王建
, 赵业思, 商志远
Wang Jian, Zhao Yesi, Shang Zhiyuan
中图分类号: P932
文献标识码: A
文章编号: 1000-0690（2016）08-1261-08
通讯作者:
收稿日期: 2015-08-25
修回日期: 2015-11-4
网络出版日期: 2016-08-20
版权声明: 2016 《地理科学》编辑部 本文是开放获取期刊文献，在以下情况下可以自由使用：学术研究、学术交流、科研教学等，但不允许用于商业目的.
基金资助:
作者简介:
作者简介：王建（1962-）,男,山东昌邑人,教授,博士,主要从事地表过程和环境变迁研究。E-mail: jwang169@vip.sina.com
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摘要
比较了中国东南地区九岭山和九连山两地马尾松（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）;两地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。
关键词：
Abstract
It has been proved that stable carbon isotope ratio（δ13C）of tree-ring is an excellent physical proxy for climatic reconstruction in warm and moist regions. However, since wholewood, the raw material of tree-ring, is composed by different chemical components and it is still uncertain which component contains the most stronger climate signal in its δ13C. In this study, climate sensitivities of δ13C in wholewood, holocellulose and α-cellulose were compared in Pinus massoniana from mountains of Jiuling and Jiulian in southeastern China. Results indicated that δ13C of α-cellulose and holocellulose were enriched by 1.211±0.121‰ and 1.170‰±0.168‰ compared with the whole wood respectively; δ13C series of the three components demonstrated high coherence with significant positive correlation coefficients (p<0.001); Hydroclimatic conditions during the middle to late growing season were both the dominated climatic factors limiting δ13C variations in the two study areas and δ13C of the three components all significantly correlated with these climatic factors（p<0.05）without obviously differences. Therefore, it can be concluded that δ13C of tree-ring whole wood in Pinus massoniana is good enough to be used in the climatic reconstruction at an annual or even longer time scale and holocellulose or α-cellulose extraction unnecessary during the studies about stable isotopes in tree-ring of Pinus massoniana.
Keywords：
树木年轮由于其分辨率高、样品分布广泛,在全球气候变化研究中发挥着重要的不可替代的作用。但在温暖湿润的气候地区,温度、降水对树木生长的限制作用较弱,树轮宽度等指标对于气候变化的敏感性减弱,利用树轮宽度等指标恢复古气候受到很大的限制[1,2]。相比宽度,树轮稳定碳同位素比率（δ13C）所受的气候作用机制更为明确,气候主要是通过影响叶片的气孔导度和光合作用速率来影响树轮中δ13C变化的[3~7],因而在暖湿地区,利用树轮δ13C研究气候变化具有更大的优势与潜力。
然而,树轮中包含多种次级组分,究竟利用什么组分进行δ13C分析可以更好地提取气候变化信息,还存在着不同的意见,成为目前研究的一个热点和难点[8~13],也成为一个限制树轮稳定碳同位素气候学继续发展的急需解决的关键问题。纵观有关树轮δ13C对于气候变化的响应问题的研究,大都针对不同地区的不同树种,如美国的道格拉斯杉（Pseudotsuga menziesii）、西黄松（Pinus ponderosa）[9,14~17];欧洲的夏栎（Quercus robur）、无梗花栎（Quercus petraea）[11,18,19];澳大利亚的辐射松（Pinus radiata）、海岸松（Pinus pinaster）、粉绿澳柏（Callitris glaucophylla）[13,20]等;亚洲的油松（Pinus tabulifornis）、樟子松（Pinus sylvestris）[12,21]。因此,产生意见分歧的原因,可能与研究的地点不同、树种不同有关。可是究竟是由于树种的不同还是由于地点的不同而导致的意见分歧,还缺乏系统的研究。如果能够对不同地点同一个树种的树轮的不同组分稳定碳同位素对于气候的响应异同进行研究,就有可能对于这个问题的解决提供新的线索。
马尾松（Pinus massoniana）是中国东部亚热带湿润地区分布最广、资源最丰富的针叶树种[22]。它分布在淮河以南的广大地区,北起秦岭淮河,南至广西十万大山、雷州半岛,西到四川盆地西缘、贵州乌蒙山,东到海滨[23]。其分布区域是被西南地区的云南松、华北地区的油松和华中东部的黄山松所包围,在中国的松属中是分布最广的一种,在数量上也是最多的一种[24],南北跨越了北亚热带、中亚热带、南亚热带与边缘热带。分布区的年均温变幅达到9~10℃,年降水量的区域差异达到1 000 mm。因此,马尾松是研究中国中东部区域空间差异影响的最理想的树种之一。
对中国不同地点的马尾松树轮不同组分稳定碳同位素对于气候的响应的敏感性进行系统的研究,试图回答以下几个问题：① 在中国中东部气候限制作用相对较弱的地区,树轮的全木、综纤维素和α纤维素哪种成分的δ13C更适合于气候的重建?② 不同地点同一树种δ13C对于气候的响应有何不同?③ 同一地点同一树种不同个体的树轮δ13C对于气候的响应是否一致?从而为平息何种组分能够更准确地提取气候信息的争论提供例证与依据,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的支撑。本文试图以马尾松分布区南界附近的九连山和中心地带的九岭山为例,探究不同组分树轮δ13C对于气候响应的敏感性。
九岭山（JLN）地处江西省西北部,大致为马尾松的分布中心区（图1）。该区气候属中亚热带湿润季风气候,年均气温15.6℃,年降水量1 653 mm,年均日照时数1 872.6 h,年均蒸发量1 053.3 mm,空气年平均相对湿度为79%[25]。九岭山树轮样品采自海拔介于600~1 000 m的武陵岩（WLY）和五梅山（WMS）2个样点。2样点水平距离约为65 km,平均坡度32°,坡向多为南坡和西南坡,土壤类型为山地黄壤。样品所采的马尾松林为原始林,平均树龄为65 a。九连山（JLA）地处江西省和广东省交界处,接近马尾松分布南界（图1）。气候属中亚热带与南亚热带过渡地带,年均气温16.4 ℃,年降水量2 155.6 mm,多年平均蒸发量790.2 mm,空气年均相对湿度85%,相对九岭山干湿季明显,2~9月为雨季,10~1月为旱季[26]。九连山样区包括九连山北坡的枧头（JT）、山坑（SK）和南坡板岭下（BLX）、路下（LX）4个采样点,样点海拔介于300~600 m之间,平均坡度21°,坡向多为东坡或东南坡,土壤类型为山地红壤。该地马尾松林均为天然次生林,平均树龄为46 a。
