Nordic<i>Empetrum</i>Dominated Ecosystems: Function and Susceptibility to Environmental Changes

Tybirk, Knud; Nilsson, M. B.; Michelsen, Anders; Kristensen, Hanne Lakkenborg; Shevtsova, Anna; Strandberg, Morten Tune; Johansson, Marianne; Nielsen, Knud Erik; Riis-Nielsen, Torben; Strandberg, Beate; Johnsen, Ib

doi:10.1579/0044-7447-29.2.90

Cited by 108 publications

(24 citation statements)

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“…However, the increased standing biomass in the heath and not in the meadow community were unexpected since evergreen dwarf shrubs (which mainly contributed to the increased standing biomass) are often avoided by herbivores due to their high content of secondary compounds [83–85]. However, the increase was caused by increased growth of the evergreen shrubs, similar to previous exclosure studies in tundra [14, 37, 86].…”

Section: Discussionsupporting

confidence: 74%

Experimental herbivore exclusion, shrub introduction, and carbon sequestration in alpine plant communities

et al. 2018

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BackgroundShrub cover in arctic and alpine ecosystems has increased in recent decades, and is predicted to further increase with climate change. Changes in shrub abundance may alter ecosystem carbon (C) sequestration and storage, with potential positive feedback on global C cycling. Small and large herbivores may reduce shrub expansion and thereby counteract the positive feedback on C cycling, but herbivore pressures have also changed in the alpine-arctic tundra; the increased shrub cover together with changes in herbivore pressure is leading to unpredictable changes in carbon sequestration and storage. In this study we investigate the importance of herbivory and shrub introduction for carbon sequestration in the short term. We measured standing biomass and daytime mid-growing season carbon fluxes in plots in a full factorial design where we excluded small and large mammalian herbivores and introduced Salix by planting Salix transplants. We used three study sites: one Empetrum-dominated heath, one herb- and cryptogam-dominated meadow, and one Salix-dominated shrub community in the low-alpine zone of the Dovre Mountains, Central Norway.ResultsAfter 2 years, significant treatment effects were recorded in the heath community, but not in the meadow and shrub communities. In the heath community cessation of herbivory increased standing biomass due to increased biomass of dwarf shrubs. Cessation of herbivory also reduced biomass of bryophytes and ecosystem respiration (ER). Except for an increase in biomass of deciduous shrubs caused by the Salix introduction, the only effect of Salix introduction was an increase in biomass of graminoids in the heath.ConclusionsOur short-term study demonstrated that herbivore exclusion had small but still significant effects on heath vegetation, whereas such effects were not apparent in the herb-and cryptogam-dominated meadow and the Salix-dominated shrub community. Following the treatments over more years is needed to estimate the long-term effects on community structure and the consequences for C sequestration in the three plant communities. Such data are important for predicting the impact of shrub expansion on C budgets from alpine regions.Electronic supplementary materialThe online version of this article (10.1186/s12898-018-0185-9) contains supplementary material, which is available to authorized users.

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Section: Discussionsupporting

confidence: 74%

Experimental herbivore exclusion, shrub introduction, and carbon sequestration in alpine plant communities

et al. 2018

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“…We established this experiment at a low (500 m) and a high (900 m The bedrock consists of salic igneous rocks and quartic and phyllitic hard schists. All of the study plots (n = 40) at both elevations were placed in heath vegetation, which is a common circumpolar vegetation type (Tybirk et al, 2000). Prior to experimental manipulations, data from each elevational site, which verified that fluxes across our plots were not spatially autocorrelated ( Figure S1).…”

Section: Study Site and Experimental Set-upmentioning

confidence: 59%

Responses of tundra plant community carbon flux to experimental warming, dominant species removal and elevation

et al. 2020

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“…The species were sampled at the end of the growing season of 2012 and at the start of the growing season in 2013. Both species are common throughout the southern Arctic and northern parts of the boreal zone and have a circumpolar distribution (groot et al 1997;tyBirK et al 2000). E. hermaphroditum is a shade-tolerant species (CaMPioli et al 2012a) and it is also an important constituent of the understorey vegetation in the boreal forest of Scandinavia, north-western Russia, and the Baltic states (tyBirK et al 2000).…”

Section: Study Sitesmentioning

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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NordicEmpetrumDominated Ecosystems: Function and Susceptibility to Environmental Changes

Cited by 108 publications

References 0 publications

Experimental herbivore exclusion, shrub introduction, and carbon sequestration in alpine plant communities

Experimental herbivore exclusion, shrub introduction, and carbon sequestration in alpine plant communities

Responses of tundra plant community carbon flux to experimental warming, dominant species removal and elevation

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

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