Later snow melt reduces dwarf shrub secondary growth (Salix polaris, Adventdalen), RiS ID 6615

In many tundra regions dwarf trees of the Arctic (i.e. shrubs) are becoming dominant and increasing in cover. Since shrubs can become old (more than 100 yrs old) and its annual ring growth register valuable environmental information, dendrochronological s tudies on tundra shrubs are becoming more important in polar studies. All previous studies conducted in the Arctic have indicated problems in developing reliable shrub chronologies, casued by limited cambial growth. Among limiting factors of shrub growt h we aim to study a snow cover duration and its influence on a secondary growth. In our project we would like to assess how the delayed snowmelt and deeper snow cover influences the secondary growth of a dwarf shrub Salix polaris in central Spitsbergen, A dventdalen. We hypothesize that a longer snow-cover period delays the onset of cambial activity and limits overall annual tree-ring growth. In our knowledge such a study was not conducted before in any Arctic region. The response in cambial production at the intra-annual level will be performed on a dwarf shrub species Salix polaris. Specifically, we aim to investigate the annual radial increments (i.e. tree-ring widths, the proportion of partially and completely missing rings) and wood anatomical featur es in the above-ground and below-ground parts of the shrub. The study will be conducted within the snow fence plots established in 2006. Overall understanding how snow cover is imparted on the growth rings and anatomy of arctic shrubs is poorly understo od. The lack of this basic knowledge of ecological and physiological settings of the annual growth of arctic shrubs addresses the importance of our study in the High Arctic. How do shrubs grow and form annual rings as a response to different snow regimes?