中国农业科学 ›› 2020, Vol. 53 ›› Issue (13): 2625-2636.doi: 10.3864/j.issn.0578-1752.2020.13.011

• 草甸草原恢复技术及原理 • 上一篇    下一篇

施氮与刈割留茬高度对草场生产力及植物群落组成的影响

王开丽,杨合龙,肖红,孙伟,戎郁萍()   

  1. 中国农业大学草业科学与技术学院,北京100193
  • 收稿日期:2019-09-11 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: 戎郁萍
  • 作者简介:王开丽,E-mail: wangkaili@cau.edu.cn。
  • 基金资助:
    国家重点研发计划(2016YFC0500603)

Effects of Nitrogen Application and Clipping Height on Vegetation Productivity and Plant Community Composition of Haying Meadow Steppe

WANG KaiLi,YANG HeLong,XIAO Hong,SUN Wei,RONG YuPing()   

  1. College of Grassland Science and Technology, China Agricultural University, Beijing 100193
  • Received:2019-09-11 Accepted:2020-02-10 Online:2020-07-01 Published:2020-07-16
  • Contact: YuPing RONG

摘要:

【目的】 改善打草场土壤养分,提高草地生产力及维持草地可持续利用。【方法】 2016—2018年在呼伦贝尔草地农业生态系统实验站打草场设置5个施氮水平(0、10、20、30、40 g·m-2·a-1)与2个刈割留茬高度(4、8 cm),裂区试验设计,分别于每年6月中旬和8月中旬进行试验处理,研究其对草地植物群落及功能群的物种丰富度、地上生物量、主要物种组成的重要值、优势种功能性状及土壤理化性质的影响过程。【结果】 施氮与刈割留茬高度对群落及功能群的物种丰富度无显著影响(P<0.05)。施氮显著增加禾草功能群及群落的地上生物量(P<0.05),分别提高了72.7%—126.3%、61.6%—96.1%,但施氮量在10—40 g·m-2·a-1的各处理间差异不显著(P<0.05),低刈割留茬高度使禾草的地上生物量显著降低了18.3%(P<0.05)。施氮显著增加羊草(Leymus chinensis)的重要值,降低无芒雀麦(Bromus inermis)的重要值(P<0.05)。施氮时低刈割留茬高度显著降低羊草的重要值,增加无芒雀麦的重要值,不施氮时则相反。低留茬高度显著增加二裂委陵菜(Potentilla bifurca)和星毛委陵菜(Potentilla acaulis)的重要值,降低糙隐子草(Cleistogenes squarrosa)的重要值(P<0.05)。施氮显著增加无芒雀麦及羊草的株高、叶面积和地上部氮素含量(P<0.05),但施氮量在20—40 g·m-2·a-1的各处理间差异不显著。土壤pH、土壤含水量随施氮量增加而显著降低,土壤NH4+-N、NO3--N及总无机氮(ION)含量随施氮量增加而显著增加(P<0.05)。群落、禾草及杂类草的物种丰富度与土壤含水量显著正相关,群落及禾草的地上生物量与土壤含水量显著负相关(P<0.05)。【结论】 短期施氮与适宜的刈割留茬高度提高草地植物群落生产力及稳定群落的物种组成,施氮效应依赖于水分的有效性。呼伦贝尔草甸草原打草适宜刈割留茬高度为8 cm,适宜施氮量为10—20 g·m-2·a-1

关键词: 施氮, 刈割, 草场, 功能群, 功能性状, 物种丰富度, 生物量, 呼伦贝尔

Abstract:

【Objective】 The aim of this study was to improve soil nutrients in haying steppe, to increase grassland productivity, and to maintain sustainable utilize of grassland. 【Method】 Five nitrogen application levels (0, 10, 20, 30, and 40 g N·m-2·a-1) and two mowing heights (4 and 8 cm) were set in the haying field of Hulunbuir Grassland Agro-ecosystem Experiment Station with spit-plot design, which was carried out in mid-June and mid-August from 2016 to 2019, respectively, and the responses of nitrogen application and clipping height to community and plant functional group’s species richness and aboveground biomass, crucial species’ important value, dominant species’ functional traits, and soil properties were investigated. 【Result】 The results showed that nitrogen application and mowing height had no significant effect on community and plant functional group’s species richness (P<0.05). Nitrogen application significantly increased the aboveground biomass of grasses and community by 69.2%-115.3% and 36.5%-84.8%, respectively (P<0.05), but there was no significant difference within 10-40 g·m-2·a-1. Lower cutting height significantly reduced the aboveground biomass of grasses by 18.3% (P<0.05). Nitrogen application significantly increased and reduced the important value of Leymus chinensis and Bromus inermis, respectively (P<0.05). Lower mowing height significantly reduced the important value of Leymus chinensis, which increased the value of Bromus inermis; nitrogen application increased the important value of Leymus chinensis, which reduced the important value of Bromus inermis(P<0.05). Lower cutting height significantly increased the important value of Potentilla bifurca and Potentilla acaulis and reduced the important value of Cleistogenes squarrosa (P<0.05). Nitrogen addition significantly increased the plant height, leaf area and shoot nitrogen content of Bromus inermis and Leymus chinensis (P<0.05), but there was no significant difference within 20-40 g·m-2·a-1. The soil pH and soil water content decreased significantly along with the increase of nitrogen application rate, while NH4+-N, NO3--N and inorganic nitrogen (ION) in soil increased (P<0.05). The species richness of community, grasses and nongraminous forbs was positively correlated with soil water content, while the aboveground biomass of community and grasses was negatively correlated with soil water content (P<0.05). 【Conclusion】 Short-term nitrogen application and suitable clipping height were beneficial to improve vegetation productivity and maintain community composition, and the effects of nitrogen addition were strongly dependent on water availability. It was suggested that the suitable mowing height of grassland in Hulunber haying meadow steppe was 8 cm, and the comfortable nitrogen application rate was 10-20 g·m-2·a-1.

Key words: nitrogen application, mowing, haying meadow steppe, functional group, functional traits, species richness, biomass, Hulunber