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树轮-气候“分异问题”形成机制的研究进展

盖学瑞1,2,于大炮1,王守乐1,2,贾翔3,吴健1,2,周旺明1,周莉1,代力民1*#br#   

  1. (1中国科学院森林生态与管理重点实验室(沈阳应用生态研究所), 沈阳 110016; 2中国科学院大学, 北京 100049; 3长白山科学研究院, 长白山生物资源与生物多样性联合重点实验室, 吉林二道白河 133613)
  • 出版日期:2017-11-10 发布日期:2017-11-10

A review of formation mechanism on the ‘divergence problem’ of tree growth-climate relationship.

GAI Xue-rui1,2, YU Da-pao1, WANG Shou-le1,2, JIA Xiang3, WU Jian1,2, ZHOU Wang-ming1, ZHOULi1, DAI Li-min1*#br#   

  1. (1Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; 2 University of Chinese Academy of Sciences, Beijing 100049, China; 3Changbai Mountain Academy of Sciences, Associated Key Laboratory of Biological Resources and Biological Diversity in Changbai Mountains, Erdaobaihe 133613, Jilin, China).
  • Online:2017-11-10 Published:2017-11-10

摘要: “分异问题”(divergence problem)最早出现于20世纪90年代。树木年轮学者在阿拉斯加的高山林线研究中,发现树木径向生长对温度敏感性降低,随后在诸多北半球中高纬度地带均有类似报道。这一发现动摇了树轮年代学建立的基本前提假设——“均一性原理”,并对基于年轮指数构建数据的科学性提出了挑战。目前,国内外关于“分异问题”形成的原因和机制还存在诸多争论。本文梳理了文献报道的“分异问题”发生的地点、涉及的树种及驱动因子,同时也分析了研究方法等可能引起的误判,以期阐明“分异问题”形成的气候机制。结果表明,“分异问题”主要涉及生长在中高纬度、高海拔地区、对水分和温度要求严格的树种,主要原因是由于气候暖干化加剧土壤水分亏缺(超出水分阈值)或温度升高致使树木生理机能发生改变(超过了正常生长或休眠的温度阈值),导致了树木的气候敏感性降低或者生长衰退。尽管目前关于“分异问题”形成机制的假说还包括:大气CO2浓度变化、人类活动的影响等,但“分异问题”形成的最可能解释是“阈值假说”。

关键词: 土壤微生物, 野外控制试验, 全球变化, 碳氮循环

Abstract: The “divergence problem” of tree radial growth-climate relationship arose in the 1990s. Initially, tree-ring researchers found the phenomenon that the temperature sensitivity of tree’s radial growth decreased at Alaska’s alpine timberline. Then, similar reports appeared in many regions of the mid and high latitudes in the northern hemisphere. This discovery raises a challenge to the established basic hypothesis in dendrochronology-“uniformity principle” of relationship of radial growth-climate, and to the scientificity of data derived from ring index based on the hypothesis. Despite extensive research published, there are lots of arguments about the causes and mechanisms of the formation of “divergence problem”. To clarify the formation mechanism of “divergence problem”, this review sorted the related research in the literature into location, tree species, driving factors and analyzed the misjudgment induced by research methods. The results showed that the tree species involved in “divergence problem” are growing mainly in the regions of midhigh latitude and high altitude, and sensitive to moisture and temperature. The climate warming and drying in these regions resulted in soil water deficit (exceeding the water threshold) or temperatureinduced physiological changes of trees (exceeding the temperature threshold of normal growth or dormancy). Consequently, climate sensitivity or tree growth decreased. There are some other explanations for the formation mechanism, including the change of atmospheric CO2 concentration, the influence of anthropogenic activities; however, the threshold hypothesis is the most possible explanation for the formation mechanism of “divergence problem”.

Key words: global change, soil microorganism, field manipulative experiment, carbon and nitrogen cycle.