2.8. Building a time machine out of a Delorean: Observing, reconstructing, and predicting vegetation change in the Arctic

27 March 2025 | 10:30 - 12:00 and 16:00 - 18:00 (MDT)

Open Session - HYBRID

Room:  Glen Miller Ballroom in UMC - 208

Organisers:  Donald Walker (Institute of Arctic Biology, University of Alaska Fairbanks, USA); Gabriela Schaepman-Strub (Department of Evolutionary Biology and Environmental Studies, University of Zurich, Switzerland); Amy Breen (University of Alaska Fairbanks, USA)

Session Description:

Arctic landscapes are rapidly changing due to factors such as climate alterations, accelerated nutrient cycling, and increased disturbances like wildfires and resource development. These changes drive shifts in vegetation composition and function, serving as key indicators of broader transformations in topography, hydrology, and permafrost.

The Circumpolar Arctic Vegetation Science Initiative (CAVSI) is proposed for ICARP IV to establish a framework for classifying, mapping, and monitoring Arctic vegetation. It aims to create a network of sites with permanent plots representing diverse Arctic conditions, using standardized methods for vegetation surveys and data management. This initiative builds on existing monitoring sites in northern Alaska and could be integrated into U.S. and international Arctic observing networks. Alternatively, the community may identify a need to establish a novel Arctic Vegetation Observatory Network.

The session will highlight recent advances in Arctic vegetation classification and monitoring, particularly as we look ahead to the 5th International Polar Year (2032–2033), with the goal of implementing CAVSI based on lessons learned from other networks and putting forth a framework that aligns with the research priorities identified by ICARP IV. We also invite studies on the impacts of vegetation change on processes such as hydrology, permafrost degradation, and carbon balance. We welcome diverse research approaches to monitor vegetation across temporal and spatial scales, including field surveys, remote sensing, and Earth system models, thereby contributing to a deeper understanding of Arctic ecosystems

Oral Presentations - Part 1 (10:30 - 12:00 MDT):

• unfold_moreArctic polar deserts: baselines to study change at the northern edge of plant life — Vitalii Zemlianskii 

  Vitalii Zemlianskii ¹; Ksenia Ermokhina ²; Nils Rietze ¹; Ramona Heim ³; Jakob Assmann ¹; Gabriela Schaepman-Strub ^{1
  1} University of Zürich; ² A.N. Severtsov Institute of Ecology and Evolution; ³ Institute of Landscape Ecology, University of Münster

  Format: Oral in-person

  Abstract:

  Arctic polar deserts make up the northernmost terrestrial biome located mainly on Arctic islands. They are characterized by near-zero summer temperature, patchy vegetation primarily consisting of cryptogams, and low diversity. Due to ongoing Arctic amplification, polar deserts are expected to shrink, giving place to continuous tundra vegetation and leading to changes in permafrost insulation, carbon storage and biodiversity.

  The study of polar desert biomass is important due to its high sensitivity to climate driven changes yet we lack baselines as monitoring in these environments is challenging. Lack of ground truth data, high landscape heterogeneity, and vegetation patchiness create methodological difficulties for biomass quantification. We show that vegetation cover but not NDVI is a useful predictor for plant and lichen biomass and emphasize the need to combine in-situ data with drone imagery to accurately estimate biomass of polar deserts.

  The cover-based approach helps establishing baselines for biomass, but gaps in monitoring of plant diversity remain. In contrast to most other terrestrial ecosystems, vascular plants play a relatively minor role in polar deserts, while cryptogams make up a majority of their diversity. Despite the importance of polar islands as potential future climate refugia for climate-threatened Arctic species, differences in diversity and their underlying factors are not fully understood as the islands vary in size, relief, and history. We estimate the diversity of the polar islands and its drivers providing a ground-truth geobotanical data for some of the most understudied part of the Russian Arctic such as Vize, Uedineniya Islands and Severnaya Zemlya.

• unfold_moreThe vegetation of the Little Ice-Age and earlier could be studied from entombed vegetation under the Barnes Icecap without a time-machine — Helga Bültmann 

  Helga Bültmann ¹; Shawnee Kasanke ²; Martha Raynolds ^{3
  1} University of Münster; ² SW Washington State University; ³ University of Alaska Fairbanks

  Format: Oral in-person

  Abstract:

  The Barnes Ice Cap, Baffin Island, Nunavut is a remnant of the Laurentide Ice Sheet and is expected to disappear within 300 years (Gilbert et al. 2017). For the IPY “Back to the Future” project (BTF no. 214), a vegetation survey from 1964 was repeated in 2007 (Dr Patrick J. Webber), demonstrating rapid changes over forty years. In 2022 the vegetation near the southern Barnes Ice Cap was studied, including a few samples of emergent vegetation that had been entombed by progressing ice of the Little Ice Age (radiocarbon dating, Raynolds et al. 2024). The entombed vegetation was in extraordinarily shape and was not unique. Other sites could only be sampled for carbon dating due to logistic restraints.

  Even older vegetation will thaw out the next decades as the Barnes Ice Cap continues to retreat, and could be a source of valuable data for reconstructing past vegetation of the Arctic. Data sampling could include vegetation (relevé), lichenometry, plant wax isotopes, DNA from plants and soil (aDNA, eaDNA), radiocarbon dating.

  The window for data collecting is short as the sites erode quickly and the organic remains are colonized by new vegetation. If not sampled, the data source will be lost. We propose an initiative sampling the vegetation being exhumed by the Barnes Ice Cap. The entombed vegetation is a unique chance for actually observing, recording and mapping ancient vegetation. The monitoring of ancient vegetation should follow the retreating ice in a longer but regular timespan.

• unfold_moreA Circumpolar Arctic Vegetation Science Initiative (CAVSI): Need for and goals of a vegetation observation network — Donald Walker 

  Donald Walker ¹; Amy Breen ²; Gabriela Schaepman-Strub ³; Helga Bültmann ⁴; Howard Epstein ⁵; Ksenia Ermokhina ⁶; Gerald Frost ⁷; William MacKenzie ⁸; Nadezhda Matveyeva ⁹; et al.
  ¹ University of Alaska Fairbanks; ² University of Alaska Fairbanks; ³ University of Zurich, Switzerland; ⁴ University of Münster, Germany; ⁵ University of Virginia, USA; ⁶ A.N. Severtsov Institute of Ecology and Evolution, Moscow, Russia; ⁷ Alaska Biological Reseearch, Fairbanks, AK, USA; ⁸ Province of British Columbia, Smithers, BC, Canada; ⁹ Komarov Botanical Institute, St. Petersburg, Russia

  Format: Oral in-person

  Abstract:

  Vegetation data, classifications, and maps have been and will continue to be crucial resources for examining and predicting circumpolar environmental changes during the next 10 years of Arctic Research, including IPY 2032-33. A well-distributed Arctic vegetation observation network with internationally accepted protocols for sampling, describing, classifying, and mapping vegetation are needed as a framework for numerous initiatives that will draw on vegetation data. The Circumpolar Arctic Vegetation Science Initiative (CAVSI) workshop at ICARP IV is a forum for discussion and development of a white paper that will provide a 10-year roadmap for: (1) creating a CAVSI observation network; (2) standardized protocols for sampling, archiving, classifying, and mapping Arctic vegetation; and (3) applications of the products to priority ICARP IV research topics. This talk focuses on the goals of the initiative from the perspective of emerging challenges and opportunities for Arctic vegetation science, and how to develop a network that considers the wide diversity of sampling, monitoring, and mapping approaches that already exist. A group of vegetation monitoring sites along a bioclimate gradient in northern Alaska and other examples will be examined as possible starting points. The workshop will solicit suggestions for incorporating new tools such as drones, high-resolution remote-sensing methods, process-based species-distribution models, and use of next-generation genomic sequencing methods to survey plots. Other needs include the training of the next generation of Arctic vegetation scientists, and involvement by indigenous people and other stake holders in the co-design, co-production and long-term observations of the network.