使用直径5.15 mm的树轮生长锥在树干胸径高度处（约1.3 m）沿坡面走向从马尾松树杆两侧分别钻取1支细树芯,以用于交叉定年分析。在采样现场,大致对树芯的年轮数初步判读,挑选树龄相对较长的马尾松个体,使用直径12 mm的生长锥沿坡面走向,在树杆两侧分别钻取2支粗树芯,以用于δ13C测定。在九岭山采集了37株树,120支树芯,在九连山采集了36株树,106支树芯。
将采集的样品装在纸筒里带至实验室内晾干,用白乳胶将细芯粘贴在样品槽内,用特制的样品夹将粗芯夹住,使用120~3 000目的干砂纸逐级打磨至年轮清晰可辨。先利用骨架图进行样芯之间的交叉定年,尽可能辨别出伪轮和缺轮,然后在体式显微镜下,利用AcuRite年轮宽度仪的Measure J2X年轮宽度测量系统（测量精度0.001 mm）读取年轮宽度,并使用COFECHA程序进行交叉定年与质量检验,从而确定各树芯每一年轮的真实年份。
选取九岭山WLY16、WLY17、WMS01、WMS06和九连山JT08、JT22、BLX04、BLX05共8株树的样芯用于δ13C测定。选择上述样品的理由是这8株树在各林分中树龄相对较长,且年轮相对较宽（表1）,不存在腐心、伤疤等问题。由于九岭山的马尾松年轮宽度自1993年后宽度值较窄,为避免样品量不足,选取1964~1993年作为研究时段,九连山样品选取1982~2011年的时段。
表1 用于δ13C测试的马尾松对应树龄与平均年轮宽度
Table 1 The age and mean tree-ring width of Pinus massoniana used for δ13C measurement
| 样芯编号 | WLY16 | WLY17 | WMS01 | WMS06 | JT08 | JT22 | BLX04 | BLX05 |
|---|---|---|---|---|---|---|---|---|
| 树龄（a） | 75 | 70 | 84 | 74 | 47 | 58 | 44 | 47 |
| 年轮平均宽度（mm） | 2.27 | 2.93 | 3.27 | 2.34 | 3.17 | 3.12 | 3.95 | 2.69 |
将树芯放在干净的玻璃板上,借助体式显微镜,找到年轮的分界线,利用洁净的手术刀截取每一年轮。将每株马尾松的4根粗芯同一年轮样品截取后混合在一起,并用干净的牛皮纸袋封装,并做好对应编号。所有样品截取完成后,放入行星式球磨机进行研磨,并过100目筛,以使样品充分混合均匀。留取一部分样品作全木δ13C测定,剩余样品用于纤维素提取。
综纤维素和α纤维素的提取方法见参考文献[27]。
在百万分天平（Starorius）上称取样品（0.20±0.05）mg装入锡杯,卷好密封,保持锡杯内部真空。在中科院沈阳应用生态研究所ThermoFinnigan-Deltaplus XP同位素比例质谱仪上进行δ13C测定（相对VPDB标准）,随机抽取36个平行样本对δ13C测量精度进行校验,整个系统误差≤0.15‰。Leavitt等指出同一地域4株树的混合δ13C序列能够较好的代表区域树轮δ13C的变化趋势与绝对值[26],因此分别计算九岭山与九连山2个样点的4株马尾松δ13C算术平均值序列,记为JLN和JLA,用于树轮δ13C对气候变化的响应分析（图2）。
图2 马尾松树轮不同组分的单体δ13C序列、区域平均δ13C序列及对应差值序列
Fig.2 Individual and regional averaged δ13C series of different tree-ring components in Pinus massoniana with their δ13C difference
距离九岭山和九连山2个样区较近的气象站分别为修水县气象站（29°02′N,114°34′E）和连平县气象站（24°22′N,114°29′E）。选取两地的月平均温度、降水量、月平均相对湿度和日照时数4个气候要素进行分析（图3）。气象数据来源于中国气象数据网。
图3 修水县（九岭山）和连平县（九连山）气候要素月平均变化
Fig. 3 Monthly variations of climate factors in Xiushui ( JLN ) and Lianping County ( JLA )
如表2所示,从平均值、中位值、最大值和最小值4个指标来看,全木δ13C相对综纤维素和α纤维素明显偏负。以平均值为例,全木δ13C相对综纤维素和α纤维素分别偏负(1.211±0.121)‰和(1.170±0.168)‰;此外,综纤维素和α纤维素δ13C相比全木δ13C具有更大的离散程度。具体表现为,除JT08以外的其他7株马尾松综纤维素和α纤维素δ13C的标准差均大于全木δ13C,所有个体综纤维素和α纤维素δ13C的变异系数绝对值均大于全木δ13C。
表2 马尾松树轮不同组分δ13C序列的统计参数
Table 2 Statistic parameters of the δ13C series in different tree-ring components of Pinus massoniana
| 九岭山 | WLY16 | WLY17 | WMS01 | WMS06 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 全木 | 综纤维素 | α纤维素 | 全木 | 综纤维素 | α纤维素 | 全木 | 综纤维素 | α纤维素 | 全木 | 综纤维素 | α纤维素 | |||
| 平均值（‰） | -26.108 | -24.933 | -24.956 | -25.215 | -23.883 | -23.993 | -25.466 | -24.269 | -24.252 | -24.606 | -23.318 | -23.475 | ||
| 中位值(‰) | -26.066 | -24.912 | -24.915 | -25.190 | -23.932 | -24.012 | -25.505 | -24.334 | -24.202 | -24.653 | -23.493 | -23.595 | ||
| 最大值(‰) | -25.112 | -24.098 | -23.652 | -23.966 | -22.638 | -22.987 | -24.610 | -23.265 | -23.248 | -24.060 | -22.343 | -22.780 | ||
| 最小值(‰) | -27.301 | -26.248 | -26.145 | -25.974 | -24.855 | -24.764 | -26.188 | -24.977 | -24.892 | -25.052 | -23.919 | -24.069 | ||
| 标准差(‰) | 0.477 | 0.495 | 0.530 | 0.454 | 0.503 | 0.467 | 0.375 | 0.429 | 0.386 | 0.281 | 0.385 | 0.357 | ||
| 变异系数(%) | -1.828 | -1.986 | -2.122 | -1.801 | -2.107 | -1.944 | -1.473 | -1.767 | -1.593 | -1.141 | -1.653 | -1.519 | ||
| 九连山 | JT08 | JT22 | BLX04 | BLX05 | ||||||||||
| 全木 | 综纤维素 | α纤维素 | 全木 | 综纤维素 | α纤维素 | 全木 | 综纤维素 | α纤维素 | 全木 | 综纤维素 | α纤维素 | |||
| 平均值(‰) | -26.001 | -24.819 | -24.881 | -26.041 | -24.828 | -24.703 | -25.833 | -24.711 | -24.803 | -25.465 | -24.281 | -24.306 | ||
| 中位值(‰) | -26.097 | -24.923 | -24.966 | -26.040 | -24.842 | -24.686 | -25.934 | -24.747 | -24.851 | -25.458 | -24.284 | -24.297 | ||
| 最大值(‰) | -24.773 | -23.731 | -23.611 | -24.993 | -23.748 | -23.741 | -24.848 | -23.505 | -23.560 | -24.699 | -23.356 | -23.274 | ||
