植物生态学报 ›› 2021, Vol. 45 ›› Issue (5): 562-572.DOI: 10.17521/cjpe.2020.0279

• 研究论文 • 上一篇    

青藏高原人工草地土壤可溶性氮组分与植被生产力动态变化过程

刘攀1,3, 王文颖3,*(), 周华坤2, 毛旭锋1, 刘艳方3   

  1. 1青海师范大学地理科学学院, 西宁 810008
    2中国科学院西北高原生物研究所, 西宁 810008
    3青海师范大学生命科学学院, 西宁 810008
  • 收稿日期:2020-08-12 接受日期:2020-11-22 出版日期:2021-05-20 发布日期:2021-04-14
  • 通讯作者: 王文颖
  • 作者简介:*(wangwy0106@163.com)
  • 基金资助:
    国家自然科学基金(41761107);第二次青藏高原综合科学考察研究项目(2019QZKK0302)

Dynamics of soil soluble nitrogen and plant productivity in artificial pastures on the Qingzang Plateau

LIU Pan1,3, WANG Wen-Ying3,*(), ZHOU Hua-Kun2, MAO Xu-Feng1, LIU Yan-Fang3   

  1. 1College of Geography Sciences, Qinghai Normal University, Xining 810008, China
    2Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
    3College of Life Sciences, Qinghai Normal University, Xining 810008, China
  • Received:2020-08-12 Accepted:2020-11-22 Online:2021-05-20 Published:2021-04-14
  • Contact: WANG Wen-Ying
  • Supported by:
    the National Natural Science Foundation of China(41761107);the Second Tibetan Plateau Scientific Expedition and Research (STEP) Program(2019QZKK0302)

摘要:

氮作为人工草地最为重要的限制性因子, 在时间、空间上分布不均匀, 且在形态上存在差异, 与种植方式及地上净初级生产力(ANPP)存在相关关系。该研究以青海省同德牧场的无芒雀麦(Bromus inermis)、老芒麦(Elymus sibiricus)、垂穗披碱草(E. nutans)、西北羊茅(Festuca ryloviana)、中华羊茅(F. sinensis)、青海扁茎早熟禾(Poa pratensis var. anceps ‘Qinghai’)、冷地早熟禾(P. crymophila)、星星草(Puccinellia tenuiflora) 8种牧草单播人工草地为研究对象, 分析人工草地土壤可溶性氮库季节和年际动态变化过程及与ANPP之间的相互关系。该人工草地种植于2013年, 在2014-2016年(二龄、三龄和四龄)生长季6-9月测定土壤铵态氮(NH4+-N)、硝态氮(NO3--N)、可溶性有机氮(SON)和可溶性总氮(STN)含量, 每年9月初测定ANPP, 所有样地没有施肥, 每年9月中旬刈割, 留茬5 cm。研究发现: (1) 8种禾本科牧草的ANPP在329.67-794.67 g·m-2之间, 其中垂穗披碱草为794.67 g·m-2, 显著高于其他牧草。(2)在二至四龄人工草地中, 土壤NO3--N、SON和STN含量均显著下降, 但NH4+-N含量却显著增加。(3)土壤可溶性氮以SON为主, 占STN的45.11%-88.76% (0-10 cm)和47.75%-88.18% (10-20 cm); 其次为NO3--N, 占STN的5.81%-34.85% (0-10 cm)和6.08%-40.42% (10-20 cm); NH4+-N最少仅3.41%-22.18% (0-10 cm)和3.09%-19.56% (10-20 cm)。(4)非度量多维尺度分析(NMDS)结果显示, 随种植年限的增加, 不同禾本科牧草对0-10 cm土壤可溶性氮影响趋于离散, 而对10-20 cm土壤的影响则相反, 且牧草对土壤可溶性氮含量的影响程度与土壤深度有关。(5)相关性分析表明, 土壤SON、STN含量与人工草地ANPP呈正相关关系, 与无机氮(IN)含量呈负相关关系。综上所述, 三至四龄人工草地增施氮肥是维持草地生产力的关键因素。以上结果为更深入了解青藏高原人工草地土壤可溶性氮动态变化及维持人工草地生产力和稳定性提供了科学依据。

关键词: 人工草地, 土壤可溶性氮库, 土壤无机氮库, 青藏高原

Abstract:

Aims Nitrogen is the most limiting factor to artificial pastures. It is distributed unevenly in time and space, and has different forms, which are correlated with cultivation approaches and above-ground net primary productivity (ANPP). This study investigated the dynamics of soil nitrogen and productivity in artificial pastures of Bromus inermis, Elymus sibiricus, E. nutans, Festuca ryloviana, F. sinensis, Poa pratensis var. anceps ‘Qinghai’, P. crymophila and Puccinellia tenuiflora in pure species cultivations in the Tongde farm of Qinghai Province. The dynamics of soil soluble nitrogen pools in each artificial pasture type and their relationships with ANPP were examined.
Methods The pastures were planted in 2013 without fertilizer application, and mowed to the level with 5 cm stubble in mid-September every year. The soil ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3--N), soluble organic nitrogen (SON) and soluble total nitrogen (STN) content were measured during growing seasons. ANPP was determined in September each year.
Important findings (1) The average ANPP across the eight pasture types ranged between 329.67-794.67 g·m -2, with the ANPP of 794.67 g·m -2 for the E. nutans significantly higher than other pasture types. (2) From the second to fourth year following planting, the content of soil NO3 --N, SON and STN significantly decreased, but that of the NH4+-N significantly increased. (3) SON accounted for the highest proportion of STN, varying between 45.11%-88.76% in the 0-10 cm soil layer and 47.75%-88.18% in the 10-20 cm soil layer, followed by NO3--N in ranges of 5.81%-34.85% (0-10 cm) and 6.08%-40.42% (10-20 cm), respectively; NH4+-N had the least proportion at 3.41%-22.18% (0-10 cm) and 3.09%-19.56% (10-20 cm), respectively. (4) The non-metric multidimensional scale analysis (NMDS) shows that the temporal effect on soil soluble nitrogen content by different pasture types diverged for the 0-10 cm soil layer, but converged for the 10-20 cm soil layer, and that the effect of pasture types on soil soluble nitrogen content was related to soil depth. (5) Soil SON and STN contents were positively correlated with ANPP, and negatively with inorganic nitrogen (IN) content. In summary, nitrogen fertilizer application is one of the key factors for maintaining the productivity of artificial pasture from three to four years. The above results provide a scientific basis for a more in-depth understanding of the dynamics of soil soluble nitrogen and the maintenance of productivity and stability of artificial pastures on the Qingzang Plateau.

Key words: artificial pasture, soil soluble nitrogen pool, soil inorganic nitrogen pool, Qingzang Plateau