• unfold_moreNext generation maps of plant aboveground biomass for the Arctic tundra biome — Kathleen Orndahl 

  Kathleen Orndahl ¹; Logan Berner ¹; Matthew Macander ²; Scott Goetz ¹; The Arctic Tundra Plant Biomass Synthesis Network ^{3
  1} Northern Arizona University; ² ABR, Inc.—Environmental Research & Services; ³ The Arctic Tundra Plant Biomass Synthesis Network

  Format: Oral in-person

  Abstract:

  The Arctic is warming faster than anywhere else on Earth, placing tundra ecosystems at the forefront of global climate change. Plant biomass is a fundamental ecosystem attribute that is sensitive to changes in climate, closely tied with ecological function and crucial for determining ecosystem carbon storage. However, the amount, composition, and distribution of plant biomass remains poorly understood across the Arctic. We developed the first moderate resolution (30m) maps of plant and woody plant aboveground biomass (gm-2) and woody dominance (%) for the Arctic tundra biome. We modeled biomass for the year 2020 using a new synthesis dataset of field measurements, Landsat satellite seasonal synthetic composites, and machine learning models. Moreover, we quantified pixel-wise uncertainty in biomass predictions using Monte Carlo simulations and validated predictions using a robust cross-validation procedure. Validation showed prediction root-mean-squared-error (RMSE)≈400 gm-2, relative RMSE.

• unfold_moreHow climate variables affect CO2 fluxes from the High Arctic Tundra vegetation? Modelling flux climate drivers as a step towards the establishment of a pan-Arctic Critical Zone observation network — Mariasilvia Giamberini 

  Mariasilvia Giamberini ¹; Francesca Avogadro di Valdengo ^1,2; Ilaria Baneschi ¹; Marta Magnani ¹; Silvio Marta ¹; Antonello Provenzale ¹; Gianna Vivaldo ^{1
  1} Institute of Geoscience and Earth Resources - National Research Council of Italy; ² Joint CNR-ENI Research Centre on the Arctic Cryosphere “Aldo Pontremoli”, Nanotec-CNR, via Monteroni, 73100, Lecce, Italy

  Format: Oral in-person

  Abstract:

  Terrestrial ecosystems regulate the carbon cycle, and therefore atmospheric CO2 and Earth climate. The Arctic plays a major role in this cycle, due to the large amount of carbon stored in Arctic soil and vegetation. During the Holocene, the tundra has been acting as a carbon sink, but it is not clear if the Arctic warming will turn it into a carbon source. Yet, data regarding Arctic CO2 fluxes are scarce and the modelling of their dynamics and fate is affected by large uncertainties.

  Aiming at investigating the tundra soil and vegetation dynamics under climate pressures, CNR established the Bayelva Critical Zone Observatory in Ny Ålesund, Svalbard, since 2019, equipped with an Eddy Covariance tower and flux chambers for measuring Gross Primary Productivity (GPP) and Ecosystem Respiration (ER) at ecosystem scale, and correlating such variables to climate and environmental parameters, vegetation types and functions, and phenology. We quantified the dependence of CO2 fluxes from a number of parameters at the local scale.

  We are proposing the creation of a network of pan-arctic observatories with different vegetation composition and climate features to generalize the CO2 fluxes modelling effort and provide a sound database as a benchmark for models at various scales, including their use for validating remote-sensing estimates that link climate and vegetation composition and phenology to CO2 fluxes. This will facilitate the identification of the main variables to be used in general vegetation models and allowing future projections of CO2 fluxes under different climate change scenarios in the Arctic tundra.

• unfold_moreWhat else matters? Influence of soil development on plant responses in a greening Arctic — Jana Rüthers 

  Jana Rüthers ¹; Lena Bakker ²; Sebastian Doetterl ³; Simone Fior ⁴; Marco Griepentrog ⁵; Annina Maier ⁶; Moritz Mainka ⁷; Kristine Bakke Westergaard ⁸; Jake Alexander ^{9
  1} Department of Environmental Systems Science, ETH Zurich; ² Department of Earth and Planetary Sciences, ETH Zurich; ³ Department of Earth Sciences, ETH Zurich; ⁴ Department of Environmental Systems Science, ETH Zurich; ⁵ Department of Earth Sciences, ETH Zurich; ⁶ Department of Earth Sciences, ETH Zurich; ⁷ Department of Earth Sciences, ETH Zurich; ⁸ Department of Natural History, NTNU University Museum, Trondheim; ⁹ Department of Environmental Systems Science, ETH Zurich

  Format: Oral in-person

  Abstract:

  Arctic Greening has been observed in recent years, with an increase in plant biomass and productivity. However, the patterns of greening are heterogenous, and the reasons for this are not fully understood. One reason for this heterogeneity might be variation in soil development and weathering processes, which could accelerate and affect vegetation responses as climate warms. In this interdisciplinary project we try to gain insight into how changing soil properties might be linked to future vegetation development. We conducted vegetation surveys, trait measurements and soil analyses on Svalbard in distinct habitat types, representing different soil development stages. Detailed analyses of the environmental and soil specific factors affecting the plant responses are still in progress for the presentation. However, initial results indicate a decrease in dwarf-shrub cover and an increase in graminoid cover on more developed and fertile soils. Species also differ in their growth and resource allocation strategies between habitats, with some species improving their performance on more developed soils. In general, a high variability in cover by plant functional type was observed both within and between habitat types. These first results hint that changing plant communities and increasing greening may be more strongly linked to soil development than to warming alone. This could also modify plant-soil-feedbacks in the Arctic and reinforce the greening. Further, certain highly specialized species, occurring only in single habitat types with little trait plasticity, may be at risk of being outcompeted by the changing plant community. This information is highly relevant for conservation purposes.

Oral Presentations - Part 2 (16:00 - 18:00 MDT): 

• unfold_moreLong-term tundra monitoring reveals hotspots of tundra vegetation change with warming and biotic interactions — Isla H. Myers-Smith 

  Sarah Elmendorf ¹; Mariana García Criado ²; Joseph Everest ³; Anne Bjorkman ⁴; Isla Myers-Smith ⁵; Robert Hollister ⁶; ITEX Consortium
  ¹ University of Colorado; ² University of Edinburgh; ³ University of Edinburgh; ⁴ University of Gothenburg; ⁵ Department of Forest & Conservation Sciences, Faculty of Forestry, University of British Columbia; ⁶ Grand Valley State University

  Format: Oral in-person

  Abstract:

