小叶青冈（壳斗科）中二氧化碳分压与气孔频率之间的新正相关关系：古二氧化碳水平的潜在替代指标。
A new positive relationship between pCO2 and stomatal frequency in Quercus guyavifolia (Fagaceae): a potential proxy for palaeo-CO2 levels.
作者信息
Hu Jin-Jin, Xing Yao-Wu, Turkington Roy, Jacques Frédéric M B, Su Tao, Huang Yong-Jiang, Zhou Zhe-Kun
机构信息
Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China, Institute of Systematic Botany, University of Zürich, Zürich 8008, Switzerland, Department of Botany, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 and University of Chinese Academy of Sciences, Beijing 100049, China Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China, Institute of Systematic Botany, University of Zürich, Zürich 8008, Switzerland, Department of Botany, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 and University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China, Institute of Systematic Botany, University of Zürich, Zürich 8008, Switzerland, Department of Botany, and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 and University of Chinese Academy of Sciences, Beijing 100049, China.
出版信息
Ann Bot. 2015 Apr;115(5):777-88. doi: 10.1093/aob/mcv007. Epub 2015 Feb 13.
BACKGROUND AND AIMS
The inverse relationship between atmospheric CO2 partial pressure (pCO2) and stomatal frequency in many species of plants has been widely used to estimate palaeoatmospheric CO2 (palaeo-CO2) levels; however, the results obtained have been quite variable. This study attempts to find a potential new proxy for palaeo-CO2 levels by analysing stomatal frequency in Quercus guyavifolia (Q. guajavifolia, Fagaceae), an extant dominant species of sclerophyllous forests in the Himalayas with abundant fossil relatives.
METHODS
Stomatal frequency was analysed for extant samples of Q. guyavifolia collected from17 field sites at altitudes ranging between 2493 and 4497 m. Herbarium specimens collected between 1926 and 2011 were also examined. Correlations of pCO2-stomatal frequency were determined using samples from both sources, and these were then applied to Q. preguyavaefolia fossils in order to estimate palaeo-CO2 concentrations for two late-Pliocene floras in south-western China.
KEY RESULTS
In contrast to the negative correlations detected for most other species that have been studied, a positive correlation between pCO2 and stomatal frequency was determined in Q. guyavifolia sampled from both extant field collections and historical herbarium specimens. Palaeo-CO2 concentrations were estimated to be approx. 180-240 ppm in the late Pliocene, which is consistent with most other previous estimates.
CONCLUSIONS
A new positive relationship between pCO2 and stomatal frequency in Q. guyavifolia is presented, which can be applied to the fossils closely related to this species that are widely distributed in the late-Cenozoic strata in order to estimate palaeo-CO2 concentrations. The results show that it is valid to use a positive relationship to estimate palaeo-CO2 concentrations, and the study adds to the variety of stomatal density/index relationships that available for estimating pCO2. The physiological mechanisms underlying this positive response are unclear, however, and require further research.
背景与目的
许多植物物种中大气二氧化碳分压（pCO₂）与气孔频率之间的反比关系已被广泛用于估算古大气二氧化碳（古CO₂）水平；然而，所得结果差异很大。本研究试图通过分析喜马拉雅硬叶林现存优势物种、有丰富化石亲属的瓜哇栎（壳斗科）的气孔频率，找到一种潜在的古CO₂水平新指标。
方法
对从海拔2493至4497米的17个野外地点采集的瓜哇栎现存样本进行气孔频率分析。还检查了1926年至2011年期间收集的标本馆标本。使用来自这两个来源的样本确定pCO₂-气孔频率的相关性，然后将其应用于前瓜哇栎化石，以估算中国西南部两个上新世晚期植物群的古CO₂浓度。
主要结果
与大多数其他已研究物种检测到的负相关相反，在从现存野外采集样本和历史标本馆标本中获取的瓜哇栎样本中，确定了pCO₂与气孔频率之间存在正相关。上新世晚期的古CO₂浓度估计约为180 - 240 ppm，这与大多数其他先前估计一致。
结论
提出了瓜哇栎中pCO₂与气孔频率之间的一种新的正相关关系，可应用于广泛分布于晚新生代地层中与该物种密切相关的化石，以估算古CO₂浓度。结果表明，使用正相关关系估算古CO₂浓度是有效的，该研究增加了可用于估算pCO₂的气孔密度/指数关系的多样性。然而，这种正响应背后的生理机制尚不清楚，需要进一步研究。
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