ISWC OpenIR  > 水保所知识产出(1956---)
热脉冲技术在林地蒸散测量中的应用
王 胜
Subtype硕士
Thesis Advisor樊 军
2015-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword蒸散发 树干液流 热脉冲技术 热比率法(hrm 最大温度法 (t-max) 最大温度法 (t-max) 单针热脉冲法(shpp)
Abstract

定量获取蒸散量并将蒸散量分割成蒸发和蒸腾两个独立的组分对理解和模
拟生态系统水文循环,指导农业生产实践具有重要意义,但是目前鲜有方法将蒸
腾和蒸发直接分开测量。本论文使用相同构造的三针热脉冲探针实现树干液流和
林地土壤蒸发测量,并探究黄土区两种立地条件下旱柳树干液流差异机制。
试验于 2014 年 7 月至 10 月在黄土高原神木县六道沟小流域风沙土地和黄绵
土地两种立地旱柳样地上进行。试验在风沙土地旱柳树干安装三针热脉冲探针,
分别运用热比率法(HRM)、最大温度法(T-max)和单针热脉冲法(SHPP)三
种方法组合获取树干液流,并使用热扩散探针对树干液流进行对比测量,对不同
测量方法进行评价。同时试验在风沙土地旱柳林土壤安装由 3 个热脉冲探针构成
的探头组和由 5 个探针构成的探头组利用显热平衡法(SHB)测量土壤蒸发,并
运用小型蒸渗仪进行验证,试验利用热脉冲技术热比率法测得树干液流经过尺度
扩展得到样地蒸腾量,两者相加即获得旱柳样地蒸散量,并用水量平衡法对比测
量蒸散量。试验利用风沙土地和黄绵土地 0-6 m 土壤剖面含水量观测(中子仪)、
2 m 内含水量动态监测(FDR)、土壤蒸发(蒸渗仪)和气象因子观测,以及旱柳
叶水势、根系栓塞程度和树干液流测定,分析两种立地旱柳生长差异和树干液流
差异机制。试验,主要结论如下:
三针热脉冲探头插入树干边材完成安装后,经历约 5 周树干液流进入稳定测
量阶段,安装初期 3 种方法测得液流密度比稳定测量时高 135%~220%。HRM 和
SHPP 与热扩散法(TDP)液流密度测量结果相关性较好,R 2 分别达到 0.93 和
0.91;T-max 与 TDP 液流测量结果相关性较差,R 2 仅为 0.73。不同方法具有不同
的适用性,可以根据试验目的不同,选取不同方法或者几种方法组合进行树干液
流测量。
由5个三针热脉冲探针构成的探针组获得的土壤日蒸发量与蒸渗仪法测量结果具有极显著(P<0.001)的线性相关性,R 2 达 0.53。在 2014 年 8 月 18 日至 10
月 21 日期间,利用热脉冲法测得风沙土地旱柳样地蒸散量为 157.4 mm,其中蒸
发量 82.3 mm,蒸腾量 75.1 mm,蒸散量测定结果比水量平衡法(135.3±23.5 mm)
略高。
黄绵土样地旱柳树干液流为风沙土样地的 2.6 倍,日液流量均与作物参考蒸
散 ET 0 有极显著线性相关关系(P<0.001),R 2 分别达 0.58 和 0.52。黄绵土质地
较细,田间持水量高、入渗慢;风沙土质地较粗,田间持水量低、入渗快。黄绵
土土壤水分含量明显高于风沙土。风沙土地田间持水量仅为黄绵土地的 1/2,2014
年黄绵土地在绝大多数降雨条件下入渗不超过 20 cm,而风沙土地入渗深度能达
到 1 m。风沙土样地蒸发是黄绵土样地的 1.5 倍。风沙土地旱柳叶水势显著小于
黄绵土地柳树,而栓塞程度显著大于黄绵土地柳树,说明风沙土地旱柳遭受了水
分胁迫。总之,土壤质地差异引起的土壤水分条件差异是造成旱柳生长状况和树
干液流差异的根本原因。
关键词:蒸散发;树干液流;热脉冲技术;热比率法(HRM);最大温度法
(T-max);单针热脉冲法(SHPP);旱柳;立地条件;黄土高原.