  Coordinated distributed experiments and long-term monitoring networks provide unique opportunities for documenting decadal scale ecological change. Longitudinal data from such networks are particularly valuable for understanding change in the tundra, where dramatic changes in climate are already underway. Here, we present recent synthetic work from the ITEX+ network, a grassroots effort consisting of permanent vegetation plots, often paired with experimental warming treatments, distributed throughout Arctic and alpine tundra worldwide. Ongoing efforts to expand the network together with dedicated data harmonization efforts have yielded a pan-Arctic dataset of vegetation composition and abundance, with over 10,000 plots, in 271 study areas distributed across 5 continents, surveyed between 1980 and 2023. Recent syntheses highlight instances of both vegetation change and stability across monitoring locations, and inform our understanding of the processes likely to alter plant species diversity under a warming climate. Over the network as a whole, we find that plant species richness is greater in lower latitude and warmer sites. Despite substantial warming, average species richness was not increasing over time. In contrast, species composition changed over time in most plots. Species turnover was highest in rapidly warming sites, whereas species loss was highest where shrubs - particularly tall shrubs - increased in dominance. Changes in functional diversity largely mirrored those in species diversity, with decreased functional diversity in colder, high latitude sites or those with increasing shrub dominance. Together, these results indicate climate and biotic interactions jointly influence the taxonomic and functional diversity of a warming tundra.

  unfold_moreExamining the impacts of land cover upscaling on wetland extent and regional carbon balance projections — Benjamin Maglio 

  Benjamin Maglio ¹; Valeria Briones ²; Ruth Rutter ¹; Tobey Carman ¹; Anja Kade ¹; Howard Epstein ³; Donald Walker ¹; Anna Liljedahl ²; Elchin Jafarov ²; Brendan Rogers ²; Helene Genet ^{1
  1} Institute of Arctic Biology, University of Alaska Fairbanks; ² Woodwell Climate Research Center; ³ Department of Environmental Sciences, University of Virginia

  Format: Oral in-person

  Abstract:

  The Arctic tundra, which occupies ～10% of the terrestrial land surface, contains about a third of the global carbon stocks. Over half of the region is characterized by ice-wedge polygonal tundra rich in wetland systems. As the region is experiencing rates of warming up to four times greater than the rest of the planet, permafrost thaw can impact both carbon and water balances, and modulate the release of methane from these wetlands. Terrestrial biosphere models (TBMs) are used to predict the impact of climate-driven permafrost thaw on ecosystem carbon balance. However, TBMs usually simulate the landscape heterogeneity at coarse spatial resolutions that are much greater than the actual scale of wetlands, resulting in underestimation of the extent and variability of Arctic wetlands. In this study, we evaluated the consequences of the misrepresentation of wetland spatial distribution in the Arctic terrestrial carbon balance. We used a state-of-the-art TBM specifically developed for Arctic regions. We compare simulations of the Alaskan coastal plain using majority-selection upscaled CircumArctic Land cover Units (CALU, 10-m resolution) at 1 and 4 km resolution to inform vegetation and soil communities in DVM-DOS-TEM, a TBM developed for the high latitudes. We compared the associated carbon budget of these simulations, with a carbon budget built on simulations representing sub-grid wetland percent cover estimated from the original 10 m resolution product. Our study shows discrepancies between carbon budgets calculated at differing resolutions and emphasizes the importance for TBMs to represent sub-grid landscape distribution in producing regional carbon budgets in the Arctic.

  unfold_moreArctic-alpine glacial forelands: refugia habitat development coinciding with ongoing rapid change — Shawnee Kasanke 

  Shawnee Kasanke ¹; Christopher Kasanke ²; Helga Bültman ³; Martha Raynolds ^{4
  1} Washington State University, Alaska Geobotany Center, University of Alaska Fairbanks; ² Walla Walla Community College; ³ University of Münster; ⁴ University of Alaska Fairbanks

  Format: Oral in-person

  Abstract:

  Primary succession by plants and microorganisms following major disturbances such as deglaciation largely governs soil development, moisture retention, and habitat formation on freshly exposed substrates. Glacial forelands have long been model systems for studying the process of primary succession, but Arctic alpine glacial forelands have largely been excluded. Pioneer organisms eventually develop habitat that can serve as refugia for Arctic taxa displaced by rapid warming and limited in range expansion opportunities. There is an urgent need to document the successional process and relationships between pioneer organisms in Arctic alpine glacial forelands to help predict ongoing effects of deglaciation and define when and what kinds of new habits will become available as a result.

  We propose an initiative to study primary succession in Arctic alpine glacial cirque forelands starting in the North American Arctic and expanding to Europe. Beginning this research within 40 years of glacial retreat is essential to accurately document primary succession, and is a unique opportunity to establish long-term study sites to observe this process over time. Data collected will include identification of plant-microbe interactions influencing succession, soil formation, vegetation classification, rates of plant and microorganism establishment, community shifts, and wildlife use. We will compare communities forming on substrates of similar ages along glacial chronosequences spanning from recently deglaciated surfaces to glacial deposits from the Little Ice Age (~500-1000 years ago). To accurately collect these data, we will also update the lichenometric curve for the region to reflect increasing temperatures, and use these measurements to date recent glacial deposits.

• unfold_moreAssessing the impact of reindeers grazing on tundra vegetation and their influence on carbon and nitrogen cycles in Svalbard Islands — Carlotta Volterrani 

  Carlotta Volterrani ¹; Angela Augusti ²; Emanuele Pallozzi ³; Enrico Brugnoli ⁴; Federica D'Alò ⁵; Olga Gavrichkova ^{6
  1} Institute of Research on Terrestrial Ecosystems (IRET), National Research Council of Italy (CNR), 05010 Porano, Italy, Department of Environmental Sciences, Informatics and Statistics (DAIS), Cà Foscari University of Venice, 30172 Mestre (VE), Italy; ² Institute of Research on Terrestrial Ecosystems (IRET), National Research Council of Italy (CNR), 05010 Porano, Italy; ³ National Biodiversity Future Center (NBFC), 90133 Palermo, Italy, Institute of Research on Terrestrial Ecosystems (IRET), National Research Council of Italy (CNR), 00015 Monterotondo, Italy; ⁴ Institute of Research on Terrestrial Ecosystems (IRET), National Research Council of Italy (CNR), 05010 Porano, Italy; ⁵ Institute of Research on Terrestrial Ecosystems (IRET), National Research Council of Italy (CNR), 05010 Porano, Italy; ⁶ Institute of Research on Terrestrial Ecosystems (IRET), National Research Council of Italy (CNR), 05010 Porano, Italy, National Biodiversity Future Center (NBFC), 90133 Palermo, Italy

  Format: Oral in-person

  Abstract:

  Climate change impacts plant physiology and the carbon (C) and nitrogen (N) cycles in Arctic ecosystems, which contain about 50% of the world’s underground organic carbon. The Arctic tundra is experiencing significant changes due to global warming and permafrost thaw, leading to increased CO₂ and CH₄ emissions. Herbivores, like reindeers, play an important role in these dynamics by influencing vegetation structure and composition, thereby altering the C and N cycles through grazing and soil modification. Because reindeer populations experience considerable fluctuations with changing climate, understanding the role of grazing in Arctic tundra dynamics is essential for predicting the ecological responses to climate change in the Arctic.

  This study investigates the effects of reindeer grazing on the tundra by comparing areas with and without big grazers (through fences) on Svalbard Islands. It focuses on the interaction between grazing, plant composition, microbial activity, and C and N cycles. A multifaceted methodological approach includes alongside vegetation monitoring, its functional performance with CO₂ flux measurements, elemental and isotopic analysis under natural abundance to characterize WUE and nutrients cycling (δ¹³C, δ¹⁵N) and isotope labeling to track N allocation dynamics.

