No divergence in Cassiope tetragona: persistence of growth response along a latitudinal temperature gradient and under multi-year experimental warming

Weijers, Stef; Alsos, Inger Greve; Eidesen, Pernille Bronken; Broekman, Rob; Loonen, Maarten J. J. E.; Rozema, J.

doi:10.1093/aob/mcs123

Cited by 44 publications

(74 citation statements)

References 34 publications

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“…5), as observed for several other arctic tundra sites and species (e.g. Wilson 1957;Havström et al 1995;Bär et al 2006;Rayback and Henry 2006;Rozema et al 2009;Forbes et al 2010;Hallinger et al 2010;Weijers et al 2010;Blok et al 2011;Weijers et al 2012). The negative response to summer (June to August) precipitation (Fig.…”

Section: Allocation Prioritiessupporting

confidence: 75%

Temperature modulates intra-plant growth of Salix polaris from a high Arctic site (Svalbard)

et al. 2013

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Arctic ecosystems are important carbon sinks. Increasing temperatures in these regions might stimulate soil carbon release. Evidence suggests that deciduous shrubs might counteract these carbon losses because they positively respond to increasing temperature, but their role in ecosystem carbon budgets remains uncertain. Many studies dealing with large-scale tundra greening and carbon sequestration in relation to increasing temperature have usually based their estimations on the aboveground components, but very little is known about belowground growth. In this context, annual rings can provide a retrospective insight into intra-plant temperature responses and seasonal growth allocation. This study presents a 70-yearlong and annually resolved intra-plant analysis of ring width and missing ring distribution from a comprehensive serial sectioning, including 142 cross-sections and the measurements of 471 radii from ten Salix polaris Wahlenb. dwarf shrubs growing in the high Arctic on Svalbard. Results indicate a high intra-plant and inter-annual growth variation, characterized by a high proportion of partially (13.6 %) and completely (11.2 %) missing rings. The annual growth and the frequency of completely missing rings were evenly distributed inside the plant and mainly controlled by summer temperatures. Radial growth in the belowground parts appeared to be proportionally higher during long and warm summers and lower in cold early growing seasons than in the aboveground parts. The results reveal a diverging allocation between aboveground and belowground growth depending on the climatic conditions. Favorable years promoted root allocation since root radial growth occurs after aboveground growth. The observed belowground responses suggest that shrub carbon allocation might be higher than estimated only from the aboveground compartments.

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Section: Allocation Prioritiessupporting

confidence: 75%

Temperature modulates intra-plant growth of Salix polaris from a high Arctic site (Svalbard)

et al. 2013

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“…In the Canadian High Arctic, evergreen dwarf shrub cover increased in response to ambient warming (HudSon and Henry 2009) and leaf size and plant height of C. tetragona also increased in response to long-term experimental warming (HudSon et al 2011). Moreover, C. tetragona shoot length has been shown to increase in response to experimental summer warming in the High Arctic (HaVStröM et al 1993;rozeMa et al 2009;WeijerS et al 2012) and annual shoot length of C. tetragona has been used as a proxy for summer temperatures in High Arctic Canada, Svalbard, and Greenland (rayBaCK and Henry 2006;WeijerS et al 2010;2013b;2017).…”

Section: Discussionmentioning

confidence: 99%

“…In addition, shrub encroachment is believed to remain limited to the relatively warm parts of the biome, as a positive effect of ambient and experimental warming has mainly been observed on the abundance of taller deciduous shrubs in the Low Arctic (elMendorf et al 2012a;. Still, evergreen dwarf shrub species have been observed to be sensitive to summer temperatures at some Arctic and alpine sites (Bär et al 2008;Buizer et al 2012;WeijerS et al 2012) and have been shown to increase their leaf size and height in response to experimental warming (HudSon et al 2011) and cover in response to ambient warming (HudSon and Henry 2009) on Ellesmere Island in High Arctic Canada. High Arctic dwarf shrub species may thus respond rapidly to increasing temperatures in absence of taller species.…”

Section: Introductionmentioning

confidence: 99%

A warmer and greener cold world: summer warming increases shrub growth in the alpine and high Arctic tundra

