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2. Tundra Trait Team : A database of plant traits spanning the tundra biome

Author

Bjorkman, Anne D., Myers-Smith, Isla H., Elmendorf, Sarah C., Normand, Signe, Thomas, Haydn J. D., Alatalo, Juha M., Alexander, Heather, Anadon-Rosell, Alba, Angers-Blondin, Sandra, Bai, Yang, Baruah, Gaurav, te Beest, Mariska, Berner, Logan, Björk, Robert G., Blok, Daan, Bruelheide, Helge, Buchwal, Agata, Buras, Allan, Carbognani, Michele, Christie, Katherine, Collier, Laura S., Cooper, Elisabeth J., Cornelissen, J. Hans C., Dickinson, Katharine J. M., Dullinger, Stefan, Elberling, Bo, Eskelinen, Anu, Forbes, Bruce C., Frei, Esther R., Iturrate-Garcia, Maitane, Good, Megan K., Grau, Oriol, Green, Peter, Greve, Michelle, Grogan, Paul, Haider, Sylvia, Hájek, Tomáš, Hallinger, Martin, Happonen, Konsta, Harper, Karen A., Heijmans, Monique M. P. D., Henry, Gregory H. R., Hermanutz, Luise, Hewitt, Rebecca E., Hollister, Robert D., Hudson, James, Hülber, Karl, Iversen, Colleen M., Jaroszynska, Francesca, Jiménez-Alfaro, Borja, Johnstone, Jill, Jorgesen, Rasmus Halfdan, Kaarlejärvi, Elina, Klady, Rebecca, Klimešová, Jitka, Korsten, Annika, Kuleza, Sara, Kulonen, Aino, Lamarque, Laurent J., Lantz, Trevor, Lavalle, Amanda, Lembrechts, Jonas J., Lévesque, Esther, Little, Chelsea J., Luoto, Miska, Macek, Petr, Mack, Michelle C., Mathakutha, Rabia, Michelsen, Anders, Milbau, Ann, Molau, Ulf, Morgan, John W., Mörsdorf, Martin Alfons, Nabe-Nielsen, Jacob, Nielsen, Sigrid Schøler, Ninot, Josep M., Oberbauer, Steven F., Olofsson, Johan, Onipchenko, Vladimir G., Petraglia, Alessandro, Pickering, Catherine, Prevéy, Janet S., Rixen, Christian, Rumpf, Sabine B., Schaepman-Strub, Gabriela, Semenchuk, Philipp, Shetti, Rohan, Soudzilovskaia, Nadejda A., Spasojevic, Marko J., Speed, James David Mervyn, Street, Lorna E., Suding, Katharine, Tape, Ken D., Tomaselli, Marcello, Trant, Andrew, Treier, Urs A., Tremblay, Jean-Pierre, Tremblay, Maxime, Venn, Susanna, Virkkala, Anna-Maria, Vowles, Tage, Weijers, Stef, Wilmking, Martin, Wipf, Sonja, and Zamin, Tara

Published
2018

5. Winters are changing : snow effects on Arctic and alpine tundra ecosystems

Author

Rixen, Christian, Hoye, Toke Thomas, Macek, Petr, Aerts, Rien, Alatalo, Juha M., Anderson, Jill T., Arnold, Pieter A., Barrio, Isabel C., Bjerke, Jarle W., Bjorkman, Mats P., Blok, Daan, Blume-Werry, Gesche, Boike, Julia, Bokhorst, Stef, Carbognani, Michele, Christiansen, Casper T., Convey, Peter, Cooper, Elisabeth J., Cornelissen, J. Hans C., Coulson, Stephen J., Dorrepaal, Ellen, Elberling, Bo, Elmendorf, Sarah C., Elphinstone, Cassandra, Forte, T'ai G. W., Frei, Esther R., Geange, Sonya R., Gehrmann, Friederike, Gibson, Casey, Grogan, Paul, Halbritter, Aud Helen, Harte, John, Henry, Gregory H. R., Inouye, David W., Irwin, Rebecca E., Jespersen, Gus, Jonsdottir, Ingibjorg Svala, Jung, Ji Young, Klinges, David H., Kudo, Gaku, Lamsa, Juho, Lee, Hanna, Lembrechts, Jonas J., Lett, Signe, Lynn, Joshua Scott, Mann, Hjalte M. R., Mastepanov, Mikhail, Morse, Jennifer, Myers-Smith, Isla H., Olofsson, Johan, Paavola, Riku, Petraglia, Alessandro, Phoenix, Gareth K., Semenchuk, Philipp, Siewert, Matthias B., Slatyer, Rachel, Spasojevic, Marko J., Suding, Katharine, Sullivan, Patrick, Thompson, Kimberly L., Vaisanen, Maria, Vandvik, Vigdis, Venn, Susanna, Walz, Josefine, Way, Robert, Welker, Jeffrey M., Wipf, Sonja, Zong, Shengwei, Rixen, Christian, Hoye, Toke Thomas, Macek, Petr, Aerts, Rien, Alatalo, Juha M., Anderson, Jill T., Arnold, Pieter A., Barrio, Isabel C., Bjerke, Jarle W., Bjorkman, Mats P., Blok, Daan, Blume-Werry, Gesche, Boike, Julia, Bokhorst, Stef, Carbognani, Michele, Christiansen, Casper T., Convey, Peter, Cooper, Elisabeth J., Cornelissen, J. Hans C., Coulson, Stephen J., Dorrepaal, Ellen, Elberling, Bo, Elmendorf, Sarah C., Elphinstone, Cassandra, Forte, T'ai G. W., Frei, Esther R., Geange, Sonya R., Gehrmann, Friederike, Gibson, Casey, Grogan, Paul, Halbritter, Aud Helen, Harte, John, Henry, Gregory H. R., Inouye, David W., Irwin, Rebecca E., Jespersen, Gus, Jonsdottir, Ingibjorg Svala, Jung, Ji Young, Klinges, David H., Kudo, Gaku, Lamsa, Juho, Lee, Hanna, Lembrechts, Jonas J., Lett, Signe, Lynn, Joshua Scott, Mann, Hjalte M. R., Mastepanov, Mikhail, Morse, Jennifer, Myers-Smith, Isla H., Olofsson, Johan, Paavola, Riku, Petraglia, Alessandro, Phoenix, Gareth K., Semenchuk, Philipp, Siewert, Matthias B., Slatyer, Rachel, Spasojevic, Marko J., Suding, Katharine, Sullivan, Patrick, Thompson, Kimberly L., Vaisanen, Maria, Vandvik, Vigdis, Venn, Susanna, Walz, Josefine, Way, Robert, Welker, Jeffrey M., Wipf, Sonja, and Zong, Shengwei

Abstract

Snow is an important driver of ecosystem processes in cold biomes. Snow accumulation determines ground temperature, light conditions, and moisture availability during winter. It also affects the growing season's start and end, and plant access to moisture and nutrients. Here, we review the current knowledge of the snow cover's role for vegetation, plant- animal interactions, permafrost conditions, microbial processes, and biogeochemical cycling. We also compare studies of natural snow gradients with snow experimental manipulation studies to assess time scale difference of these approaches. The number of tundra snow studies has increased considerably in recent years, yet we still lack a comprehensive overview of how altered snow conditions will affect these ecosystems. Specifically, we found a mismatch in the timing of snowmelt when comparing studies of natural snow gradients with snow manipulations. We found that snowmelt timing achieved by snow addition and snow removal manipulations (average 7.9 days advance and 5.5 days delay, respectively) were substantially lower than the temporal variation over natural spatial gradients within a given year (mean range 56 days) or among years (mean range 32 days). Differences between snow study approaches need to be accounted for when projecting snow dynamics and their impact on ecosystems in future climates.

