Jan 15:908:168282. doi: 10.1016/j.scitotenv.2023.168282. Epub 2023 Nov 3.

Authors

Peng Lv¹, Shanshan Sun², Yuqiang Li³, Shenglong Zhao⁴, Jing Zhang⁵, Ya Hu⁶, Ping Yue⁶, Xiaoan Zuo⁷

Affiliations

¹ Naiman Desertification Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Urat Desert-Grassland Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Key Laboratory of Stress Physiology and Ecology in Cold and Arid Regions, Gansu Province, Lanzhou 730000, China.
² Urat Desert-Grassland Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.
³ Naiman Desertification Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Key Laboratory of Stress Physiology and Ecology in Cold and Arid Regions, Gansu Province, Lanzhou 730000, China.
⁴ College of Resources and Environmental Engineering, Tianshui Normal University, Tianshui 741000, China.
⁵ Information Center, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
⁶ Urat Desert-Grassland Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Key Laboratory of Stress Physiology and Ecology in Cold and Arid Regions, Gansu Province, Lanzhou 730000, China.
⁷ Naiman Desertification Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Urat Desert-Grassland Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Key Laboratory of Stress Physiology and Ecology in Cold and Arid Regions, Gansu Province, Lanzhou 730000, China. Electronic address: zuoxa@lzb.ac.cn.

PMID: 37923269
DOI: 10.1016/j.scitotenv.2023.168282

Abstract

Human activities induce alterations of the nitrogen (N) cycle, climate drought, and disturbance (e.g., livestock grazing) regimes at the global scale. Their individual, interactive, and combined effects on soil N cycling in grasslands are unclear. We investigated the N addition, drought, and grazing effects on the N mineralization, as well as their correlations with N-related variables, including the C4 species, shoot biomass (SB), root biomass (RB), plant total nitrogen (PTN), plant total carbon (PTC), soil total nitrogen (STN), soil total carbon (STC), and soil microbial N and C, during a three-year field experiment conducted in a semi-arid grassland in North China. The results showed that N addition increased the nitrate N (NO₃^--N) and ammonium N (NH₄⁺-N) concentrations, whereas drought decreased the NO₃^--N concentration because of strengthened N limitation. Pronounced temporal variation in the N mineralization occurred under seasonal drought (maxima in August and September) and under its combination with N addition and grazing (minima in August). RB and the C4 species were positively correlated, whereas STC and the NO₃^--N concentration were negatively correlated with the N mineralization under the combined influence of the three factors. The structural equation model showed that at the site affected by all three factors, drought indirectly increased the N mineralization by reducing the NO₃^--N concentration, whereas N addition and grazing did not alter the N mineralization. N addition directly increased while indirectly reduced N mineralization by increasing the NO₃^--N concentration. Additionally, N addition and grazing increased the C4 species and decreased the STC, consequently enhanced N mineralization. These results highlight the predominant role of drought, when combined with N addition and grazing, in controlling the N mineralization. The N supply balance in semi-arid grasslands could be stabilized in response to increased N addition, climate drought, and grazing.

Keywords: Biomass allocation; C4 species; Nitrogen cycling; Plant C and N; Soil C and N; Soil inorganic N pool.

MeSH terms

Carbon / analysis
China
Droughts
Ecosystem
Grassland*
Humans
Nitrogen / analysis
Plants
Soil* / chemistry

Substances

Soil
Nitrogen
Carbon