Other Abstract

Quantifying evapotranspiration (ET) and partitioning it into its individual
components, evaporation (E) and transpiration (T), is essential to the understanding of
eco-hydrological systems and to guide agricultural productive practices. However, E
and T are rarely measured separately. Our objective was to determine the ET of a small
tree stand by measuring E and T with heat-pulse-probes (HPP) and applying the
sensible heat balance (SHB) and heat ratio based sap flow methods (HRM), respectively,
and to investigate sap flow discrepancy mechanism of Chinese willow (Salix
matsudana) under two different soil conditions, in Loess Plateau, China.
Experiments were conducted on two different sites, a sandy soil field and a loess
soil stand, in Loess Plateau, during July to October in 2014. Three three-needle heat-
pulse probes were installed in three sample Chinese willow trees in sandy soil stand,
and a combination of heat-ratio method (HRM), T-max method (T-max) and single
heat-pulse probe method (SHPP) was used to calculate sap flux density (V s ), and V s
comparable measurement was conducted with thermal diffusion probes (TDP),
afterwards different heat-pulse based sap flow methods evaluation was carried out.
Simultaneously, two HPP-arrangements, using three and five HPP-sets, were used to
measure E from subsurface soil layers with sensible heat balance method (SHB), and E
comparable measurement was done with micro-lysimeters (MLS). Transpiration was
determined by upscaling HPP-V s to stand level, and ET was then determined by
summing its two individual components, E and T, and ET comparable measurements
were done using water budget method. Experiments were also performed in sandy soil
stand and loess soil stand to obtain soil profile (depth 0-6 m) volumetric water content  (VWC) with neutron probes, VWC dynamic with EC-5 sensors (depth 0-2 m), E with
MLSs and meteorological data, in addition with leaf water potential, root embolism
degree, and TDP-V s measurements, to investigate Chinese willow growth and sap flow
discrepancy of two different soil conditions. Results were as follows:
It took five week to reach a stable measurement statue after HPP installation, V s
measured with three methods in early stage after installation is 135%~220% higher than
Vs in stable measurement stage. HRM-V s and SHPP-V s were high significant linearly
correlation (P<0.001) with TDP-V s , with R 2  of 0.93 and 0.91, respectively. T-max-Vs
was significant linearly correlation with TDP-V s , with R 2 of 0.73, lower than other two
methods. Characteristics and applicability were distinctly unlike for different
methodologies, and proper methods and a combination of them should be selected to
sap flow measurements based on different study purposes and characteristics.
Daily evaporation determined by HPP-set with five HPPs were significant linearly
correlation (P<0.001) with MLS-E, with R 2 of 0.53. During Aug. 18 to Oct. 21 in 2014,
Chinese willow sandy soil stand total HPP-ET was 157 mm, within which HPP-E was
157.4 mm, and HPP-T was 75.1 mm determined by upscaling from HPP-V s , and HPP-
ET was slightly higher than SHB-ET (135±23.5 mm).
In the study sits, Chinese willow sap flow in loess soil stand was 2.6 times the
amount of that in sandy soil stand, and daily sap flow amount in two sits were
significant linear correlation (P<0.01) with reference crop ET 0 ,  with R 2 of 0.58 and 0.52,
respectively. Loess soil had a high field moisture capacity and poor infiltration
capability, while sandy soil had a low field moisture capacity and good infiltration
capability. The sandy soil stand moisture capacity was only half of loess soil stand, and
sandy soil stand MLS-E was 1.5 times the amount of loess soil stand, and in most cases
loess soil infiltration depth wouldn’t exceed 20 cm, while sandy soil could exceed more
than 1 m. Sandy soil evaporation amount was 1.5 times as that of loess soil stand. Sandy
soil stand Chinese willow leaf water potential was remarkably lower than loess soil
stand, and root embolism degree was about twice as large of loess soil stand, indicating
sandy soil stand Chinese willow suffered from heavy soil water stress. To sum up, soil
water condition differences caused by soil texture, in addition to willow physiological  morphology differences adapted for local soil water conditions, was the key to Chinese
willow growth status and sap flow discrepancy under two different soil conditions in
Loess Plateau, China.
Keywords: evapotranspiration; sap flow; Heat-pulse probe; heat-ratio method
(HRM); T-max method; single heat-pulse probe method (SHPP); Salix matsudana;
soil conditions; Loess Plateau

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/9028
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
王 胜. 热脉冲技术在林地蒸散测量中的应用[D]. 北京. 中国科学院研究生院,2015.
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