Published
2022
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6. Can bryophyte groups increase functional resolution in tundra ecosystems?

Author

Lett, Signe, Jónsdóttir, Ingibjörg S., Becker-Scarpitta, Antoine, Christiansen, Casper T., During, Heinjo, Ekelund, Flemming, Henry, Gregory H. R., Lang, Simone I., Michelsen, Anders, Rousk, Kathrin, Alatalo, Juha M., Betway, Katlyn R., Rui, Sara B., Callaghan, Terry, Carbognani, Michele, Cooper, Elisabeth J., Cornelissen, J. Hans C., Dorrepaal, Ellen, Egelkraut, Dagmar, Elumeeva, Tatiana G., Haugum, Siri V., Hollister, Robert D., Jägerbrand, Annika K., Keuper, Frida, Klanderud, Kari, Lévesque, Esther, Liu, Xin, May, Jeremy, Michel, Pascale, Mörsdorf, Martin, Petraglia, Alessandro, Rixen, Christian, Robroek, Bjorn J. M., Rzepczynska, Agnieszka M., Soudzilovskaia, Nadejda A., Tolvanen, Anne, Vandvik, Vigdis, Volkov, Igor, Volkova, Irina, van Zuijlen, Kristel, Lett, Signe, Jónsdóttir, Ingibjörg S., Becker-Scarpitta, Antoine, Christiansen, Casper T., During, Heinjo, Ekelund, Flemming, Henry, Gregory H. R., Lang, Simone I., Michelsen, Anders, Rousk, Kathrin, Alatalo, Juha M., Betway, Katlyn R., Rui, Sara B., Callaghan, Terry, Carbognani, Michele, Cooper, Elisabeth J., Cornelissen, J. Hans C., Dorrepaal, Ellen, Egelkraut, Dagmar, Elumeeva, Tatiana G., Haugum, Siri V., Hollister, Robert D., Jägerbrand, Annika K., Keuper, Frida, Klanderud, Kari, Lévesque, Esther, Liu, Xin, May, Jeremy, Michel, Pascale, Mörsdorf, Martin, Petraglia, Alessandro, Rixen, Christian, Robroek, Bjorn J. M., Rzepczynska, Agnieszka M., Soudzilovskaia, Nadejda A., Tolvanen, Anne, Vandvik, Vigdis, Volkov, Igor, Volkova, Irina, and van Zuijlen, Kristel

Abstract

The relative contribution of bryophytes to plant diversity, primary productivity, and ecosystem functioning increases towards colder climates. Bryophytes respond to environmental changes at the species level, but because bryophyte species are relatively difficult to identify, they are often lumped into one functional group. Consequently, bryophyte function remains poorly resolved. Here, we explore how higher resolution of bryophyte functional diversity can be encouraged and implemented in tundra ecological studies. We briefly review previous bryophyte functional classifications and the roles of bryophytes in tundra ecosystems and their susceptibility to environmental change. Based on shoot morphology and colony organization, we then propose twelve easily distinguishable bryophyte functional groups. To illustrate how bryophyte functional groups can help elucidate variation in bryophyte effects and responses, we compiled existing data on water holding capacity, a key bryophyte trait. Although plant functional groups can mask potentially high interspecific and intraspecific variability, we found better separation of bryophyte functional group means compared with previous grouping systems regarding water holding capacity. This suggests that our bryophyte functional groups truly represent variation in the functional roles of bryophytes in tundra ecosystems. Lastly, we provide recommendations to improve the monitoring of bryophyte community changes in tundra study sites.

Published
2022
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11. Global plant trait relationships extend to the climatic extremes of the tundra biome

Author

Thomas, Haydn J D, Bjorkman, Anne D, Myers-Smith, Isla H, Elmendorf, Sarah C, Kattge, Jens, Diaz, Sandra, Vellend, Mark, Blok, Daan, Cornelissen, J Hans C, Forbes, Bruce C, Henry, Gregory H R, Hollister, Robert D, Normand, Signe, Prevey, Janet S, and Wookey, Philip A

Subjects
Biogeography, Ecology, Theoretical ecology, Macroecology
Abstract

The majority of variation in six traits critical to the growth, survival and reproduction of plant species is thought to be organised along just two dimensions, corresponding to strategies of plant size and resource acquisition. However, it is unknown whether global plant trait relationships extend to climatic extremes, and if these interspecific relationships are confounded by trait variation within species. We test whether trait relationships extend to the cold extremes of life on Earth using the largest database of tundra plant traits yet compiled. We show that tundra plants demonstrate remarkably similar resource economic traits, but not size traits, compared to global distributions, and exhibit the same two dimensions of trait variation. Three quarters of trait variation occurs among species, mirroring global estimates of interspecific trait variation. Plant trait relationships are thus generalizable to the edge of global trait-space, informing prediction of plant community change in a warming world.

Published
2020

13. Tundra Trait Team:A database of plant traits spanning the tundra biome

Author

Bjorkman, Anne D., Myers-Smith, Isla H., Elmendorf, Sarah C., Normand, Signe, Thomas, Haydn J. D., Alatalo, Juha M., Alexander, Heather, Anadon-Rosell, Alba, Angers-Blondin, Sandra, Bai, Yang, Baruah, Gaurav, te Beest, Mariska, Berner, Logan, Bjork, Robert G., Blok, Daan, Bruelheide, Helge, Buchwal, Agata, Buras, Allan, Carbognani, Michele, Christie, Katherine, Collier, Laura S., Cooper, Elisabeth J., Cornelissen, J. Hans C., Dickinson, Katharine J. M., Dullinger, Stefan, Elberling, Bo, Eskelinen, Anu, Forbes, Bruce C., Frei, Esther R., Iturrate-Garcia, Maitane, Good, Megan K., Grau, Oriol, Green, Peter, Greve, Michelle, Grogan, Paul, Haider, Sylvia, Hajek, Tomas, Hallinger, Martin, Happonen, Konsta, Harper, Karen A., Heijmans, Monique M. P. D., Henry, Gregory H. R., Hermanutz, Luise, Hewitt, Rebecca E., Hollister, Robert D., Hudson, James, Huelber, Karl, Iversen, Colleen M., Jaroszynska, Francesca, Jimenez-Alfaro, Borja, Johnstone, Jill, Jorgensen, Rasmus Halfdan, Kaarlejarvi, Elina, Klady, Rebecca, Klimesova, Jitka, Korsten, Annika, Kuleza, Sara, Kulonen, Aino, Lamarque, Laurent J., Lantz, Trevor, Lavalle, Amanda, Lembrechts, Jonas J., Levesque, Esther, Little, Chelsea J., Luoto, Miska, Macek, Petr, Mack, Michelle C., Mathakutha, Rabia, Michelsen, Anders, Milbau, Ann, Molau, Ulf, Morgan, John W., Morsdorf, Martin Alfons, Nabe-Nielsen, Jacob, Nielsen, Sigrid Scholer, Ninot, Josep M., Oberbauer, Steven F., Olofsson, Johan, Onipchenko, Vladimir G., Petraglia, Alessandro, Pickering, Catherine, Prevey, Janet S., Rixen, Christian, Rumpf, Sabine B., Schaepman-Strub, Gabriela, Semenchuk, Philipp, Shetti, Rohan, Soudzilovskaia, Nadejda A., Spasojevic, Marko J., Speed, James David Mervyn, Street, Lorna E., Suding, Katharine, Tape, Ken D., Tomaselli, Marcello, Trant, Andrew, Treier, Urs A., Tremblay, Jean-Pierre, Tremblay, Maxime, Venn, Susanna, Virkkala, Anna-Maria, Vowles, Tage, Weijers, Stef, Wilmking, Martin, Wipf, Sonja, Zamin, Tara, Systems Ecology, Spatial Ecology and Global Change, and Environmental Sciences

