Experimental icing affects growth, mortality, and flowering in a high Arctic dwarf shrub

Jos M. Milner, Øystein Varpe, Rene van der Wal, Brage Bremset Hansen

Research output: Contribution to journalArticle

11 Citations (Scopus)
4 Downloads (Pure)

Abstract

Effects of climate change are predicted to be greatest at high latitudes, with more pronounced warming in winter than summer. Extreme mid-winter warm spells and heavy rain-on-snow events are already increasing in frequency in the Arctic, with implications for snow-pack and ground-ice formation. These may in turn affect key components of Arctic ecosystems. However, the fitness consequences of extreme winter weather events for tundra plants are not well understood, especially in the high Arctic. We simulated an extreme mid-winter rain-on-snow event at a field site in high Arctic Svalbard (78°N) by experimentally encasing tundra vegetation in ice. After the subsequent growing season, we measured the effects of icing on growth and fitness indices in the common tundra plant, Arctic bell-heather (Cassiope tetragona). The suitability of this species for retrospective growth analysis enabled us to compare shoot growth in pre and postmanipulation years in icing treatment and control plants, as well as shoot survival and flowering. Plants from icing treatment plots had higher shoot mortality and lower flowering success than controls. At the individual sample level, heavily flowering plants invested less in shoot growth than nonflowering plants, while shoot growth was positively related to the degree of shoot mortality. Therefore, contrary to expectation, undamaged shoots showed enhanced growth in ice treatment plants. This suggests that following damage, aboveground resources were allocated to the few remaining undamaged meristems. The enhanced shoot growth measured in our icing treatment plants has implications for climate studies based on retrospective analyses of Cassiope. As shoot growth in this species responds positively to summer warming, it also highlights a potentially complex interaction between summer and winter conditions. By documenting strong effects of icing on growth and reproduction of a widespread tundra plant, our study contributes to an understanding of Arctic plant responses to projected changes in winter climatic conditions.
Original languageEnglish
Pages (from-to)2139-2148
Number of pages10
JournalEcology and Evolution
Volume6
Issue number7
Early online date28 Feb 2016
DOIs
Publication statusPublished - Apr 2016

Fingerprint

flowering
Arctic region
shoot growth
shrub
shrubs
mortality
shoots
tundra
winter
shoot
snow
ice
summer
fitness
warming
Tetragona
rain
angiosperm
snowpack
growing season

Keywords

  • anoxia tolerance
  • cassiope tetragona
  • climate change
  • extreme weather event
  • resource allocation
  • winter warming

Cite this

Experimental icing affects growth, mortality, and flowering in a high Arctic dwarf shrub. / Milner, Jos M.; Varpe, Øystein; van der Wal, Rene; Hansen, Brage Bremset .

In: Ecology and Evolution, Vol. 6, No. 7, 04.2016, p. 2139-2148.

Research output: Contribution to journalArticle

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note = "Acknowledgments This study was funded by the Research Council of Norway (POLARPROG grant 216051; SFF-III grant 223257/F50) and Svalbard Environmental Protection Fund (SMF grant 13/74). We thank Mathilde Le Moullec for helping with the fieldwork and the Norwegian Meteorological Institute for access to weather data.",
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