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Impact of climate warming on Arctic plant diversity: Phylogenetic diversity unravels opposing shrub responses in a warming tundra
Department of Earth Sciences, University of Gothenburg.
Ansvarig organisation
2022 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The Arctic biome is at significant risk, with recent observations suggesting thatclimate change is warming the Arctic nearly four times faster than the globalaverage. Last decade, evidence from experimental warming studies andobservations of ambient warming over time shows how increasing airtemperature in the Arctic has led to changes to arctic vegetation, andencroachment of trees and shrubs into the tundra. Thus, this amplified Arcticwarming is threatening biodiversity, changing vegetation patterns, and thawingpermafrost with implications for carbon and nutrient dynamics. These are oneof the main concerns of observed plant biodiversity changes (except the lossof biodiversity itself) as they feedback on the global climate through theireffects on carbon cycling, albedo, and ecosystem energy balance. Studies ofArctic biodiversity have reported responses in either taxonomic, functional, orphylogenetic diversity, though phylogenetic has so far been understudied inthe Arctic. These different measures of quantifying biodiversity will vary intheir explanatory value and can have complementary value when looking atthe implications of vegetation changes. The overall aim of this thesis is todeepen the knowledge of the effect of ambient and experimental climatewarming on taxonomic, functional, and phylogenetic aspects of plant diversitywithin and between communities.In Latnjajaure (northern Sweden) I used a long-term passive warmingexperiment using open-top chambers, which include five distinct plantcommunities. The communities had distinct soil moisture conditions, leadingto community-specific responses of the plant growth forms (deciduous shrubs,evergreen shrubs, forbs, and graminoids) and phylogenetic dissimilarity. Moistcommunities tended to decrease in soil moisture, which drove similarity todryer, more nutrient-poor communities. Warming significantly affectedgrowth forms, but the direction of the response was not consistent across thecommunities. Evidence of shrub expansion was found in nearly allcommunities, with soil moisture determining whether it was driven bydeciduous or evergreen shrubs. These changes are expected to affect climatefeedback as the dry, evergreen-dominated heath community, has slower carboncycling. This slowdown in carbon cycling is at least partially due to theevergreen shrubs whose material is harder to decompose than most other arcticvegetation. As the studied communities are common in the region, it is likelythat future warming will drive community shifts in the tundra landscape.On a Pan-arctic dataset of warming studies, I explored the effect of scalingabundance weighting as well as the importance of deeper against shallownodes in the phylogeny on warming response and its interaction with soil moisture and site temperature in the tundra biome. For all metrics, we lookedat both plot level (α-diversity), and the difference between plots (βdissimilarity). We show that β-dissimilarity is more sensitive to warming thanα-diversity metrics. Furthermore, we show that sensitivity to abundance andphylogenetic weighting depends on local soil moisture conditions.In conclusion, the combined use of taxonomic, phylogenetic, and functionaldiversity measures enhances the quality of our assessment of the implicationsof arctic vegetation response to warming.

Ort, förlag, år, upplaga, sidor
University of Gothenburg , 2022. , s. 50
Serie
Doctoral thesis A series 174, ISSN 1400-3813
Nyckelord [en]
Arctic, Oroarctic, Tundra, long-term warming, soil moisture, vegetation change, shrubification, biodiversity, phylogenetic diversity, plant community structure
Nationell ämneskategori
Klimatforskning Ekologi
Identifikatorer
URN: urn:nbn:se:polar:diva-8930ISBN: 978-91-8069-017-1 (tryckt)ISBN: 978-91-8069-017-1 (digital)OAI: oai:DiVA.org:polar-8930DiVA, id: diva2:1716249
Tillgänglig från: 2022-12-05 Skapad: 2022-12-05 Senast uppdaterad: 2022-12-05Bibliografiskt granskad
Delarbeten
1. Decreased soil moisture due to warming drives phylogenetic diversity and community transitions in the tundra
Öppna denna publikation i ny flik eller fönster >>Decreased soil moisture due to warming drives phylogenetic diversity and community transitions in the tundra
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2021 (Engelska)Ingår i: Environmental Research Letters, E-ISSN 1748-9326, Vol. 16, nr 6, artikel-id 064031Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Global warming leads to drastic changes in the diversity and structure of Arctic plant communities. Studies of functional diversity within the Arctic tundra biome have improved our understanding of plant responses to warming. However, these studies still show substantial unexplained variation in diversity responses. Complementary to functional diversity, phylogenetic diversity has been useful in climate change studies, but has so far been understudied in the Arctic. Here, we use a 25 year warming experiment to disentangle community responses in Arctic plant phylogenetic β diversity across a soil moisture gradient. We found that responses varied over the soil moisture gradient, where meadow communities with intermediate to high soil moisture had a higher magnitude of response. Warming had a negative effect on soil moisture levels in all meadow communities, however meadows with intermediate moisture levels were more sensitive. In these communities, soil moisture loss was associated with earlier snowmelt, resulting in community turnover towards a more heath-like community. This process of ‘heathification’ in the intermediate moisture meadows was driven by the expansion of ericoid and Betula shrubs. In contrast, under a more consistent water supply Salix shrub abundance increased in wet meadows. Due to its lower stature, palatability and decomposability, the increase in heath relative to meadow vegetation can have several large scale effects on the local food web as well as climate. Our study highlights the importance of the hydrological cycle as a driver of vegetation turnover in response to Arctic climate change. The observed patterns in phylogenetic β diversity were often driven by contrasting responses of species of the same functional growth form, and could thus provide important complementary information. Thus, phylogenetic diversity is an important tool in disentangling tundra response to environmental change.

