Journal of Ecology and Rural Environment ›› 2019, Vol. 35 ›› Issue (2): 189-196.doi: 10.19741/j.issn.1673-4831.2017.0869

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Characteristics and Influencing Factors in Sap Flow of Four Broadleaved Tree Species for Typical Weather Conditions of Beijing

LI Shao-ning1,2,3, LU Shao-wei1,2,3, ZHAO Yun-ge1, ZHAO Na1, CHEN Bo1   

  1. 1. Beijing Academy of Forestry and Pomology Sciences, Beijing 100093, China;
    2. Beijing Collaborative Innovation Center for Eco-Environmental Improvement with Forestry and Fruit Trees, Beijing 100093, China;
    3. Beijing Yanshan Forest Ecosystem Research Station, Beijing, 100093, China
  • Received:2017-12-29 Online:2019-02-25 Published:2019-03-25


To illustrate the differences in characteristics of sap flow of broadleaved species and their main influences in typical weather condition, sap flow rates of four broadleaved tree species were continuously monitored through the thermal dissipation probes (TDP) in plain areas of Beijing, combining simultaneous observations of environmental factors via automatic weather station, to explore the transpiration patterns of tree species and influencing environmental factors. The results show that diurnal variations in sap flow rates of 4 broadleaved species presented single-peak curves in sunny days, bimodel curves in cloudy days and multi-peaks curves in rainy days. The sap flow began at 6:00 a.m. in sunny and cloudy days which were earlier than that in rainy days (06:30 a.m.). The diurnal patterns of solar radiation were consistent with that in sap flow. There exist interactions among environmental factors. Particularly, there is a lag-effect in variations between solar radiation and temperature. Considering the influencing extent of environmental factors on sap flow, solar radiation, temperature, wind speed and water vapor pressure deficit (VPD) were significantly positively related with the sap flow rates of four tree species (P<0.01), whereas there were remarkable negative correlationships between relative air humidity and sap flow rates (P<0.01). Diurnal variations of environmental factors were not in synchrony with that of sap flow rates of tree species. Based on the principal component analysis, as the main influentors, air temperature and solar radiation were responsible for 74.37% on variations of sap flow of tree species, while water vapor pressure deficit contributing 14.33%. Total monthly water consumptions of four tree species in July were ranked as Populus tomentosa (289.23 kg) > Robinia pseudoacacia (235.04 kg) > Sophora japonica (151.53 kg) > Koelreuteria paniculata (133.80 kg). The daily water consumption of above species had the same sequence with that of monthly water consumption mentioned above. The water consumptions of tree species in sunny days were observed higher than that in rainy days. The results of the study can provide a certain scientific basis for the comprehensive evaluation on ecological hydrological processes and determination on influencing factors of garden tree species in Beijing.

Key words: broadleaved trees, sap flow, environmental factors, typical weather conditions

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