Subjects
Ekologi, Chemistry, Arctic, plant functional traits, tundra, Ecology, Economics, Ecological Applications, alpine, VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497, VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497, Biology
Abstract

Motivation: The Tundra Trait Team (TTT) database includes field-based measurements of key traits related to plant form and function at multiple sites across the tundra biome. This dataset can be used to address theoretical questions about plant strategy and trade-offs, trait environment relationships and environmental filtering, and trait variation across spatial scales, to validate satellite data, and to inform Earth system model parameters. Main types of variable contained: The database contains 91,970 measurements of 18 plant traits. The most frequently measured traits (>1,000 observations each) include plant height, leaf area, specific leaf area, leaf fresh and dry mass, leaf dry matter content, leaf nitrogen, carbon and phosphorus content, leaf C:N and N:P, seed mass, and stem specific density. Spatial location and grain: Measurements were collected in tundra habitats in both the Northern and Southern Hemispheres, including Arctic sites in Alaska, Canada, Greenland, Fennoscandia and Siberia, alpine sites in the European Alps, Colorado Rockies, Caucasus, Ural Mountains, Pyrenees, Australian Alps, and Central Otago Mountains (New Zealand), and sub-Antarctic Marion Island. More than 99% of observations are georeferenced. Time period and grain: All data were collected between 1964 and 2018. A small number of sites have repeated trait measurements at two or more time periods. Major taxa and level of measurement: Trait measurements were made on 978 terrestrial vascular plant species growing in tundra habitats. Most observations are on individuals (86%), while the remainder represent plot or site means or maximums per species. Software format: csv file and GitHub repository with data cleaning scripts in R; contribution to TRY plant trait database (www.try-db.org) to be included in the next version release. 2Ecoinformatics and Biodiversity, Department of Bioscience, Aarhus University, Aarhus, Denmark 3Senckenberg Gesellschaft fD?r Naturforschung, Biodiversity and Climate Research Centre (BiK?F), Frankfurt, Germany 4Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado 5National Ecological Observatory Network, Boulder, Colorado 6Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 7Arctic Research Center, Department of Bioscience, Aarhus University, Aarhus, Denmark 8Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Bioscience, Aarhus University, Aarhus, Denmark 9Department of Biological and Environmental Sciences, Qatar University, Doha, Qatar 10Department of Forestry, Forest and Wildlife Research Center, Mississippi State University, Mississippi 11Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Spain 12Biodiversity Research Institute, University of Barcelona, Barcelona, Spain 13Institute of Botany and Landscape Ecology, Greifswald University, Greifswald, Germany 14Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Xishuangbanna, China 15Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland 16Department of Ecology and Environmental Science, Ume� University, Ume�, Sweden 17Environmental Sciences, Copernicus Institute of Sustainable Development, Utrecht University, Utrecht, The Netherlands 18School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, Arizona 19Department of Earth Sciences, University of Gothenburg, Gothenburg, Sweden 20Gothenburg Global Biodiversity Centre, GD?teborg, Sweden 21Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden 22Martin Luther University Halle?Wittenberg, Institute of Biology / Geobotany and Botanical Garden, Halle (Saale), Germany 23German Centre for Integrative Biodiversity Research (iDiv) Halle?Jena?Leipzig, Leipzig, Germany 24Adam Mickiewicz University, Institute of Geoecology and Geoinformation, Poznan, Poland 25University of Alaska Anchorage, Department of Biological Sciences, Anchorage, Alaska 26Technische Universit�t MD?nchen, Freising, Germany 27Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy 28The Alaska Department of Fish and Game, Anchorage, Alaska 29Department of Biology, Memorial University, St. John�s, Newfoundland and Labrador, Canada 30Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT? The Arctic University of Norway, Troms�, Norway 31Systems Ecology, Department of Ecological Science, Vrije Universiteit, Amsterdam, The Netherlands 32Department of Botany, University of Otago, Dunedin, New Zealand 33Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria 34Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark 35Department of Physiological Diversity, Helmholtz Centre for Environmental Research ? UFZ, Leipzig, Germany 36Department of Ecology and Genetics, University of Oulu, Oulu, Finland 37Arctic Centre, University of Lapland, Rovaniemi, Finland 38Swiss Federal Research Institute WSL, Birmensdorf, Switzerland 39Department of Geography, University of British Columbia, Vancouver, British Columbia, Canada 40Faculty of Science and Technology, Federation University, Ballarat, Victoria, Australia 41Global Ecology Unit, CREAF?CSIC?UAB, Bellaterra, Catalonia, Spain 42CREAF, Bellaterra, Cerdanyola del Vall�s, Catalonia, Spain 43Department of Ecology, Environment and Evolution, La Trobe University, Bundoora, Australia 44Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa 45Department of Biology, Queen�s University, Kingston, Ontario, Canada Scopus

Published
2018
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14. Plant functional trait change across a warming tundra biome

