鼎湖山典型森林水文过程氢氧稳定同位素特征研究

发布时间：2018-03-30 16:26

  本文选题：氢氧稳定同位素　切入点：水文过程　出处：《中国林业科学研究院》2017年博士论文

【摘要】：鼎湖山自然保护区地处我国热带与亚热带交汇处,在全球气候变化研究中占居独特而重要的地位。关于鼎湖山森林水文模型建立、降水量和地表径流水化学特征等方面前人用传统水文学方法做了较好地研究,但对鼎湖山典型森林(季风常绿阔叶林、马尾松针阔混交林和马尾松针叶林)生态系统水循环过程还缺乏全面理解和整体认识,林中优势植物水分来源、水分利用率以及森林生态系统水文过程定量研究较少;而在研究森林植被对水文过程的影响中,已存在于水分子中的氢氧稳定同位素是很好的示踪剂。稳定同位素技术在森林水文过程研究中的优势在于:它可以将森林生态系统水文过程,包括大气降水→地表水→土壤水→地下水→植物水作为一个整体来研究,阐明其过程与机制,克服传统水文学方法的缺点,综合反映植被和土壤对降水的截留能力,将降水对各层土壤水的贡献率、植物吸水率及林冠层对水分的截留效应定量化。本研究以我国广东鼎湖山典型森林(马尾松针叶林、马尾松针阔混交林、季风常绿阔叶林)为研究对象,运用氢氧稳定同位素技术、定位观测和数学模型等手段研究其大气降水、土壤水、植物水、地表水(溪水)和地下水氢氧稳定同位素特征,以及不同量级降水在土壤剖面中运移规律和林中乔、灌、草层优势植物水分利用率及利用策略,为揭示鼎湖山森林植被结构对降水格局变化的适应机制以及区域水资源合理利用和科学管理等提供理论依据。得出主要结论如下:(1)鼎湖山大气降水δD和δ~(18)O的关系式为:δD=7.875δ~(18)O+9.412(R2=0.982,n=120);大气降水δD和δ~(18)O值范围分别为�c1~(18).26‰~15.52‰和�c16.05‰~2.25‰,均值分别为�c36.35‰和�c5.81‰;大气降水过量氘(d)显示出冬高夏低的季节变化。鼎湖山干季的水气团主要来自局地蒸发、中国华北地区及寒冷干燥的亚欧大陆,湿季的水气团主要来自温暖湿润的西太平洋、南海和印度洋。(2)鼎湖山森林土壤水主要来源于大气降水和浅层地下水。表层(0~10 cm)土壤水δD与降水δD变化趋势一致,显示出鼎湖山森林表层土壤水δD主要大气受降水δD的控制;降水强度越大,降水从土壤表层向深层土壤渗透速度越快,降水对各层次土壤水的贡献率也越大;小雨(5 mm降水量≤10 mm)后5天内,对枯枝落叶层水贡献率最高(0~47.7%),对40~100 cm深层土壤水的贡献率最低(接近于0);中雨(10 mm降水量≤20 mm)后5天内,对0~10 cm表层土壤水的贡献率较高(29.6%~83.1%),对80~100 cm深处土壤水的贡献率最低(14.3%~55.5%);无论湿季还是干季,大雨(降水量30 mm)后第1天,该次降水可入渗到80 cm以下深层土壤,且雨后5天内对80~100 cm深层土壤水的贡献率高达16.1%~70.7%。无论小雨还是中雨,80 cm以下深层土壤水δD值变化幅度较小,表明鼎湖山森林植被结构和土壤结构对降水在土壤剖面入渗过程具有一定的调控作用。(3)林中主要优势植物(锥栗、木荷、九节、乌毛蕨和马尾松)水主要来源于大气降水与雨前土壤水。当5mm降水量≤20 mm时,雨后5天内,在针阔混交林中,草本层乌毛蕨对该次降水利用率最高(0~80.1%),亚乔木层木荷对降水利用率最低(0~37.5%);在季风常绿阔叶林中,亚乔木层木荷对降水利用率最高(6.9%~59.4%),乔木层锥栗对降水利用率最低(0~22.7%)。当降水量30 mm时,雨后5天内,草本层乌毛蕨对降水利用率最高(31.6%~91.5%),亚乔木层木荷对降水利用率最低(4.7%~26.5%)。在鼎湖山针阔混交林和马尾松针叶林中,无论何种强度降水,优势植物对降水利用率大小顺序为:乌毛蕨锥栗马尾松木荷。在季风常绿阔叶林中,小雨和中雨(5 mm降水量≤20 mm)时,优势植物对降水利用率大小顺序为:木荷乌毛蕨九节锥栗;大雨(降水量30 mm)时,这4种植物对降水利用率大小顺序为:乌毛蕨九节锥栗木荷。鼎湖山森林优势植物水分利用策略与其细根分布密切相关,林中乔、灌、草不同功能型植物水分利用策略不同,从而更好地维持该群落的稳定性。(4)小雨(5 mm降水量≤10 mm)后,降水对地表水(溪水)的影响微弱。降水δD(δ~(18)O)的升高或降低引起地表水(溪水)δD(δ~(18)O)的升高或降低,这种影响在降水后第4天滞后发生:中雨(10 mm降水量≤20 mm)后,地表水(溪水)δD(δ~(18)O)的变化曲线随降水δD(δ~(18)O)的变化而变化,这种影响在降水后第3天发生;大雨(降水量30 mm)时,这种影响在降雨后当天发生,这显示鼎湖山森林植被结构对地表水(溪水)具有一定的调控作用。
[Abstract]:Dinghu Mountain Nature Reserve is located in the tropical and subtropical interchange in the field of global climate change has a unique and important position. On the establishment of Dinghu mountain forest hydrological model, rainfall and surface runoff on water chemistry characteristics of predecessors with traditional hydrology method as well, but on the typical Dinghu mountain forest (the monsoon evergreen broad Ye Lin, pine and broad-leaved mixed forest and pine needle Ye Lin) water circulation of ecological