Investigations on European larch were started in Lithuania in
2007. The larch trees were planted in Lithuania as early as at the
beginning of 19th c. (Januškevičius 2004). The ecology
of larch was investigated in several studies (for example,
Jankauskas 1954), but there was little information on the effects
of environmental factors on radial growth in Lithuania. The
tree-ring widths of European larch have been investigated in
several studies in Lithuania (Kaminskaitė 2002, Kaselytė 2003,
Pukienė and Bitvinskas 2000), however, the results are based on
one or few research plots and they are controversial. Therefore,
there was an urgent need to assess the radial growth of European
larch over a wide network of experimental plots in Lithuania. The
aims of this study were to (1) establish such a network including
all known growing places of larch in Lithuania, (2) construct a
regional tree-ring chronology of larch and (3) assess the
tree-ring growth dynamics and compare it with other coniferous
species (Scots pine and Norway spruce) at the same stands.
Our investigation were based on 25 experimental plots (351 larches). Tree-ring widths using image analysis (flatbed scanner and Cybis CooRecorder 7.1 program) were measured and local chronologies compiled. The average age of investigated larches is ca. 107 years with the oldest tree being 157 years old. The average tree-ring width of all trees is 2.18 mm and the average mean sensitivity - 0.35. The similarity between the site chronologies usually is statistically reliable, even if the plots are located 100-200 km apart from each other. The average correlation coefficients decrease from 0.50-0.55 to 0.30-0.40, whereas the distance increases from 50 to 200-250 km. Hence, the similar growth pattern is characteristic for larch growing across Lithuania.
A regional chronology shows a high inter-annual variation. The high mean sensitivity of larch may be explained with the frequent occurrence of light rings. A Fourier analysis confirms the dominance of short-term cyclic components ranging from 2 to 17 years. The compiled regional tree-ring chronology ranges from 1850 to 2008. The analysis of signature years has revealed that the formation of narrow rings is linked to hot/dry summers and of wide rings to warm winters and springs. The tree-ring patterns of larch and Norway spruce, growing in a mixed stand, are similar (correlations from 0.26 to 0.51, p≤0.01), while the similarity with Scots pine is much lower (correlations from 0.16 to 0.20, p from 0.03 to 0.13).