  The aim is to clarify how grazing influences the Arctic carbon balance and its long-term consequences for climate and land management. By understanding the complex interactions between vegetation, soil, and herbivores, the findings will improve climate models and support efforts to mitigate climate change impacts through better land management practices.

• unfold_moreVariability of major vegetation types in Arctic Alaska: Key gradients, vegetation units, and syntaxonomy — Jozef Sibik 

  Jozef Sibik ¹; Skip Walker ²; Amy Breen ²; Helga Bültmann ³; Olivia Hobgood ²; Bryana McNeal ²; Jana Peirce ²; Maria Sibikova ¹; Martha Raynolds ²; David Cooper ⁴; Marilyn Walker ^{5
  1} Plant Science and Biodiversity Center of Slovak Academy of Sciences; ² Department of Biology and Wildlife, Alaska Geobotany Center, Institute of Arctic Biology, University of Alaska Fairbanks, AK, USA; ³ University of Münster, Germany; ⁴ Department of Forest & Rangeland Stewardship, Colorado State University, CO, USA; ⁵ Homer Energy (retired), Boulder, CO, USA

  Format: Oral in-person

  Abstract:

  The Arctic is experiencing rapid changes driven by climate fluctuations, enhanced nutrient cycling, and increasing disturbances like wildfires and resource extraction. These changes significantly impact vegetation patterns, serving as indicators of broader landscape shifts, including alterations in topography, hydrology, and permafrost dynamics. In response, the Arctic Vegetation Classification (AVC) is essential to the Circumpolar Arctic Vegetation Science Initiative (CAVSI) under ICARP IV, which aims to create a comprehensive framework for classifying, mapping, and monitoring Arctic vegetation.

  Since 1992, the Arctic Vegetation Archive (AVA) and AVC have been developed through collaborative workshops, recently using the Turboveg system for data management and the Braun-Blanquet classification method, which has proven effective across the Arctic. With around 31,000 documented vegetation plots, the AVA enhances understanding of diverse Arctic habitats and builds on monitoring efforts in northern Alaska, potentially integrating into broader Arctic observation networks or creating a dedicated Arctic Vegetation Observatory Network (AVON).

  Our research emphasizes the diversity of major vegetation types, both zonal and azonal, reflecting a range of environmental conditions, disturbances, and changes over time. We advocate for the Braun-Blanquet units as a universal system for vegetation classification that can be applied globally while also considering the structural and textural characteristics of plant communities. This approach is crucial for understanding microclimatic properties, the ecological roles of species, and mapping vegetation effectively. It indicates that vegetation structure should be a key component in developing a universal phytosociological system alongside floristic criterion.

• unfold_moreMonitoring Arctic Shrubification and Its Environmental Covariates Using Machine Learning — Gerald Frost 

  Gerald Frost ¹; Matthew Macander ¹; Paul Montesano ²; Anna Derkacheva ³; Jordan Caraballo-Vega ²; Mark Carroll ²; Howard Epstein ⁴; Ksenia Ermokhina ⁵; Nora Fried ¹; Christopher Neigh ^{2
  1} Alaska Biological Research, Inc.; ² Goddard Space Flight Center, National Aeronautics and Space Administration; ³ International Laboratory of Landscape Ecology, HSE University; ⁴ Department of Environmental Sciences, University of Virginia; ⁵ A. N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences

  Format: Oral in-person

  Abstract:

  Tundra shrub expansion is a crucial form of change in warming Arctic ecosystems, but spatio-temporal patterns of shrubification vary across multiple spatial scales, complicating efforts to understand its drivers and consequences. Here we demonstrate imagery analysis workflows using Convolutional Neural Networks (CNNs) to identify spatio-temporal patterns of tall shrub expansion in very-high resolution satellite image pairs acquired 10–23 years apart (circa 2000–2023). We also examine patterns of change and stability to identify relationships between shrub occurrence, landscape-scale environmental covariates, and antecedent shrub cover in diverse Arctic landscapes. In our first workflow we apply a tile-based image analysis framework to map four canopy cover classes within 12 x 12 m map tiles in three Low Arctic landscapes in northwestern Siberia. Our models detected shrub increase in all three landscapes, but with substantial variation in the rate of increase (+2.4–26.1% decade-1). Locally, the distribution of canopy cover classes was strongly influenced by metrics of soil wetness and potential insolation derived from the ArcticDEM. Our second workflow uses a more scalable approach that applies a K-means clustering algorithm to high-resolution imagery that has been processed to pseudo-surface reflectance, with a canopy height estimate applied as a fifth band, to map shrub ecotypes at 2 m resolution across large spatial extents in Arctic Alaska. Collectively, this work demonstrates the strengths and limitations of different machine learning workflows and mapping units in addressing key knowledge gaps regarding Arctic shrub expansion and its environmental covariates.

• unfold_moreTransformative Space based Mapping, Classification, and Monitoring of Arctic Vegetation — Charles Miller 

  Charles Miller ¹; Peter Griffith ²; Elizabeth Hoy ³; Scott Goetz ⁴; Laura Duncanson ⁵; Phil Townsend ⁶; Laura Bourgeau-Chavez ⁷; Daryl Yang ^{8
  1} Jet Propulsion Laboratory, California Institute of Technology; ² NASA Goddard Space Flight Center; ³ NASA Goddard Space Flight Center; ⁴ Northern Arizona University; ⁵ University of Maryland; ⁶ University of Wisconsin; ⁷ Michigan Tech; ⁸ Oak Ridge National Laboratory

  Format: Oral in-person

  Abstract:

  New space-based remote sensing technologies will transform our ability to map, classify, and monitor vegetation and its changes in the rapidly evolving Arctic. Here, we present results from airborne imaging spectroscopy, L-band synthetic aperture radar (SAR), Ka-band water surface elevation, and full waveform lidar surveys acquired over Alaska and northwestern Canada from 2017 to 2024 during NASA’s Arctic Boreal Vulnerability Experiment (ABoVE). These surveys helped pioneer the application of these techniques to Arctic vegetation and give us initial insights into how they can help us monitor interannual to decadal scale change. Additionally, they pave the way for pan-Arctic vegetation remote sensing by current and upcoming missions including IceSAT-2, SWOT, NISAR, ROSE-L, PACE, EnMAP, PRISMA, PRISMA-SG, SBG-VSWIR, and CHIME.

• unfold_moreDendrochronology and Climate Change: Insights from the Arctic Tundra Shrub Growth — Agata Buchwal 

  Agata Buchwal ^{1
  1} Laboratory of Tree-Ring Research, Tucson, University of Arizona, US, Adam Mickiewicz University, Poznan, Poland

  Format: Oral in-person

  Abstract:

  Climate change in the Arctic, characterized by rising air temperatures and shrinking sea ice extent, is altering the conditions crucial for the growth of the region’s northernmost woody plants, specifically tundra shrubs. Understanding these changes is vital for multiple aspects of Arctic ecosystem functioning, including heat and water flux, the carbon cycle, and herbivore dynamics.

  This study examines the influence of changing climatic conditions, particularly air temperature, on the radial growth of key shrub species such as Betula and Salix in Spitsbergen, Greenland, and Alaska, along with Juniperus in the Low Arctic. I will highlight the heterogeneous growth responses of these species and explore the use of wood anatomy to investigate climate-growth relationships in tundra shrubs.

