关键词: 森林, 气温, 水汽压, 垂直梯度, 对数规律

Abstract:

Using the data of air temperature and vapor pressure observed at temperate coniferous and broad-leaved mixed forest ecosystem over Changbai mountain during 2003 to 2005, with April, July, October and January represented as spring, summer, autumn and winter, respectively, the vertical distribution patterns of them and their diurnal variations were analyzed on typical sunny days in four representative months, and the profile functions of air temperature and vapor pressure with observed height under the canopy top were constructed by method of using the top of canopy air temperature and water vapor pressure as normalized values. The results are as followed: (1)the diurnal variation of air temperature characterized by single peak curve obviously with the highest value at 15：00 and the lowest at dawn. The diurnal air temperature range decreased with higher height in all seasons and with the maximum diurnal air temperature range in autumn and minimum in winter. (2)In spring, autumn and winter, air temperature within forest increased as height ascended accompanied by obvious diurnal change pattern. The vertical gradient of air temperature was extremely large at times except noon, whereas the gradient was small and even showed the trend of air temperature decreasing as height ascended at noon. In summer, air temperature increased with observed height higher at any times. (3)The diurnal variations of the vapor pressure were different in four seasons. The vapor pressure showed diurnal patterns by single peak curve in spring, autumn and winter contract with that by double peak curve in summer. (4)The vertical distribution of vapor pressure at given time was seasonal divergence obviously, whereas at given season they had the similar vertical distribution at different times. The vertical gradient of vapor pressure was larger in summer than that in other seasons characterized by vapor pressure went down with observed height higher. (5)The profiles of air temperature and vapor pressure within forest can be fitted with logarithm law.

Key words: Forest, Air temperature, Vapor pressure, Vertical gradient, Logarithm law