Author

Bjorkman, Anne D., Myers-Smith, Isla H., Elmendorf, Sarah C., Normand, Signe, Rüger, Nadja, Beck, Pieter S. A., Blach-Overgaard, Anne, Blok, Daan, Cornelissen, J. Hans C., Forbes, Bruce C., Georges, Damien, Goetz, Scott J., Guay, Kevin C., Henry, Gregory H. R., HilleRisLambers, Janneke, Hollister, Robert D., Karger, Dirk N., Kattge, Jens, Manning, Peter, Prevéy, Janet S., Rixen, Christian, Schaepman-Strub, Gabriela, Thomas, Haydn J. D., Vellend, Mark, Wilmking, Martin, Wipf, Sonja, Carbognani, Michele, Hermanutz, Luise, Lévesque, Esther, Molau, Ulf, Petraglia, Alessandro, Soudzilovskaia, Nadejda A., Spasojevic, Marko J., Tomaselli, Marcello, Vowles, Tage, Alatalo, Juha M., Alexander, Heather D., Anadon-Rosell, Alba, Angers-Blondin, Sandra, Beest, Mariska te, Berner, Logan, Björk, Robert G., Buchwal, Agata, Buras, Allan, Christie, Katherine, Cooper, Elisabeth J., Dullinger, Stefan, Elberling, Bo, Eskelinen, Anu, Frei, Esther R., Grau, Oriol, Grogan, Paul, Hallinger, Martin, Harper, Karen A., Heijmans, Monique M. P. D., Hudson, James, Hülber, Karl, Iturrate-Garcia, Maitane, Iversen, Colleen M., Jaroszynska, Francesca, Johnstone, Jill F., Jørgensen, Rasmus Halfdan, Kaarlejärvi, Elina, Klady, Rebecca, Kuleza, Sara, Kulonen, Aino, Lamarque, Laurent J., Lantz, Trevor, Little, Chelsea J., Speed, James D. M., Michelsen, Anders, Milbau, Ann, Nabe-Nielsen, Jacob, Nielsen, Sigrid Schøler, Ninot, Josep M., Oberbauer, Steven F., Olofsson, Johan, Onipchenko, Vladimir G., Rumpf, Sabine B., Semenchuk, Philipp, Shetti, Rohan, Collier, Laura Siegwart, Street, Lorna E., Suding, Katharine N., Tape, Ken D., Trant, Andrew, Treier, Urs A., Tremblay, Jean-Pierre, Tremblay, Maxime, Venn, Susanna, Weijers, Stef, Zamin, Tara, Boulanger-Lapointe, Noémie, Gould, William A., Hik, David S., Hofgaard, Annika, Jónsdóttir, Ingibjörg S., Jorgenson, Janet, Klein, Julia, Magnusson, Borgthor, Tweedie, Craig, Wookey, Philip A., Bahn, Michael, Blonder, Benjamin, van Bodegom, Peter M., Bond-Lamberty, Benjamin, Campetella, Giandiego, Cerabolini, Bruno E. L., Chapin, F. Stuart, Cornwell, William K., Craine, Joseph, Dainese, Matteo, de Vries, Franciska T., Díaz, Sandra, Enquist, Brian J., Green, Walton, Milla, Ruben, Niinemets, Ülo, Onoda, Yusuke, Ordoñez, Jenny C., Ozinga, Wim A., Penuelas, Josep, Poorter, Hendrik, Poschlod, Peter, Reich, Peter B., Sandel, Brody, Schamp, Brandon, Sheremetev, Serge, Weiher, Evan, Bjorkman, Anne D., Myers-Smith, Isla H., Elmendorf, Sarah C., Normand, Signe, Rüger, Nadja, Beck, Pieter S. A., Blach-Overgaard, Anne, Blok, Daan, Cornelissen, J. Hans C., Forbes, Bruce C., Georges, Damien, Goetz, Scott J., Guay, Kevin C., Henry, Gregory H. R., HilleRisLambers, Janneke, Hollister, Robert D., Karger, Dirk N., Kattge, Jens, Manning, Peter, Prevéy, Janet S., Rixen, Christian, Schaepman-Strub, Gabriela, Thomas, Haydn J. D., Vellend, Mark, Wilmking, Martin, Wipf, Sonja, Carbognani, Michele, Hermanutz, Luise, Lévesque, Esther, Molau, Ulf, Petraglia, Alessandro, Soudzilovskaia, Nadejda A., Spasojevic, Marko J., Tomaselli, Marcello, Vowles, Tage, Alatalo, Juha M., Alexander, Heather D., Anadon-Rosell, Alba, Angers-Blondin, Sandra, Beest, Mariska te, Berner, Logan, Björk, Robert G., Buchwal, Agata, Buras, Allan, Christie, Katherine, Cooper, Elisabeth J., Dullinger, Stefan, Elberling, Bo, Eskelinen, Anu, Frei, Esther R., Grau, Oriol, Grogan, Paul, Hallinger, Martin, Harper, Karen A., Heijmans, Monique M. P. D., Hudson, James, Hülber, Karl, Iturrate-Garcia, Maitane, Iversen, Colleen M., Jaroszynska, Francesca, Johnstone, Jill F., Jørgensen, Rasmus Halfdan, Kaarlejärvi, Elina, Klady, Rebecca, Kuleza, Sara, Kulonen, Aino, Lamarque, Laurent J., Lantz, Trevor, Little, Chelsea J., Speed, James D. M., Michelsen, Anders, Milbau, Ann, Nabe-Nielsen, Jacob, Nielsen, Sigrid Schøler, Ninot, Josep M., Oberbauer, Steven F., Olofsson, Johan, Onipchenko, Vladimir G., Rumpf, Sabine B., Semenchuk, Philipp, Shetti, Rohan, Collier, Laura Siegwart, Street, Lorna E., Suding, Katharine N., Tape, Ken D., Trant, Andrew, Treier, Urs A., Tremblay, Jean-Pierre, Tremblay, Maxime, Venn, Susanna, Weijers, Stef, Zamin, Tara, Boulanger-Lapointe, Noémie, Gould, William A., Hik, David S., Hofgaard, Annika, Jónsdóttir, Ingibjörg S., Jorgenson, Janet, Klein, Julia, Magnusson, Borgthor, Tweedie, Craig, Wookey, Philip A., Bahn, Michael, Blonder, Benjamin, van Bodegom, Peter M., Bond-Lamberty, Benjamin, Campetella, Giandiego, Cerabolini, Bruno E. L., Chapin, F. Stuart, Cornwell, William K., Craine, Joseph, Dainese, Matteo, de Vries, Franciska T., Díaz, Sandra, Enquist, Brian J., Green, Walton, Milla, Ruben, Niinemets, Ülo, Onoda, Yusuke, Ordoñez, Jenny C., Ozinga, Wim A., Penuelas, Josep, Poorter, Hendrik, Poschlod, Peter, Reich, Peter B., Sandel, Brody, Schamp, Brandon, Sheremetev, Serge, and Weiher, Evan

Abstract

The tundra is warming more rapidly than any other biome on Earth, and the potential ramifications are far-reaching because of global feedback effects between vegetation and climate. A better understanding of how environmental factors shape plant structure and function is crucial for predicting the consequences of environmental change for ecosystem functioning. Here we explore the biome-wide relationships between temperature, moisture and seven key plant functional traits both across space and over three decades of warming at 117 tundra locations. Spatial temperature–trait relationships were generally strong but soil moisture had a marked influence on the strength and direction of these relationships, highlighting the potentially important influence of changes in water availability on future trait shifts in tundra plant communities. Community height increased with warming across all sites over the past three decades, but other traits lagged far behind predicted rates of change. Our findings highlight the challenge of using space-for-time substitution to predict the functional consequences of future warming and suggest that functions that are tied closely to plant height will experience the most rapid change. They also reveal the strength with which environmental factors shape biotic communities at the coldest extremes of the planet and will help to improve projections of functional changes in tundra ecosystems with climate warming.

