PHOTOSYNTHETIC GAS EXCHANGE OF SCOTS PINE NEEDLES IN SWAMPY PHYTOCENOSES OF THE MIDDLE AND NORTHERN TAIGA
V. V. Tuzhilkina
Komi Scientific Center, Russian Academy of Sciences, Ural Branch, Institute of Biology, Syktyvkar, Russian Federation
Keywords: Pinus sylvestris L, photosynthesis, needles, carbon dioxide, swampy pine forests, taiga
Abstract
The photosynthetic activity of Scots pine ( Pinus sylvestris L.) needles growing in swampy forests in the subzones of the northern and middle taiga of the European Northeast has been studied. Some ecological aspects of photosynthetic fixation of carbon dioxide by needles in sphagnum and sedge-sphagnum pine forests are considered. The features of the daytime and seasonal dynamics of photosynthesis and its relationship to environmental factors are revealed. It has been established, that in summer, during the daytime, the intensity of photosynthesis largely depends on the intensity of solar radiation. There is a positive relationship between pine photosynthesis and temperature and humidity during the day. The daily productivity of photosynthesis of pine needles growing in the middle taiga sphagnum pine during the growing season has been determined. The fixation of carbon dioxide by needles is greatest in summer under favorable light, thermal and edaphic conditions, about 50 % of carbon was absorbed during photosynthesis in July. The linear dependence of the daily productivity of photosynthesis on the air temperature and the total photosynthetically active solar radiation per day is shown. It has been established that the daily photosynthetic productivity of pine needles within the taiga zone of the Komi Republic decreases with increasing geographical latitude. The optimal values of the main environmental factors have been determined, at which the maximum level of photosynthetic activity of needles is manifested during the summer growing season. The variability of the light and temperature optima of pine photosynthesis in the zonal aspect has been revealed.
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