Retrospective growth analysis of the dwarf shrub Cassiope tetragona allows local estimation of vascular plant productivity in high arctic Svalbard

Jos M Milner (Corresponding Author), Audun Stien, Rene Van der Wal

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Abstract

Question
Vascular plant productivity of arctic tundra has often been viewed as varying little between years and thus being largely insensitive to the high inter‐annual variation in summer weather conditions. Yet, remote‐sensing data and retrospective growth analyses of the circumpolar dwarf shrub, Cassiope tetragona, commonly show considerable between‐year variability in plant growth in response to variation in summer temperature. Given that both Cassiope growth and vascular plant biomass production share a common environmental driver, summer temperature, we would expect positive co‐variation between them. Here we investigate whether this is indeed the case and if so over what spatial scale.

Location
Nordenskiöldland, high arctic Svalbard.

Methods
We brought dendroecology and plot‐based field estimation methodologies together in an empirical study using retrospective analysis of Cassiope growth and annual estimation of above‐ground vegetation biomass production to investigate their temporal and spatial co‐variation and sensitivity to summer weather conditions.

Results
Despite substantial small‐scale heterogeneity, we found spatial co‐variation in Cassiope growth patterns, which weakened as distance between sampling sites increased from 0 to 25 km. Furthermore, we found a strong positive correlation between annual estimates of above‐ground live vascular plant biomass and Cassiope shoot growth over a 12‐year period at a local scale. The correlation declined with distance, likely due to increasing differences in local weather conditions.

Conclusions
We demonstrate that Cassiope growth can be used as a proxy for above‐ground tundra vegetation productivity at the local scale. Our findings suggest that Arctic plant productivity is as sensitive to between‐year variation in summer temperature as the well‐established growth response of Cassiope. This challenges the view that tundra plant productivity varies little between years and provides a mechanistic understanding that helps reconcile field‐ and satellite‐based annual estimation methods.
Original languageEnglish
Pages (from-to)943-951
Number of pages9
JournalJournal of Vegetation Science
Volume29
Issue number5
DOIs
Publication statusPublished - Sep 2018

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Keywords

  • Arctic bell heather
  • cassiope tetragona
  • Arctic climate change
  • dendrochronology
  • plant-climate interaction
  • spatial scale
  • Svalbard
  • Tundra vegetation
  • Vascular plant productivity
  • vegetation biomass

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