Published
2018

15. Plant functional trait change across a warming tundra biome

Author

Spatial Ecology and Global Change, Environmental Sciences, Bjorkman, Anne D., Myers-Smith, Isla H., Elmendorf, Sarah C., Normand, Signe, Rüger, Nadja, Beck, Pieter S. A., Blach-Overgaard, Anne, Blok, Daan, Cornelissen, J. Hans C., Forbes, Bruce C., Georges, Damien, Goetz, Scott J., Guay, Kevin C., Henry, Gregory H. R., HilleRisLambers, Janneke, Hollister, Robert D., Karger, Dirk N., Kattge, Jens, Manning, Peter, Prevéy, Janet S., Rixen, Christian, Schaepman-Strub, Gabriela, Thomas, Haydn J. D., Vellend, Mark, Wilmking, Martin, Wipf, Sonja, Carbognani, Michele, Hermanutz, Luise, Lévesque, Esther, Molau, Ulf, Petraglia, Alessandro, Soudzilovskaia, Nadejda A., Spasojevic, Marko J., Tomaselli, Marcello, Vowles, Tage, Alatalo, Juha M., Alexander, Heather D., Anadon-Rosell, Alba, Angers-Blondin, Sandra, Beest, Mariska te, Berner, Logan, Björk, Robert G., Buchwal, Agata, Buras, Allan, Christie, Katherine, Cooper, Elisabeth J., Dullinger, Stefan, Elberling, Bo, Eskelinen, Anu, Frei, Esther R., Grau, Oriol, Grogan, Paul, Hallinger, Martin, Harper, Karen A., Heijmans, Monique M. P. D., Hudson, James, Hülber, Karl, Iturrate-Garcia, Maitane, Iversen, Colleen M., Jaroszynska, Francesca, Johnstone, Jill F., Jørgensen, Rasmus Halfdan, Kaarlejärvi, Elina, Klady, Rebecca, Kuleza, Sara, Kulonen, Aino, Lamarque, Laurent J., Lantz, Trevor, Little, Chelsea J., Speed, James D. M., Michelsen, Anders, Milbau, Ann, Nabe-Nielsen, Jacob, Nielsen, Sigrid Schøler, Ninot, Josep M., Oberbauer, Steven F., Olofsson, Johan, Onipchenko, Vladimir G., Rumpf, Sabine B., Semenchuk, Philipp, Shetti, Rohan, Collier, Laura Siegwart, Street, Lorna E., Suding, Katharine N., Tape, Ken D., Trant, Andrew, Treier, Urs A., Tremblay, Jean-Pierre, Tremblay, Maxime, Venn, Susanna, Weijers, Stef, Zamin, Tara, Boulanger-Lapointe, Noémie, Gould, William A., Hik, David S., Hofgaard, Annika, Jónsdóttir, Ingibjörg S., Jorgenson, Janet, Klein, Julia, Magnusson, Borgthor, Tweedie, Craig, Wookey, Philip A., Bahn, Michael, Blonder, Benjamin, van Bodegom, Peter M., Bond-Lamberty, Benjamin, Campetella, Giandiego, Cerabolini, Bruno E. L., Chapin, F. Stuart, Cornwell, William K., Craine, Joseph, Dainese, Matteo, de Vries, Franciska T., Díaz, Sandra, Enquist, Brian J., Green, Walton, Milla, Ruben, Niinemets, Ülo, Onoda, Yusuke, Ordoñez, Jenny C., Ozinga, Wim A., Penuelas, Josep, Poorter, Hendrik, Poschlod, Peter, Reich, Peter B., Sandel, Brody, Schamp, Brandon, Sheremetev, Serge, Weiher, Evan, Spatial Ecology and Global Change, Environmental Sciences, Bjorkman, Anne D., Myers-Smith, Isla H., Elmendorf, Sarah C., Normand, Signe, Rüger, Nadja, Beck, Pieter S. A., Blach-Overgaard, Anne, Blok, Daan, Cornelissen, J. Hans C., Forbes, Bruce C., Georges, Damien, Goetz, Scott J., Guay, Kevin C., Henry, Gregory H. R., HilleRisLambers, Janneke, Hollister, Robert D., Karger, Dirk N., Kattge, Jens, Manning, Peter, Prevéy, Janet S., Rixen, Christian, Schaepman-Strub, Gabriela, Thomas, Haydn J. D., Vellend, Mark, Wilmking, Martin, Wipf, Sonja, Carbognani, Michele, Hermanutz, Luise, Lévesque, Esther, Molau, Ulf, Petraglia, Alessandro, Soudzilovskaia, Nadejda A., Spasojevic, Marko J., Tomaselli, Marcello, Vowles, Tage, Alatalo, Juha M., Alexander, Heather D., Anadon-Rosell, Alba, Angers-Blondin, Sandra, Beest, Mariska te, Berner, Logan, Björk, Robert G., Buchwal, Agata, Buras, Allan, Christie, Katherine, Cooper, Elisabeth J., Dullinger, Stefan, Elberling, Bo, Eskelinen, Anu, Frei, Esther R., Grau, Oriol, Grogan, Paul, Hallinger, Martin, Harper, Karen A., Heijmans, Monique M. P. D., Hudson, James, Hülber, Karl, Iturrate-Garcia, Maitane, Iversen, Colleen M., Jaroszynska, Francesca, Johnstone, Jill F., Jørgensen, Rasmus Halfdan, Kaarlejärvi, Elina, Klady, Rebecca, Kuleza, Sara, Kulonen, Aino, Lamarque, Laurent J., Lantz, Trevor, Little, Chelsea J., Speed, James D. M., Michelsen, Anders, Milbau, Ann, Nabe-Nielsen, Jacob, Nielsen, Sigrid Schøler, Ninot, Josep M., Oberbauer, Steven F., Olofsson, Johan, Onipchenko, Vladimir G., Rumpf, Sabine B., Semenchuk, Philipp, Shetti, Rohan, Collier, Laura Siegwart, Street, Lorna E., Suding, Katharine N., Tape, Ken D., Trant, Andrew, Treier, Urs A., Tremblay, Jean-Pierre, Tremblay, Maxime, Venn, Susanna, Weijers, Stef, Zamin, Tara, Boulanger-Lapointe, Noémie, Gould, William A., Hik, David S., Hofgaard, Annika, Jónsdóttir, Ingibjörg S., Jorgenson, Janet, Klein, Julia, Magnusson, Borgthor, Tweedie, Craig, Wookey, Philip A., Bahn, Michael, Blonder, Benjamin, van Bodegom, Peter M., Bond-Lamberty, Benjamin, Campetella, Giandiego, Cerabolini, Bruno E. L., Chapin, F. Stuart, Cornwell, William K., Craine, Joseph, Dainese, Matteo, de Vries, Franciska T., Díaz, Sandra, Enquist, Brian J., Green, Walton, Milla, Ruben, Niinemets, Ülo, Onoda, Yusuke, Ordoñez, Jenny C., Ozinga, Wim A., Penuelas, Josep, Poorter, Hendrik, Poschlod, Peter, Reich, Peter B., Sandel, Brody, Schamp, Brandon, Sheremetev, Serge, and Weiher, Evan

