J Plant Ecol ›› 2023, Vol. 16 ›› Issue (5): rtad010.DOI: 10.1093/jpe/rtad010

• Research Articles •    

Kobresia pygmaea meadows as disclimax communities in the same geographic and climatic environments in Qinghai-Tibet Plateau, China

Li Lin1,2, Guangmin Cao1, Xingliang Xu3, Fawei Zhang1, Junjie Huang4, Bo Fan1, Bencuo Li1, Yikang Li1,*   

  1. 1Qinghai Haibei National Field Research Station of Alpine Grassland Ecosystem and Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China;
    2University of Chinese Academy of Sciences, Beijing 100049, China;
    3Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 130028, China;
    4School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo 454000, China
  • Received:2022-08-17 Revised:2022-10-12 Accepted:2023-02-03 Online:2023-03-18 Published:2023-10-01
  • Contact: E-mail: ykli@nwipb.cas.cn

高寒小嵩草草甸可能成为青藏高原相同地理和气候单元下多种类型草地的偏途演替状态

Abstract: Kobresia meadows are the main pastures for animal husbandry on the Qinghai-Tibet Plateau, and may represent alternative steady states associated with different grazing intensities. The ability of other plant communities to succeed these meadows remains unclear. In this study, the historical data of plant communities were analyzed in terms of the soil profile, and the present characteristics were identified by investigating their plant communities. Four types of steady states were identified, corresponding to grazing intensities of >11, 8-11, 5.5-8 and <5.5 sheep/ha. Drought alpine swamp meadows and shrub meadows could succeed to K. pygmaea meadows and K. humilis meadows under overgrazing, and their total biomass and edible biomass (estimated by Gramineae and Cyperaceae) decreased with increasing grazing intensity. The regime shift of the states occurred at a grazing intensity of 8-11 sheep/ha. This value thus represented the threshold of significant change in the production and ecological service function in the Kobresia meadow succession process. In general, increasing grazing intensities can adversely affect the service ability of meadows for livestock production and ecosystem stabilization. Our results revealed the potential degraded succession process of the alpine Kobresia meadow and the succession direction in the restoration process of degraded meadows. Additionally, this study provided a theoretical basis for evaluating the fitness between the livestock bearing capacity and carrying capacity in steady states and academic reference for policy setting pertaining to the utilization of Kobresia meadows in a sustainable development framework.

Key words: plant community succession, soil profile features, sustainable development, ecological stabilization, regime shift

摘要:
高寒嵩草(Kobresia)草甸是青藏高原冬春放牧草场的主体,在放牧强度分异的条件下可以形成特征迥异的稳态。然而,目前还不清楚在不同放牧强度下其他类型草地是否可以演替成为这些稳态。本研究通过土壤剖面特征推断其历史植物群落特征,以植物群落现场调查确定其现实植物群落特征,以非结构式问卷调查确定草地放牧强度,采用多元回归树模型分析导致草地稳态转化的节点。研究结果表明,高寒灌丛草甸和旱化沼泽草甸在过度放牧条件下均可转化成为高寒矮嵩草(K. humilis)草甸和高寒小嵩草(K. pygmaea)草甸,从而使高寒灌丛草甸和旱化沼泽化草甸进入高寒矮嵩草草甸退化演替序列,最终转化成为黑土滩-杂类草次生裸地。以放牧强度为分节点,最多可以将这些植物群落划分为4类稳态,各稳态转化的节点依次为11.0、8.0、5.5羊/ha。所有研究草地总体表现为随放牧强度的增高地上总生物量呈下降趋势。其中,11.0羊/ha是草地转化成为黑土滩-杂类草次生裸地的节点。放牧强度改变可以影响植物群落特征及其演替方向,进而改变草地的畜牧生产服务能力,因此放牧强度可以作为反映牧场畜牧生产服务能力的表观指标。未来牧场的可持续发展策略应以草畜平衡为主,合理控制放牧强度,增加草地生产附加值和延伸畜牧业产业链以实现区域草场生态和生产效益的双赢。

关键词: 植物群落演替, 土壤剖面特征, 区域可持续发展, 生态系统稳定性, 状态转化