Carbon dioxide exchange in the photosynthetic apparatus of trees in a mature spruce phytocenosis of the northern taiga subzone

Carbon dioxide exchange was studied in the photosynthetic apparatus of Siberian spruce (Picea obovata Ledeb.), Siberian larch (Larix sibirica Ledeb.), and weeping birch (Betula pendula Roth.) in a mature spruce forest. Parameters of CO₂ balance in different weather were characterized quantitatively on the basis of daily measurements of CO₂ exchange in needles and leaves of woody plants. The percent ratios of the components of carbon balance in needles and leaves of woody plants depending on daily photosynthetic fixation of carbon were determined. In summer, trees consumed 210 kg CO₂/ha (57 kg C/ha) in variable weather and 117 kg CO₂/ha (32 kg C/ha) in cloudy weather. Species specificity of CO₂ consumption was revealed, and the effects of environmental factors on the assimilatory activity of trees were determined.