中国农业科学 ›› 2020, Vol. 53 ›› Issue (13): 2562-2572.doi: 10.3864/j.issn.0578-1752.2020.13.005

• 草甸草原退化过程与机制 • 上一篇    下一篇

放牧强度对草甸草原羊草功能性状的影响

侯路路,闫瑞瑞,张宇,辛晓平()   

  1. 中国农业科学院农业资源与农业区划研究所,北京 100081
  • 收稿日期:2019-09-20 接受日期:2020-02-10 出版日期:2020-07-01 发布日期:2020-07-16
  • 通讯作者: 辛晓平
  • 作者简介:侯路路,E-mail: 82101176057@caas.cn。
  • 基金资助:
    国家重点研发计划(2016YFC0500608);国家重点研发计划-中美政府间合作项目(2017YFE0104500);国家自然科学基金面上项目(41771205);中央级公益性科研院所基本科研业务费专项(1610132018023);中央级公益性科研院所基本科研业务费专项(1610132018009);中央级公益性科研院所基本科研业务费专项(1610132019031);呼伦贝尔科技计划项目(YYYFHZ201903)

Effects of Grazing Intensity on Functional Traits of Leymus chinensis in Meadow Steppe

HOU LuLu,YAN RuiRui,ZHANG Yu,XIN XiaoPing()   

  1. Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081
  • Received:2019-09-20 Accepted:2020-02-10 Online:2020-07-01 Published:2020-07-16
  • Contact: XiaoPing XIN

摘要:

【目的】 研究草甸草原优势种羊草群落重要值(IV)和其功能性状对放牧强度的响应规律,观察羊草是否通过调整自身各功能性状(如个体、茎、叶等)来适应外界环境的变化,以便为草原合理放牧利用提供参考依据。【方法】 通过控制试验设置6个放牧强度,即对照(G0:0)、轻度(G0.23:0.23 cow.AU/hm2)、轻中度(G0.34:0.34 cow.AU/hm2)、中度(G0.46:0.46 cow.AU/hm2)、重度(G0.69:0.69 cow.AU/hm2)、极重度(G0.92:0.92 cow.AU/hm2),3个重复,采用随机区组排列。在每个处理中分别测定优势种羊草IV以及其植株性状(株高、茎重、叶重、茎叶比、单株重)和叶片性状(形态性状:叶面积、单片叶重、比叶面积(SLA)、叶长、叶宽;生理性状:叶片C、N含量、C/N),其中羊草IV通过随机选取试验小区内5个1 m×1 m群落样方调查得到,羊草功能性状通过随机选取每个试验小区内的羊草单株进行测定。【结果】 (1)与不放牧G0相比,羊草IV的降低幅度随着放牧强度的增加依次为42.9%、66.0%、82.7%、91.8%、91.2%;(2)羊草植株性状(株高、茎重、叶重、茎叶比、单株重)随着放牧强度增加逐渐降低。不同放牧强度下羊草植株茎叶比均小于1,并且与G0相比,G0.92显著降低39.22%;叶片性状中叶面积、单片叶重、叶长、叶宽均随着放牧强度的增加逐渐降低,而SLA却随着放牧强度的增加而增加,且在G0.92时最大,为136.61 cm2·g-1,其与G0、G0.23、G0.34、G0.46、G0.69相比,增加幅度分别为23.7%、19.0%、17.8%、20.2%、13.2%;(3)羊草叶片C、N含量在极重度放牧(G0.92)下分别为44.2%、2.8%。随着放牧强度的增加,羊草叶片C含量整体变化相对稳定,但叶片N含量则不断增加,相比于G0,G0.69与G0.92中N含量分别增加21.8%、43.2%;(4)相关分析表明,羊草叶片SLA与N含量存在极显著正相关,与C含量存在极显著负相关;叶片形态性状与生理性状存在显著相关。同时典型相关分析表明,形态性状中主要以单片叶重为主,生理性状中以C/N为主。【结论】 放牧强度改变了羊草的优势度,使羊草植株个体变小,茎叶比降低,但羊草为适应外界环境的变化而改变自身叶片SLA、N含量,尤其在极重度放牧条件下,SLA与N含量协同增加。

关键词: 放牧强度, 草甸草原, 羊草, 功能性状

Abstract:

【Objective】 The objective of this study was to study the response of important value (IV) and functional traits of dominant species of Leymus chinensis to grazing intensity in meadow steppe and to observe whether Leymus chinensis adapts to changes in the external environment by adjusting its various functional traits (such as plants, stems, leaves and so on) , so as to provide reference for rational grazing utilization of grassland. 【Method】 Six grazing intensities were set by control experiments, including control (G0: 0), mild (G0.23: 0.23 cow.AU/hm 2), light to moderate (G0.34: 0.34 cow.AU/hm2), moderate (G0.46: 0.46 cow.AU/hm2), heavy(G0.69: 0.69 cow.AU/hm2), and extremely very heavy (G0.92: 0.92 cow.AU/hm2), with three replicates. The IV of the dominant species of Leymus chinensis and its plant traits (plant height, stem weight, leaf weight, stem﹕leaf, and plant weight) and leaf traits (morphological traits:leaf area, single leaf weight, specific leaf area (SLA), leaf length, and leaf width; physiological traits: leaf carbon(C) and nitrogen (N) content, and C/N) were determined in each treatment. Among them, IV of Leymus chinensis was obtained by randomly selecting five 1 m×1 m plant community plots in the experiment plots. The functional characteristics of Leymus chinensis were determined by randomly selecting individual Leymus chinensis plants in each experiment plot. 【Result】 (1) Compared with G0, the decrease of Leymus chinensis IV was 42.9%, 66.0%, 82.7%, 91.8%, and 91.2% with the increase of grazing intensity. (2) Leymus chinensis plant traits (plant height, stem weight, leaf weight, and stem﹕leaf) decreased gradually with the increase of grazing intensity. The stem﹕leaf of Leymus chinensis plants was less than 1 in different grazing intensities, and G0.92 was significantly reduced by 39.22% compared with G0. The leaf area, leaf weight, leaf length and leaf width of leaf traits gradually decreased with the increase of grazing intensity. However, the SLA increased with the increase of grazing intensity, and it was the largest at G0.92, with a value of 136.61 cm 2·g-1, which increased 23.7%, 19.0%, 17.8%, 20.2%, and 13.2%, respectively, compared to G0, G0.23, G0.34, G0.46, and G0.69. (3) Leymus chinensis leaves C and N content was 44.2% and 2.8% under extremely heavy grazing (G0.92), respectively. With the increase of grazing intensity, the overall change of Leymus chinensis leaves C content was relatively stable, but leaves N content increased continuously. Compared with G0, the Leymus chinensis leaves N content in G0.69 and G0.92 increased by 21.8% and 43.2%, respectively. (4) Correlation analysis showed that Leymus chinensis leaves SLA was a significant positive correlation with N content and a significant negative correlation with C content. The leaf morphological traits were significantly correlated with physiological traits, the morphological traits were mainly with single leaf weight, and the physiological traits were mainly with C/N. 【Conclusion】 The grazing intensity changed the dominance of Leymus chinensis and made the individual Leymus chinensis plants smaller, reduced stem: leaf, but Leymus chinensis changed the leaves SLA and N content in response to changes in the external environment. Especially under extremely heavy grazing conditions, the SLA and N content increased synergistically.

Key words: grazing intensity, meadow steppe, Leymus chinensis, functional traits