中国地理科学 ›› 2014, Vol. 0 ›› Issue (4): 488-498.doi: 10.1007/s11769-014-0697-y

• 论文 • 上一篇    

Effects of Grazing Exclusion on Plant Productivity and Soil Carbon, Nitrogen Storage in Alpine Meadows in Northern Tibet, China

XIONG Dingpeng1,2, SHI Peili1, SUN Yinliang1,2, WU Jianshuang1, ZHANG Xianzhou1   

  1. 1. Lhasa National Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • 收稿日期:2013-11-13 修回日期:2014-03-12 出版日期:2014-05-27 发布日期:2014-07-03
  • 通讯作者: SHI Peili E-mail:shipl@igsnrr.ac.cn
  • 基金资助:

    Under the auspices of Strategic Priority Research Program of Chinese Academy of Sciences (No. XDA05060700), Postdoctoral Science Foundation of China (No. 2013M530716)

Effects of Grazing Exclusion on Plant Productivity and Soil Carbon, Nitrogen Storage in Alpine Meadows in Northern Tibet, China

XIONG Dingpeng1,2, SHI Peili1, SUN Yinliang1,2, WU Jianshuang1, ZHANG Xianzhou1   

  1. 1. Lhasa National Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2013-11-13 Revised:2014-03-12 Online:2014-05-27 Published:2014-07-03
  • Contact: SHI Peili E-mail:shipl@igsnrr.ac.cn
  • Supported by:

    Under the auspices of Strategic Priority Research Program of Chinese Academy of Sciences (No. XDA05060700), Postdoctoral Science Foundation of China (No. 2013M530716)

摘要:

Grazing exclusion is widely adopted in restoring degraded alpine grasslands on the Qinghai-Tibetan Plateau. However, its effectiveness remains poorly understood.In this study, we investigated the effects of grazing exclusion on plant productivity, species diversity and soil organic carbon (SOC) and soil total nitrogen (STN) storage along a transect spanning from east to west of alpine meadows in northern Tibet, China. After six years of grazing exclusion, plant cover, aboveground biomass (AGB), belowground biomass (BGB), SOC and STN were increased, but species diversity indices declined. The enhancement of AGB and SOC caused by grazing exclusion was correlated positively with mean annual precipitation (MAP). Grazing exclusion led to remarkable biomass increase of sedge species, especially Kobresia pygmaea, whereas decrease of biomass in forbs and no obvious change in grass, leguminous and noxious species. Root biomass was concentrated in the near surface layer (10 cm) after grazing exclusion. The effects of grazing exclusion on SOC storage were confined to shallow soil layer in sites with lower MAP. It is indicated that grazing exclusion is an effective measure to increase forage production and enhance soil carbon sequestration in the studied region. The effect is more efficient in sites with higher precipitation. However, the results revealed a tradeoff between vegetation restoration and ecological biodiversity. Therefore, carbon pools recover more quickly than plant biodiversity in the alpine meadows. We suggest that grazing exclusion should be combined with other measures to reconcile grassland restoration and biodiversity conservation.

关键词: aboveground biomass, belowground biomass, soil organic carbon (SOC), soil total nitrogen (STN), biodiversity, grazing exclusion, precipitation, alpine meadow

Abstract:

Grazing exclusion is widely adopted in restoring degraded alpine grasslands on the Qinghai-Tibetan Plateau. However, its effectiveness remains poorly understood.In this study, we investigated the effects of grazing exclusion on plant productivity, species diversity and soil organic carbon (SOC) and soil total nitrogen (STN) storage along a transect spanning from east to west of alpine meadows in northern Tibet, China. After six years of grazing exclusion, plant cover, aboveground biomass (AGB), belowground biomass (BGB), SOC and STN were increased, but species diversity indices declined. The enhancement of AGB and SOC caused by grazing exclusion was correlated positively with mean annual precipitation (MAP). Grazing exclusion led to remarkable biomass increase of sedge species, especially Kobresia pygmaea, whereas decrease of biomass in forbs and no obvious change in grass, leguminous and noxious species. Root biomass was concentrated in the near surface layer (10 cm) after grazing exclusion. The effects of grazing exclusion on SOC storage were confined to shallow soil layer in sites with lower MAP. It is indicated that grazing exclusion is an effective measure to increase forage production and enhance soil carbon sequestration in the studied region. The effect is more efficient in sites with higher precipitation. However, the results revealed a tradeoff between vegetation restoration and ecological biodiversity. Therefore, carbon pools recover more quickly than plant biodiversity in the alpine meadows. We suggest that grazing exclusion should be combined with other measures to reconcile grassland restoration and biodiversity conservation.

Key words: aboveground biomass, belowground biomass, soil organic carbon (SOC), soil total nitrogen (STN), biodiversity, grazing exclusion, precipitation, alpine meadow