亚热带针阔混交林土壤-植物-大气连续体(SPAC)中水稳定同位素特征  

Characteristics of Water Stable Isotopes in Soil-plant-atmosphere Continuum (SPAC) in the Needle-leaf and Broad-leaf Mixed Forest in Subtropical Region

作　　者：王锐 章新平[1,2] 戴军杰 罗紫东 贺新光[1,2] 关华德 WANG Rui;ZHANG Xinping;DAI Junjie;LUO Zidong;HE Xinguang;GUAN Huade(College of Resources and Environmental Sciences,Hunan Normal University,Changsha 410081,China;Key Laboratory of Geospatial Big Data Mining and Application,Changsha 410081,China;National Centre for Groundwater Research and Training,Flinders University,Adelaide,SA 5001,Australia)

机构地区：[1]湖南师范大学资源与环境科学学院,湖南长沙410081 [2]湖南师范大学/地理空间大数据挖掘与应用湖南省重点实验室,湖南长沙410081 [3]National Centre for Groundwater Research and Training,Flinders University,Adelaide,SA 5001,Australia

出　　处：《生态环境学报》2021年第6期1148-1157,共10页Ecology and Environmental Sciences

基　　金：国家自然科学基金项目(41571021);湖南省人影办自立项科研课题(201901)。

摘　　要：为揭示亚热带湿润地区森林系统内部的水文过程,通过分析长沙地区针阔混交林内降水、土壤水、樟树(Cinnamomum camphora)和刺杉(Cunninghamia lanceolate)茎杆水与叶片水中稳定同位素组成,并结合相关环境因子,分析了亚热带地区水分在森林系统(SPAC)内部转换过程中稳定同位素的变化特征及其影响因素。结果表明:研究区降水、土壤水和樟树、刺杉茎杆水中δ^(18)O均表现出在湿润期(10月至次年6月)偏正,在干旱期(7—9月)偏负的季节变化趋势。其中,林下土壤水中δ^(18)O随深度的增加季节变化逐渐减小。与茎杆水中δ^(18)O明显的季节变化不同,在湿润期和干旱期典型晴日樟树与刺杉茎杆水中δ^(18)O不存在明显的日内变化。相较于茎杆水中δ^(18)O,樟树和刺杉叶片水中稳定同位素既存在明显季节变化也存在明显的日内变化。在湿润期内,两种植物叶片水中δ^(18)O、Δ^(18)OL(叶片水同位素富集程度)均大于干旱期两种植物叶片水中δ^(18)O、Δ^(18)OL,叶片水线(LWL)的斜率则小于干旱期两种植物LWL的斜率。在湿润期典型晴日内,樟树和刺杉叶片水中δ^(18)O、Δ^(18)OL明显大于干旱期典型晴日内叶片水中δ^(18)O、Δ^(18)OL,LWL的斜率则小于干旱期典型晴日内两种植物LWL的斜率。基于Δ^(18)OL与各气象因子的相关性分析得到,在季节变化上,相对湿度、太阳辐射和饱和水汽压差是影响樟树和刺杉叶片水中稳定同位素富集程度的主要因子;在日内变化上,温度、相对湿度和饱和水汽压差对两种植物叶片水中稳定同位素富集程度影响最大。In order to determine the hydrological processes of the forest system in subtropical humid region, the stable isotopic compositions in precipitation, soil water, twig xylem water and leaf water of Cinnamomum camphora and Cunninghamia lanceolate in the needle-leaf and broad-leaf mixed forest in Changsha were analyzed and combined with environmental factors, the characteristics of stable isotope variations and their influencing factors during the internal conversion of water in the forest system (SPAC) in the subtropical region were analyzed. The results showed that: The δ^(18)O in precipitation, soil water, xylem water of C. camphora and C. lanceolate in the study area showed higher in wet period (October-June of the following year) and lower in dry period (July-September). To be more specific, the range of δ^(18)O in soil water decreased with the increase of depth. Different from the obvious seasonal variation in the δ^(18)O of xylem water, there were no obvious variation in the δ^(18)O in xylem water of C. camphora and C. lanceolate on typical sunny days during both wet and dry periods. Compared with the δ^(18)O in xylem water, the stable isotopes in leaf water of C. camphora and C. lanceolate showed obvious seasonal and diurnal variation. In wet period, the δ^(18)O and Δ^(18)OL in leaf water of the two species were higher than in dry period, otherwise the slope of LWL was smaller than in dry period. In typical sunny days of wet period, the δ^(18)O and Δ^(18)OL in leaf water of C. camphora and C. lanceolate were significantly higher than dry period, but slope of the LWL was smaller than in dry period. Based on the correlation analysis between Δ^(18)OL and meteorological factors, in terms of seasonal variations, RH, RS and VPD were the main factors affecting the enrichment of stable isotopes in leaf water of C. camphora and C. lanceolata;but for the diurnal variations, the greatest influence was exerted by T, RH and VPD.

关 键 词：降水 土壤水 茎杆水 叶片水 水稳定同位素 

分 类 号：S715[农业科学—林学] X17[环境科学与工程—环境科学]