Influence of climate and soil hydrothermal regime on radial growth of Larix cajanderi and Pinus sylvestris in Central Yakutia, Russia

This paper presents the results of investigations of tree-ring growth in Dahurian larch (Larix cajanderi Mayr.) and Scots pine (Pinus sylvestris L.) in Central Yakutia, Eastern Siberia. The study used dendrochronological methods to analyse the influence of climate on tree growth and forest development in a permafrost area. Three larch sites and one pine site were investigated. The duration of tree-ring chronologies at all four sites was more than 200 years. Analysis of soil temperature influences on radial increment was carried out for the period from 1934 to 2006. For dependence of larch growth from soil moisture content on different depths, the data since 1988 were used. The study demonstrated that tree growth was largely dependent on soil hydrothermal conditions. The results of statistical analyses indicated that the radial growth of Dahurian larch and Scots pine in Central Yakutia was significantly correlated with soil temperature and moisture at various depths. Correlations with soil temperature at the different depths were 0.4–0.5 (p<0.05), especially during the winter period. Negative correlations with soil temperature were revealed in summer on the dry sites. Taking into account the droughty climate of Central Yakutia, soil moisture correlates well with the radial increment of trees (up to r=0.8, or higher). The highest correlation was revealed with the last year's autumn soil moisture.