中国农业气象

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青藏高原高寒金露梅灌丛湍流热通量交换与分配特征及其环境影响机制

张法伟,韩赟,李红琴,李英年,曹广民,周华坤   

  1. 1. 洛阳师范学院生命科学学院,洛阳 471934;2. 中国科学院西北高原生物研究所高原生物适应与进化重点实验室,西宁 810008;3. 中国科学院西北高原生物研究所青海省寒区恢复生态学重点实验室,西宁 810008
  • 出版日期:2020-02-20 发布日期:2020-03-20
  • 作者简介:张法伟,E-mail:mywing963@126.com
  • 基金资助:
    国家自然科学基金(41877547;41730752);国家重点研发计划(2017YFA0604801);青海省科技基础条件平台建设专项项目(2018-ZJ-T09);青海省创新平台建设专项(2017-ZJ-Y20)

Turbulent Heat Exchange and Partitioning and Its Environmental Controls between the Atmosphere and an Alpine Potentilla Fruticosa Shrublands over the Qinghai- Tibetan Plateau

ZHANG Fa-wei, HAN Yun, LI Hong-qin, LI Ying-nian, CAO Guang-min, ZHOU Hua-kun   

  1. 1. College of Life Sciences, Luoyang Normal University, Luoyang 471934, China; 2. Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008; 3. Qinghai Provincial Key Laboratory of Restoration Ecology in Cold Region, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008
  • Online:2020-02-20 Published:2020-03-20

摘要: 青藏高原重要植被类型之一高寒灌丛的湍流热通量交换是局地微气候特征和植被物候事件的主要调控因素,但其时间格局与分配特征及环境影响机制尚不明确。以青藏高原东北隅的高寒金露梅(Potentilla fruticosa)灌丛为研究对象,基于涡度相关系统连续观测的湍流热通量,研究该生态系统显热通量和潜热通量交换与分配的特征及潜在环境调控过程。结果表明(1)全年逐时显热通量和逐时潜热通量的平均日变化均表现出单峰型特征,最大值出现在13:30左右。在非生长季(11月-翌年4月)、生长初期(5月)和生长季末期(10月),热量交换以显热通量为主,而在生长季中期(6-9月)则以潜热通量居多;(2)显热通量呈现出双峰型季节特征,最大峰和次高峰分别出现在4月中旬和10月上旬。潜热通量为单峰型季节变化,最大值在7月下旬;(3)湍流热通量的逐时、逐日变异均主要受控于太阳短波辐射;(4)波文比呈现出U型季节变化,而解耦系数、蒸散比例表现为钟型季节变化,热量分配指标在非生长季和生长季分别受控于土壤表层温度和增强植被指数。高寒金露梅灌丛的热量交换主要受控于太阳辐射,热量分配则受下垫面温度和植被覆盖影响。

关键词: 潜热通量, 显热通量, 涡度相关系统, 波文比, 解耦系数

Abstract: The turbulent heat flux plays important role in micro-climate environment and vegetation phenology but its temporal patterns and partitioning characteristics and associated environmental controls remain unclear in alpine shrublands, which is one of the most important vegetation types on the Qinghai-Tibetan Plateau. The continuous turbulent heat flux and routine environmental variables measured by the eddy covariance techniques were analyzed to quantify the exchange and partitioning of sensible heat flux and latent heat flux over an alpine Potentilla fruticosa shrublands on the northeastern Qinghai-Tibetan Plateau. The results showed that (1) the averaged diurnal variations of turbulent heat exchange both exhibited unimodal patterns, peaking at about 13:30 over the whole year-round period. The diurnal heat flux was dominated by sensible heat flux during non-growth season (November to next April) and the beginning and end of growth season (May and October), while by latent heat flux in mid-growth season from June to September; (2) The daily sensible heat flux exhibited a bimodal seasonal pattern, with the largest peak and the second peak appearing in mid-April and beginning October, respectively. The daily latent heat flux presented a unimodal seasonal pattern with a maximum in end July; (3) The diurnal and daily variations of turbulent heat flux were both mainly controlled by solar shortwave radiation; (4) Bowen ratio showed a U-shape seasonal change, while decoupling coefficient, evaporation ratio exhibited a bell-shape seasonal variation. These partitioning indices were controlled by soil temperature during non-growth season and enhanced vegetation index in growth season, respectively. These results revealed that the turbulent heat exchange was determined by solar radiation while the partitioning between sensible heat flux and latent heat flux was regulated by underlying surface temperature and plant coverage in the alpine shrublands.

Key words: Latent heat flux, Sensible heat flux, Eddy covariance technique, Bowen ratio, Decoupling coefficient