Data from: Annual ring growth of a widespread high-arctic shrub reflects past fluctuations in community-level plant biomass

1. Long time-series of primary production are rarely available,
restricting our mechanistic understanding of vegetation and ecosystem
dynamics under climate change. Dendrochronological tools are increasingly
used instead, particularly in the Arctic – the world’s most rapidly
warming biome. Yet, high-latitude plant species are subject to strong
energy allocation trade-offs, and whether annual allocations to secondary
growth (e.g. ‘tree-rings’) actually reflects primary production
above-ground remains unknown. Taking advantage of a unique ground-based
monitoring time-series of annual vascular plant biomass in high Arctic
Svalbard (78N), we evaluated how well retrospective ring growth of the
widespread dwarf shrub Salix polaris represents above-ground biomass
production of vascular plants. 2. Using a balanced design in permanent
plots for plant biomass monitoring, we collected 30 S. polaris shrubs
across five sites in each of two habitats. We established annual ring
growth time-series using linear mixed-effects models and related them to
local weather records and 13 years of above-ground biomass production in
six habitats. 3. Annual ring growth was positively correlated with
above-ground biomass production of both S. polaris (r = 0.56) and the
vascular plant community as a whole (r = 0.70). As for above-ground
biomass, summer temperature was the main driver of ring growth, with this
ecological signal becoming particularly clear when accounting for plant,
site and habitat heterogeneity. The results suggest that ring growth
measurements performed on this dominating shrub can be used to track
fluctuations in past vascular plant production of high-arctic tundra. 4.
Synthesis. Dendrochronological tools are increasingly used on arctic
shrubs to enhance our understanding of vegetation dynamics in the world’s
most rapidly warming biome. Fundamental to such applications is the
assumption that annual ring growth reflects between-year variation in
above-ground biomass production. Here we showed that ring growth indeed
was a robust proxy for the annual above-ground productivity of both the
focal shrub and the vascular plant community as a whole. Despite the
challenges of constructing ring growth chronologies from irregularly
growing arctic shrubs, our findings confirm that shrub dendrochronology
can open new opportunities for community-dynamic studies under climate
change, including in remote places where annual field sampling is
difficult to achieve.