Landnám birkis í frumframvindu og áhrif þess á vistkerfið - verkefni lokið

Fréttatilkynning verkefnisstjóra

31.5.2023

Ásýnd efri hlutar Skeiðarársands hefur tekið miklum breytingum í kjölfar þess að gróður fór að nema þar land, einkum eftir að birki (Betula pubescens spp. tortuosa) tók að vaxa upp. Landnám birkis hófst um 1990 af fræi sem kom að mestu frá Bæjarstaðarskógi og fannst á 35 km2 aldarfjórðungi síðar. Önnur kynslóð birkiplantna vex nú upp á svæðinu og það hefur hraðað enn frekar þróun vistkerfa. Á tímabilinu 2008–2018 jókst þéttleiki og stærð birkiplantna á fjórum rannsóknarsvæðum, en þó mjög mismikið eftir svæðum. Það sem kom helst á óvart var hversu mikill munur reyndist vera árið 2018 á
tveimur nálægum svæðum, með aðeins um 500 m fjarlægð á milli, en sem voru sambærileg áratug
fyrr. Á öðru svæðinu var vaxtarhraði meiri, plöntur voru beinvaxnari, fræframleiðsla var meiri og
annarrar kynslóðar plöntur uxu þar betur upp. Gæði birkifræs á Skeiðarársandi eru almennt léleg en mikil fræframleiðsla og góð lifun smáplantna vinna það upp. Rannsóknin sýnir jafnframt að birki
mótar umhverfi sitt og getur haft áhrif á stefnu og hraða framvindu með því að auka niðurbrotshraða í jarðvegi og jafnframt breytist tegundasamsetning sveppa og baktería í jarðvegi þegar birki vex upp. Sú gagngera umbreyting sem á sér stað á Skeiðarársandi sýnir vel hvað framvinda getur verið hröð þegar aðstæður eru hagstæðar.

English:
An incipient state shift is now apparent on the previously barren glacial outwash plain Skeiðarársandur in SE Iceland. Following slowly accelerated expansion of continuous vegetation on its upper part in the latter part of the 20th century, mountain birch (Betula pubescens spp. tortuosa) began colonizing the outwash plain around 1990, through long-distance dispersal from seed originating mostly from Bæjarstaðarskógur, approx. 10 km distance. Twenty-five years later, it occurred on at least 35 km2. Our research on the spatio-temporal patterns of the first two generations showed that during the decadal interval from 2008–2018, there had been an increase in all measured birch variables at four sites, but contrary to our predictions of converging dynamics, the sites had significantly diverged. This was especially clear for two sites only 500 m apart that were similar in 2008, but 10 years later, one of them had much faster growth rate, more upright trees growing, greater reproductive effort, and much greater second-generation seedling recruitment. Seed quality was very low at all sites due to pre-dispersal predation and seed abortion. However, great seed quantity counteracts this, together with high young seedling survival. Our research shows that colonization of mountain birch into a barren environment influences the soil environment by enhancing litter decomposition and affecting both the soil bacterial and fungal communities. The rapid change that has occurred on the outwash plain present an example of how fast natural regeneration can be when conditions are favourable. Our study on the colonization of mountain birch on Skeiðarársandur should contribute to improving the methodology of birch woodland restoration, which is one of the main official strategies for climate mitigation in Iceland.

Information on how the results will be applied
Haldið verður áfram að koma niðurstöðum verkefnisins á framfæri við vísindasamfélagið, almenning og aðra sem efnið tengist.

A list of the project's outputs

GREINAR:
Óskarsdóttir, G., Thorhallsdóttir, Th.E., Birkisdóttir, H.M., Jónsdóttir, A.H. & Svavarsdóttir, K. (2022).
Establishment of mountain birch (Betula pubescens ssp. tortuosa) on glacial outwash plain: Spatial
patterns and decadal processes. Ecology and Evolution 2022: 12:e9430. https://doi.org/10.1002/ece3.9430 [Opinn aðgangur]

Pálsson, S., Wasowicz, P., Heiðmarsson, S. & Magnússon, K.P. (2023). Population structure and genetic variation of fragmented mountain birch forests in Iceland. Journal of Heredity. esac062. https://doi.org/10.1093/jhered/esac062 [Opinn aðgangur]

Thórhallsdóttir, Th.E. & Svavarsdóttir, K. (2022). The environmental history of Skeiðarársandur glacial outwash plain, SE Iceland. Journal of the North Atlantic 12: 1-212022. https://doi.org/10.3721/037.006.4303 [Greinin er aðgengileg í gegnum ResearchGate]

Þórhallsdóttir, Þóra Ellen, Svavarsdóttir, Kristín & Óskarsdóttir, Guðrún (2022). Establishment of mountain birch (Betula pubescens ssp. tortuosa) on a glacial outwash plain: spatial patterns and decadal processes. Dryad, Dataset, https://doi.org/10.5061/dryad.4b8gthtgj [Opin gögn]

HANDRIT:
Pálsson, S., Thórhallsdóttir, Th.E., Svavarsdóttir, K. & Magnússon, K.P. (innsent). Genetic variation and origin of mountain birch on a recently colonize glacial outwash plain, Skeiðarársandur south of Vatnajökull glacier, Iceland. Hefur verið sent til Tree Genetics and Genomes.

