学术
Relationship between effective solar radiation and sap flow process during an entire growing season in Western Mountains of Beijing
Xu Jun-liang[1,2] Ma Lv-yi[2]
[1]College of Forestry, Henan University of Science and Technology, Luoyang 471003, P. R. China [2]College of Forestry, Beijing Forestry University, Beijing 100083, E R. China
文章出处:
《中国林学：英文版》-2007年9卷4期 -251-255页
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Relationship between effective solar radiation and sap flow process during an entire growing season in Western Mountains of Beijing
Abstract:
In order to explore the relationship between the time processes of solar radiation and sap flow, sap flow velocity （SFV） of Platycladus orientalis and Pinus tabulaeformis, effective solar radiation （ESR） and other environmental factors were synchronously monitored for one year in the Beijing Western Mountains by using a thermal dissipation probe （TDP） system and an automatic weather station. Results showed significant differences between changes in diurnal characteristics of ESR and sap flow in sunny days during three seasons. Starting times of sap flow occurred generally 1.5-3 hours later than those of solar radiation and there were small differences between Platycladus orientalis and Pinus tabulaeformis. But peak times and stopping times of sap flow varied considerably with large contrasts in ESR. The duration of sap flow showed clear differences among the seasons owing to the variable rhythms of climate factors in Beijing. Fluctuation amplitude in the duration of sap flow remained relatively stable during the autumn but changed greatly during spring and summer. Changes in diurnal sap flow velocity of both Platycladus orientalis and Pinus tabulaeformis were about 0-3 hours later than those of ESR but with the same configuration. The start of sap flow was mainly induced by the sudden intensification of ESR （sunrise effect）. Seasonal models of SFV indicated that a cubic equation had the best fit. It was more practical to simulate seasonal water consumption models of trees with ESR. In further investigations, these models should be optimized.[著者文摘]
Key words:
Platycladus orientalis, Pinus tabulaeformis, time process, solar radiation, sap flow velocity, hysteresis
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