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短期增温对藏北高寒草甸植物群落特征的影响

姜炎彬1,2,范苗1,张扬建2*#br#   

  1. (1 华中农业大学资源与环境学院, 农业部长江中下游耕地保育重点实验室, 武汉 430070; 2 中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室, 北京 100101)
  • 出版日期:2017-03-10 发布日期:2017-03-10

Effect of shortterm warming on plant community features of alpine meadow in Northern Tibet.

JIANG Yan-bin1,2, FAN Miao1, ZHANG Yang-jian2*#br#   

  1. (1 Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China; 2 Lhasa Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China).
  • Online:2017-03-10 Published:2017-03-10

摘要: 青藏高原是全球变化的敏感区域,过去几十年以来,在全球气候变暖的背景下,藏北高原增温明显。本研究在藏北典型高寒草甸区采用开顶式生长室(OTC)模拟增温的方法,根据OTC的不同高度设置了4个增温梯度(40、60、80和100 cm),分析了植物群落的生长、结构和组成以及生物量对增温的响应。结果表明:不同高度的OTC作用使得年平均空气温度增加了1.13~2.72 ℃,且OTC的高度越高,其增温效果越明显;伴随着温度的升高,空气湿度以及土壤湿度均有所降低;高山嵩草在所有群落中占有绝对优势,梯度增温作用使得其重要值不断下降;随着温度的升高,莎草类植物的盖度逐渐下降;对整个群落而言,增温幅度较低时,增温对群落的生长和生物量的积累以及多样性都会有明显的促进作用,当温度升高超过一定值,这种促进作用会逐渐减弱甚至变成抑制作用。本研究表明,藏北高寒草甸对增温作用具有敏感而迅速的响应,温度升高使该地区的气候朝着暖干化趋势发展,而一定程度的升温会促进植物群落的生长,但温度升高超过一定幅度时,会导致草地生产力下降,草地退化加剧。

Abstract: Tibetan Plateau is one of the regions that are most sensitive to global change. In the past decades, Northern Tibet experienced significant warming. In this study, opentop chambers (OTCs) were used to simulate warming in alpine meadow in Northern Tibet. A warming gradient was generated by using different heights of OTCs (40, 60, 80 and 100 cm). The responses of plant growth, community composition and structure, and aboveground biomass to warming treatments were investigated. Under the series of treatment, air temperature increment ranged from 1.13 to 2.72 ℃. The temperatures in upper layer soil were also increased, accompanied by the decreased air and soil humidity. Kobresia pygmaea is the primary dominant species in the targeted communities. With increasing temperature, the importance value of K. pygmaea and the cover of sedges decreased. The warming effect on community growth and aboveground biomass accumulation varied with the warming magnitude. Warming promoted plant growth when it was lower than 2.1 ℃. When the warming magnitude was greater than 2.1 ℃, its stimulation effect was weakened, even prohibited plant growth. This study illustrated that the alpine meadow in Northern Tibet was a good indicator for global warming. The varied responses of community structure and biomass to the warming gradient indicated that moderate warming would promote the growth and development of plant communities, but fast temperature increasing would induce warming and drying environment, and less water availability for the ecosystem. Consequently, the productivity of plant community decreased, and the meadow ecosystem deteriorated.