本文選題：氫氧穩(wěn)定同位素　切入點：水文過程　出處：《中國林業(yè)科學(xué)研究院》2017年博士論文

【摘要】：鼎湖山自然保護區(qū)地處我國熱帶與亞熱帶交匯處,在全球氣候變化研究中占居獨特而重要的地位。關(guān)于鼎湖山森林水文模型建立、降水量和地表徑流水化學(xué)特征等方面前人用傳統(tǒng)水文學(xué)方法做了較好地研究,但對鼎湖山典型森林(季風(fēng)常綠闊葉林、馬尾松針闊混交林和馬尾松針葉林)生態(tài)系統(tǒng)水循環(huán)過程還缺乏全面理解和整體認識,林中優(yōu)勢植物水分來源、水分利用率以及森林生態(tài)系統(tǒng)水文過程定量研究較少;而在研究森林植被對水文過程的影響中,已存在于水分子中的氫氧穩(wěn)定同位素是很好的示蹤劑。穩(wěn)定同位素技術(shù)在森林水文過程研究中的優(yōu)勢在于:它可以將森林生態(tài)系統(tǒng)水文過程,包括大氣降水→地表水→土壤水→地下水→植物水作為一個整體來研究,闡明其過程與機制,克服傳統(tǒng)水文學(xué)方法的缺點,綜合反映植被和土壤對降水的截留能力,將降水對各層土壤水的貢獻率、植物吸水率及林冠層對水分的截留效應(yīng)定量化。本研究以我國廣東鼎湖山典型森林(馬尾松針葉林、馬尾松針闊混交林、季風(fēng)常綠闊葉林)為研究對象,運用氫氧穩(wěn)定同位素技術(shù)、定位觀測和數(shù)學(xué)模型等手段研究其大氣降水、土壤水、植物水、地表水(溪水)和地下水氫氧穩(wěn)定同位素特征,以及不同量級降水在土壤剖面中運移規(guī)律和林中喬、灌、草層優(yōu)勢植物水分利用率及利用策略,為揭示鼎湖山森林植被結(jié)構(gòu)對降水格局變化的適應(yīng)機制以及區(qū)域水資源合理利用和科學(xué)管理等提供理論依據(jù)。得出主要結(jié)論如下:(1)鼎湖山大氣降水δD和δ~(18)O的關(guān)系式為:δD=7.875δ~(18)O+9.412(R2=0.982,n=120);大氣降水δD和δ~(18)O值范圍分別為㧟1~(18).26‰~15.52‰和㧟16.05‰~2.25‰,均值分別為㧟36.35‰和㧟5.81‰;大氣降水過量氘(d)顯示出冬高夏低的季節(jié)變化。鼎湖山干季的水氣團主要來自局地蒸發(fā)、中國華北地區(qū)及寒冷干燥的亞歐大陸,濕季的水氣團主要來自溫暖濕潤的西太平洋、南海和印度洋。(2)鼎湖山森林土壤水主要來源于大氣降水和淺層地下水。表層(0~10 cm)土壤水δD與降水δD變化趨勢一致,顯示出鼎湖山森林表層土壤水δD主要大氣受降水δD的控制;降水強度越大,降水從土壤表層向深層土壤滲透速度越快,降水對各層次土壤水的貢獻率也越大;小雨(5 mm降水量≤10 mm)后5天內(nèi),對枯枝落葉層水貢獻率最高(0~47.7%),對40~100 cm深層土壤水的貢獻率最低(接近于0);中雨(10 mm降水量≤20 mm)后5天內(nèi),對0~10 cm表層土壤水的貢獻率較高(29.6%~83.1%),對80~100 cm深處土壤水的貢獻率最低(14.3%~55.5%);無論濕季還是干季,大雨(降水量30 mm)后第1天,該次降水可入滲到80 cm以下深層土壤,且雨后5天內(nèi)對80~100 cm深層土壤水的貢獻率高達16.1%~70.7%。無論小雨還是中雨,80 cm以下深層土壤水δD值變化幅度較小,表明鼎湖山森林植被結(jié)構(gòu)和土壤結(jié)構(gòu)對降水在土壤剖面入滲過程具有一定的調(diào)控作用。(3)林中主要優(yōu)勢植物(錐栗、木荷、九節(jié)、烏毛蕨和馬尾松)水主要來源于大氣降水與雨前土壤水。當5mm降水量≤20 mm時,雨后5天內(nèi),在針闊混交林中,草本層烏毛蕨對該次降水利用率最高(0~80.1%),亞喬木層木荷對降水利用率最低(0~37.5%);在季風(fēng)常綠闊葉林中,亞喬木層木荷對降水利用率最高(6.9%~59.4%),喬木層錐栗對降水利用率最低(0~22.7%)。當降水量30 mm時,雨后5天內(nèi),草本層烏毛蕨對降水利用率最高(31.6%~91.5%),亞喬木層木荷對降水利用率最低(4.7%~26.5%)。在鼎湖山針闊混交林和馬尾松針葉林中,無論何種強度降水,優(yōu)勢植物對降水利用率大小順序為:烏毛蕨錐栗馬尾松木荷。在季風(fēng)常綠闊葉林中,小雨和中雨(5 mm降水量≤20 mm)時,優(yōu)勢植物對降水利用率大小順序為:木荷烏毛蕨九節(jié)錐栗;大雨(降水量30 mm)時,這4種植物對降水利用率大小順序為:烏毛蕨九節(jié)錐栗木荷。鼎湖山森林優(yōu)勢植物水分利用策略與其細根分布密切相關(guān),林中喬、灌、草不同功能型植物水分利用策略不同,從而更好地維持該群落的穩(wěn)定性。(4)小雨(5 mm降水量≤10 mm)后,降水對地表水(溪水)的影響微弱。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,這種影響在降水后第4天滯后發(fā)生:中雨(10 mm降水量≤20 mm)后,地表水(溪水)δD(δ~(18)O)的變化曲線隨降水δD(δ~(18)O)的變化而變化,這種影響在降水后第3天發(fā)生;大雨(降水量30 mm)時,這種影響在降雨后當天發(fā)生,這顯示鼎湖山森林植被結(jié)構(gòu)對地表水(溪水)具有一定的調(diào)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 鍑洪紟婀栧北媯灄琛ㄥ眰鍦熷￥姘次碊涓昏澶ф皵鍙楅檷姘次碊鐨勬帶鍒，

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