Published
2018

16. Tundra Trait Team: A database of plant traits spanning the tundra biome

Author

Spatial Ecology and Global Change, Environmental Sciences, Bjorkman, Anne D., Myers-Smith, Isla H., Elmendorf, Sarah C., Normand, Signe, Thomas, Haydn J. D., Alatalo, Juha M., Alexander, Heather, Anadon-Rosell, Alba, Angers-Blondin, Sandra, Bai, Yang, Baruah, Gaurav, te Beest, Mariska, Berner, Logan, Björk, Robert G., Blok, Daan, Bruelheide, Helge, Buchwal, Agata, Buras, Allan, Carbognani, Michele, Christie, Katherine, Collier, Laura S., Cooper, Elisabeth J., Cornelissen, J. Hans C., Dickinson, Katharine J. M., Dullinger, Stefan, Elberling, Bo, Eskelinen, Anu, Forbes, Bruce C., Frei, Esther R., Iturrate-Garcia, Maitane, Good, Megan K., Grau, Oriol, Green, Peter, Greve, Michelle, Grogan, Paul, Haider, Sylvia, Hájek, Tomáš, Hallinger, Martin, Happonen, Konsta, Harper, Karen A., Heijmans, Monique M. P. D., Henry, Gregory H. R., Hermanutz, Luise, Hewitt, Rebecca E., Hollister, Robert D., Hudson, James, Hülber, Karl, Iversen, Colleen M., Jaroszynska, Francesca, Jiménez-Alfaro, Borja, Johnstone, Jill, Jorgensen, Rasmus Halfdan, Kaarlejärvi, Elina, Klady, Rebecca, Klimešová, Jitka, Korsten, Annika, Kuleza, Sara, Kulonen, Aino, Lamarque, Laurent J., Lantz, Trevor, Lavalle, Amanda, Lembrechts, Jonas J., Lévesque, Esther, Little, Chelsea J., Luoto, Miska, Macek, Petr, Mack, Michelle C., Mathakutha, Rabia, Michelsen, Anders, Milbau, Ann, Molau, Ulf, Morgan, John W., Mörsdorf, Martin Alfons, Nabe-Nielsen, Jacob, Nielsen, Sigrid Schøler, Ninot, Josep M., Oberbauer, Steven F., Olofsson, Johan, Onipchenko, Vladimir G., Petraglia, Alessandro, Pickering, Catherine, Prevéy, Janet S., Rixen, Christian, Rumpf, Sabine B., Schaepman-Strub, Gabriela, Semenchuk, Philipp, Shetti, Rohan, Soudzilovskaia, Nadejda A., Spasojevic, Marko J., Speed, James David Mervyn, Street, Lorna E., Suding, Katharine, Tape, Ken D., Tomaselli, Marcello, Trant, Andrew, Treier, Urs A., Tremblay, Jean-Pierre, Tremblay, Maxime, Venn, Susanna, Virkkala, Anna-Maria, Vowles, Tage, Weijers, Stef, Wilmking, Martin, Wipf, Sonja, Zamin, Tara, Spatial Ecology and Global Change, Environmental Sciences, Bjorkman, Anne D., Myers-Smith, Isla H., Elmendorf, Sarah C., Normand, Signe, Thomas, Haydn J. D., Alatalo, Juha M., Alexander, Heather, Anadon-Rosell, Alba, Angers-Blondin, Sandra, Bai, Yang, Baruah, Gaurav, te Beest, Mariska, Berner, Logan, Björk, Robert G., Blok, Daan, Bruelheide, Helge, Buchwal, Agata, Buras, Allan, Carbognani, Michele, Christie, Katherine, Collier, Laura S., Cooper, Elisabeth J., Cornelissen, J. Hans C., Dickinson, Katharine J. M., Dullinger, Stefan, Elberling, Bo, Eskelinen, Anu, Forbes, Bruce C., Frei, Esther R., Iturrate-Garcia, Maitane, Good, Megan K., Grau, Oriol, Green, Peter, Greve, Michelle, Grogan, Paul, Haider, Sylvia, Hájek, Tomáš, Hallinger, Martin, Happonen, Konsta, Harper, Karen A., Heijmans, Monique M. P. D., Henry, Gregory H. R., Hermanutz, Luise, Hewitt, Rebecca E., Hollister, Robert D., Hudson, James, Hülber, Karl, Iversen, Colleen M., Jaroszynska, Francesca, Jiménez-Alfaro, Borja, Johnstone, Jill, Jorgensen, Rasmus Halfdan, Kaarlejärvi, Elina, Klady, Rebecca, Klimešová, Jitka, Korsten, Annika, Kuleza, Sara, Kulonen, Aino, Lamarque, Laurent J., Lantz, Trevor, Lavalle, Amanda, Lembrechts, Jonas J., Lévesque, Esther, Little, Chelsea J., Luoto, Miska, Macek, Petr, Mack, Michelle C., Mathakutha, Rabia, Michelsen, Anders, Milbau, Ann, Molau, Ulf, Morgan, John W., Mörsdorf, Martin Alfons, Nabe-Nielsen, Jacob, Nielsen, Sigrid Schøler, Ninot, Josep M., Oberbauer, Steven F., Olofsson, Johan, Onipchenko, Vladimir G., Petraglia, Alessandro, Pickering, Catherine, Prevéy, Janet S., Rixen, Christian, Rumpf, Sabine B., Schaepman-Strub, Gabriela, Semenchuk, Philipp, Shetti, Rohan, Soudzilovskaia, Nadejda A., Spasojevic, Marko J., Speed, James David Mervyn, Street, Lorna E., Suding, Katharine, Tape, Ken D., Tomaselli, Marcello, Trant, Andrew, Treier, Urs A., Tremblay, Jean-Pierre, Tremblay, Maxime, Venn, Susanna, Virkkala, Anna-Maria, Vowles, Tage, Weijers, Stef, Wilmking, Martin, Wipf, Sonja, and Zamin, Tara

Published
2018

17. Plant functional trait change across a warming tundra biome

Author

Bjorkman, Anne D., primary, Myers-Smith, Isla H., additional, Elmendorf, Sarah C., additional, Normand, Signe, additional, Rüger, Nadja, additional, Beck, Pieter S. A., additional, Blach-Overgaard, Anne, additional, Blok, Daan, additional, Cornelissen, J. Hans C., additional, Forbes, Bruce C., additional, Georges, Damien, additional, Goetz, Scott J., additional, Guay, Kevin C., additional, Henry, Gregory H. R., additional, HilleRisLambers, Janneke, additional, Hollister, Robert D., additional, Karger, Dirk N., additional, Kattge, Jens, additional, Manning, Peter, additional, Prevéy, Janet S., additional, Rixen, Christian, additional, Schaepman-Strub, Gabriela, additional, Thomas, Haydn J. D., additional, Vellend, Mark, additional, Wilmking, Martin, additional, Wipf, Sonja, additional, Carbognani, Michele, additional, Hermanutz, Luise, additional, Lévesque, Esther, additional, Molau, Ulf, additional, Petraglia, Alessandro, additional, Soudzilovskaia, Nadejda A., additional, Spasojevic, Marko J., additional, Tomaselli, Marcello, additional, Vowles, Tage, additional, Alatalo, Juha M., additional, Alexander, Heather D., additional, Anadon-Rosell, Alba, additional, Angers-Blondin, Sandra, additional, Beest, Mariska te, additional, Berner, Logan, additional, Björk, Robert G., additional, Buchwal, Agata, additional, Buras, Allan, additional, Christie, Katherine, additional, Cooper, Elisabeth J., additional, Dullinger, Stefan, additional, Elberling, Bo, additional, Eskelinen, Anu, additional, Frei, Esther R., additional, Grau, Oriol, additional, Grogan, Paul, additional, Hallinger, Martin, additional, Harper, Karen A., additional, Heijmans, Monique M. P. D., additional, Hudson, James, additional, Hülber, Karl, additional, Iturrate-Garcia, Maitane, additional, Iversen, Colleen M., additional, Jaroszynska, Francesca, additional, Johnstone, Jill F., additional, Jørgensen, Rasmus Halfdan, additional, Kaarlejärvi, Elina, additional, Klady, Rebecca, additional, Kuleza, Sara, additional, Kulonen, Aino, additional, Lamarque, Laurent J., additional, Lantz, Trevor, additional, Little, Chelsea J., additional, Speed, James D. M., additional, Michelsen, Anders, additional, Milbau, Ann, additional, Nabe-Nielsen, Jacob, additional, Nielsen, Sigrid Schøler, additional, Ninot, Josep M., additional, Oberbauer, Steven F., additional, Olofsson, Johan, additional, Onipchenko, Vladimir G., additional, Rumpf, Sabine B., additional, Semenchuk, Philipp, additional, Shetti, Rohan, additional, Collier, Laura Siegwart, additional, Street, Lorna E., additional, Suding, Katharine N., additional, Tape, Ken D., additional, Trant, Andrew, additional, Treier, Urs A., additional, Tremblay, Jean-Pierre, additional, Tremblay, Maxime, additional, Venn, Susanna, additional, Weijers, Stef, additional, Zamin, Tara, additional, Boulanger-Lapointe, Noémie, additional, Gould, William A., additional, Hik, David S., additional, Hofgaard, Annika, additional, Jónsdóttir, Ingibjörg S., additional, Jorgenson, Janet, additional, Klein, Julia, additional, Magnusson, Borgthor, additional, Tweedie, Craig, additional, Wookey, Philip A., additional, Bahn, Michael, additional, Blonder, Benjamin, additional, van Bodegom, Peter M., additional, Bond-Lamberty, Benjamin, additional, Campetella, Giandiego, additional, Cerabolini, Bruno E. L., additional, Chapin, F. Stuart, additional, Cornwell, William K., additional, Craine, Joseph, additional, Dainese, Matteo, additional, de Vries, Franciska T., additional, Díaz, Sandra, additional, Enquist, Brian J., additional, Green, Walton, additional, Milla, Ruben, additional, Niinemets, Ülo, additional, Onoda, Yusuke, additional, Ordoñez, Jenny C., additional, Ozinga, Wim A., additional, Penuelas, Josep, additional, Poorter, Hendrik, additional, Poschlod, Peter, additional, Reich, Peter B., additional, Sandel, Brody, additional, Schamp, Brandon, additional, Sheremetev, Serge, additional, and Weiher, Evan, additional

