Jansons, A., Matisons, R*., Libiete-Zālīte, Z., Baders, E. and Rieksts-Riekstiņš, J. 2013. Relationships of Height Growth of Lodgepole Pine (Pinus contorta var. latifolia) and Scots Pine (Pinus sylvestris) with Climatic Factors in Zvirgzde, Latvia. Baltic

Lodgepole pine (Pinus contorta var. latifolia Dougl.) is one of the few exotic tree species that has been successfully used in forestry in Northern Europe. Considering the increasing demand for energy wood and timber, this species could be applied in plantation forestry in Latvia; however, knowledge about its growth dynamics in relation to environmental factors is necessary for sustainable management. Annual height increment (HI) was measured for 297 lodgepole pine trees from three provenances (Pink Mountain, Fort Nelson and Summit Lake) and for 135 Scots pine (Pinus sylvestris L.) trees for the period from 1990 to 2009. Mean HI and diameter between species and provenances was compared by ANOVA. Height-growth-climate relationships were assessed using dendrochronological methods. Chronologies of HI were produced based on cross-dated time-series; the effects of climatic factors on yearly variation of HI were determined by Pearson correlation analysis.

There were no significant differences in diameter between species and provenances; however, HI of Summit Lake provenance and Scots pine was the highest. Common signatures in yearly variation of HI were observed in ~ 40 and ~60 % of lodgepole pine and Scots pine trees, respectively, suggesting effect of climatic factors. Sets of climatic factors affecting HI differed between species and provenances. Temperature in spring, summer and precipitation in the dormant period showed the strongest effect (positive) on HI of Pink Mountain, Fort Nelson and Summit Lake provenances, respectively. In contrast, HI of Scots pine was sensitive to climatic factors related to water deficit in May and June of the year preceding growth. Apparently height growth of Scots pine was more affected by conditions in the year preceding growth than in current year, compared with lodgepole pine.

Key words: shoot elongation, introduced species, adaptation, climate, pine species.