 

Poster Presentations (during Poster Exhibit and Session on Wednesday 26 March): 

• unfold_moreThe Raster CAVM – hard-copy and digital versions to support current and future research applications — Martha Raynolds 

  Martha Raynolds ¹; Donald Walker ^{1
  1} University of Alaska Fairbanks

  Format: Poster in-person

  Poster number: #264

  Abstract:

  A raster version of the Circumpolar Arctic Vegetation Map (CAVM) was created in 2019, building on the success of the 2003 vector CAVM. The raster version uses the same Arctic extent as originally defined by the CAVM and the same circumpolar legend based on plant physiognomy. The raster format, based on analysis of 1-km AVHRR data, is compatible with remote sensing data, making it easier to use for analysis and modeling.

  The CAVM provides a base map for many studies, and its boundaries are the most common delineation used to define the Arctic. The Raster version has been used for mapping studies, modeling, and for extrapolating local or regional findings to larger areas.

  There are aspects of the CAVM that could be improved on. The treeline boundaries and the ice boundaries could be updated using recent mapping. The 1-km resolution makes a very manageable dataset size, but many studies are now working at finer resolutions. We expect the CAVM will continue to be useful at the circumpolar scale. We also expect that the legend, with its easily understood units and its hierarchical nature, will continue to provide a framework for other arctic vegetation maps.

  We have a new hard-copy version of the Raster CAVM, which displays the map on the front and details about the map and the legend units on the back. Photographs illustrate landscape views and characteristic plants of the units. We hope this beautiful map will inspire new avenues of Arctic research.

• unfold_moreGreening of Svalbard — Stein Rune Karlsen 

  Stein Rune Karlsen ^{1
  1} NORCE - Norwegian Research Cente AS

  Format: Poster in-person

  Poster number: #104

  Abstract:

  Phenological observations designed to be up-scaled by Sentinel-2/Landsat data were established in Svalbard and in mountain areas of Norway in 2012. Phenocam has been used since 2013. In-situ measurement of plant productivity was established in Svalbard in 2015. In 2009 we established permanent plots for monitoring vegetation changes in six mountain areas of Norway, and these plots are reanalyzed each 7-years.

  A cloud-free time-series of MODIS data for the entire Svalbard and Sentinel-2 for central Svalbard has been processed. The datasets are interpolated to daily data. The onset of growth, with a clear phenological definition as validate form the phenocam data, has been mapped each year with the datasets. Then the integrated NDVI from the onset (O) of growth each year to the time of average peak (P) of growth (OP NDVI) have been calculated. OP NDVI shown high correlation with field-based tundra productivity and with growing degree days (°C-days) computed from onset to time of peak of growth. On average for the entire Svalbard, the year 2016 first had the highest greening (OP NDVI values) recorded since the year 2000, then the greening in 2018 surpassed 2016, then 2020 surpassed 2018, and finally 2022 was the year with the overall highest greening by far for the whole 2000‒2022 period. The preliminary results for the last two years (2023-2024) also show very high plant productivity. This shows a rapid recent greening of Svalbard very strongly linked to temperature increase. In alpine parts of mainland Norway, the greening trend is weaker.

• unfold_moreHigh-resolution classified vegetation map of evolving ice-wedge-polygon terrain, Prudhoe Bay, Alaska — Olivia Hobgood 

  Olivia Hobgood ¹; Donald Walker ¹; Martha Raynolds ¹; Amy Breen ¹; Julia White ^{1
  1} University of Alaska Fairbanks

  Format: Poster in-person

  Poster number: #122

  Abstract:

  Many Arctic regions are experiencing rapid changes due to ice-wedge degradation and the formation of new thermokarst ponds. Because vegetation is a stationary, above-ground reflection of many factors, such as air temperature, precipitation, hydrology, animal activity, and soil chemistry, mapping vegetation is a useful method for investigating the multiple facets of landscape evolution. Although modern pan-Arctic vegetation maps exist, few have mapped vegetation to the ice-wedge polygon scale, and none have mapped the unique non-acidic vegetation at Prudhoe Bay to this scale. We present a vegetation map of a 5.7-km2 area near Deadhorse, Alaska, created using an automated machine-learning classifier trained on field data. The source imagery is an 8-band, 0.46-m resolution WorldView-02 image taken in July 2022; due to the high source resolution, the classified map shows how vegetation varies across polygonal landscape features, such as troughs, centers, and rims. At a broader scale, the map shows how vegetation composition changes between areas with different thaw-lake histories and relative ice richness. Through extrapolation of field data, the map provides insights into how factors such as biomass, snow depth, and carbon flux vary across a changing landscape. We present the advantages and limitations of this efficient, repeatable approach to landscape monitoring.

• unfold_moreFen tundra or tundra fen? – Challenge of Braun-Blanquet-vegetation classification of mosaic tundra vegetation in the Prudhoe Bay Area — Helga Bueltmann 

  Helga Bueltmann ¹; Donald Walker ²; Amy Breen ²; Jozef Šibík ³; Olivia Hobgood ²; Briana McNeal ²; Jana Peirce ²; Maria Šibíková ^{3
  1} University of Münster; ² University of Alaska Fairbanks; ³ Slovak Academy of Science, Bratislava

  Format: Poster in-person

  Poster number: #361

  Abstract:

  The tundra is a large-scale landscape with small-scale habitat pattern of freezing and thawing. The striking habitat feature of the polygon loess tundra vegetation of the Alaskan Arctic Plain in the Prudhoe Bay area is that while there are aquatic, wet (marl) and dry habitats (rims), common is a type between: not wet, but with species, which are strict wetland species in azonal vegetation elsewhere and with those species occurring far into dry habitats e.g. ruderal sites with shrubs and even slight depressions on pingo tops.

  Crucial factor is permafrost, a habitat complex creating a moisture gradient working from within. Cryoturbation and tiny erosion gaps, which are characteristic of so many vegetation types of Arctic and mountain tundra, are of lesser impact.

  This variation is difficult to place with the existing Braun-Blanquet-classification system and we are discussing a new unit, a new syntaxon, on a higher level for this fen-tundra or tundra-fen. We will explain the relation of Braun-Blanquet-syntaxa and habitat types of Skip Walker (e-g. 1985). We will discuss pros and cons of different classification systems and contextualise the Prudhoe Bay vegetation with communities from other tundra vegetation and azonal fen. We will present a scheme where to place the Prudhoe Bay tundra vegetation in the existing Braun-Blanquet system.

  We do not propose to change the method of recording for any existing observation network, but the hierarchical structure of an additional Braun-Blanquet classification may facilitate comparison with networks from other parts of the Arctic.

• unfold_moreLinking vegetation change in permanent plots to regional ecosystem change in Arctic Alaska — Robert Hollister 

  Robert Hollister ¹; Sarah Elmendorf ²; Jeremy May ³; Katlyn Betway-May ⁴; Steven Oberbauer ⁵; Craig Tweedie ⁶; Jeffrey Welker ⁷; Sergio Vargas ⁸; Katie Young ⁹; Karl F Huemmrich ^{10
  1} Biology Department, Grand Valley State University, Allendale, Michigan, USA; ² Institute of Arctic and Alpine Research, Department of Ecology and Evolutionary Biology, University of Colorado; ³ Biology and Environmental Science, Marietta College; ⁴ USDA Forest Service, Research and Development, Río Piedras, PR, USA Forest Service, Research and Development, Río Piedras, PR, USA; ⁵ Department of Biological Sciences, Florida International University; ⁶ Biological Sciences, University of Texas at El Paso; ⁷ Biological Sciences, University of Alaska Anchorage; ⁸ Biological Sciences, University of Texas at El Paso; ⁹ Biological Sciences, University of Texas at El Paso; ¹⁰ Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, MD, USA

  Format: Poster in-person

  Poster number: #190

  Abstract:

  Documenting vegetation change on long-term permanent plots provides the detailed information necessary to understand ecosystem changes occurring across the landscape. Here we show the change in plant cover, measured at the top of the canopy, across multiple sites in Arctic Alaska and show how the change in plant cover and plant height correlates with NDVI measured near the surface and from space. Plant height has consistently increased and the cover of shrubs and graminoids have increased, but the magnitude varies greatly across regions and by moisture groups within a region. The diversity of response within a region helps explain the NDVI measured from space. The mechanistic studies co-located also help predict future change. These observations are an essential component of international efforts aimed at understanding ecosystem change across the tundra.