Óskarsdóttir, G., Svavarsdóttir, K. & Thorhallsdóttir, Th.E. (lokadrög). Spatio-temporal patterns in reproductive effort and seed quality of Betula pubescens in early successional subarctic environment. Verður sent fljótlega til Annals of Botany.

Birkisdóttir, H.M., et al. Age structure and size distributions of a colonizing tree population in an early successional environment. Handritsdrög.

Birkisdóttir, H.M. et al. Growth patterns of a colonising Betula pubescens population. Handritsdrög.

Tómasson, J.B.U. et al. Soil carbon dynamics during mountain birch colonization of a sparsely vegetated glacial outwash plain in Iceland. Handritsdrög.

Tómasson, J.B.U. et al. Characterization of microbial communities during the early establishment of mountain birch (Betula pubescens ssp. tortuosa) in SE Iceland. Handritsdrög.

RÁÐSTEFNUR:
Ráðstefna VistÍs (Vistfræðifélag Íslands) 2018, Reykjavík; https://nordicsocietyoikos.org/sites/default/files/contentfiles/Icelandic%20Ecological%20Society/agrip_vistis_20180315.pdf Þóra Ellen Þórhallsdóttir og Kristín Svavarsdóttir (erindi). Skeiðarársandur frá landnámi til 1500. Bls. 5.

Kristín Svavarsdóttir og Þóra Ellen Þórhallsdóttir (veggspjald). Skeiðarársandur: lifandi rannsóknastofa fyrir framvindurannsóknir. Bls. 12.

Ráðstefna VistÍs (Vistfræðifélag Íslands) 2019, Hólum; https://nordicsocietyoikos.org/sites/default/files/contentfiles/Icelandic%20Ecological%20Society/20190404_abstracts.pdf Kristín Svavarsdóttir o.fl. (erindi). Fyrstu framvindustig víðáttumesta birkiskógar á Íslandi? E22.
Kristinn P. Magnússon o.fl. (erindi). The colonization of downy birch (Betula pubescens) in early succession at Skeiðarársandur south of Vatnajökull is originated from Skaftafell. E15.

Guðrún Óskarsdóttir o.fl. (veggspjald). Colinization of downy birch in early succession. P5.

Hulda Margrét Birkisdóttir o.fl. (veggspjald). Growth and age of Downy Birch on Skeiðarársandur: Age and size distribution and growth patterns of a colonising population of downy birch on a early successional outwash plain. P6.

Jóhannes Bjarki Urbancic Tómasson o.fl. (veggspjald). The effects of birch colonization on soil organic matter decomposition. P15.

Vigdís Freyja Helmutsdóttir o.fl. (veggspjald). Hlutverk gulvíðis og loðvíðis í frumframvindu gróðurvistkerfa. P9.

Líffræðiráðstefnan 2019, Reykjavík; http://biologia.is/liffraediradstefnan-2019/dagskra/
Guðrún Óskarsdóttir o.fl. (erindi). Spatial and temporal patterns of early population establishment and growth of downy birch (Betula pubescens Ehr.) on a glacial outwash plain.  http://biologia.is/files/agrip_2019/E47.html

Hulda Margrét Birkisdóttir o.fl. (veggspjald). Growth rates and age of downy birch on Skeiðarársandur. http://biologia.is/files/agrip_2019/V15.htmlIRF

Jóhannes Bjarki Urbancic Tómasson o.fl. (veggspjald). Áhrif landnáms birkis á Skeiðarársandi á kolefnishringrás í jarðvegi. http://biologia.is/files/agrip_2019/V41.html

Benedikt Traustason o.fl. (veggspjald). Landnám birkis. http://biologia.is/files/agrip_2019/V42.html

Vigdís Freyja Helmutsdóttir o.fl. (veggspjald). Woolly willow: an ecosystem engineer in Iceland. http://biologia.is/files/agrip_2019/V42.html

Oikos 2020, Reykjavík; https://www.eventure-online.com/eventure/login.form?U877898d5-0a10-4cf7-bfde-11dcd43c2291#

Guðrún Óskarsdóttir o.fl. (erindi). Spatial and temporal patterns of early population establishment of downy birch (Betula pubescens Ehr.) on a glacial outwash plain.

