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首页> 美国卫生研究院文献>Philosophical Transactions of the Royal Society B: Biological Sciences >Recent trends in the intrinsic water-use efficiency of ringless rainforest trees in Borneo
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Recent trends in the intrinsic water-use efficiency of ringless rainforest trees in Borneo

机译：婆罗洲无环雨林树木内在用水效率的最新趋势

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Stable carbon isotope (δ13C) series were developed from analysis of sequential radial wood increments from AD 1850 to AD 2009 for four mature primary rainforest trees from the Danum and Imbak areas of Sabah, Malaysia. The aseasonal equatorial climate meant that conventional dendrochronology was not possible as the tree species investigated do not exhibit clear annual rings or dateable growth bands. Chronology was established using radiocarbon dating to model age–growth relationships and date the carbon isotopic series from which the intrinsic water-use efficiency (IWUE) was calculated. The two Eusideroxylon zwageri trees from Imbak yielded ages of their pith/central wood (±1 sigma) of 670 ± 40 and 759 ± 40 years old; the less dense Shorea johorensis and Shorea superba trees at Danum yielded ages of 240 ± 40 and 330 ± 40 years, respectively. All trees studied exhibit an increase in the IWUE since AD 1960. This reflects, in part, a response of the forest to increasing atmospheric carbon dioxide concentration. Unlike studies of some northern European trees, no clear plateau in this response was observed. A change in the IWUE implies an associated modification of the local carbon and/or hydrological cycles. To resolve these uncertainties, a shift in emphasis away from high-resolution studies towards long, well-replicated time series is proposed to develop the environmental data essential for model evaluation. Identification of old (greater than 700 years) ringless trees demonstrates their potential in assessing the impacts of climatic and atmospheric change. It also shows the scientific and applied value of a conservation policy that ensures the survival of primary forest containing particularly old trees (as in Imbak Canyon and Danum).
机译：通过分析来自马来西亚沙巴州Danum和Imbak地区的四棵成熟的原始雨林树木，从公元1850年到2009年连续放射状木材增量分析，开发出了稳定的碳同位素（δ 13 C）系列。季节性的赤道气候意味着常规的树木年代学是不可能的，因为所调查的树种没有表现出清晰的年轮或可追溯的生长带。利用放射性碳年代测定法建立了年代学模型，以建立年龄与增长的关系，并对碳同位素系列进行日期测算，从而从中计算出内在的用水效率（IWUE）。来自Imbak的两棵Eusideroxylon zwageri树的髓/中心木（±1 sigma）年龄分别为670±40和759±40岁。 Danum的密度较低的柔佛州树（Shora johorensis）和树胶树（Shorea superba）的树龄分别为240±40和330±40岁。自公元1960年以来，所有研究的树木的IWUE都有所增加。这部分反映了森林对大气二氧化碳浓度增加的反应。与对一些北欧树木的研究不同，在这种反应中没有观察到稳定的平台。 IWUE的变化意味着当地碳和/或水文循环的相关变化。为了解决这些不确定性，建议将重点从高分辨率研究转移到长时间复制的时间序列，以开发模型评估必不可少的环境数据。对古老（超过700年）无环乔木的鉴定表明了它们在评估气候和大气变化影响方面的潜力。它还显示了保护政策的科学和应用价值，该政策可确保包含特别是老树的原始森林（例如在Imbak Canyon和Danum中）的生存。

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