• unfold_moreQuantifying changes resulting from recent climate warming to water bodies, surficial landforms, and vegetation in ice-wedge-polygon landscapes, Deadhorse, Alaska — Hannah Chapman-Dutton 

  Hannah Chapman-Dutton ¹; Briana McNeal ¹; Donald Walker ^{1
  1} University of Alaska Fairbanks

  Format: Poster in-person

  Poster number: #156

  Abstract:

  Arctic thaw-lake landscapes are made up of thaw lakes, drained lake basins (DLBs), and residual surfaces (areas that have not been subjected to thaw-lake processes). On residual surfaces and DLBs with well-developed low-centered ice wedge polygons, the quickly warming climate is driving formation of ice-wedge thermokarst ponds and transitional polygon morphologies and plant communities. Using high-resolution aerial imagery from 1987/88, and 2020, as well as digital surface models and accuracy points, we produced detailed (1:500 scale) maps of the surficial geology, surface features, and vegetation of five transects that represent a surface-age gradient near Deadhorse, Alaska. We then calculated the change in polygon rim, trough, and basin area as well as vegetation type from 1987/88 to 2020 to present a story of trough widening, rim degradation, and basin draining in ice-wedge polygon landscapes. Preliminary results from one transect in an older lake basin shows a 6% increase in trough area, a 14% decrease in rim area, and a 47% decrease in basin area over 32 years as troughs have widened, polygon rims have eroded, and low-centered polygons basins have drained. Percentage cover of moist, wet, and aquatic vegetation types changed from 14%/28%/1% in 1988 to 15%/7%/5% in 2020. Results from the full sequence of landscapes will be presented at the conference. This work can better inform our understanding of the polygonal life cycle across different evolving landscapes and could lead the way to predicting ice content from changes in vegetation types determined from aerial imagery and remote-sensing products.

• unfold_moreSmall rodent disturbance impact on Arctic graminoid forage quality — Matt Sponheimer 

  Gerardo Celis ¹; Kari Anne Bråthen ²; Dorothee Ehrich ³; Oliver Paine ⁴; Matt Sponheimer ⁵; Mary Heskel ⁶; Peter Ungar ^{7
  1} University of Arkansas; ² The Arctic University of Norway; ³ The Arctic University of Norway; ⁴ Sand Diego State University; ⁵ University of Colorado at Boulder; ⁶ Macalester College; ⁷ University of Arkansas

  Format: Poster in-person

  Poster number: #201

  Abstract:

  Arctic rodents influence tundra plant communities by altering species diversity, structure, and nutrient dynamics. These dynamics are intensified during rodent population peaks. Grasses and sedges are well known to defend themselves in response to rodent grazing by increasing silica and/or phenolics. However, changes in plant tissue digestibility may also play a role in deterring rodents or impacting their survival. This study presents a first look at the impacts of rodent herbivory on crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) of three of the most common graminoid species (Calamagrostis sp., Carex nigra and Deschampsia cespitosa) in the tundra meadows of the Varanger Peninsula, Norway. We created 32 experimental plots representing both rodent-disturbed and adjacent, undisturbed graminoid patches. During a rodent population peak, we found significant differences due to intensified rodent activity, with more disturbed plots showing higher ADF (28.5%) values than less disturbed ones (26.6%), controlling for plant species. We also found differences between species, with Carex nigra having the lowest fiber content (24.3% ADF) and highest protein content (18.2% CP) – making it the most palatable species. These results show that rodent activity can potentially alter plant food quality, suggesting that increased fiber content may be a defensive adaptation against herbivory.

• unfold_moreUtilization of Fine-Scale Mapping to Quantify Landscape, Permafrost and Vegetation Evolution in Prudhoe Bay, Alaska — Briana McNeal 

  Briana McNeal ¹; Donald Walker ¹; Olivia Hobgood ¹; Helga Bültmann ²; Jozef Šibík ³; Martha Raynolds ¹; Amy Breen ¹; Jana Peirce ¹; Hannah Chapman-Dutton ^{1
  1} University of Alaska Fairbanks; ² University of Münster; ³ Slovak Academy of Science

  Format: Poster in-person

  Poster number: #209

  Abstract:

  Ice-rich permafrost landscapes are a key feature in Arctic ecosystems that are increasingly susceptible to change with climate warming due to their ice content. In coastal tundra regions, these ice-rich systems often appear as polygonal matrices formed through ice wedge development. These landscapes also give rise to ice-cored mounds known as pingos. This study aims to quantify the small-scale changes occurring in these polygonal landscapes and on pingos through the use of fine-scale mapping. Change was analyzed over a period of 32 years using orthomosaic and aerial imagery from 1987, 1988, and 2020 alongside digital surface models and accuracy assessment points obtained in the field. A 350 x 300 m section located in Prudhoe Bay, Alaska, was mapped for the two time periods using photo interpretation and ArcGIS Pro 3.3.1 elevation surface geoprocessing tools. The area of interest is contained within a drained thaw lake basin with a well-developed polygonal network and steep-sided pingo. The changes in vegetation, surficial features, and surficial feature elements were compared between the two time periods. The preliminary analysis reveals a decrease in low-centered polygons and very wet vegetation of 86% and 56%, respectively, from 1988 along with an 18% increase in trough width. Significant changes in pingo drainage features were also observed. The knowledge of these fine-scale changes can be used to predict future ecosystem changes in these vulnerable Arctic ecosystems. This study can also help to inform future work that aims to utilize remote sensing to map Arctic landscapes in greater detail.

• unfold_moreRevisiting Climate Drivers of Arctic Tundra Variability and Change with a View to the Future — Uma Bhatt 

  Uma Bhatt ¹; Donald Walker ²; Gerald Frost ³; Martha Raynolds ⁴; Christine Waigl ⁵; Matthew Macander ⁶; Howard Epstein ⁷; Jorge Pinzon ⁸; Compton Tucker ⁹; Josephino Comiso ^{10
  1} University of Alaska Fairbanks; ² University of Alaska Fairbanks; ³ Alaska Biological Research; ⁴ University of Alaska Fairbanks; ⁵ University of Alaska Fairbanks; ⁶ Alaska Biological Research Inc; ⁷ University of Virginia; ⁸ SSAI & NASA; ⁹ NASA GSFC; ¹⁰ NASA GSFC

  Format: Poster in-person

  Poster number: #313

  Abstract:

  Much of the large-scale variability in the Normalized Difference Vegetation Index (NDVI) is driven by climate variations in the Arctic. Declining coastal sea ice and associated warmer temperatures were found to be significantly correlated with NDVI in a study that covered the period 1982-2008 (Bhatt et al. 2010). As the climate has continued to warm and late summer sea ice is largely absent along the Arctic coast, the relationships among sea ice, summer temperatures, and NDVI are changing at varied rates across the Arctic tundra biome. This spatially varying response to change across the Arctic necessitates an updated regional analysis of NDVI and climate drivers over tundra vegetation regionally.

