Influence of Climatic Factors on the Annual Radial Growth of Scots Pine (Pinus sylvestris L.) in Western Latvia

Dendroclimatological research has been perfomed in Latvia after a break of about 25 years. The growth pattern of Scots pine (Pinus sylvestris L.) in six districts of western Latvia is analysed in relation to climatic factors (monthly and seasonal mean air temperature and precipitation). Applying various statistical techniques, it was observed that in this area the growth of pine on mineral soils with normal moisture conditions has been affected most significantly by the mean air temperature during the period from the second half of January to the first half of April of the same year. Thus, the period when mean air temperature is the most significant influence is similar across an area at least from Lithuania (inclusive) to southern Scandinavia, while further north it is mean summer air temperature that gradually becomes the determining factor in the radial growth of pine. Also the quality of the dendrochronological signal in tree-ring chronologies of pine growing in the environmental conditions of Latvia was determined and signature years during the 20th century were identified, when the majority of pines throughout the territory of the Baltic States exhibit a similar change in annual radial growth.