Weijers¹,

Myers‐Smith²,

Löffler³

2018

Erdkunde

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Link: Link to publication record in Edinburgh Research Explorer Document Version:Publisher's PDF, also known as Version of record Published In: Erdkunde General rightsCopyright for the publications made accessible via the Edinburgh Research Explorer is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. Take down policyThe University of Edinburgh has made every reasonable effort to ensure that Edinburgh Research Explorer content complies with UK legislation. If you believe that the public display of this file breaches copyright please contact openaccess@ed.ac.uk providing details, and we will remove access to the work immediately and investigate your claim. Summary: The Arctic and alpine biome is rapidly warming, which might be causing an encroachment of relatively tall woody shrub vegetation into tundra ecosystems, which will probably result in an overall positive feedback to climate warming. This encroachment is, however, believed to remain limited to the relatively warm parts of the biome, where taller shrubs may displace shorter species. Still, climate sensitivity of shrub growth strongly differs between species and sites and High Arctic dwarf shrub species may respond rapidly to increasing temperatures in absence of taller species. In addition, it remains largely unknown whether shrubs from different functional groups from the same sites respond similarly to climate drivers. In the present study we examined the climate-growth relationships of six different site-species combinations: one evergreen and one deciduous shrub species at two alpine sites, and one evergreen dwarf shrub species at two High Arctic sites. We compared linear mixed models for each combination, explaining existing shrub growth data with site-specific interpolated monthly and seasonal climate data from the gridded meteorological dataset CRU TS4.00. Shrub growth rates were found to be sensitive to summer climate for all species at all sites. Continued and projected warming is thus likely to stimulate a further encroachment of shrubs in these systems, at least through a densification of existing stands. Dwarf shrub growth strongly responded to the recent warming at both High Arctic sites, contrasting with previous work suggesting that shrub expansion might remain limited to warmer tundra regions. At the alpine sites, growth of evergreen shrubs was found to be more dependent on summer climate than growth of deciduous shrubs, perhaps because these evergreen species are less prone to herbivory. However, biome-wide generalizations at the functional group level may be difficult to interpolate to the species level. Micro-site conditions, such as the determination of growing season length and winter soil temperatures, and influence on growing season soil moisture by snow depth, may determine the strength of the climate-growth relationships found.Zusammenfassung: Gegenwärtig ist eine rapide klimatische E...

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“…Bär et al (2006Bär et al ( , 2007 constructed the first ring width chronologies of alpine dwarf shrub black crowberry (Empetrum hermaphroditum L.) from the Norwegian part of the Scandinavian Mountains. Rayback and Henry (2005) as well as Weijers et al (2010Weijers et al ( , 2012 used growth increments from the internode length of white Arctic mountain heather (Cassiope tetragona L.) as the climate proxy records. Of these, Weijers et al (2012) constructed the longest chronology, of nearly 200 years, for the High Arctic.…”

Section: Introductionmentioning

confidence: 99%

“…Rayback and Henry (2005) as well as Weijers et al (2010Weijers et al ( , 2012 used growth increments from the internode length of white Arctic mountain heather (Cassiope tetragona L.) as the climate proxy records. Of these, Weijers et al (2012) constructed the longest chronology, of nearly 200 years, for the High Arctic. Most dendroclimatic studies emphasise the temperature signal recorded by the growth ring of dwarf shrub but the new data shows the possibility to also reconstruct moisture stress during the growing season (Blok et al, 2011;Rayback et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Dendrochronology and extreme pointer years in the tree-ring record (AD 1951–2011) of polar willow from southwestern Spitsbergen (Svalbard, Norway)

Owczarek

Opała

2016

Geochronometria

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Greater warmth and precipitation over the past several decades in the High Arctic, as recorded in meteorological data, have caused shrub expansion and affected growth ring widths. The main aim of the study was to develop a tree-ring chronology of polar willow (Salix polaris Wahlenb.) from southwest Spitsbergen, attempt to explain its extreme pointer years (extremely low value of growthring widths) and to demonstrate the dendrochronological potential of this species. This plant is a deciduous, prostrate, creeping dwarf shrub that produces anatomically distinct annual growth rings with the consistent ring width variation. After using serial sectioning we developed rigorously cross-dated ring width chronology covering the period 1951-2011. Since the beginning of the 1980s an increase of the mean and maximum growth ring width has been observed which is consistent with the increase of both temperature and precipitation in the Arctic reported from meteorological sources. Nine negative extreme years were distinguished and explained by complex hydroclimatic drivers, which highlight the importance of availability of moisture from snowpack and spring precipitation. An additional negative factor present in the years with very low dwarf shrubs growth is rapid thawing and fast freezing during winter as well as low sunshine duration. Our results contradict the prior assumption that inter-annual tree growth variability of dwarf shrubs from polar regions is controlled simply by temperature.

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No divergence in Cassiope tetragona: persistence of growth response along a latitudinal temperature gradient and under multi-year experimental warming

Cited by 44 publications

References 34 publications

Temperature modulates intra-plant growth of Salix polaris from a high Arctic site (Svalbard)

Temperature modulates intra-plant growth of Salix polaris from a high Arctic site (Svalbard)

A warmer and greener cold world: summer warming increases shrub growth in the alpine and high Arctic tundra

Dendrochronology and extreme pointer years in the tree-ring record (AD 1951–2011) of polar willow from southwestern Spitsbergen (Svalbard, Norway)

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