  This analysis will employ the NASA GIMMS-3g+ biweekly NDVI derived from circumpolar AVHRR satellite observations, which now covers more than four decades (1982-2023), ERA5 climate reanalysis, passive microwave sea ice concentration, and select local station data. The climate variables for the analysis will include seasonal air temperature, precipitation, snow water equivalent, and others. Climate and NDVI data will be analyzed for trends and interannual-to-decadal variations in the context of atmospheric teleconnections. Analysis of temperature and precipitation from CMIP6 future climate scenarios to 2100 will be conducted to anticipate what climate conditions the Arctic tundra will experience at the end of this century.

  Bhatt, U.S., D.A. Walker, M.K. Raynolds, J.C. Comiso, H.E. Epstein, G.Jia, R. Gens, J.E. Pinzon, C.J. Tucker, C.E. Tweedie, and P.J. Webber, 2010: Circumpolar Arctic tundra vegetation change is linked to sea-ice decline, Earth Interactions. 14(8), 1-20.

• unfold_moreArctic-Alpine Treeline Communities – where the forest meets tundra: Challenges of vegetation and habitat classification — Maria Sibikova 

  Maria Sibikova ¹; Skip Walker ²; Amy Breen ³; Helga Bueltmann ⁴; Jozef Sibik ^{5
  1} Plant Science and Biodiversity Center of Slovak Academy of Sciences; ² Department of Biology and Wildlife, Alaska Geobotany Center, Institute of Arctic Biology, University of Alaska Fairbanks, AK, USA; ³ Department of Biology and Wildlife, Alaska Geobotany Center, Institute of Arctic Biology, University of Alaska Fairbanks, AK, USA; ⁴ University of Münster, Germany; ⁵ Plant Science and Biodiversity Center of Slovak Academy of Sciences

  Format: Poster in-person

  Poster number: #316

  Abstract:

  The treeline represents a crucial interface between two distinct zonal vegetation types: the boreal forest and the arctic tundra. Alongside this zonal gradient, azonal communities such as alluvial forests and scrub play an indispensable role in the ecosystem. The transition from boreal forest to arctic tundra is not abrupt but rather gradual, encompassing a wide transitional area (Viereck 1979). Understanding the fundamental mechanisms that govern northern treelines is essential for accurately predicting shifts in biomes and assessing vegetation's response to climate change (Maher et al. 2021).

  Boreal forests, which delineate the northern treeline, are characterized by a diversity of plant communities, each with unique structural features, ecological requirements, and species compositions. These communities can be classified as "habitats" using various classification systems (EUNIS in Europe, EcoVeg habitat system in the United States). Additionally, they can be categorized as "syntaxonomical units" through the phytosociological classification system (Braun-Blanquet approach, e.g. Mucina et al. 2016) which has a long-standing application in Europe since the early 20th century and has also been effectively utilized in the US (e.g. Walker et al. 2018). This syntaxonomical classification relies on standardized vegetation plots, facilitating comparative analyses across continents. However, it is noteworthy that vegetation scientists often sample under optimal conditions, potentially resulting in the under-sampling of specific boreal forest variants found in transitional zones.

  This study aims to consolidate current knowledge on the habitats and syntaxonomical classification of treeline forest communities in both Europe and the US, while also identifying gaps and research needs for future exploration.

• unfold_moreA Changing Arctic: Assessment of carbon and nitrogen in soil, surface water, and vegetation across stages of ice-wedge degradation and stabilization in the tundra of northern Alaska — Kelcy Kent 

  Kelcy Kent ¹; Howard Epstein ²; Torre Jorgenson ³; Claire Griffin ⁴; Mikhail Kanevskiy ⁵; Lindsay Grose ⁶; Anna Liljedahl ⁷; Ronald Daanen ^{8
  1} Woodwell Climate Research Center, University of Virginia; ² University of Virginia; ³ Alaska Ecoscience; ⁴ Allegheny College; ⁵ University of Alaska Fairbanks; ⁶ University of Rhode Island; ⁷ Woodwell Climate Research Center; ⁸ Department of Natural Resources - Geological and Geophysical Surveys

  Format: Poster in-person

  Poster number: #330

  Abstract:

  Ice-wedge polygons – commonly found in Arctic tundra regions – produce high spatial variability in topography, hydrology, vegetation distribution, and biogeochemical processes at local to landscape scales. Recent warming has caused ice-wedge thaw, driving dramatic landscape changes. Water and nutrient availability can vary substantially across stages of ice-wedge degradation, impacting vegetation distribution, which can lead to further degradation or facilitate stabilization. These processes, however, are poorly understood, contributing to uncertainty in predicting future Arctic ecosystem trajectories. This study examined differences in carbon and nitrogen in the soil and surface water among stages of ice-wedge degradation and stabilization, as well as differences in plant functional group biomass and foliar N. To explore the impact of local conditions on these patterns, trends among ice-wedge stages were compared between two north Alaskan tundra sites (Jago River and Prudhoe Bay, Alaska). Field data were also used to calibrate and validate a nutrient-based Arctic vegetation model to assess the influence of ice-wedge degradation on Arctic vegetation communities and vegetative C and N stocks at coarser scales. At both sites, vegetation communities shifted from terrestrial moss, graminoid, and shrub-dominated to aquatic moss and hydrophilic sedge-dominated following degradation. There were ice-wedge stage-specific differences in soil and surface water nutrients, and differences in plant foliar N content. Modeled extrapolations suggest warming and ice-wedge degradation could significantly increase vegetation biomass due to the proliferation of aquatic moss. Increases in aquatic moss biomass could even exceed biomass loss following degradation, although this was specific to warmer, more southern Arctic locations.

• unfold_moreInfluence of site moisture and vegetation on ground temperatures in an ice-rich permafrost landscape, Prudhoe Bay, Alaska — Jana Peirce 

  Jana Peirce ¹; Donald Walker ¹; Ina Timling ¹; Melissa Ward Jones ¹; Hannah Chapman-Dutton ¹; Briana McNeal ^{1
  1} University of Alaska Fairbanks

  Format: Poster in-person

  Poster number: #355

  Abstract:

  Near-surface ground temperatures are increasing across the Arctic in response to rapidly rising air temperatures. Small changes in mean annual ground temperature (MAGT) can threaten the thermal state of permafrost, transforming landscapes through increased thermokarst and surface water hydrology, resulting in changes to snow distribution, soil moisture, vegetation, soil carbon, and greenhouse-gas fluxes. We have been investigating the impact of surficial geology, landforms, microtopography, soil moisture, vegetation, and disturbance on active layers depths, ground ice, and permafrost temperatures at the Natural Ice-Rich Permafrost Observatory (NIRPO) in Deadhorse, AK. Here we share findings from a 2022–2023 survey of ground temperature trends at 0, -15, and -40 cm depths in 59 vegetation plots located along a site-moisture/vegetation gradient from a dry pingo summit to aquatic habitats. Preliminary analysis indicates a strong positive trend of ground temperatures along the gradient. Mean annual ground surface temperatures varied from: -7.39˚C on a windblown pingo summit with dry tundra (habitat type Dz) to -2.86 ˚C in aquatic thermokarst-pond habitats with approximately 50–100 cm of water and thick aquatic moss (Scorpidium scorpiodes and Calliergon richardsonii) (habitat type A3t) — a +4.53 ˚C difference. Mean annual ground temperatures at -40 cm in the same habitats varied from -8.04 ˚C in type Dz to -4.28 ˚C in type A3t) — a +3.76 ˚C difference. Other factors affecting the ground temperatures included the depth of snow, and the thickness of organic soil layers.

