Annual growth trends and response to weather of larch trees at Järvselja Training and Experimental Forest Center stands (Estonia)

Larch is widely used in tree-ring studies, while tree-ring width and signature years provide information on environmental changes with annual resolution. The aim of the study was to build tree-ring (TR), early- (EW) and latewood (LW) width chronologies by larch species (Hybrid, European, Russian, Japanese, Kuril), and to study the response of the radial increment of larches to weather at Järvselja forest stands by using correlation, redundancy analysis, and the pointer year method. The increment cores were collected from 233 trees in Järvselja larch stands during autumn 2014. The increment cores were collected from 24 stands and divided into five groups by larch species. High EPS values (≥ 0.887) for the larch species in all groups indicate that a sufficient number of trees was included in the chronologies to be representable. The results show that different species have a similar sensitivity to various weather variables. Among the factors influencing the size of radial growth of larches were the weather conditions prevailing in the autumn of the previous year and the spring of the current year. An overall RDA revealed that 63.9% of tree growth variation in larch species was explained by the considered weather variables (F = 4.925, p < 0.001). The pointer year analysis distinguished between several common extreme pointer years by larch species; it revealed a significant response to the winter temperature and the temperature in spring. However, these weather characteristics are very complex and the causes that can affect tree growth may vary from year to year.