system is a lack of comprehensive understanding and overall understanding of the source of water in the forest water use efficiency advantage, and the hydrological process of forest ecosystem less quantitative research; and in the study of impacts of forest vegetation on hydrological processes, stable isotopes in water molecules is a good tracer. The advantages of stable isotope techniques in the research of forest hydrology process: it can be forest ecosystem water The process includes precipitation, surface water, soil water, groundwater, water plants as a whole to study, to clarify its process and mechanism, to overcome the traditional hydrology method, a comprehensive reflection of vegetation and soil water retention capacity, the contribution of precipitation to soil water rate, water absorption rate and plant canopy interception of water layer effect. The quantitative study on China's Guangdong Dinghu mountain typical forest (Pinus massoniana coniferous forest, pine and broad-leaved mixed forest, monsoon evergreen broad-leaved forest) as the research object, the use of stable isotope technique, to study the atmospheric precipitation, positioning observation and mathematical model method of soil water, plant water. The surface water (water) and groundwater features of hydrogen and oxygen isotopes, and different precipitation migration in soil profile rules and Joe, irrigation, water use efficiency of plant layer grass and use tactics in order to reveal the tripod The forest vegetation structure on the precipitation pattern changes and adaptation mechanism of regional water resources rational utilization and scientific management to provide a theoretical basis. The main conclusions are as follows: (1) Dinghu mountain precipitation D and 6 ~ (18) O: relationship between Delta D=7.875 delta ~ (18) O+9.412 (R2= 0.982, n=120); precipitation D and 6 ~ (18) O range respectively? 1~ (18).26% ~15.52% and ~2.25%? 16.05 per thousand, average was 36.35 per thousand and 5.81??%; precipitation deuterium excess (d) showed seasonal variation in winter and lower in summer water group in Dinghu mountain the dry season mainly from local evaporation in North China and the Eurasian China cold and dry wet season, water group mainly from the West Pacific warm and humid, the South China Sea and India ocean. (2) Dinghu mountain forest soil water mainly from meteoric water and shallow groundwater. The surface (0~10 cm) of soil water and precipitation of D. D same trend display 鍑洪紟婀栧北妫�鏋楄〃灞傚湡澹ゆ按未D涓昏�佸ぇ姘斿彈闄嶆按未D鐨勬帶鍒，

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