Home – Home – Jornals – Siberian Journal of Forest Science 2015 number 2

The timeframes of processes responsible for the number of cells, their radial diameters and wall thickness in annual wood increment of Scots pine in the course of season vegetation were studied. The number of cells produced by cambium, cell radial diameters in the cell growth expansion zone and the thickness/wall tracheid cross-sectional area in the secondary wall thickening zone were estimated at the transverse sections of samples taken from the stems in 10 days. The data obtained were used for the calculation of the development durations of tracheids in the zones of differentiation and the dependence of these characteristics of the processes on air temperature. Throughout the season, the processes of the production by cambium of early and late tracheids, their radial growth and secondary wall thickening occurs at different times and may overlap each with another in time. In the conditions of Middle Siberia (Russia), the production of cambium cells was observed in June and July. Radial diameter growth of earlywood tracheids occurred mainly in June, latewood tracheids - in July. The development of secondary wall thickening of earlywood cells occurred in June-July, latewood ones - in August to the first half of September. Hydrothermal conditions of these months affect considerably the morphological parameters of the tracheids. Each of the processes reacted to environmental factors independently and had their own optimum temperatures causing the differences in cell wall biomass deposited in separate periods of the season. The data should be considered in addressing the problem of productivity and quality of wood produced in different climate conditions.