秦岭南坡落叶松树轮α-纤维素葡萄糖单元内氧同位素组成的年内变化特征及其气候关联  

Intra-annual δ^(18)O profiles of growth rings of Larix gmelinii grown on the south slope of the Qinling Mountains:Implications for high resolution reconstruction of past temperature and humidity

作　　者：祁瑶婷 马然 赵雨 何荣[1] QI Yaoting;MA Ran;ZHAO Yu;HE Rong(Isotopomics in Chemical and Biology(ICB),College of Chemistry and Chemical Engineering,Shaanxi University of Science&Technology,Xi'an 710021,Shaanxi;Shaanxi Key Laboratory of Chemical Additives for Industry,Shaanxi University of Science&Technology,Xi'an 710021,Shaanxi)

机构地区：[1]陕西科技大学化学与化工学院,天然产物稳定同位素组学(ICB)实验室,陕西西安710021 [2]陕西科技大学,陕西省轻化工助剂重点实验室,陕西西安710021

出　　处：《第四纪研究》2023年第5期1354-1363,共10页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:42007408和41973072);中国博士后基金面上项目(批准号:2019M650253)共同资助。

摘　　要：年际或更长时间尺度树木年轮α-纤维素稳定氧同位素组成(δ^(18)O_(α-cell))已被证明与相应时间尺度气候条件(如温度、相对湿度和源水)定量相关,已成为研究(全球)气候历史及植被生态响应的重要指标之一。然而,气候因子和植物生理/代谢过程如何在年内(季节、月甚至周)时间尺度上影响α-纤维素δ^(18)O却知之甚少。本研究选取秦岭南坡针叶树种落叶松为对象,分析其树轮年内α-纤维素分子平均δ^(18)O_(α-cell)(葡萄糖单元中O-2~O-6)及其葡萄糖单元特定位点氧稳定同位素δ^(18)O_(2)及δ^(18)O_(PG)(葡萄糖单元中O-2及O-3~O-6)组成,并结合小时尺度树木径向生长动态记录仪(dendrometer)野外观察记录,基于日尺度气象数据的降雨同位素模拟结果,获得如下认识:1)落叶松α-纤维素葡萄糖单元中O-3~O-6平均同位素组成(δ^(18)O_(PG))与温度和相对湿度的相关性高于α-纤维素分子平均氧同位素组成(δ^(18)O_(α-cell))(温度:糖脎R^(2)=0.736>α-纤维素R^(2)=0.481;相对湿度:糖脎R^(2)=0.488>α-纤维素R2=0.097);2)生长季初期树轮α-纤维素葡萄糖单元中O-2氧同位素组成(δ^(18)O_(2))与源水(source water)的δ^(18)O_(sw)具有一定的相关性(R^(2)=0.378)。Stable oxygen isotope ratios in tree ringα-cellulose(δ^(18)O_(α-cell))has been used as a proxy for climate during tree growth,such as to explore long-term precipitation patterns,seasonality of precipitation,and intra-annual patterns of transpiration rates.The oxygen isotopic composition of tree ringα-cellulose is determined by the combination of evaporative effects,the isotopic composition of source water and opportunities for post-assimilation exchange.Position-specific analysis can provide a way to reconstruct the source water isotope abundance as well as the evaporative enrichment of water in the leaf,allowing precipitation and/or temperature reconstruction and resolving the complication of overlapping environmental and physiological influences.In addition,stable isotope values that vary only slightly across each tree ring will probably not provide enough additional information,and high-resolution within intra-annual tree ring analysis is on demand to gain the seasonal and even sub-seasonal information.In this context,we investigated the seasonal changes ofδ^(18)O_(α-cell)、δ^(18)O_(PG),and δ^(18)O_(2) of tree ring cellulose of Larix gmelinii and their response to climatic parameters.The sampling site is located in the Huoditang Forest Area(33°18'~33°28'N,109°20'~109°29'E;1450~2500 m a.s.l.)in Ningshaan County,China.This area has a forest cover rate of 91.8%,a mean annual temperature of 12℃,and a mean annual precipitation of 1023 mm,which is belonging to a humid mountain forest area.The vegetation forms are various,including 4 vegetation types.Temperatures,relative humidity(RH),and monthly precipitation amounts(P)were obtained from the Zhen'an Meteorological Station(33°26'N,109°09'E;693.9 m a.s.l.).In June 2021,we sampled tree ring samples of Larix gmelinii in Huoditang forest at elevations of 2000 m a.s.l.After preparing the surface with fine sandpaper,tree-ring widths were measured with 0.01-mm resolution and cross-dated.The ring of 1987 seasons,when the tree was 41 years old,was selected as

关 键 词：年内变化 树木年轮 Α-纤维素 稳定氧同位素 气候响应 

分 类 号：P597.2[天文地球—地球化学] Q945.79[天文地球—地质学]