Published
2018
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18. Reproduction as a bottleneck to treeline advance across the circumarctic forest tundra ecotone

Author

Brown, Carissa D., primary, Dufour‐Tremblay, Geneviève, additional, Jameson, Ryan G., additional, Mamet, Steven D., additional, Trant, Andrew J., additional, Walker, Xanthe J., additional, Boudreau, Stéphane, additional, Harper, Karen A., additional, Henry, Gregory H. R., additional, Hermanutz, Luise, additional, Hofgaard, Annika, additional, Isaeva, Ludmila, additional, Kershaw, G. Peter, additional, and Johnstone, Jill F., additional

Published
2018
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20. Greater temperature sensitivity of plant phenology at colder sites: implications for convergence across northern latitudes

Author

Prevéy, Janet, primary, Vellend, Mark, additional, Rüger, Nadja, additional, Hollister, Robert D., additional, Bjorkman, Anne D., additional, Myers‐Smith, Isla H., additional, Elmendorf, Sarah C., additional, Clark, Karin, additional, Cooper, Elisabeth J., additional, Elberling, Bo, additional, Fosaa, Anna M., additional, Henry, Gregory H. R., additional, Høye, Toke T., additional, Jónsdóttir, Ingibjörg S., additional, Klanderud, Kari, additional, Lévesque, Esther, additional, Mauritz, Marguerite, additional, Molau, Ulf, additional, Natali, Susan M., additional, Oberbauer, Steven F., additional, Panchen, Zoe A., additional, Post, Eric, additional, Rumpf, Sabine B., additional, Schmidt, Niels M., additional, Schuur, Edward A. G., additional, Semenchuk, Phillip R., additional, Troxler, Tiffany, additional, Welker, Jeffrey M., additional, and Rixen, Christian, additional

Published
2017
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21. Reproduction as a bottleneck to treeline advance across the circumarctic forest tundra ecotone.

Author

Brown, Carissa D., Dufour‐Tremblay, Geneviève, Jameson, Ryan G., Mamet, Steven D., Trant, Andrew J., Walker, Xanthe J., Boudreau, Stéphane, Harper, Karen A., Henry, Gregory H. R., Hermanutz, Luise, Hofgaard, Annika, Isaeva, Ludmila, Kershaw, G. Peter, and Johnstone, Jill F.

Subjects
TUNDRA ecology, CLIMATE change, PLANT growth & the environment, PLANT colonization, SEED production (Botany), SPECIES distribution
Abstract

The fundamental niche of many species is shifting with climate change, especially in sub‐arctic ecosystems with pronounced recent warming. Ongoing warming in sub‐arctic regions should lessen environmental constraints on tree growth and reproduction, leading to increased success of trees colonising tundra. Nevertheless, variable responses of treeline ecotones have been documented in association with warming temperatures. One explanation for time lags between increasingly favourable environmental conditions and treeline ecotone movement is reproductive limitations caused by low seed availability. Our objective was to assess the reproductive constraints of the dominant tree species at the treeline ecotone in the circumpolar north. We sampled reproductive structures of trees (cones and catkins) and stand attributes across circumarctic treeline ecotones. We used generalized linear mixed models to estimate the sensitivity of seed production and the availability of viable seed to regional climate, stand structure, and species‐specific characteristics. Both seed production and viability of available seed were strongly driven by specific, sequential seasonal climatic conditions, but in different ways. Seed production was greatest when growing seasons with more growing degree days coincided with years with high precipitation. Two consecutive years with more growing degree days and low precipitation resulted in low seed production. Seasonal climate effects on the viability of available seed depended on the physical characteristics of the reproductive structures. Large‐coned and ‐seeded species take more time to develop mature embryos and were therefore more sensitive to increases in growing degree days in the year of flowering and embryo development. Our findings suggest that both moisture stress and abbreviated growing seasons can have a notable negative influence on the production and viability of available seed at treeline. Our synthesis revealed that constraints on predispersal reproduction within the treeline ecotone might create a considerable time lag for range expansion of tree populations into tundra ecosystems. [ABSTRACT FROM AUTHOR]

Published
2019
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24. Contrasting effects of warming and increased snowfall on Arctic tundra plant phenology over the past two decades

Author

Bjorkman, Anne D., Elmendorf, Sarah C., Beamish, Alison L., Vellend, Mark, Henry, Gregory H. R., Bjorkman, Anne D., Elmendorf, Sarah C., Beamish, Alison L., Vellend, Mark, and Henry, Gregory H. R.

Abstract

Recent changes in climate have led to significant shifts in phenology, with many studies demonstrating advanced phenology in response to warming temperatures. The rate of temperature change is especially high in the Arctic, but this is also where we have relatively little data on phenological changes and the processes driving these changes. In order to understand how Arctic plant species are likely to respond to future changes in climate, we monitored flowering phenology in response to both experimental and ambient warming for four widespread species in two habitat types over 21 years. We additionally used long-term environmental records to disentangle the effects of temperature increase and changes in snowmelt date on phenological patterns. While flowering occurred earlier in response to experimental warming, plants in unmanipulated plots showed no change or a delay in flowering over the 21-year period, despite more than 1 °C of ambient warming during that time. This counterintuitive result was likely due to significantly delayed snowmelt over the study period (0.05–0.2 days/yr) due to increased winter snowfall. The timing of snowmelt was a strong driver of flowering phenology for all species – especially for early-flowering species – while spring temperature was significantly related to flowering time only for later-flowering species. Despite significantly delayed flowering phenology, the timing of seed maturation showed no significant change over time, suggesting that warmer temperatures may promote more rapid seed development. The results of this study highlight the importance of understanding the specific environmental cues that drive species’ phenological responses as well as the complex interactions between temperature and precipitation when forecasting phenology over the coming decades. As demonstrated here, the effects of altered snowmelt patterns can counter the effects of warmer temperatures, even to the point of generating phenological responses opposite

Published
2015

25. Long‐term deepened snow promotes tundra evergreen shrub growth and summertime ecosystem net CO2 gain but reduces soil carbon and nutrient pools.

Author

Christiansen, Casper T., Lafreniére, Melissa J., Henry, Gregory H. R., and Grogan, Paul

Subjects
SNOW, TUNDRAS, SHRUBS, CARBON in soils, BIOGEOCHEMISTRY
Abstract

Abstract: Arctic climate warming will be primarily during winter, resulting in increased snowfall in many regions. Previous tundra research on the impacts of deepened snow has generally been of short duration. Here, we report relatively long‐term (7–9 years) effects of experimentally deepened snow on plant community structure, net ecosystem CO2 exchange (NEE), and soil biogeochemistry in Canadian Low Arctic mesic shrub tundra. The snowfence treatment enhanced snow depth from 0.3 to ~1 m, increasing winter soil temperatures by ~3°C, but with no effect on summer soil temperature, moisture, or thaw depth. Nevertheless, shoot biomass of the evergreen shrub Rhododendron subarcticum was near‐doubled by the snowfences, leading to a 52% increase in aboveground vascular plant biomass. Additionally, summertime NEE rates, measured in collars containing similar plant biomass across treatments, were consistently reduced ~30% in the snowfenced plots due to decreased ecosystem respiration rather than increased gross photosynthesis. Phosphate in the organic soil layer (0–10 cm depth) and nitrate in the mineral soil layer (15–25 cm depth) were substantially reduced within the snowfences (47–70 and 43%–73% reductions, respectively, across sampling times). Finally, the snowfences tended (p = .08) to reduce mineral soil layer C% by 40%, but with considerable within‐ and among plot variation due to cryoturbation across the landscape. These results indicate that enhanced snow accumulation is likely to further increase dominance of R. subarcticum in its favored locations, and reduce summertime respiration and soil biogeochemical pools. Since evergreens are relatively slow growing and of low stature, their increased dominance may constrain vegetation‐related feedbacks to climate change. We found no evidence that deepened snow promoted deciduous shrub growth in mesic tundra, and conclude that the relatively strong R. subarcticum response to snow accumulation may explain the extensive spatial variability in observed circumpolar patterns of evergreen and deciduous shrub growth over the past 30 years. [ABSTRACT FROM AUTHOR]

Published
2018
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27. Climate adaptation is not enough: warming does not facilitate success of southern tundra plant populations in the high Arctic.