• unfold_moreInternational Tundra Experiment (ITEX) Phenocam Synthesis: Image processing and data analysis workflow — Craig E. Tweedie 

  Katherine I. Young ¹; Sergio A. Vargas ¹; Victoria Villagomez ¹; Daniel Cruz ¹; Tabatha Fuson ¹; Santiago Hoyos Echeverri ¹; Craig E. Tweedie ^{1
  1} University of Texas El Paso

  Format: Poster in-person

  Poster number: #521

  Abstract:

  Arctic tundra is undergoing changes in satellite-derived “greening” and “browning” trends, reflecting a complex landscape-scale vegetation response to Arctic Change. Plant phenology is sensitive to climate variability and is recognized as an important indicator of ecosystem change. Repeat photography using affordable digital cameras (Phenocams) has emerged as an effective, low-cost tool for monitoring phenological changes in arctic tundra ecosystems. Here we present our workflow for acquiring and synthesizing phenocam data from over 200 arctic tundra sites to address broad research questions focused on 1) variation in the onset and peak of the growing season, 2) shifts in tundra seasonality due to climate change and extreme events, 3) differences in phenological seasonality across plant communities and vegetation types, and 4) correlation between near surface and remotely sensed phenological measurements. Our workflow integrates streamlined data sharing, storage, processing, and analysis using high performance computing (HPC) and local workstations. We utilize multiple software resources (Python, R, Futura, Phenocamanalyzer (an in-house analytical software), and custom image classification code) for image processing, automated quality control, and time-series analysis. This flexible procedure accommodates diverse research questions and scales, from landscape to plot-level and vegetation community analyses. Images, metadata, and analytical deliverables will be shared and managed through our University of Texas El Paso team. Researchers interested in contributing to the synthesis or providing feedback can do so HERE. This effort is being coordinated through the International Tundra Experiment.

• unfold_moreEvolution of Arctic heatwaves: characterizing extreme heat events using a 3D clustering approach — Grégoire Canchon 

  Grégoire Canchon ¹; Gabriele Hegerl ^{1
  1} University of Edinburgh

  Format: Poster in-person

  Poster number: #564

  Abstract:

  The first year of my PhD project has been spent assessing and characterizing Arctic heatwaves using satellite data (MODIS Land Surface Temperature).

  The MODIS dataset product used in this project offers 23 years of data, which has been used to understand how Arctic heatwaves have evolved over time, by investigating changes in amplitude, frequency, duration, etc. This is done by calculating the 90th percentile values of the dataset using a rolling window of 11 days, and then plotting trends and timeseries.

  Additionally, I aim to present a unique method I used to cluster and classify Arctic heatwaves. I implemented a 2D DBSCAN algorithm to identify spatio-temporal heatwaves. This method allows to explore the differences between Arctic regions (Siberia, North America, Northern Europe) and compare heatwave clusters.

  Ultimately, this research will be tied to land cover information, to try and understand the dynamics between vegetation-covered or snow-covered grounds with heatwave characteristics. This will allow for a better understanding of Arctic heatwave formation, as well as providing a solid starting point to investigate the impact of heatwaves on Arctic greening/browning, and wildfire occurrences.

• unfold_moreCatalogue of biotopes of East European tundra — Igor Lavrinenko

  Igor Lavrinenko ¹; Olga Lavrinenko ²; Nadezhda Matveyeva ²; Daria Karsonova ²; Vasiliy Neshataev ²; Anna Lapina ²; Ksenia Simonova ²; Natalia Tsyvkunova ²; Evgeniy Kotlyarchuk ^{2
  1} Russian Botanical Society (RBS); ² Komarov Botanical Institure RAS

  Format: Poster virtual

  Poster number: #291

  Abstract:

  The habitats (biotopes) of the Arctic are the basis for the existence of its fauna and flora, so monitoring of their status is more effective than that of species populations (EU Habitats Directive, 1992, Natura 2000, EUNIS, CarHAB, etc.). When delineating Arctic habitats, the use of European classifications (Palaearctic Habitats, CORINE, EUNIS, etc.) is problematic due to the absence of many of them in Western Europe. We are developing a hierarchical classification of biotopes in the Russian Arctic using the example of East European tundra. It is based on the location of biotopes on the geomorphological profile and ecological features of the site. Syntaxonomic composition of vegetation used as the most important diagnostic indicator for different categories of biotopes. To diagnose habitats a typological scheme was developed, which makes it possible to identify on the map territorial units of vegetation (TUV) of different complexity and rank with preservation of information on the composition of syntaxa and spatial structure of contours. A scheme of step-by-step merging of TUV categories from phytocenosis to geobotanical area is proposed for generalisation of maps as the scale decreases (Lavrinenko, 2020). Among the most important characteristics of habitats is their resource significance for biota species and humans. Large-scale mapping of biotopes is carried out in some areas of East European tundra and categories with high resource significance and high numbers of rare and in need of protection of fauna and flora are identified. Based on these materials, a Red List of habitats is being developed.

• unfold_moreVegetation of the Russian Arctic from class to associations — Olga Lavrinenko 

  Olga Lavrinenko ¹; Nadezhda Matveyeva ¹; Igor Lavrinenko ¹; Nadezhda Sinelnikova ²; Mikhail Telyatnikov ^{3
  1} Komarov Botanical Institute; ² Институт биологических проблем Севера ДВО РАН; ³ Центральный Сибирской ботанический сад СО РАН

  Format: Poster virtual

  Poster number: #290

  Abstract:

  As part of a large initiative project (see Plugatar et al., 2020) to create a serial publication “Prodromus of the vegetation of Russia”, work was carried out to inventory the vegetation of the Russian Arctic to the level of associations. The checklist of syntaxa of the Russian Arctic (Matveeva and Lavrinenko, 2021) became the basis for the compilation of the Prodromus. The main Arctic classes unite: Drabo corymbosae–Papaveretea dahliani Daniöls, Elvebakk et Matveyeva in Daniöls et al. 2016 – 1 order, 6 alliances (5 of which need to be described) and 20 associations; Carici arctisibiricae–Hylocomietea alaskani Matveyeva et Lavrinenko 2023 – 3 orders, 6 alliances and 37 associations; Carici rupestris–Kobresietea bellardii Ohba 1974 – 1 order, 3 alliances and 26 associations; Loiseleurio procumbentis–Vaccinietea Eggler ex Schubert 1960 – 1 order, 4 alliances and 41 associations. For all syntaxonomic units, information on individual code, name, synonyms, diagnostic species, habitats, range, subsyntaxa, and sources of information is given. Descriptions of “arctic” orders, unions and associations are also presented in many classes of intrazonal (snowbed, mire, aquatic, halophytic, etc.) vegetation. Such a review will serve as a modern basis for characterizing the Arctic vegetation cover, mapping it, assessing species diversity, and studying its transformation under the influence of climatic and anthropogenic factors.