• Energy Research

The ongoing climatic changes are causing the extinction of numerous species or their withdrawal from previously occupied areas. The environmental and economic significance of introduced species may increase. The aim of the present study was to examine the rate of growth of coniferous species growing in northwestern Poland and to analyze the tree ring width–climate relationships. Six tree species were selected for this study. Two of these species have natural occurrences in Poland: Pinus sylvestris and Larix decidua. The remaining four species were introduced from North America: Chamaecyparis lawsoniana, Thuja plicata, Pseudotsuga menziesii, and Pinus strobus. Samples were collected from 131 trees using a Pressler borer at 1.3 m above ground. Tree ring widths were measured down to 0.01 mm. Climatic data were retrieved from a weather station located 23 km from the study plot. The average tree ring width reaches the lowest value for the P. sylvestris chronology (1.62 mm/year) and for P. strobus (1.69 mm/year), and the highest value is reached for T. plicata (2.80 mm/year) and P. menziesii (2.56 mm/year). The analysis of weather conditions in the designated pointer years and the response function analysis indicate that winter and early spring air temperature is the factor responsible for the formation of wide tree rings in the following species studied: P. sylvestris, C. lawsoniana, P. menziesii, and T. plicata. For L. decidua and P. strobus, the climate–growth relationships are different: weather conditions in the previous growth year are important, and it is the weather in the late spring and summer months. Two of the investigated introduced species (T. plicata and P. menziesii) are characterized by very good acclimatization and are best adapted to the new habitat during the current climate changes. These tree species can constitute a basis for replacing native species, which, due to increasingly severe droughts and higher temperatures, are doing less and less well in their current habitats. Foresters wanting to conduct sustainable forest management will look for replacement species that are well adapted to new habitat conditions in order to maintain the continuity of forest cover.

AbstractThe role of future forests in global biogeochemical cycles will depend on how different tree species respond to climate. Interpreting the response of forest growth to climate change requires an understanding of the temporal and spatial patterns of seasonal climatic influences on the growth of common tree species. We constructed a new network of 310 tree‐ring width chronologies from three common tree species (Quercus robur, Pinus sylvestris and Fagus sylvatica) collected for different ecological, management and climate purposes in the south Baltic Sea region at the border of three bioclimatic zones (temperate continental, oceanic, southern boreal). The major climate factors (temperature, precipitation, drought) affecting tree growth at monthly and seasonal scales were identified. Our analysis documents that 20th century Scots pine and deciduous species growth is generally controlled by different climate parameters, and that summer moisture availability is increasingly important for the growth of deciduous species examined. We report changes in the influence of winter climate variables over the last decades, where a decreasing influence of late winter temperature on deciduous tree growth and an increasing influence of winter temperature on Scots pine growth was found. By comparing climate–growth responses for the 1943–1972 and 1973–2002 periods and characterizing site‐level growth response stability, a descriptive application of spatial segregation analysis distinguished sites with stable responses to dominant climate parameters (northeast of the study region), and sites that collectively showed unstable responses to winter climate (southeast of the study region). The findings presented here highlight the temporally unstable and nonuniform responses of tree growth to climate variability, and that there are geographical coherent regions where these changes are similar. Considering continued climate change in the future, our results provide important regional perspectives on recent broad‐scale climate–growth relationships for trees across the temperate to boreal forest transition around the south Baltic Sea.