树轮不同组分稳定碳同位素对气候响应敏感性的研究-以我国马尾松为例

Stable isotopes in tree rings play an important and unique role on global change research in virtue of two great advantages - they allow palaeoclimatic reconstructions with perfect annual resolution, and the con?dence limits can be statistically de?ned. In addition, trees grow widespread, and so it is possible to examine past climatic variations over large areas. Isotope ratios in tree rings have the added advantage that the physiological controls on their variation are reasonably well understood and relatively simple in comparison to the numerous factors controlling annual growth increment. Most research on stable isotopes in tree rings has focused on the stable isotopes of carbon, because they are the easiest to measure and show the most rapid development. However, to date, there is no consensus on which component of tree rings best reflects the climatic and environmental changes in terms of the carbon isotope ratio (δ13C). In consequence, it is necessary to perform comprehensive analysis between different compositions of tree ring δ13C for same species in different study areas. Unfortunately, such research has not been reported yet. In this study, we aim to investigate the differences in δ13C among different tissue components of tree rings for Pinus massoniana which will be collected from different areas in the central and eastern part of China. The proposed project will take into account location differences to explore the different components of the stable carbon isotopic response to climate sensitivity differences. The project will provide the basis for an applied climate change research, and will facilitate the research on stable carbon isotope with respect to tree rings.

树木年轮具有分辨率高、样品分布广泛等优势，在全球变化研究中发挥着重要而不可替代的作用。与年轮宽度或密度等指标相比，树轮稳定同位素对环境变化的敏感性更显著，也更适用于气候非限制性因子地区。其中，树轮稳定碳同位素应用最为广泛。然而，在利用什么组分进行稳定碳同位素分析能够更好地提取气候变化信息方面，目前学术界还存在不同的意见，成为限制树轮同位素气候学发展的一个急需解决的关键问题。产生分歧的原因，可能与研究地点或树种的不同有关，但目前还缺乏系统研究。对不同地点同一树种的树轮不同组分稳定碳同位素进行气候响应的研究将为这一问题的解决提供新的线索。本项目拟对我国中东部不同地点的马尾松树轮不同组分稳定碳同位素进行系统研究，从而在充分考虑地点差异的前提下，探讨不同组分稳定碳同位素对气候响应的敏感性差异，为平息上述分歧争论提供例证与依据，也为树轮稳定碳同位素更好地应用于气候变化研究提供分析方法支撑。

树轮δ13Ｃ与宽度对气候变化的响应存在差异，部分研究表明树轮δ13Ｃ相比宽度对暖湿地区的气候变化响应更敏感，在暖湿地区重建气候变化具有一定潜力。但在利用树轮δ13Ｃ重建气候时，究竟该选用全木、综纤维素和α纤维素这几种组分中何种组分测定δ13Ｃ，能够更好地反映气候变化，目前还缺乏一致的意见。本研究选择我国东部亚热带地区广泛分布的马尾松为例，在分析树轮δ13Ｃ与宽度所包含的气候信息差异的同时，重点比较树轮不同组分δ13Ｃ对气候变化响应的敏感性，从而为树轮气候学研究提供组分选取的依据。通过比较了五个地点马尾松（Pinus massoniana）树轮不同组分δ13C 对气候变化响应的敏感性，结果表明：α纤维素δ13C 和综纤维素δ13C 在均数方面较全木δ13C 分别偏正 1.170‰±0.168‰和 1.211‰±0.121‰；3 种组分δ13C 年际变化序列显著正相关（p < 0.001）；生长季中晚期水分状况是制约马尾松树轮δ13C的主要因子，3种组分δ13C 与此时段的气候要素相关性均达到显著水平（p<0.05），3 种组分δ13C 对气候变化响应的敏感性没有显著差异。