Temperature modulates intra-plant growth of Salix polaris from a high Arctic site (Svalbard)

Abstract

Arctic ecosystems are important carbon sinks. Increasing temperatures in these regions might stimulate soil carbon release. Evidence suggests that deciduous shrubs might counteract these carbon losses because they positively respond to increasing temperature, but their role in ecosystem carbon budgets remains uncertain. Many studies dealing with large-scale tundra greening and carbon sequestration in relation to increasing temperature have usually based their estimations on the aboveground components, but very little is known about belowground growth. In this context, annual rings can provide a retrospective insight into intra-plant temperature responses and seasonal growth allocation. This study presents a 70-yearlong and annually resolved intra-plant analysis of ring width and missing ring distribution from a comprehensive serial sectioning, including 142 cross-sections and the measurements of 471 radii from ten Salix polaris Wahlenb. dwarf shrubs growing in the high Arctic on Svalbard. Results indicate a high intra-plant and inter-annual growth variation, characterized by a high proportion of partially (13.6 %) and completely (11.2 %) missing rings. The annual growth and the frequency of completely missing rings were evenly distributed inside the plant and mainly controlled by summer temperatures. Radial growth in the belowground parts appeared to be proportionally higher during long and warm summers and lower in cold early growing seasons than in the aboveground parts. The results reveal a diverging allocation between aboveground and belowground growth depending on the climatic conditions. Favorable years promoted root allocation since root radial growth occurs after aboveground growth. The observed belowground responses suggest that shrub carbon allocation might be higher than estimated only from the aboveground compartments.

The role of summer precipitation and summer temperature in establishment and growth of dwarf shrub Betula nana in northeast Siberian tundra

“…Standardized precipitation evapotranspiration index (SPEI, VicenteSerrano et al 2010) data were obtained for the study site location from the global SPEI database v2.3 (sac.csic.es/ spei/database.html, Vicente-Serrano et al 2010). Since climatic conditions can also affect next year's radial growth (Buchwal et al 2013), the Pearson's correlations for the relation between RWI and the climatic variables of the preceding year were included into the analyses.…”

Surface radiation climatology for Ny-Ålesund, Svalbard (78.9° N), basic observations for trend detection

“…Using temperature as a potential indicator for the snow cover free season, the first day after summer of each year from 1993 to 2013 with a daily mean temperature below the freezing point has shifted by +9.0±11.2 days per decade, postponing the cold season by more than 2 weeks over the 21-year observation period. The prolonged season above the freezing point and consequently shorter period of snow covered ground allows for changes in vegetation growth and related behavior of migratory birds (Buchwal et al 2013;Kuhlmann Clausen and Clausen 2013).…”

Impacts of Geomorphic Disturbances on Plant Colonization in Ebba Valley, Central Spitsbergen, Svalbard

“…These three species occur in all the sites along the transect. Dwarf shrubs such as Salix polaris had well developed root systems and many of them reaches the age of several decades (Buchwał et al 2013). Marcante et al (2009) points out that survival of adult perennials of this type serves as a buffer against temporal variations.…”