Summer droughts depress radial growth of Picea abies in pristine taiga of the Arkhangelsk province, northwestern Russia

Knowledge of how climate affects tree growth is essential for understanding forest ecosystem dynamics in a changing environment. We assessed the relationships between climate and radial growth of Picea abies in pristine taiga forest on a mesic site type in the Arkhangelsk province, northwestern Russia. In these forests periodic droughts have been suggested to be a major disturbance factor. We used measurements of tree-ring widths and correlation and response function analyses to examine the relationship between radial growth of a total of 119 living and dead trees, and monthly temperature, precipitation, and soil moisture deficits. We analyzed these at high frequencies, i.e., at interannual time scales, and supplemented these analyses with an analysis of the medium-frequency relationship, i.e., at decadal time scales, between seasonal averages of the climatic variables and tree-ring widths. The results indicated that, at interannual time scales, high summer temperatures were the most important climatic factor limiting tree radial growth, which implies limited moisture availability as a growth-depressing factor. At decadal time scales, radial growth of trees was best related to summer soil moisture deficits: periods of high soil moisture availability promoted tree growth, while the opposite conditions were detrimental to tree growth. The results indicate that moisture availability is a crucial factor influencing the growth and dynamics of trees in these northern forest ecosystems.