| 最小值/‰ | -27.241 | -26.109 | -25.874 | -26.748 | -25.746 | -25.610 | -26.541 | -25.753 | -25.575 | -26.219 | -25.268 | -25.255 | ||
| 标准差(‰) | 0.530 | 0.523 | 0.514 | 0.438 | 0.457 | 0.474 | 0.405 | 0.468 | 0.437 | 0.421 | 0.522 | 0.507 | ||
| 变异系数(%) | -2.037 | -2.105 | -2.067 | -1.682 | -1.840 | -1.920 | -1.569 | -1.894 | -1.763 | -1.652 | -2.149 | -2.085 | ||
综纤维素与α纤维素δ13C差异不显著,在不同个体中两者大小关系并不一致。在每个个体中,综纤维素和α纤维素两者间的δ13C差值时正时负,并未表现出单一的正负性。
尽管全木、综纤维素和α纤维素三者δ13C存在绝对值差异,但树轮不同组分δ13C对气候变化响应敏感性的研究关注的是组分δ13C变化趋势与气候要素变化趋势的差异,因而各组分δ13C变化趋势的差异大小是判断各组分可否相互替代的重要依据。在此使用一元线性回归分析衡量组分δ13C的变化趋势的相似性,拟合结果如表3所示。
表3 马尾松树轮不同组分δ13C两两间一元线性回归分析结果
Table 3 Results of simple linear regression for the δ13C between every two kinds of tree-ring components in Pinus massoniana
| 样本 | 回归方程 | 校正R2 | P值 | 样本 | 回归方程 | 校正R2 | P值 | |
|---|---|---|---|---|---|---|---|---|
| WLY16 | δ13C综纤维素=0.988·δ13C全木+0.854 | 0.933 | <0.001 | JT08 | δ13C综纤维素=0.954·δ13C全木-0.019 | 0.904 | <0.001 | |
| δ13Cα纤维素=1.072·δ13C全木+1.400 | 0.924 | <0.001 | δ13Cα纤维素=0.935·δ13C全木-0.579 | 0.932 | <0.001 | |||
| δ13Cα纤维素=1.02·δ13C综纤维素+0.482 | 0.937 | <0.001 | δ13Cα纤维素=0.954·δ13C综纤维素-1.202 | 0.907 | <0.001 | |||
| WLY17 | δ13C综纤维素=1.06·δ13C全木+2.839 | 0.853 | <0.001 | JT22 | δ13C综纤维素=0.967·δ13C全木+0.342 | 0.912 | <0.001 | |
| δ13Cα纤维素=0.966·δ13C全木+0.353 | 0.792 | <0.001 | δ13Cα纤维素=0.968·δ13C全木+0.504 | 0.880 | <0.001 | |||
| δ13Cα纤维素=0.84·δ13C综纤维素-3.935 | 0.789 | <0.001 | δ13Cα纤维素=0.927·δ13C综纤维素-1.696 | 0.815 | <0.001 | |||
| WMS01 | δ13C综纤维素=1.106·δ13C全木+3.906 | 0.844 | <0.001 | BLX04 | δ13C综纤维素=1.064·δ13C全木+2.782 | 0.934 | <0.001 | |
| δ13Cα纤维素=0.993·δ13C全木+1.036 | 0.796 | <0.001 | δ13Cα纤维素=0.967·δ13C全木+0.177 | 0.927 | <0.001 | |||
| δ13Cα纤维素=0.863·δ13C综纤维素-3.319 | 0.766 | <0.001 | δ13Cα纤维素=0.822·δ13C综纤维素-4.484 | 0.913 | <0.001 | |||
| WMS06 | δ13C综纤维素=1.161·δ13C全木+5.258 | 0.758 | <0.001 | BLX05 | δ13C综纤维素=1.086·δ13C全木+3.372 | 0.704 | <0.001 | |
| δ13Cα纤维素=1.016·δ13C全木+0.147 | 0.814 | <0.001 | δ13Cα纤维素=1.092·δ13C全木+3.491 | 0.627 | <0.001 | |||
| δ13Cα纤维素=0.832·δ13C综纤维素-4.078 | 0.738 | <0.001 | δ13Cα纤维素=0.839·δ13C综纤维素-3.922 | 0.801 | <0.001 |
同一马尾松个体3种组分δ13C序列两两间一元线性回归校正R2算术平均值为0.842,中位值0.849（标准差SD=0.085,样本量N=24）;概率P值均小于0.001;斜率K值介于0.822和1.161之间,接近K=1,说明3种组分δ13C的年际变化序列具有极为一致的变化趋势,3种组分δ13C之间存在极其显著的正相关性。
通过比较不同组分δ13C与气候要素的Pearson相关系数大小,可以判定不同组分δ13C对气候响应敏感性的强弱差异[11,13,28]。由表4可以看出,气候因素对两地马尾松树轮δ13C变化的影响主要集中在马尾松生长季的中晚期,其中最为显著的是响应关系是九岭山和九连山分别与所在区域8~9月和9~11月相对湿度显著负相关。此外,九岭山马尾松树轮δ13C还与8月气温,8~9月日照时数显著正相关,与8月降水亦接近显著负相关水平。九连山马尾松树轮δ13C则还与10月日照时数显著正相关。但就3种组分δ13C与上述气候要素的响应关系而言,3种组分δ13C与这些时段的气候要素的相关关系绝大多数均达到显著水平,相关系数间的差异微小。
表4 马尾松树轮不同组分δ13C与限制性气候因子间的相关系数
Table 4 Correlation coefficients between δ13C of different tree-ring components in Pinus massoniana and dominated climate factors
| 九岭山（JLN） | 全木 | 综纤维素 | α纤维素 | 极差 | 九连山（JLA） | 全木 | 综纤维素 | α纤维素 | 极差 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 8月相对湿度 | -0.645 | -0.663 | -0.693 | 0.048 | 9月相对湿度 | -0.453 | -0.383 | -0.478 | 0.095 | ||
| 9月相对湿度 | -0.585 | -0.574 | -0.558 | 0.027 | 10月相对湿度 | -0.666 | -0.659 | -0.727 | 0.068 | ||
| 8月平均气温 | 0.443 | 0.458 | 0.499 | 0.056 | 11月相对湿度 | -0.491 | -0.526 | -0.537 | 0.046 | ||
| 8月日照时数 | 0.506 | 0.528 | 0.559 | 0.053 | 10月日照时数 | 0.433 | 0.505 | 0.518 | 0.085 | ||
| 9月日照时数 | 0.440 | 0.443 | 0.377 | 0.066 |
全木与纤维素δ13C存在显著差异的原因主要是因为叶片合成的初级光合产物通过树干韧皮部进入木质部时,将进一步合成转化为其他次级组分,而不同组分的生化合成过程伴随着不同程度的稳定碳同位素分馏,进而导致纤维素和全木相对初级的光合产物具有不同的δ13C值。本文研究结果表明全木较纤维素δ13C偏负1.2‰左右,与其他关于松属的研究结果处于同一范围。如法国科西嘉岛的欧洲黑松（Pinus nigra）全木相对综纤维素δ13C偏负(1.2±0.5)‰[29];中国西北祁连山油松（Pinus tabulacformis）全木相对综纤维素和α纤维素分别偏负1.06‰和1.28‰[30];西班牙东北部的阿勒颇松（Pinus halepensis）全木相对综纤维素δ13C偏负1.2‰[31]。
关于综纤维素和α纤维素δ13C的大小关系一直存在较大争议,部分研究表明α纤维素δ13C相对综纤维素δ13C稳定偏负[13,32],而有关针对橡树和雪松的研究表明α纤维素δ13C要比综纤维素δ13C稳定偏正[33]。本文发现α纤维素与综纤维素δ13C差值在不同个体不同年份中的正负关系并不一致,变化范围介于-0.883‰~0.763‰间,这可能与α纤维素中残留的半纤维素有关[34]。α纤维素是指综纤维素在经浓度为17.5%的NaOH溶液浸泡后不溶的部分,实验过程中温度、处理时长的微小变化均有可能影响到NaOH溶液浓度的变化,进而导致综纤维素在转化为α纤维素的过程中存在少量半纤维素残留,影响到两者间δ13C大小关系。
两地马尾松树轮δ13C与生长季中晚期相对湿度显著负相关,可能是因为此时温度较高而降水较少,空气湿度相对较低,正值生长季的马尾松为减小水分蒸腾,缩小气孔导度,导致叶肉细胞对13C与12C的判识力降低,从而导致δ13C上升。根据表4所呈现的3种组分δ13C与这一时段气候要素的相关系数与极差,可以发现3种组分δ13C气候敏感性存在如下2个特点：
1） 3种组分δ13C所显著响应的气候要素虽然一致,但三者对这些气候要素响应敏感性的强弱程度具有变动性。首先,随着响应的气候要素不同,三者气候敏感性强弱关系亦随之发生变化。例如九岭山的3种组分δ13C与8月相对湿度的相关性表现为α纤维素>综纤维素>全木,而与9月相对湿度的相关性则表现为全木>综纤维素>α纤维素。其次,即使是同一气候要素,三者的气候敏感性强弱关系还存在地域差异。例如九岭山的3种组分δ13C与9月相对湿度的相关性表现为全木>综纤维素>α纤维素,但在九连山中却表现为α纤维素>全木>综纤维素。事实上,以往部分研究也表明,并不存在某种组分的δ13C与任一气候要素的相关性均高于其他组分δ13C的情形。例如有研究指出全木δ13C与气温的相关性要高于纤维素δ13C,而纤维素δ13C与降水的相关性则高于全木δ13C[28,30]。
2） 3种组分δ13C对应的相关系数极差较小,最大值仅为0.095。相比马利民等的研究结果计算[30],其3种组分δ13C与6~8月的平均气温和2~7月的降水量相关系数极差分别高达到0.676 和0.761,本文研究所得两地马尾松树轮不同组分δ13C对气候响应敏感性差异极小,可以忽略。
总体来看,3种组分δ13C与气候要素间的相关系数差异较小,并不存在某种组分的δ13C与任一气候要素的相关性均高于其他组分的情况,因而认为中国东南地区马尾松全木、综纤维素和α纤维素三者δ13C对气候变化响应敏感性相近,不存在显著差异。
1） 两地生长季中晚期水分状况是制约马尾松树轮δ13C的主要因子。其中九岭山马尾松树轮δ13C与8~9月相对湿度显著负相关,九连山马尾松树轮δ13C与10月相对湿度显著负相关。
2） α纤维素δ13C、综纤维素δ13C和全木δ13C对气候变化响应的敏感性没有显著差异。
3） 在利用两地马尾松树轮δ13C重建区域年际及更长时间尺度气候变化时,使用全木δ13C即可,无需提取综纤维素或α纤维素。
The authors have declared that no competing interests exist.
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通过地史变迁、冰川影响、地形特点、生态条件的分析与植株原始形态的调查检测,提出四川盆地的马尾松种源是我国古老马尾松的原始类型。由于盆地的特殊地形,使马尾松渡过冰期的影响得以保存而生长到现在。经检测该地区马尾松针叶树脂道数目最少,只有大多数种源的一半,条叶型苗木比例最高,比大多数种源高 2-6倍。树脂道少与条叶型苗木多都是较为原始的形态特征,证明四川盆地种源属于原始类型,是马尾松地理起源种群。
Geographical origin and evolution of Masson Pine.
通过地史变迁、冰川影响、地形特点、生态条件的分析与植株原始形态的调查检测,提出四川盆地的马尾松种源是我国古老马尾松的原始类型。由于盆地的特殊地形,使马尾松渡过冰期的影响得以保存而生长到现在。经检测该地区马尾松针叶树脂道数目最少,只有大多数种源的一半,条叶型苗木比例最高,比大多数种源高 2-6倍。树脂道少与条叶型苗木多都是较为原始的形态特征,证明四川盆地种源属于原始类型,是马尾松地理起源种群。
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Trees provide within the physical characteristics of their rings (width, relative density, reflectance), a record of past environmental changes, which, when expressed strongly, may be used successfully to extract palaeoclimatic information. Such approaches are now well established and have been applied globally. Trees can live for many hundreds or even thousands of years; it is, therefore, possible using these physical parameters to reconstruct climatic change throughout the life of the tree. Along with these established physical proxies, the stable carbon, hydrogen, and oxygen isotopic analyses of tree ring series provide a powerful suite of additional climate proxies. In comparison with the measurement of the physical proxies, the analysis of stable isotope ratios in tree rings is demanding, in terms of both personnel and resources. Consequently, the stable isotope analysis of tree rings can only be justified if the resulting data can provide additional, reliable climate information that cannot be obtained through alternative methods such as ring width or relative density. This chapter provides an introduction to the application of modern stable isotope techniques for the reconstruction and study of past climate from tree rings. Current challenges and limitations are discussed with specific emphasis placed on the development of robust isotope-based palaeoclimate time series and their potential for both isotopic and multiproxy analysis, using examples from a well-replicated site located close to the Boreal tree line.
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用树轮α-纤维素δ13C重建天目山地区近160年气候 [J].https://doi.org/10.3321/j.issn:1006-9267.2001.04.010 URL 摘要
对采自天目山的柳杉树轮进行交叉定年后,测得树轮的δ13C年序 列. 经谱分析,树轮的δ13C变化有与厄尔尼诺事件基本一致的准4.4年的周期. 将δ13C年序列去除大气CO2的影响, 利用其附近气象站资料, 分析δ13C 对气候要素的响应. 结果表明: 天目山地区的树轮δ13C的高频振荡与季节的气温、降水等要素有显著相关, 并有滞后效应,此外还与东亚季风的强弱变化有一定关系. 通过建立回归方程重建浙江北部地区的气候序列, 分析了这一地区一百多年来的气候变化状况及演化趋势.
Reconstruction of the climate in the Tianmu Mountain area,Zhejiang Province,in the last 160 years by δ13C sequence of tree ring α-cellulose. https://doi.org/10.3321/j.issn:1006-9267.2001.04.010 URL 摘要
对采自天目山的柳杉树轮进行交叉定年后,测得树轮的δ13C年序 列. 经谱分析,树轮的δ13C变化有与厄尔尼诺事件基本一致的准4.4年的周期. 将δ13C年序列去除大气CO2的影响, 利用其附近气象站资料, 分析δ13C 对气候要素的响应. 结果表明: 天目山地区的树轮δ13C的高频振荡与季节的气温、降水等要素有显著相关, 并有滞后效应,此外还与东亚季风的强弱变化有一定关系. 通过建立回归方程重建浙江北部地区的气候序列, 分析了这一地区一百多年来的气候变化状况及演化趋势.
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Sampling strategy for stable Carbon isotope analysis of tree rings in pine [J]. |
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Comparison of whole wood and cellulose Carbon and Oxygen isotope series from Pinus nigra ssp laricio (Corsica/France) [J].https://doi.org/10.1016/j.dendro.2011.04.001 Magsci [本文引用: 1] 摘要
Stable isotopes in tree rings have widely been used for palaeoclimate reconstructions since tree rings record climatic information at annual resolution. However, various wood components or different parts of an annual tree-ring may differ in their isotopic compositions. Thus, sample preparation and subsequent laboratory analysis are crucial for the isotopic signal retained in the final tree-ring isotope series used for climate reconstruction and must therefore be considered for the interpretation of isotope-climate relationships. This study focuses on wood of Corsican Pine trees (Pinus nigra ssp. laricio) as this tree species allows to reconstruct the long-term climate evolution in the western Mediterranean. In a pilot study, we concentrated on methodological issues of sample preparation techniques in order to evaluate isotope records measured on pooled whole tree-ring cellulose and whole tree-ring bulk wood samples. We analysed 80-year long carbon and oxygen chronologies of Corsican Pine trees growing near the upper tree line on Corsica. Carbon and oxygen isotope records of whole tree-ring bulk wood and whole tree-ring cellulose from a pooled sample of 5 trees were correlated with the climate parameters monthly precipitation, temperature and the self-calibrating Palmer Drought Severity Index (sc-PDSI). Results show that the offsets in carbon and oxygen isotopes of bulk wood and cellulose are not constant over time. Both isotopes correlate with climate parameters from late winter and summer. The carbon and oxygen isotope ratios of cellulose are more sensitive to climatic variables than those of bulk wood. The results of this study imply that extraction of cellulose is a pre-requisite for the reconstruction of high-resolution climate records from stable isotope series of P. nigra ssp. laricio. (C) 2011 Istituto Italiano di Dendrocronologia. Published by Elsevier GmbH. All rights reserved.
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Multiple stable isotopes from oak trees in southwestern Scotland and the potential for stable isotope dendroclimatology in maritime climatic regions [J].https://doi.org/10.1016/j.chemgeo.2008.01.006 URL 摘要
Across much of Europe, Eurasia and N. America there exist networks of long tree-ring chronologies which, under favourable circumstances, may be used to provide a record of palaeoclimate information. A proportion of these tree-ring archives, primarily those collected for archaeological dating purposes, represent a significant and largely untapped palaeoenvironmental archive. Such records may be unsuitable for palaeoclimatic reconstruction based solely upon their physical characteristics (ring width and density) owing to weak or poorly expressed climatic forcing. This is especially true of oak chronologies from maritime regions. This study explores the potential for extracting a climate signal from such chronologies by comparing the stable isotope ratios of C, H and O from the rings of common oak ( Quercus robur ) trees in southwestern Scotland, with local and regional meteorological data. Summer (growing season) climate influences all three isotopes and the relationships identified are consistent with published empirical and mechanistic studies. The climate signal appears strongest in O and weakest in H. The C and O series, in combination, explain 31% of the variance in July–August mean temperature measured locally and 26% when compared with a homogenised gridded dataset for the period AD1957-2002. Over longer timescales the combination of C and O isotopes may also preserve a significant low-frequency signal (July–August r 2 02=020.57, 9-year running mean AD1879–1998). These findings demonstrate the potential of stable isotope dendroclimatology for investigating climatic change from oak chronologies in maritime regions.
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Tree Physiol. 2015 Jan;35(1):1-3. doi: 10.1093/treephys/tpu115.
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树轮δ13C值方位分布及年际变化的普遍性研究——以中国东部亚热带地区为例 [J].URL 摘要
对采自中国东部亚热带地区的浙江天目山、江西庐山及江苏南京紫金山地区的金钱松（Pseudolarix kaemp feri）、冷杉（Abiesfab ricraib）及马尾松（Pinus massoniana）树轮,分别测定它们不同方位10 a、20 a及3 a树轮δ13C序列,探讨不同树种树轮δ13C存在的方位差异与年际变化普遍性。结果表明,在中国东部亚热带地区,树轮δ13C方位差异与年际变化存在普遍性。表现为3个地区、3个树种之间存在差异;同一地区不同树种及相同树种不同个体之间也存在差异;同一个体在相同年份存在方位差异及相同方位存在年际变化等;表明研究树轮δ13C的方位差异与研究其年际变化同样具有重要价值与意义。
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树木年轮中不同组分稳定碳同位素含量对气候的响应 [J].
通过研究贺兰山油松树轮中全木、综纤维素、α-纤维素中δ13C值的变化 ,来探讨树木生长过程中引起其中同位素差别的原因 ,以及它们对环境变化的响应。研究发现不同组分的δ13C值在过去 30 a中变化并不一致 ,其中 ,树轮中 α-纤维素中 δ13C序列含有最强周围环境变化的信息。δ13C序列和周围大气平均气温和降雨量关系密切 ,其中和 6～ 8月份的平均气温相关系数为 0 .42 7( α=0 .0 5 ) ;和 2～ 7月份总降水量的相关系数为 ( r=- 0 .5 1 4,α=0 .0 1 )。分析发现树轮 α-纤维素序列和树轮宽度序列呈显著负相关 ( r=- 0 .5 4 5 ,α= 0 .0 1 )。对比树轮各种组分的 δ13C值和气候之间的相关性及和树木的生长量的关系可以发现 ,树轮 α-纤维素中碳在经历了光合作用的固碳过程中的同位素分馏后 ,其 δ13C值就保持了相对稳定 ,是研究过去环境变化的良好载体。
Response of stable-carbon isotope composition of different tree-ring compounds to climatic change.
通过研究贺兰山油松树轮中全木、综纤维素、α-纤维素中δ13C值的变化 ,来探讨树木生长过程中引起其中同位素差别的原因 ,以及它们对环境变化的响应。研究发现不同组分的δ13C值在过去 30 a中变化并不一致 ,其中 ,树轮中 α-纤维素中 δ13C序列含有最强周围环境变化的信息。δ13C序列和周围大气平均气温和降雨量关系密切 ,其中和 6～ 8月份的平均气温相关系数为 0 .42 7( α=0 .0 5 ) ;和 2～ 7月份总降水量的相关系数为 ( r=- 0 .5 1 4,α=0 .0 1 )。分析发现树轮 α-纤维素序列和树轮宽度序列呈显著负相关 ( r=- 0 .5 4 5 ,α= 0 .0 1 )。对比树轮各种组分的 δ13C值和气候之间的相关性及和树木的生长量的关系可以发现 ,树轮 α-纤维素中碳在经历了光合作用的固碳过程中的同位素分馏后 ,其 δ13C值就保持了相对稳定 ,是研究过去环境变化的良好载体。
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| [6] |
The universality of Azimuth distribution and inter-annual variation of δ13C in tree rings—A case study in eastern subtropics areas of China. URL 摘要
对采自中国东部亚热带地区的浙江天目山、江西庐山及江苏南京紫金山地区的金钱松（Pseudolarix kaemp feri）、冷杉（Abiesfab ricraib）及马尾松（Pinus massoniana）树轮,分别测定它们不同方位10 a、20 a及3 a树轮δ13C序列,探讨不同树种树轮δ13C存在的方位差异与年际变化普遍性。结果表明,在中国东部亚热带地区,树轮δ13C方位差异与年际变化存在普遍性。表现为3个地区、3个树种之间存在差异;同一地区不同树种及相同树种不同个体之间也存在差异;同一个体在相同年份存在方位差异及相同方位存在年际变化等;表明研究树轮δ13C的方位差异与研究其年际变化同样具有重要价值与意义。
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钱君龙天目山柳杉树轮δ13C序列所反映的植物水分利用率对大气CO2 浓度变化的生理响应 [J].
工业化以来,由于大量化石燃料CO<sub>2</sub>排入大气,引起大气CO<sub>2</sub>浓度的持续升高。研究表明,植物的光合作用、水分利用率及作物生物量等均对周围大气CO<sub>2</sub>浓度的增加产生明显的正响应,而植物叶片的气孔导度及蒸腾速率对CO<sub>2</sub>浓度增加产生负响应。对采自浙江西天目山地区的三株柳杉树盘交叉定年后,测定了三株树轮的δ<sup>13</sup>C年序列,并利用3株柳杉树轮δ<sup>13</sup>C序列探讨了天目山地区树木生长对大气CO<sub>2</sub>浓度增加的生理响应——水分利用率的变化状况。结果是,三株树轮δ<sup>13</sup>C序列反映的水分利用率均是增加的,且增长趋势基本一致。研究结果反映了工业革命前后,树木生长对大气CO<sub>2</sub>浓度增加所产生的明显正响应。
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Temperature and vapour pressure deficit [J]. |
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Chemical pretreatment of Thuja occidentalis tree rings:implications for dendroisotopic studies [J].https://doi.org/10.1139/X09-091 URL [本文引用: 1] 摘要
Whether or not extractives, lignin, and (or) hemicelluloses, all of which have specific isotopic signatures, should be removed prior to dendroisotopic analysis is still debated. This study reports the range of modern tree-ring 未13C values of cellulose from Thuja occidentalis L., a species that has been under-utilized in dendroisotopic research despite its broad distribution and great longevity ...
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Foliage physiological response to increase of atmospheric CO2 concentration reflected by δ13 C series of tree ring in Tianmu Mountains.
工业化以来,由于大量化石燃料CO<sub>2</sub>排入大气,引起大气CO<sub>2</sub>浓度的持续升高。研究表明,植物的光合作用、水分利用率及作物生物量等均对周围大气CO<sub>2</sub>浓度的增加产生明显的正响应,而植物叶片的气孔导度及蒸腾速率对CO<sub>2</sub>浓度增加产生负响应。对采自浙江西天目山地区的三株柳杉树盘交叉定年后,测定了三株树轮的δ<sup>13</sup>C年序列,并利用3株柳杉树轮δ<sup>13</sup>C序列探讨了天目山地区树木生长对大气CO<sub>2</sub>浓度增加的生理响应——水分利用率的变化状况。结果是,三株树轮δ<sup>13</sup>C序列反映的水分利用率均是增加的,且增长趋势基本一致。研究结果反映了工业革命前后,树木生长对大气CO<sub>2</sub>浓度增加所产生的明显正响应。
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12C/13C in cellulose and lignin as palaeothermometers [J]. |
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Evaluation of wood pretreatments on oak and cedar [J]. |
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Wood cellulose preparation methods and mass spectrometric analyses of δ13C, δ18O, and nonexchangeable δ2H values in cellulose, sugar, and starch: an interlaboratory comparison [J].https://doi.org/10.1021/ac0700023 URL PMID: 17503767 [本文引用: 1] 摘要
Interlaboratory comparisons involving nine European stable isotope laboratories have shown that the routine methods of cellulose preparation resulted in data that generally agreed within the precision of the isotope ratio mass spectrometry (IRMS) method used: +/- 0.2% for carbon and +/- 0.3% for oxygen. For carbon, the results suggest that holocellulose is enriched up to 0.39% in C-13 relative to the purified alpha-cellulose. The comparisons of IRMS measurements of carbon on cellulose, sugars, and starches showed low deviations from -0.23 to +0.23% between laboratories. For oxygen, IRMS measurements varied between means from -0.39 to 0.58%, -0.89 to 0.42%, and -1.30 to 1.16% for celluloses, sugars, and starches, respectively. This can be explained by different effects arising from the use of low- or high-temperature pyrolysis and by the variation between laboratories in the procedures used for drying and storage of samples. The results of analyses of nonexchangeable hydrogen are very similar in means with standard deviations between individual methods from +/- 2.7 to +/- 4.9%. The use of a one-point calibration (IAEA-CH7) gave significant positive offsets in delta H-2 values up to 6%. Detailed analysis of the results allows us to make the following recommendations in order to increase quality and compatibility of the common data bank: (1) removal of a pretreatment with organic solvents, (2) a purification step with 17% sodium hydroxide solution during cellulose preparation procedure, (3) measurements of oxygen isotopes under an argon hood, (4) use of calibration standard materials, which are of similar nature to that of the measured samples, and (5) using a two-point calibration method for reliable result calculation.
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| [9] |
Carbon-13 in tree-ring cellulose as an indicator of past climates [J].https://doi.org/10.1038/287432a0 URL [本文引用: 1] 摘要
Amount of 13C was measured as the ratio 13C/12C ( delta 13C) on dendrochronologically dated tree sections of ponderosa pine (AD 810-1045) and Abies concolor (AD 931-1047) from an archaeological site in Chaco Canyon, New Mexico. Patterns of delta 13C for cellulose (and to a lesser extent, lignin) from single sections both corresponded well with climate as indicated by standard tree ring index fo...
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| [10] |
Reducing uncertainties in δ13C analysis of tree rings: Pooling, milling, and cellulose extraction. https://doi.org/10.1029/98JD01169 URL 摘要
Recent developments of on-line methods have provided another boost to the determination of stable isotope ratios in organic material. Along with a significant increase in sample throughput, the sample sizes decrease, both of which are necessary conditions to acquire long time series from limited wood amounts. In view of this new technique we reconsidered the most important factors influencing the measured isotopic signature which are (1) pooling, (2) homogeneity, and (3) cellulose extraction. In most cases, pooling (i.e., mixing wood of the same year from different trees) can be made in a simple way by mixing the whole wood available because mass-weighted and unweighted isotope measurements were the same within the error. More attention must be paid in homogenizing the sample. Theoretical considerations underpinned by experimental results suggest a fineness of 0.15 mm (115 mesh) if cellulose is extracted and 0.1 mm (165 mesh) for direct wood analysis. Many of previous studies did not achieve this fineness. We find that wood is as good a climate proxy as cellulose. This is shown by comparing correlations of wood and corresponding cellulose isotope values with meteorological data, which are identical within the uncertainty.
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| [11] |
Comparison of stable Carbon isotope ratios in the whole wood,cellulose and lignin of oak tree-rings [J].https://doi.org/10.1016/S0031-0182(03)00466-8 URL [本文引用: 2] 摘要
The stable carbon isotope ratios (δ 13 C) of whole wood, cellulose and acid-insoluble lignin from annual latewood increments of Quercus robur L., from modern and sub-fossil wood, were measured and their potential use as palaeoenvironmental indicators examined. The resulting time series demonstrate a very high degree of coherence, with δ 13 C of cellulose isotopically enriched by approximately 3‰ compared to δ 13 C of lignin. The δ 13 C values of all three components are influenced by the climate of July and August. Modern whole wood retains the strongest climate signal, perhaps because its composition is closest to that of leaf sugars. In sub-fossil wood there is no evidence that differential decay leads to fractionation of carbon within either cellulose or lignin, but differential decay can alter the cellulose to lignin ratio.
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| [12] |
樟子松树轮不同组分的稳定碳同位素分析 [J].
对大兴安岭北部樟子松树轮中的全木、综纤维素和α纤维素3种组分按早晚材分别测定稳定碳同位素(<em>δ</em><sup>13</sup>C)值,分析比较早晚材两种材质的3种组分<em>δ</em><sup>13</sup>C值差异,探讨其对气候环境变化的响应。结果表明:从组分来看,樟子松树轮综纤维素的<em>δ</em><sup>13</sup>C指标更接近于α纤维素;从材质来看,樟子松树轮晚材不同组分的稳定碳同位素信号对气候环境变化响应的一致性和敏感程度要大于早材。樟子松树轮晚材的综纤维素<em>δ</em><sup>13</sup>C指标是研究过去气候或环境变化的理想载体,而α纤维素在提取过程中很可能丢失了部分气候信息。
Analysis of stable Carbon isotopes in different components of tree rings of Pinus sylvestris var.mongolica.
对大兴安岭北部樟子松树轮中的全木、综纤维素和α纤维素3种组分按早晚材分别测定稳定碳同位素(<em>δ</em><sup>13</sup>C)值,分析比较早晚材两种材质的3种组分<em>δ</em><sup>13</sup>C值差异,探讨其对气候环境变化的响应。结果表明:从组分来看,樟子松树轮综纤维素的<em>δ</em><sup>13</sup>C指标更接近于α纤维素;从材质来看,樟子松树轮晚材不同组分的稳定碳同位素信号对气候环境变化响应的一致性和敏感程度要大于早材。樟子松树轮晚材的综纤维素<em>δ</em><sup>13</sup>C指标是研究过去气候或环境变化的理想载体,而α纤维素在提取过程中很可能丢失了部分气候信息。
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| [13] |
Is cellulose extraction necessary for developing stable Carbon and Oxygen isotopes chronologies from Callitris glaucophylla? [J].https://doi.org/10.1016/j.palaeo.2005.11.003 URL [本文引用: 4] 摘要
We examined the necessity of extracting cellulose for the development of stable carbon and oxygen isotope chronologies from Callitris glaucophylla J. Thompson and L.A.S. Johnson (Cupressaceae). We compared relationships among isotopes of whole wood, cellulose and climate for the period 1979–1999 and using a moving interval technique with a 10-year window. Isotopes of whole wood and cellulose were significantly correlated and had similar relationships with climate when considered over the entire period. In general, variation in δ 13 C and δ 18 O was related to summer temperature relative humidity and rainfall. However, δ 13 C and δ 18 O of whole wood generally exhibited weaker and more variable correlations with climate through time than cellulose. In addition, isotopes of whole wood did not deviate from 1979 to 1999 mean values in the same way as isotopes of cellulose. The instability of whole wood–climate relationships may be due to the inclusion in whole wood of a climate signal from lignin that is more variable between tree rings than cellulose. Overall, it appears that C. glaucophylla at least whole wood does not record climate in the same way as cellulose and stable isotopes of cellulose provide a more temporally stable proxy of past climate. We suggest that when developing isotope chronologies for other species the suitability of whole wood vs. cellulose as a proxy for climate should be assessed with consideration of the temporal stability of their relationship with climate.
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| [14] |
Radial patterns of Carbon isotopes in the xylem extractives and cellulose of Douglas-fir [J].https://doi.org/10.1093/treephys/27.6.921 URL PMID: 17331910 [本文引用: 1] 摘要
Heartwood extractives (nonstructural wood components) are believed to be formed from a combination of compounds present in the adjacent sapwood and materials imported from the phloem. The roles of local compounds and imported material in heartwood formation could have important implications for the wood quality of species having naturally durable wood. Stable isotope composition (delta(13)C) was analyzed to assess radial variation in sapwood extractives, and to estimate the relative importance of adjacent sapwood extractives and imported photosynthate in the formation of heartwood extractives. Cellulose and extractives from the outer 39 annual rings of six ((Mirb.) Franco) trees were isolated and their delta(13)C composition determined. Although the extractives and the cellulose showed different absolute delta(13)C values, the patterns of change over time (as represented by the annual rings) were similar in most cases. Within an annual ring, carbon isotope ratios of extractives were correlated with the cellulose isotope ratio (R2 = 0.33 in sapwood, R2 = 0.34 in heartwood for aqueous -soluble extractives; R2 = 0.41 in sapwood for hot-water-soluble extractives). These data suggest that some sapwood extractives are formed when the wood ring forms, and remain in place until they are converted to heartwood extractives many years later. Sapwood extractives appear to be important sources of materials for the of heartwood extractives in .
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| [15] |
Correlation of Carbon isotope ratios in the cellulose and wood extractives of Douglas-fir [J].https://doi.org/10.1016/j.dendro.2007.05.005 Magsci 摘要
<h2 class="secHeading" id="section_abstract">Abstract</h2><p id="">Cellulose is usually isolated from the other components of plant material for analysis of carbon stable isotope ratios (<em>δ</em><sup>13</sup>C). However, many studies have shown a strong correlation between whole-wood and cellulose <em>δ</em><sup>13</sup>C values, prompting debate about the necessity of cellulose extraction for tree-ring studies. The <em>δ</em><sup>13</sup>C values were measured in whole wood, extractive-free wood, purified cellulose, acetone/water-soluble extractives and hot water-soluble extractives of Douglas-fir sapwood. Cellulose and acetone/water-soluble extractives from heartwood from the same trees also were compared. Although the various materials showed different absolute <em>δ</em><sup>13</sup>C values, the components of the same samples, including the extractives, were correlated. The correlations of carbon isotope ratios of cellulose, extractive-free wood and extractives, and the relatively low concentration of the extractives in the wood, suggests that extraction of purified cellulose from Douglas-fir wood samples may not be necessary for some tree-ring analyses.</p>
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| [16] |
Vegetation control effects on untreated wood, crude cellulose and holocellulose delta C-13 of early and latewood in 3- to 5-year-old rings of Douglas-fir [J].https://doi.org/10.1007/s00468-008-0227-6 Magsci 摘要
<a name="Abs1"></a>The stable carbon (C) composition of tree rings expressed as δ<sup>13</sup>C, is a measure of intrinsic water-use efficiency and can indicate the occurrence of past water shortages for tree growth. We examined δ<sup>13</sup>C in 3- to 5-year-old rings of Douglas-fir (<i>Pseudotsuga menziesii</i> (Mirb) Franco) trees to elucidate if decreased water supply or uptake was a critical factor in the observed growth reduction of trees competing with understory herb and shrub vegetation compared to those growing without competition. We hypothesized that there would be no differences in δ<sup>13</sup>C of earlywood in trees growing in plots with competing vegetation and those in plots receiving complete vegetation control during 5 years because earlywood formed early in the growing season when soil water was ample. We also hypothesized that δ<sup>13</sup>C in latewood which was formed during the later half of the growing season when precipitation was low, would be greater (less negative) in trees in plots without vegetation control. We then separated early and latewood from rings for three consecutive years and analyzed their δ<sup>13</sup>C composition. No significant differences in earlywood δ<sup>13</sup>C in years 3–5 were observed for trees in the two vegetation control treatments. δ<sup>13</sup>C of untreated latewood separated from wood cores was greater in 4- and 5-year-old rings of trees growing with competing vegetation compared to trees growing without vegetation competition (i.e., −25.5 vs. −26.3‰ for year 4, and −26.1 vs. −26.8‰ for year 5). Results suggest that water shortages occurred in Douglas-fir trees on this coastal Washington site in the latewood-forming portion of the growing season of years 4 and 5 in the no-vegetation control treatment. We also compared δ<sup>13</sup>C from untreated wood, crude cellulose extracted with the Diglyme–HCl method, and holocellulose extracted with toluene–ethanol to see if the extraction method would increase the sensitivity of the analysis. δ<sup>13</sup>C values from the two extraction methods were highly correlated with those from untreated samples (<i>r</i> <sup>2</sup> = 0.97, 0.98, respectively). Therefore, using untreated wood would be as effective as using crude cellulose or holocellulose to investigate δ<sup>13</sup>C patterns in young Douglas-fir.
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| [17] |
The effects of α-cellulose extraction and blue-stain fungus on retrospective studies of Carbon and Oxygen isotope variation in live and dead trees [J].https://doi.org/10.1002/rcm.5192 URL PMID: 21953963 [本文引用: 1] 摘要
Abstract Tree-ring carbon and oxygen isotope ratios from live and recently dead trees may reveal important mechanisms of tree mortality. However, wood decay in dead trees may alter the δ(13)C and δ(18)O values of whole wood obscuring the isotopic signal associated with factors leading up to and including physiological death. We examined whole sapwood and α-cellulose from live and dead specimens of ponderosa pine (Pinus ponderosa), one-seed juniper (Juniperous monosperma), pi09on pine (Pinus edulis) and white fir (Abies concolor), including those with fungal growth and beetle frass in the wood, to determine if α-cellulose extraction is necessary for the accurate interpretation of isotopic compositions in the dead trees. We found that the offset between the δ(13)C or δ(18)O values of α-cellulose and whole wood was the same for both live and dead trees across a large range of inter-annual and regional climate differences. The method of α-cellulose extraction, whether Leavitt-Danzer or Standard Brendel modified for small samples, imparts significant differences in the δ(13)C (up to 0.4‰) and δ(18) O (up to 1.2‰) of α-cellulose, as reported by other studies. There was no effect of beetle frass or blue-stain fungus (Ophiostoma) on the δ(13)C and δ(18)O of whole wood or α-cellulose. The relationships between whole wood and α-cellulose δ(13)C for ponderosa, pi09on and juniper yielded slopes of ~1, while the relationship between δ(18)O of whole wood and α-cellulose was less clear. We conclude that there are few analytical or sampling obstacles to retrospective studies of isotopic patterns of tree mortality in forests of the western United States. Published in 2011 by John Wiley & Sons, Ltd.
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| [18] |
Biochemical composition is not the main factor influencing variability in Carbon isotope composition of tree rings [J]. |
| [19] |
The diversity of (13)C isotope discrimination in a Quercus robur full-sib family is associated with differences in intrinsic water use efficiency, transpiration efficiency, and stomatal conductance [J].https://doi.org/10.1118/1.2372216 URL PMID: 19380420 [本文引用: 1] 摘要
(13)C discrimination in organic matter with respect to atmospheric CO(2) ((13)C) is under tight genetic control in many plant species, including the (L.) full-sib progeny used in this study. (13)C is expected to reflect intrinsic use efficiency, but this assumption requires confirmation due to potential interferences with mesophyll conductance to CO(2), or post-photosynthetic discrimination. In order to dissect the observed (13)C variability in this progeny, six genotypes that have previously been found to display extreme phenotypic values of (13)C [either very high ('high ') or low ('low ') phenotype] were selected, and efficiency (TE; accumulated biomass/transpired ), net CO(2) assimilation rate (A), stomatal conductance for vapour (g(s)), and intrinsic use efficiency (W(i)=A/g(s)) were compared with (13)C in bulk leaf matter, wood, and in wood. As expected, 'high ' displayed higher values of (13)C not only in bulk leaf matter, but also in wood and . This confirmed the stability of the genotypic differences in (13)C recorded earlier. 'High ' also displayed lower TE, lower W(i), and higher g(s). A small difference was detected in photosynthetic capacity but none in mesophyll conductance to CO(2). 'High ' and 'low ' displayed very similar leaf anatomy, except for higher stomatal density in 'high '. Finally, diurnal courses of leaf gas exchange revealed a higher g(s) in 'high ' in the morning than in the afternoon when the difference decreased. The gene , involved in the control of use efficiency, leaf differentiation, and stomatal density, displayed higher expression levels in 'low '. In this progeny, the variability of (13)C correlated closely with that of W(i) and TE. Genetic differences of (13)C and W(i) can be ascribed to differences in stomatal conductance and stomatal density but not in photosynthetic capacity.
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| [20] |
Water availability and Carbon isotope discrimination in conifers [J].https://doi.org/10.1007/s004420000609 Magsci [本文引用: 1] |
| [21] |
The environmental signals of stable Carbon isotope in various tree-ring components of Pinus tabulaeformis [J].https://doi.org/10.1007/s00468-010-0518-6 URL [本文引用: 1] 摘要
Chinese pine (Pinus tabulaeformis) trees were sampled in the Helan Mountain, northwest China. The stable carbon isotope (δ13C) values of whole wood, holocellulose and alpha-cellulose in tree rings ove
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