Ort, förlag, år, upplaga, sidor
IOP Publishing, 2021
Nationell ämneskategori
Ekologi Klimatforskning
Identifikatorer
urn:nbn:se:polar:diva-8739 (URN)10.1088/1748-9326/abfe8a (DOI)
Tillgänglig från: 2021-07-21 Skapad: 2021-07-21 Senast uppdaterad: 2024-01-17Bibliografiskt granskad
2. Vegetation responses to 26 years of warming at Latnjajaure Field Station, northern Sweden
Öppna denna publikation i ny flik eller fönster >>Vegetation responses to 26 years of warming at Latnjajaure Field Station, northern Sweden
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2022 (Engelska)Ingår i: Arctic Science, E-ISSN 2368-7460, Vol. 8, nr 3, s. 858-877Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Climate change is rapidly warming high latitude and high elevation regions influencing plant community composition. Changes in vegetation composition have motivated the coordination of ecological monitoring networks across the Arctic, including the International Tundra Experiment. We have established a long-term passive warming experiment using open-top chambers, which includes five distinct plant communities (Dry Heath; Tussock Tundra; and Dry, Mesic, and Wet Meadow). We measured changes in plant community composition based on relative abundance differences over 26 years. In addition, relative abundance changes in response to fertilization and warming treatments were analyzed based on a seven-year Community-Level Interaction Program experiment. The communities had distinct soil moisture conditions, leading to community-specific responses of the plant growth forms (deciduous shrubs, evergreen shrubs, forbs, and graminoids). Warming significantly affected growth forms, but the direction of the response was not consistent across the communities. Evidence of shrub expansion was found in nearly all communities, with soil moisture determining whether it was driven by deciduous or evergreen shrubs. Graminoids increased in relative abundance in the Dry Meadow due to warming. Growth form responses to warming are likely mediated by edaphic characteristics of the communities and their interactions with climate.

Ort, förlag, år, upplaga, sidor
Ottawa, ON: Canadian Science Publishing, 2022
Nyckelord
International Tundra Experiment (ITEX), climate warming, Arctic, vegetation, Latnjajaure
Nationell ämneskategori
Ekologi
Identifikatorer
urn:nbn:se:polar:diva-8929 (URN)10.1139/as-2020-0042 (DOI)2-s2.0-85139987120 (Scopus ID)
Forskningsfinansiär
EU, Horisont 2020, 657627Forskningsrådet Formas, 2016-01187Forskningsrådet Formas, 942-2015-1382Vetenskapsrådet, 2018-04202
Anmärkning

Funding: BECC – Biodiversity and Ecosystem services in a Changing Climate (MPB, HR), The European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 657627 (MPB), The Swedish Research Council FORMAS – future research leaders No. 2016-01187 (MPB), The Swedish Research Council FORMAS No. 942-2015-1382 (RGB), The Swedish Research Council No. 2018-04202 (RGB), Swedish National Space Board No. 136/15 (HR), Carl Tryggers stiftelse för vetenskaplig forskning (MPB, JMA), Qatar Petroleum (JMA), and Stiftelsen Oscar och Lilli Lamms Minne (JMA).

Tillgänglig från: 2022-04-04 Skapad: 2022-12-05 Senast uppdaterad: 2022-12-05Bibliografiskt granskad
3. Limited decadal growth of mountain birch saplings has minor impact on surrounding tundra vegetation
Öppna denna publikation i ny flik eller fönster >>Limited decadal growth of mountain birch saplings has minor impact on surrounding tundra vegetation
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2022 (Engelska)Ingår i: Ecology and Evolution, E-ISSN 2045-7758, Vol. 12, nr 6, artikel-id e9028Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Temperatures over the Arctic region are increasing at three times the rate of the global average. Consequently, Arctic vegetation is changing and trees are encroaching into the tundra. In this study, we examine the establishment and growth of mountain birch (Betula pubescens ssp. tortuosa), which forms the treeline in subarctic Europe, and its impact on community composition across the treeline ecotone nearby Abisko, Sweden. Birch advancement along elevational gradients was studied by comparing data collected in 2016 with data collected 10 and 15 years previously. Species identity, cover, and phylogenetic relatedness were used to assess the impact of birch encroachment on community composition. Our results show that birch occurrence above the treeline did not affect plant community composition, probably owing to the observed lack of significant growth due to herbivore browsing, nitrogen limitation, or a reduction in snow cover. Independent of birch performance, the tundra community structure shifted toward a novel community dissimilar from the forest plant community found below the treeline. Taken together, our findings are explained by species-specific responses to climate change, rather than by a linear forest advance. Future treeline advancements are likely more restricted than previously expected.

Ort, förlag, år, upplaga, sidor
John Wiley & Sons, Ltd, 2022
Nyckelord
Betula pubescens, climate change, Oroarctic, phylogenetic diversity, plant community structure, treeline advance
Nationell ämneskategori
Ekologi
Identifikatorer
urn:nbn:se:polar:diva-8899 (URN)10.1002/ece3.9028 (DOI)
Tillgänglig från: 2022-12-02 Skapad: 2022-12-02 Senast uppdaterad: 2024-01-17Bibliografiskt granskad

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