The response of intra-annual stem circumference of prevailing in Lithuania tree species to meteorology and air pollution under different site condition

Abstract

Global change in Lithuania is predicted to promote increasing air temperature across seasons, a decrease in snow cover and an increase in heavy rain as well as more frequent drought events. Changes in atmospheric circulation reduce seasonal climatic amplitudes, but enhance air pollution most presumably induced by ozone, acidification and UV radiation which in turn will affect tree growth and ecosystem performance in general. Intensive investigations at selected different humidity and nutrition regime forest sites combine seasonal growth of Scots pine, Norway spruce, and silver and downy birch trees analysis with ecophysiological assessments of tree water consumption under the presses of different environmental conditions. Significance of the effect of the hourly, daily and weekly data on intra-annual stem circumference was esteblished. We hypothesized that Scots pine is becoming a climax tree species under progressively declining soil water availability, while Norway spruce is more sensitive to short term drought events on water limited sites than pine and birch trees, whereas birch trees are more sensitive to short term drought events on eutrophic peat sites in Lithuania. The obtained data on intra-annual stem circumference revealed that coniferous tree species were more sensitive to environmental changes than broadleaf tree species like birch trees due to their lower transpiration rates. The study is based on the results obtained conducting national project supported by Lithuanian Council of Research "FOREstRESS" (SIT- 3/2015).