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Different parts, different stories: climate sensitivity of growth is stronger in root collars versus stems in tundra shrubs.

https://arctichealth.org/en/permalink/ahliterature279563
Source
Glob Chang Biol. 2017 Jan 20;
Publication Type
Article
Date
Jan-20-2017
Author
Pascale Ropars
Sandra Angers-Blondin
Marianne Gagnon
Isla H Myers-Smith
Esther Lévesque
Stéphane Boudreau
Source
Glob Chang Biol. 2017 Jan 20;
Date
Jan-20-2017
Language
English
Publication Type
Article
Abstract
Shrub densification has been widely reported across the circumpolar arctic and subarctic biomes in recent years. Long-term analyses based on dendrochronological techniques applied to shrubs have linked this phenomenon to climate change. However, the multi-stemmed structure of shrubs makes them difficult to sample and therefore leads to non-uniform sampling protocols among shrub ecologists, who will favor either root collars or stems to conduct dendrochronological analyses. Through a comparative study of the use of root collars and stems of Betula glandulosa, a common North American shrub species, we evaluated the relative sensitivity of each plant part to climate variables, and assessed if this sensitivity is consistent across three different types of environments in northwestern Québec, Canada (terrace, hilltop and snowbed). We found that root collars had greater sensitivity to climate than stems, and that these differences were maintained across the three types of environment. Growth at the root collar was best explained by spring precipitation and summer temperature, whereas stem growth showed weak and inconsistent responses to climate variables. Moreover, sensitivity to climate was not consistent among plant parts, as individuals having climate sensitive root collars did not tend to have climate sensitive stems. These differences in sensitivity of shrub parts to climate highlight the complexity of resource allocation in multi-stemmed plants. Whereas stem initiation and growth are driven by micro-environmental variables such as light availability and competition, root collars integrate the growth of all plant parts instead, rendering them less affected by mechanisms such as competition and more responsive to signals of global change. Although further investigations are required to determine the degree to which these findings are generalizable across the tundra biome, our results indicate that consistency and caution in the choice of plant parts are a key consideration for the success of future dendroclimatological studies on shrubs. This article is protected by copyright. All rights reserved.
PubMed ID
28107770 View in PubMed
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Divergence of Arctic shrub growth associated with sea ice decline.

https://arctichealth.org/en/permalink/ahliterature303904
Source
Proc Natl Acad Sci U S A. 2020 12 29; 117(52):33334-33344
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Date
12-29-2020
Author
Agata Buchwal
Patrick F Sullivan
Marc Macias-Fauria
Eric Post
Isla H Myers-Smith
Julienne C Stroeve
Daan Blok
Ken D Tape
Bruce C Forbes
Pascale Ropars
Esther Lévesque
Bo Elberling
Sandra Angers-Blondin
Joseph S Boyle
Stéphane Boudreau
Noémie Boulanger-Lapointe
Cassandra Gamm
Martin Hallinger
Grzegorz Rachlewicz
Amanda Young
Pentti Zetterberg
Jeffrey M Welker
Author Affiliation
Institute of Geoecology and Geoinformation, Adam Mickiewicz University, 61-680 Poznan, Poland; kamzik@amu.edu.pl.
Source
Proc Natl Acad Sci U S A. 2020 12 29; 117(52):33334-33344
Date
12-29-2020
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Keywords
Arctic Regions
Climate
Humidity
Ice Cover
Models, Theoretical
Plant Development
Seasons
Soil
Temperature
Abstract
Arctic sea ice extent (SIE) is declining at an accelerating rate with a wide range of ecological consequences. However, determining sea ice effects on tundra vegetation remains a challenge. In this study, we examined the universality or lack thereof in tundra shrub growth responses to changes in SIE and summer climate across the Pan-Arctic, taking advantage of 23 tundra shrub-ring chronologies from 19 widely distributed sites (56°N to 83°N). We show a clear divergence in shrub growth responses to SIE that began in the mid-1990s, with 39% of the chronologies showing declines and 57% showing increases in radial growth (decreasers and increasers, respectively). Structural equation models revealed that declining SIE was associated with rising air temperature and precipitation for increasers and with increasingly dry conditions for decreasers. Decreasers tended to be from areas of the Arctic with lower summer precipitation and their growth decline was related to decreases in the standardized precipitation evapotranspiration index. Our findings suggest that moisture limitation, associated with declining SIE, might inhibit the positive effects of warming on shrub growth over a considerable part of the terrestrial Arctic, thereby complicating predictions of vegetation change and future tundra productivity.
PubMed ID
33318214 View in PubMed
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Experiment, monitoring, and gradient methods used to infer climate change effects on plant communities yield consistent patterns.

