植物生态学报 ›› 2025, Vol. 49 ›› Issue (6): 965-974.DOI: 10.17521/cjpe.2023.0222  cstr: 32100.14.cjpe.2023.0222

• 研究论文 • 上一篇    下一篇

晋北农牧交错带草地土壤无机氮含量的季节变化及其对放牧强度的响应

马腾飞1,2,3, 郝杰1,2,3, 刁华杰1,2,3, 宁亚楠1,2,3, $\boxed{\hbox{王常慧}}$1,2,3,*(), 董宽虎1,2,3,*   

  1. 1山西农业大学草业学院, 山西太谷 030801
    2草地生态保护与乡土草种质创新山西省重点实验室, 山西太谷 030801
    3山西右玉黄土高原草地生态系统国家定位观测研究站, 山西右玉 037200
  • 收稿日期:2023-08-03 接受日期:2024-05-06 出版日期:2025-06-20 发布日期:2024-05-07
  • 通讯作者: *董宽虎(dongkuanhu@sxau.edu.cn)
  • 基金资助:
    国家自然科学基金(U22A20576);国家重点研发计划(2022YFF1302801);山西省重点实验室项目(202104010910017)

Seasonal variations of soil inorganic nitrogen contents and their responses to changing grazing intensity in grasslands of an agro-pastoral ecotone in northern Shanxi, China

MA Teng-Fei1,2,3, HAO Jie1,2,3, DIAO Hua-Jie1,2,3, NING Ya-Nan1,2,3, $\boxed{\hbox{WANG Chang-Hui}}$ 1,2,3,*(), DONG Kuan-Hu1,2,3,*   

  1. 1College of Grassland Science, Shanxi Agricultural University, Taigu, Shanxi 030801, China
    2Shanxi Key Laboratory of Grassland Ecological Protection and Native Grass Germplasm Innovation, Taigu, Shanxi 030801, China
    3and Shanxi Youyu Loess Plateau Grassland Ecosystem National Observation and Research Station, Shanxi Agricultural University, Youyu, Shanxi 037200, China
  • Received:2023-08-03 Accepted:2024-05-06 Online:2025-06-20 Published:2024-05-07
  • Contact: *(Dong KH, dongkuanhu@sxau.edu.cn)
  • Supported by:
    National Natural Science Foundation of China(U22A20576);National Key R&D Program of China(2022YFF1302801);Shanxi Key Laboratory Project(202104010910017)

摘要:

土壤无机氮包括铵态氮(NH4+-N)和硝态氮(NO3--N), 是陆地植物生长必需的养分。放牧通过家畜采食、践踏和粪尿归还影响土壤理化性质及微生物活性, 改变土壤无机氮含量, 进而影响植物生产力。然而, 不同放牧强度下, 土壤无机氮季节动态及年际差异尚不清晰。该研究以晋北农牧交错带草地为研究对象, 依托2016年8月建立的不同放牧强度试验平台(不放牧(UG)、轻度放牧(LG, 每生长季2.35羊单位·hm-2)、中度放牧(MG, 每生长季4.80羊单位·hm-2)、重度放牧(HG, 每生长季7.85羊单位·hm-2)), 通过测定2017-2021年生长季(5-9月)土壤无机氮含量的季节变化, 研究不同放牧强度下土壤无机氮季节动态及年际差异特征。结果表明: (1)不同放牧强度对土壤无机氮含量季节均值没有产生显著影响, 然而显著降低植物生物量, 这与生长季不同时期放牧效应的变化有关。(2)土壤无机氮含量在整个生长季呈现出先升高再降低的变化趋势。(3)土壤无机氮含量呈现出显著的年际差异, 这与年际间降水的变化有关。该研究结果表明北方农牧交错带草地土壤无机氮含量对短期不同放牧强度的响应不显著, 季节降水变化是引起土壤无机氮含量年际变异的主要原因, 未来草地管理应该更多地关注降水变化对土壤无机氮的影响。

关键词: 放牧强度, 铵态氮, 硝态氮, 年际变化, 植物生物量

Abstract:

Aims Soil inorganic nitrogen, including ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3--N), is one of essential nutrients for plant growth. Grazing affects soil physical and chemical properties and microbial activities through livestock feeding, trampling and manure return, changing soil inorganic nitrogen content, and thus affecting plant productivity. However, under different grazing intensities, the seasonal dynamics and interannual differences of soil inorganic nitrogen are not clear.

Methods This study takes the grassland in an agro-pastoral ecotone of northern Shanxi as the research object, using the grazing intensity manipulation experiment established in August 2016 (no grazing (UG), light grazing (LG, 2.35 sheep unit·hm-2 per growing season), moderate grazing (MG, 4.80 sheep unit·hm-2 per growing season), heavy grazing (HG, 7.85 sheep unit·hm-2 per growing season)). The seasonal variations (May to September) of soil inorganic nitrogen contents from 2017 to 2021 were measured, and the seasonal dynamics and interannual differences of soil inorganic nitrogen contents under different grazing intensity were studied.

Important findings Results showed that: (1) different grazing intensity had no significant effect on the seasonal means of soil inorganic nitrogen contents, but significantly decreased plant biomass, which was related to the changes in the grazing effect in different periods of the growing season. (2) The soil inorganic nitrogen content increased at first and then decreased in the whole growing season. (3) The soil inorganic nitrogen content showed significant interannual difference, which was related to the changes in the interannual precipitation. Results showed that the responses of soil inorganic nitrogen content in northern agro-pastoral ecotone to short-term grazing intensity was not significant, and the changes in seasonal precipitation was the main reason for the interannual variations of soil inorganic nitrogen content. In the future, grassland management should pay more attention to the effect of precipitation changes on soil inorganic nitrogen.

Key words: grazing intensity, ammonium nitrogen, nitrate nitrogen, interannual variation, plant biomass