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Deepened winter snow increases stem growth and alters stem δ13C and δ15N in evergreen dwarf shrub Cassiope tetragona in high-arctic Svalbard tundra

Blok, Daan LU ; Weijers, Stef; Welker, Jeffrey M.; Cooper, Elisabeth J.; Michelsen, Anders; Löffler, Jörg and Elberling, Bo (2015) In Environmental Research Letters 10(4).
Abstract

Deeper winter snow is hypothesized to favor shrub growth and may partly explain the shrub expansion observed in many parts of the arctic during the last decades, potentially triggering biophysical feedbacks including regional warming and permafrost thawing. We experimentally tested the effects of winter snow depth on shrub growth and ecophysiology by measuring stem length and stem hydrogen (δ2H), carbon (δ13C), nitrogen (δ15N) and oxygen (δ18O) isotopic composition of the circumarctic evergreen dwarf shrub Cassiope tetragona growing in high-arctic Svalbard, Norway. Measurements were carried out on C. tetragona individuals sampled from three tundra sites, each representing a distinct moisture... (More)

Deeper winter snow is hypothesized to favor shrub growth and may partly explain the shrub expansion observed in many parts of the arctic during the last decades, potentially triggering biophysical feedbacks including regional warming and permafrost thawing. We experimentally tested the effects of winter snow depth on shrub growth and ecophysiology by measuring stem length and stem hydrogen (δ2H), carbon (δ13C), nitrogen (δ15N) and oxygen (δ18O) isotopic composition of the circumarctic evergreen dwarf shrub Cassiope tetragona growing in high-arctic Svalbard, Norway. Measurements were carried out on C. tetragona individuals sampled from three tundra sites, each representing a distinct moisture regime (dry heath, meadow, moist meadow). Individuals were sampled along gradients of experimentally manipulated winter snow depths in a six-year old snow fence experiment: in ambient (c. 20 cm), medium (c. 100 cm), and deep snow (c. 150 cm) plots. The deep-snow treatment consistently and significantly increased C. tetragona growth during the 2008-2011 manipulation period compared to growth in ambient-snow plots. Stem δ15N and stem N concentration values were significantly higher in deep-snow individuals compared to individuals growing in ambient-snow plots during the course of the experiment, suggesting that soil N-availability was increased in deep-snow plots as a result of increased soil winter N mineralization. Although inter-annual growing season-precipitation δ2H and stem δ2H records closely matched, snow depth did not change stem δ2H or δ18O, suggesting that water source usage by C. tetragona was unaltered. Instead, the deep insulating snowpack may have protected C. tetragona shrubs against frost damage, potentially compensating the detrimental effects of a shortened growing season and associated phenological delay on growth. Our findings suggest that an increase in winter precipitation in the High Arctic, as predicted by climate models, has the potential to alter the growth and ecophysiology of evergreen shrub C. tetragona through changes in plant mineral nutrition and frost damage protection.

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author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Cassiope tetragona, climate change, High Arctic, snow, stable isotope
in
Environmental Research Letters
volume
10
issue
4
publisher
IOP Publishing
external identifiers
  • Scopus:84928742203
ISSN
1748-9318
DOI
10.1088/1748-9326/10/4/044008
language
English
LU publication?
no
id
78401530-7c29-43ec-982d-b2c03fca220f
date added to LUP
2016-06-29 22:10:36
date last changed
2016-11-14 12:48:17
@misc{78401530-7c29-43ec-982d-b2c03fca220f,
  abstract     = {<p>Deeper winter snow is hypothesized to favor shrub growth and may partly explain the shrub expansion observed in many parts of the arctic during the last decades, potentially triggering biophysical feedbacks including regional warming and permafrost thawing. We experimentally tested the effects of winter snow depth on shrub growth and ecophysiology by measuring stem length and stem hydrogen (δ<sup>2</sup>H), carbon (δ<sup>13</sup>C), nitrogen (δ<sup>15</sup>N) and oxygen (δ<sup>18</sup>O) isotopic composition of the circumarctic evergreen dwarf shrub Cassiope tetragona growing in high-arctic Svalbard, Norway. Measurements were carried out on C. tetragona individuals sampled from three tundra sites, each representing a distinct moisture regime (dry heath, meadow, moist meadow). Individuals were sampled along gradients of experimentally manipulated winter snow depths in a six-year old snow fence experiment: in ambient (c. 20 cm), medium (c. 100 cm), and deep snow (c. 150 cm) plots. The deep-snow treatment consistently and significantly increased C. tetragona growth during the 2008-2011 manipulation period compared to growth in ambient-snow plots. Stem δ<sup>15</sup>N and stem N concentration values were significantly higher in deep-snow individuals compared to individuals growing in ambient-snow plots during the course of the experiment, suggesting that soil N-availability was increased in deep-snow plots as a result of increased soil winter N mineralization. Although inter-annual growing season-precipitation δ<sup>2</sup>H and stem δ<sup>2</sup>H records closely matched, snow depth did not change stem δ<sup>2</sup>H or δ<sup>18</sup>O, suggesting that water source usage by C. tetragona was unaltered. Instead, the deep insulating snowpack may have protected C. tetragona shrubs against frost damage, potentially compensating the detrimental effects of a shortened growing season and associated phenological delay on growth. Our findings suggest that an increase in winter precipitation in the High Arctic, as predicted by climate models, has the potential to alter the growth and ecophysiology of evergreen shrub C. tetragona through changes in plant mineral nutrition and frost damage protection.</p>},
  author       = {Blok, Daan and Weijers, Stef and Welker, Jeffrey M. and Cooper, Elisabeth J. and Michelsen, Anders and Löffler, Jörg and Elberling, Bo},
  issn         = {1748-9318},
  keyword      = {Cassiope tetragona,climate change,High Arctic,snow,stable isotope},
  language     = {eng},
  month        = {04},
  number       = {4},
  publisher    = {ARRAY(0xb521b50)},
  series       = {Environmental Research Letters},
  title        = {Deepened winter snow increases stem growth and alters stem δ<sup>13</sup>C and δ<sup>15</sup>N in evergreen dwarf shrub Cassiope tetragona in high-arctic Svalbard tundra},
  url          = {http://dx.doi.org/10.1088/1748-9326/10/4/044008},
  volume       = {10},
  year         = {2015},
}