Hulda Margrét Birkisdóttir o.fl. (veggspjald). Patterns of population growth rates of downy birch (Betula pubescens Ehrh.) on an early successional outwash plain.

Jóhannes Bjarki Urbancic Tómasson o.fl. (veggspjald). Soil microbial community chages during a chronosequence of downy birch colonization on a glacial flood plain.

Kristinn P. Magnússon o.fl. (veggspjald). The search for the origin of the nascent birch forest on Skeiðarársandur: genetic comparison with the neghboring birch woodlands south of Vatnajökull.
Benedikt Traustason o.fl. (veggspjald). Early birch colonization of a steep scree slope, lava flow and outhwash plain.

Vigdís Freyja Helmutsdóttir o.fl. (veggspjald). Woolly willow: an ecosystem engineer in Iceland?

Ráðstefna VistÍs (Vistfræðifélag Íslands) 2021, vefráðstefna; https://nordicsocietyoikos.glueup.com/event/icelandicecological-society-meeting-2021-32791/
Guðrún Óskarsdóttir o.fl. (erindi). High seed quantity and seedling survival of Betula pubescens can counteract poor seed quality.

Hulda Margrét Birkisdóttir o.fl. (erindi). Correlates of annual growth fluctuations in a colonizing birch population.

Jóhannes Bjarki Urbancic Tómasson o.fl. (erindi). Tiny changes – how do soil fungal communities change during downy birch (Betula pubescens) succession?

Kristinn P. Magnússon o.fl. (erindi). Genetic diversity, population structure, and relationships in a downy birch (Betula pubescens) across Iceland revealed by genotyping-by-sequencing (GBS).

https://nordicsocietyoikos.glueup.com/event/icelandic-ecological-society-meeting-2021-32791/posters.html

Vigdís Freyja Helmutsdóttir o.fl. (veggspjald). Impacts of dioecious woolly willow on soil processes.

Líffræðiráðstefnan 2021, Reykjavík; http://biologia.is/liffraediradstefnan-2019/dagskra/

Guðrún Óskarsdóttir o.fl. (erindi). Deterministic versus stochastic processes during succession: Insights from early tree establishment on a glacial outwash plain. http://biologia.is/files/agrip_2021/E7.html

Benedikt Traustason o.fl. (veggspjald). Growth rates and structural traits of different growth forms of mountain birch (Betula pubescens). http://biologia.is/files/agrip_2021/V10.html

Vigdís Freyja Helmutsdóttir o.fl. (veggspjald). Woolly willow: an engineer of Icelandic ecosystems?
http://biologia.is/files/agrip_2021/V6.html

Ráðstefna BES (British Ecological Society), EAB2021, netráðstefna; https://www.britishecologicalsociety.org/events/festival-ofecology/ecology-across-borders-2021/
https://www.britishecologicalsociety.org/wp-content/uploads/2021/11/EAB2021-Online-Meeting-Overview.pdf

Guðrún Óskarsdóttir o.fl. (veggspjald). A stage-based transition model for Betula pubescens colonizing an early successional outwash plain. https://eab2021.events.whova.com/Artifact/36805

Ráðstefna BES (British Ecological Society), EAB2022, Edinburgh 18-21. Desember 2022; Guðrún Óskarsdóttir, Thora Ellen Thorhallsdóttir, Kristín Svavarsdóttir 2022 (veggspjald). Seed quality, losses, and fates in a young Betula pubescens population. https://eab2021.events.whova.com/Artifact/36805

NÁMSVERKEFNI:
Benedikt Traustason (2022). Biomass, growth and life history traits in mountain birch (Betula pubescens subsp. tortuosa (Ledeb.) Nyman) of contrasting growth form (Ís: Lífmassi vöxtur og lífsögubreytur birkis (Betula pubescens subsp. tortuosa (Ledeb.) Nyman) með ólík vaxtarform). MS ritgerð á verkfræði – og náttúruvísindasviði, Háskóla Íslands.  https://skemman.is/handle/1946/41536

Vigdís Freyja Helmutsdóttir (2022). Woolly willow (Salix lanata L.): an engineer of subarctic ecosystems? (Ís: Loðvíðir (Salix lanata L.): vistmeitill í lágarktískum vistkerfum?). MS ritgerði á verkfræði- og náttúruvísindasviði, Háskóla Íslands. https://skemman.is/handle/1946/41577

Heiti verkefnis: Landnám birkis í frumframvindu og áhrif þess á vistkerfið/ Colonisation of downy birch in early succession and its ecosystem impact
Verkefnisstjóri: Kristín Svavarsdóttir, Landgræðslunni
Tegund styrks: Verkefnisstyrkur
Styrktímabil: 2017-2019
Fjárhæð styrks kr. 54.717.000
Tilvísunarnúmer Rannís: 173688