Comparing carbon isotope composition of bulk wood and holocellulose from Quercus cerris, Fraxinus ornus and Pinus radiata tree rings
Comparing carbon isotope composition of bulk wood and holocellulose from Quercus cerris, Fraxinus ornus and Pinus radiata tree rings
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比较来自栎树、白蜡树和辐射松树轮的散装木材和全纤维素的碳同位素组成
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发表时间：
2004
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通讯作者：
S. Saracino
中科院分区：
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作者：
Dalin N. D’Alessandro;G. Guerrieri;S. Saracino
摘要：树轮δ13C是光合作用(A)和气孔导度(G)比值的综合指标，反映了植物的内在水分利用效率，受到植物生命周期内环境条件的强烈影响，因此被广泛应用于生态生理研究中。树轮δ13C也反映了大气二氧化碳浓度及其碳同位素组成的长期变化，部分原因是人为排放的增加。树木年轮中的碳同位素丰度可以在原木和木材生化成分上进行评估，但由于生物合成过程中的二次区分，它们表现出不同的δ13C值。本文比较了近三年(1999年、2000年和2001年)两种阔叶树(栎树和水曲柳)和一种针叶树(辐射松种)的原木和综纤维素样品的δ~(13)C。我们发现，不同树种的13C值有很大差异，无论是在综纤维素的情况下，还是在散装木材的情况下，但只有辐射松的散装木材样品倾向于提供比综纤维素更负的δ13C值，正如文献报道的那样。我们认为，至少对于所研究的两种阔叶树种来说，散装木材是用于δ13C评估的合适材料，而在辐射松中，综纤维素可以提供一个更稳定和可靠的指标，用于研究植物对环境条件变化的生态生理反应。
Abstract: Tree-ring δ13C is widely employed in ecophysiological studies, because it represents an integrated proxy of the ratio between photosynthesis (A) and stomatal conductance (g), which expresses the intrinsic water use efficiency (iWUE), strongly affected by the environmental conditions experienced by the plant during its life span. Tree-ring δ13C also reflects long term variations of atmospheric CO2 concentration and of its carbon isotope composition, partly due to increasing anthropogenic emissions. Carbon isotope abundances in tree rings can be assessed on bulk wood as well as on wood biochemical components, wich show different δ13C values because of secondary discrimination during biosynthesis. We present the results of a comparison between δ13C values of bulk wood and holocellulose samples obtained from the last three (1999, 2000 and 2001) annual growth rings of two hardwood (Quercus cerris L. and Fraxinus ornus L. and one conifer (Pinus radiata D. Don, species. We found that 13C values differed significantly among tree species, both in the case of holocellulose and bulk wood, but only in the case of P. radiata bulk wood samples tend to provide more negative δ13C values than holocellulose, as reported in the literature. We suggest that, at least for the two hardwood species studied, bulk wood is a suitable material to work with for δ13C assessment, whilst in P. radiata holocellulose could provide a more stable and reliable index, when studying plant ecophysiological responses to changing environmental conditions.