Vitas, A. and Erlickytė, R. 2007. Influence of Droughts to the Radial Growth of Scots Pine (Pinus sylvestris L.) at Different Site Conditions. Baltic Forestry 13 (1): 10-16

Dendroclimatological research on the radial growth of Scots pine in the Aukštaitija National Park in north-eastern Lithuania has been conducted. The aim of the study was to estimate the differences of the impact of droughts on the radial growth of pines growing on dry and wet sites. For this purpose event years of the radial growth were estimated. Investigation has revealed that the fluctuations of the soil water level have different impact on the radial growth of pines. An increase in the soil water level stimulates the radial growth on sites with organic soil, but on sites with mineral soil the growth is positively affected by the abatement of the water level. We found that droughts in spring and early summer (May-June) are much more dangerous for the radial growth of pines, as compared to August. Droughts of three-month duration have been acknowledged to be more stressful than short one-month droughts. The affect of drought to the radial growth of pines depends on climate conditions before and after the drought. The investigation did not reveal significant differences between the number of pines with negative event years growing on sites in organic peat and mineral soils.

Key words: tree rings, dendroclimatology, event year, drought, bog, soil water, Scots pine