https://arctichealth.org/en/permalink/ahliterature259277
Source
Proc Natl Acad Sci U S A. 2014 Dec 29;
Publication Type
Article
Date
Dec-29-2014
Author
Sarah C Elmendorf
Gregory H R Henry
Robert D Hollister
Anna Maria Fosaa
William A Gould
Luise Hermanutz
Annika Hofgaard
Ingibjörg I Jónsdóttir
Janet C Jorgenson
Esther Lévesque
Borgþór Magnusson
Ulf Molau
Isla H Myers-Smith
Steven F Oberbauer
Christian Rixen
Craig E Tweedie
Marilyn Walker
Source
Proc Natl Acad Sci U S A. 2014 Dec 29;
Date
Dec-29-2014
Language
English
Publication Type
Article
Abstract
Inference about future climate change impacts typically relies on one of three approaches: manipulative experiments, historical comparisons (broadly defined to include monitoring the response to ambient climate fluctuations using repeat sampling of plots, dendroecology, and paleoecology techniques), and space-for-time substitutions derived from sampling along environmental gradients. Potential limitations of all three approaches are recognized. Here we address the congruence among these three main approaches by comparing the degree to which tundra plant community composition changes (i) in response to in situ experimental warming, (ii) with interannual variability in summer temperature within sites, and (iii) over spatial gradients in summer temperature. We analyzed changes in plant community composition from repeat sampling (85 plant communities in 28 regions) and experimental warming studies (28 experiments in 14 regions) throughout arctic and alpine North America and Europe. Increases in the relative abundance of species with a warmer thermal niche were observed in response to warmer summer temperatures using all three methods; however, effect sizes were greater over broad-scale spatial gradients relative to either temporal variability in summer temperature within a site or summer temperature increases induced by experimental warming. The effect sizes for change over time within a site and with experimental warming were nearly identical. These results support the view that inferences based on space-for-time substitution overestimate the magnitude of responses to contemporary climate warming, because spatial gradients reflect long-term processes. In contrast, in situ experimental warming and monitoring approaches yield consistent estimates of the magnitude of response of plant communities to climate warming.
PubMed ID
25548195 View in PubMed
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Greater temperature sensitivity of plant phenology at colder sites: implications for convergence across northern latitudes.

https://arctichealth.org/en/permalink/ahliterature279042
Source
Glob Chang Biol. 2017 Jan 11;
Publication Type
Article
Date
Jan-11-2017
Author
Janet Prevéy
Mark Vellend
Nadja Rüger
Robert D Hollister
Anne D Bjorkman
Isla H Myers-Smith
Sarah C Elmendorf
Karin Clark
Elisabeth J Cooper
Bo Elberling
Anna Maria Fosaa
Gregory H R Henry
Toke T Høye
Ingibjörg Svala Jónsdóttir
Kari Klanderud
Esther Lévesque
Marguerite Mauritz
Ulf Molau
Susan M Natali
Steven F Oberbauer
Zoe A Panchen
Eric Post
Sabine B Rumpf
Niels M Schmidt
Ted Schuur
Phillip R Semenchuk
Tiffany Troxler
Jeffrey M Welker
Christian Rixen
Source
Glob Chang Biol. 2017 Jan 11;
Date
Jan-11-2017
Language
English
Publication Type
Article
Abstract
Warmer temperatures are accelerating the phenology of organisms around the world. Temperature sensitivity of phenology might be greater in colder, higher-latitude sites than in warmer regions, in part because small changes in temperature constitute greater relative changes in thermal balance at colder sites. To test this hypothesis, we examined up to 20 years of phenology data for 47 tundra plant species at 18 high-latitude sites along a climatic gradient. Across all species, the timing of leaf emergence and flowering were more sensitive to a given increase in summer temperature at colder than warmer high-latitude locations. A similar pattern was seen over time for the flowering phenology of a widespread species, Cassiope tetragona. These are among the first results highlighting differential phenological responses of plants across a climatic gradient, and suggest the possibility of convergence in flowering times and therefore an increase in gene flow across latitudes as the climate warms. This article is protected by copyright. All rights reserved.
PubMed ID
28079308 View in PubMed
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Trophic mismatch and its effects on the growth of young in an Arctic herbivore.

https://arctichealth.org/en/permalink/ahliterature265113
Source
Glob Chang Biol. 2015 Aug 1;
Publication Type
Article
Date
Aug-1-2015
Author
Madeleine Doiron
Gilles Gauthier
Esther Lévesque
Source
Glob Chang Biol. 2015 Aug 1;
Date
Aug-1-2015
Language
English
Publication Type
Article
Abstract
In highly seasonal environments, timing of breeding of organisms is typically set to coincide with the period of highest resource availability. However, breeding phenology may not change at a rate sufficient to keep up with the rapid changes in the environment in the wake of climate change. The lack of synchrony between the phenology of consumers and that of their resources can lead to a phenomenon called trophic mismatch, which may have important consequences on the reproductive success of herbivores. We analysed long-term data (1991-2010) on climate, plant phenology and the reproduction of a long-distance arctic migrant, the greater snow goose (Chen caerulescens atlantica), in order to examine the effects of mismatched reproduction on the growth of young. We found that geese are only partially able to adjust their breeding phenology to compensate for annual changes in the timing of high quality food plants, leading to mismatches of up to 20 days between the two. The peak of nitrogen concentration in plants, an index of their nutritive quality for goslings, occurred earlier in warm springs with an early snow melt. Likewise, mismatch between hatch dates of young and date of peak nitrogen was more important in years with early snow melt. Gosling body mass and structural size at fledging was reduced when trophic mismatch was high, particularly when the difference between date of peak nitrogen concentration and hatching was greater than 9 days. Our results support the hypothesis that trophic mismatch can negatively affect the fitness of arctic herbivores, and that this is likely to be exacerbated by rising global temperatures. This article is protected by copyright. All rights reserved.
PubMed ID
26235037 View in PubMed
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