树轮氧同位素在土壤水分重建中的应用及挑战  

Application and challenges of tree-ring stable oxygen isotope in soil moisture reconstructions

作　　者：王璐 刘鸿雁[2] WANG Lu;LIU Hongyan(Institute of Subtropical Agriculture,Chinese Academy of Sciences,Changsha 410125,Hunan;College of Urban and Environmental Sciences,Peking University,Beijing 100871)

机构地区：[1]中国科学院亚热带农业生态研究所,湖南长沙410125 [2]北京大学城市与环境学院,北京100871

出　　处：《第四纪研究》2024年第4期1021-1030,共10页Quaternary Sciences

基　　金：国家重点研究发展计划项目(批准号:2022YFF0801803)资助。

摘　　要：土壤水分是评估农业和生态干旱的基本指标。目前,长时间连续土壤水分记录缺乏,严重影响了土壤水分的模拟和预测可靠性,导致全球各地的农业和生态干旱评估结果准确性和可信度偏低。近年来,基于树木年轮的土壤水分重建工作逐渐开展,在不同干湿气候区重建了长时间连续的土壤水分动态,对于认识当前农业和生态干旱及其驱动因子具有重要意义。本研究通过与树轮宽度指标对比,总结了树轮δ^(18)O指标在土壤水分重建中的优势;其次构建了一个包含237条序列的全球树轮δ^(18)O数据库,发现超过20%的树轮δ^(18)O年表与夏季土壤水分有显著相关(p<0.05),且干旱和湿润地区的相关系数无显著差异,表明树轮δ^(18)O在不同气候区域均有重建土壤水分的潜力;此外,讨论了重建过程中在选择土壤水分产品和确定土壤水分重建深度两方面的主要挑战。在未来的土壤水分重建实践中,可重点关注以下几个关键内容:1)干旱和湿润地区百年~千年土壤水分变化的趋势、变率和幅度;2)土壤水分变化的主要驱动因素;3)土壤水分重建数据与气候模式数据的比较。Soil moisture stands as a pivotal metric for evaluating agroecological drought conditions.The scarcity of long-term soil moisture records significantly hampers the accuracy and reliability of soil moisture simulations and forecasts,leading to imprecise and low-confidence assessments of agroecological drought across various global regions.In light of this,recent advancements have seen the implementation of soil moisture reconstructions derived from tree rings,offering insights into the historical dryness or wetness of soils and the driving factors behind agro-ecological droughts in both arid and humid locales.This review begins by highlighting the superiority of the tree-ringδ^(18)O index over traditional tree-ring width index for soil moisture reconstruction.We proceed to establish a comprehensive global database of tree-ringδ^(18)O,consisting of 237 chronologies,to explore its utility in soil moisture reconstruction efforts.Notably,over 20%of these chronologies show a significant correlation with soil moisture during summer months(p<0.05),with no significant difference in the correlation coefficients between arid and humid areas.This finding underscores the substantial potential of tree-ringδ^(18)O as a tool for reconstructing soil moisture across diverse climatic regions.Furthermore,we identify and discuss two primary challenges in the selection of soil moisture products and the depth of soil moisture reconstruction.Looking forward,in the quest to reconstruct soil water dynamics,it is crucial to focus on several key areas:the trends,variability,and range of soil moisture changes over centennial to millennial scales in both arid and humid zones;the principal factors driving changes in soil moisture;and the proxy-model comparison of soil moisture data.

关 键 词：土壤水分 树木年轮δ^(18)O 气候重建 农业和生态干旱 

分 类 号：P467[天文地球—大气科学及气象学]