Dendrochronological characteristics of Finland


Finnish dendrochronology - dendroclimatology and dendroecology - is shaped by the unique nature of the country. Finland is one of the northernmost countries in the world. Country is located between 60° and 70° northern latitudes. A quarter of the land lies to the north of the Arctic Circle. Proximity to North Atlantic adds one more spice (perhaps salt?) to the characteristics of climate in Finland. These features create significant north-south gradient across the country that can be depicted in climate, ecography, and in tree-rings!

Recent study used four regional tree-ring chronologies from the forest-limit region in northernmost Lapland, and the northern, middle and southern boreal forest zones. The dataset formed transect through Finland. Comparison of tree-ring statistics between the regions show ecogeographical gradient from northern to southern Finland: a gradual decline of the common growth signal occurs from north to south along with increasing growth competition in the same direction. Ring-width variance also exhibits a drop in chronology variance from the forest-limit southward. Based on response functions, the three northernmost regions (forest-limit, northern and middle boreal forests) show a positive response to mid-summer temperatures. May precipitation has a positive impact on tree-rings in all four regions. Moreover, the North Atlantic Oscillation (NAO) seems to be a pacemaker for tree-rings from north to south. Narrow rings are associated with volcanic events over the three northernmost regions. Volcanic effects on tree rings were found to be generally severest in the northernmost regions, where the growth response to summer temperatures was also strongest.

 

Click HERE to read the research paper!