Temperature‐induced recruitment pulses of Arctic dwarf shrub communities

Büntgen, Ulf; Hellmann, Lena; Tegel, Willy; Normand, Signe; Myers‐Smith, Isla H.; Kirdyanov, Alexander V.; Nievergelt, Daniel; Schweingruber, Fritz Hans

doi:10.1111/1365-2745.12361

Cited by 101 publications

(126 citation statements)

References 104 publications

(115 reference statements)

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“…WeijerS et al 2017). However, shrub recruitment pulses may actually be driven by either increasing summer (Büntgen et al 2015) or winter temperatures (MyerS-SMitH and HiK 2018), and rising winter temperatures may thus be responsible for the colonization of new areas for some species. In addition, re-colonization of forefronts of retreating glaciers by species as C. tetragona may very well be possible in the High Arctic, as sometimes intact subfossil individuals of this species are found at such locations (HaVStröM et al 1995;loWell et al 2013).…”

Section: Discussionmentioning

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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Section: Discussionmentioning

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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“…The increase in shrub cover and abundance is widespread across northern circumpolar regions and has been recorded at both high-latitude and high-altitude sites in North America (Sturm et al, 2001a;Tape et al, 2006;Myers-Smith et al, 2011a;Ropars & Boudreau, 2012), northern Europe (B€ ar et al, 2008;Hallinger et al, 2010) and Russia (Forbes et al, 2010). Shrubs either have expanded in patch size (Sturm et al, 2001a;Tape et al, 2006;Ropars & Boudreau, 2012;Tremblay et al, 2012), recruited in areas where they were less abundant in the past (Sturm et al, 2001a;Frost et al, 2013;Frost & Epstein, 2014;B€ untgen et al, 2015) or have increased in height (Myers-Smith et al, 2011b;Paradis et al, 2016). Though this increase in tundra shrubs has been attributed to recent warming in tundra ecosystems (Elmendorf et al, 2012;Ropars et al, 2015), the climate sensitivity of shrub growth has been demonstrated to be variable across the tundra biome (Myers-Smith et al, 2015a).…”

Section: Introductionmentioning

confidence: 99%

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

Ropars

Angers‐Blondin

Gagnon

et al. 2017

Global Change Biology

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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 whether 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 environments. 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 microenvironmental 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.

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“…It has been shown that increased summer or winter temperatures strongly favor shrub recruitment in the Arctic tundra (Büntgen et al. , Myers‐Smith and Hik ). Water availability and demand could also codetermine shrub recruitment in drought‐prone cold or continental areas (Meyer and Pendleton , Moreno et al.…”

Section: Introductionmentioning

confidence: 99%

Past the climate optimum: Recruitment is declining at the world's highest juniper shrublines on the Tibetan Plateau

Liang

Wang

et al. 2019

Ecology

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Alpine biomes are climate change hotspots, and treeline dynamics in particular have received much attention as visible evidence of climate‐induced shifts in species distributions. Comparatively little is known, however, about the effects of climate change on alpine shrubline dynamics. Here, we reconstruct decadally resolved shrub recruitment history (age structure) through the combination of field surveys and dendroecology methods at the world's highest juniper (Juniperus pingii var. wilsonii) shrublines on the south‐central Tibetan Plateau. A total of 1,899 shrubs were surveyed at 12 plots located in four regions along an east‐to‐west declining precipitation gradient. We detected synchronous recruitment with 9 out of 12 plots showing a gradual increase from 1600 to 1900, a peak at 1900–1940, and a subsequent decrease from the 1930s onward. Shrub recruitment was significantly and positively correlated with reconstructed summer temperature from 1600 to 1940, whereas it was negatively associated with temperature in recent decades (1930–2000). Recruitment was also positively correlated with precipitation, except in the 1780–1830 period, when a trend toward wetter climate conditions began. Warming‐induced drought limitation has likely reduced the recruitment potential of alpine juniper shrubs in recent decades. Ongoing warming without a simultaneous increase in precipitation is expected to further impair recruitment at the world's highest juniper shrublines and alter the dynamics and competitive balance between woody plant species throughout these alpine biomes.

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Temperature‐induced recruitment pulses of Arctic dwarf shrub communities

Cited by 101 publications

References 104 publications

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

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

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

Past the climate optimum: Recruitment is declining at the world's highest juniper shrublines on the Tibetan Plateau

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