Four-decadal series of dendrometric measurements reveals trends in Pinus sylvestris inter- and intra-annual growth response to climatic conditions

Abstract

We analyzed a 42-year series (1976–2017) of Scots pine (Pinus sylvestris L.) tree-diameter data, obtained using band dendrometers, from our study site in Aukštaitija National Park, Lithuania. We evaluated the intra- and inter-annual growth dynamics of tree diameter and their response to meteorological forcing, as well as the long-term annual and monthly growth-rate changes in tree diameter in the study area. On average, the largest growth in tree diameter was found to have taken place in June (35% of the annual increase). After 24 June, the tree-diameter growth rate strongly decreased. Pine growth in May and August was mostly affected by the temperature during the previous month. Precipitation was the main driver that determined tree growth in June–August, with heavy precipitation events having the largest impact on short-term increases in tree diameter. We determined that the largest positive growth-rate changes in Scots pine tree diameter occurred as a result of higher air temperature in May and June between 1976 and 2017.