Author

Bjorkman, Anne D., Vellend, Mark, Frei, Esther R., and Henry, Gregory H. R.

Subjects
GLOBAL warming, TUNDRAS, PLANT populations, HIGH temperature (Weather)
Abstract

Rapidly rising temperatures are expected to cause latitudinal and elevational range shifts as species track their optimal climate north and upward. However, a lack of adaptation to environmental conditions other than climate - for example photoperiod, biotic interactions, or edaphic conditions - might limit the success of immigrants in a new location despite hospitable climatic conditions. Here, we present one of the first direct experimental tests of the hypothesis that warmer temperatures at northern latitudes will confer a fitness advantage to southern immigrants relative to native populations. As rates of warming in the Arctic are more than double the global average, understanding the impacts of warming in Arctic ecosystems is especially urgent. We established experimentally warmed and nonwarmed common garden plots at Alexandra Fiord, Ellesmere Island in the Canadian High Arctic with seeds of two forb species ( Oxyria digyna and Papaver radicatum) originating from three to five populations at different latitudes across the Arctic. We found that plants from the local populations generally had higher survival and obtained a greater maximum size than foreign individuals, regardless of warming treatment. Phenological traits varied with latitude of the source population, such that southern populations demonstrated substantially delayed leaf-out and senescence relative to northern populations. Our results suggest that environmental conditions other than temperature may influence the ability of foreign populations and species to establish at more northerly latitudes as the climate warms, potentially leading to lags in northward range shifts for some species. [ABSTRACT FROM AUTHOR]

Published
2017
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28. Experiment, monitoring, and gradient methods used to infer climate change effects on plant communities yield consistent patterns

Author

Elmendorf, Sarah C., primary, Henry, Gregory H. R., additional, Hollister, Robert D., additional, Fosaa, Anna Maria, additional, Gould, William A., additional, Hermanutz, Luise, additional, Hofgaard, Annika, additional, Jónsdóttir, Ingibjörg S., additional, Jorgenson, Janet C., additional, Lévesque, Esther, additional, Magnusson, Borgþór, additional, Molau, Ulf, additional, Myers-Smith, Isla H., additional, Oberbauer, Steven F., additional, Rixen, Christian, additional, Tweedie, Craig E., additional, and Walker, Marilyn D., additional

Published
2014
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29. Global assessment of experimental climate warming on tundra vegetation : heterogeneity over space and time

Author

Elmendorf, Sarah C., Henry, Gregory H. R., Hollister, Robert D., Alatalo, Juha, Bjork, Robert G., Bjorkman, Anne D., Callaghan, Terry V., Collier, Laura Siegwart, Cooper, Elisabeth J., Cornelissen, Johannes H. C., Day, Thomas A., Fosaa, Anna Maria, Gould, William A., Gretarsdottir, Jarngerdur, Harte, John, Hermanutz, Luise, Hik, David S., Hofgaard, Annika, Jarrad, Frith, Jonsdottir, Ingibjorg Svala, Keuper, Frida, Klanderud, Kari, Klein, Julia A., Koh, Saewan, Kudo, Gaku, Lang, Simone I., Loewen, Val, May, Jeremy L., Mercado, Joel, Michelsen, Anders, Molau, Ulf, Myers-Smith, Isla H., Oberbauer, Steven F., Pieper, Sara, Post, Eric, Rixen, Christian, Robinson, Clare H., Schmidt, Niels Martin, Shaver, Gaius R., Stenstrom, Anna, Tolvanen, Anne, Totland, Orjan, Troxler, Tiffany, Wahren, Carl-Henrik, Walker, Marilyn D., Webber, Patrick J., Welker, Jeffery M., Wookey, Philip A., Elmendorf, Sarah C., Henry, Gregory H. R., Hollister, Robert D., Alatalo, Juha, Bjork, Robert G., Bjorkman, Anne D., Callaghan, Terry V., Collier, Laura Siegwart, Cooper, Elisabeth J., Cornelissen, Johannes H. C., Day, Thomas A., Fosaa, Anna Maria, Gould, William A., Gretarsdottir, Jarngerdur, Harte, John, Hermanutz, Luise, Hik, David S., Hofgaard, Annika, Jarrad, Frith, Jonsdottir, Ingibjorg Svala, Keuper, Frida, Klanderud, Kari, Klein, Julia A., Koh, Saewan, Kudo, Gaku, Lang, Simone I., Loewen, Val, May, Jeremy L., Mercado, Joel, Michelsen, Anders, Molau, Ulf, Myers-Smith, Isla H., Oberbauer, Steven F., Pieper, Sara, Post, Eric, Rixen, Christian, Robinson, Clare H., Schmidt, Niels Martin, Shaver, Gaius R., Stenstrom, Anna, Tolvanen, Anne, Totland, Orjan, Troxler, Tiffany, Wahren, Carl-Henrik, Walker, Marilyn D., Webber, Patrick J., Welker, Jeffery M., and Wookey, Philip A.

Abstract

Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation and associated ecosystem consequences have the potential to be much greater than we have observed to date., The following authors were added to this article (see correction below):Alatalo, JuhaWalker, MarilynCorrection in: Ecology Letters, Vol. 17, Issue 2, page 260 (Feb 2014).DOI: 10.1111/ele.12218

Published
2012
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30. Plot-scale evidence of tundra vegetation change and links to recent summer warming

Author

Elmendorf, Sarah C., Henry, Gregory H. R., Hollister, Robert D., Bjork, Robert G., Boulanger-Lapointe, Noemie, Cooper, Elisabeth J., Cornelissen, Johannes H. C., Day, Thomas A., Dorrepaal, Ellen, Elumeeva, Tatiana G., Gill, Mike, Gould, William A., Harte, John, Hik, David S., Hofgaard, Annika, Johnson, David R., Johnstone, Jill F., Jonsdottir, Ingibjorg Svala, Jorgenson, Janet C., Klanderud, Kari, Klein, Julia A., Koh, Saewan, Kudo, Gaku, Lara, Mark, Levesque, Esther, Magnusson, Borgthor, May, Jeremy L., Mercado-Diaz, Joel A., Michelsen, Anders, Molau, Ulf, Myers-Smith, Isla H., Oberbauer, Steven F., Onipchenko, Vladimir G., Rixen, Christian, Schmidt, Niels Martin, Shaver, Gaius R., Spasojevic, Marko J., Porhallsdottir, Pora Ellen, Tolvanen, Anne, Troxler, Tiffany, Tweedie, Craig E., Villareal, Sandra, Wahren, Carl-Henrik, Walker, Xanthe, Webber, Patrick J., Welker, Jeffrey M., Wipf, Sonja, Elmendorf, Sarah C., