Responses of carbon isotope ratios of C3 herbs to humidity index in northern China
Responses of carbon isotope ratios of C3 herbs to humidity index in northern China
复制标题
DOI：
10.3906/yer-1305-2
复制
发表时间：
2014-05
影响因子：
1
通讯作者：
Xianzhao Liu;Qingqing Su;Chao Li;Yong Zhang;Qing Wang
中科院分区：
文献类型：
--
作者：
Xianzhao Liu;Qingqing Su;Chao Li;Yong Zhang;Qing Wang
在delta13C值与温度等环境因素之间的关系中存在不确定性，导致不可靠的古气候重建。因此，在植物Delta13C与能够综合反映温度和降水的古气候重建指标之间建立合理的关系是非常重要的。通过对生长在中国北部不同气候带的大量C3草本植物的delta13C的测量，收集了研究区早期报道的C3草本植物的delta13C值，分析了C3草本植物的delta13C值的空间特征及其与湿度指数的关系。中国北部C3草本植物的Delta13C值变化范围为-29.9‰~-25.4‰，平均值为-27.3‰，从半湿润带到半干旱带再到干旱区，C3草本植物的delta13C平均值显著增加，3个气候带C3草本植物的delta13C值变化幅度分别为-29.9‰~-26.7‰(半湿润区)、-28.4‰~-25.6‰(半干旱区)和-28.0‰~-25.4‰(干旱区)。在半干旱区、半湿润区和整个北部地区，C3草本植物的delta13C值与湿度指数呈显著的线性负相关(P<；0.05)。随着湿度指数的增加，C3草本植物的平均delta13C值有不同程度的下降趋势。而在干旱区，两者呈线性正相关(P<；0.05)。湿度指数每增加0.1，平均~(13)C值显著增加1.3%。温度是不同采样点C3草本植物~(13)C分馏能力不同的主要原因。C3草本植物的Delta13C对湿润指数的响应差异很大，提醒我们应根据不同的气候带进行基于Delta13C植物的古气候重建。
Uncertainties would exist in the relationship between delta13C values and environmental factors such as temperature, resulting in unreliable reconstruction of paleoclimates. It is therefore important to establish a rational relationship between plant delta13C and a proxy for paleoclimate reconstruction that can comprehensively reflect temperature and precipitation. By measuring the delta13C of a large number of C3 herbaceous plants growing in different climate zones in northern China and collecting early reported delta13C values of C3 herbs in this study area, the spatial features of delta13C values of C3 herbs and their relationships with humidity index were analyzed. The delta13C values of C3 herbaceous plants in northern China ranged from -29.9%o to -25.4%o, with the average value of -27.3%o. The average delta13C value of C3 herbaceous plants increased notably from the semihumid zone to the semiarid zone to the arid zone; the variation ranges of delta13C values of C3 plants in those 3 climatic zones were -29.9%o to -26.7%o (semihumid area), -28.4%o to -25.6%o (semiarid area), and -28.0%o to -25.4%o (arid area). In the semiarid zone, the semihumid zone, and the whole northern area, delta13C values of C3 herbs showed obvious linear negative correlation to humidity indexes (P < 0.05). With the increase of humidity indexes, the average delta13C value of C3 herbaceous plants tended to decrease to different extents. In the arid zone, however, a linear positive correlation was found between them (P < 0.05). With every 0.1 increase in humidity index, the average delta13C value increased significantly by 1.3%o. Temperature is the main reason for different 13C fractionation abilities of C3 herbs occurring in different sampling sites. The highly varying response of delta13C of C3 herbaceous plants to humid index reminds us that delta13Cplant-based paleoclimate reconstruction in northern China should be carried out according to the different climatic zones.