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中国沙漠 ›› 2013, Vol. 33 ›› Issue (5): 1377-1384.DOI: 10.7522/j.issn.1000-694X.2013.00202

• 生物与土壤 • 上一篇    下一篇

胡杨(Populus euphratica)蒸腾耗水对水汽压差的响应

李 炜, 司建华, 冯 起, 鱼腾飞   

  1. 中国科学院寒区旱区环境与工程研究所 内陆河流域生态水文重点实验室/阿拉善荒漠生态水文试验研究站, 甘肃 兰州 730000
  • 收稿日期:2012-07-23 修回日期:2013-01-05 出版日期:2013-09-20 发布日期:2013-01-05

Response of Transpiration to Water Vapour Pressure Defferrential of Populus euphratica

LI Wei, SI Jian-hua, FENG Qi, YU Teng-fei   

  1. Key Laboratory of Eco-hydrology of Inland River Basin/Alashan Desert Eco-hydrology Experimental Research Station, Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China
  • Received:2012-07-23 Revised:2013-01-05 Online:2013-09-20 Published:2013-01-05

摘要:

利用热耗散技术(TDP)对荒漠河岸胡杨(Populus euphratica)林生长季树干液流速率进行连续测定,分析了胡杨时步长蒸腾耗水(E)对水汽压差(VPD)的响应关系。结果表明:(1)不同天气条件对E的日过程有影响,晴天下E的主峰值突显,主峰时刻滞后于VPD,而阴天E与VPD的同步性较好。(2)晴天VPD对E存在制约作用,高耗水期的生长季(5—7月),随月均VPD的升高,阈值点依次后移(2.13 kPa<3.01 kPa<3.82 kPa),且制约关系越发明显(R2:0.2946<0.4638<0.5336),日冠层气孔阻力(rc)响应VPD(rc =-2.5423+2.1909VPD,R2=0.4032),协同控制胡杨蒸腾耗水。(3)不同等级光合有效辐射和不同水平VPD影响胡杨树干液流速率的峰值时刻和频率分布。阴天峰值时刻滞后于晴天,高值VPD(>3.82 kPa)液流峰值频率分布更为集中,说明气孔调节与周围水汽压亏缺的敏感性较强。E与VPD间的量化结果对明晰荒漠河岸胡杨林耗水机理有一定的理论意义。

关键词: 蒸腾, 水汽压差, 热耗散技术, 冠层阻力, 胡杨

Abstract:

Sap flow velocity was measured using thermal dissipation probe continuously on growing season in extreme arid desert riparian Polulus euphratica stand. Response of hourly-step transpiration of P. euphratica to vapor pressure defferrential (VPD) was researched based on the parameters above. The results indicated that: (1) Diurnal patterns of transpiration were impacted by different atmospheric conditions. Lagging behind the process of VPD, dominating transpiration peak was more distinct in sunny days than in cloudy days. (2) P. euphratica avoided excessive transpiration during periods of high VPD in sunny days from May to July,which was acknowledged as highly water consumption. Following increased average monthly VPD, critical threshold of VPD to transpiration (E), counted as 2.13 kPa, 3.01 kPa, 3.82 kPa gradually, showed similar tendency. The phenomenon, quantized by relationship between canopy stomatal resistance (rc) and VPD by linear equation(rc =-2.5423+2.1909*VPD,R2=0.4032) might be interpreted as the result of a gradual canopy stomatal closure as VPD increased. (3) Frequency of sap flow velocity (Fv) peak time of P. euphratica was influenced by different level of photosynthetically active radiation (PAR) and VPD. Fv peak time in relative lower PAR lagged behind that of higher ones, while frequency of Fv peak time appeared as more concentrated under higher VPD than that of lower ones. According to the point above, canopy stomatal responded more sensitive to ambient water vapor pressure deficit under highly VPD than others. Concluded above, it is expected to provide theoretical significance to water use of desert riparian forest from the quantized relationship between E and VPD.

Key words: transpiration, vapour pressure deficit, thermal dissipation probe, canopy resistance, Polulus euphratica

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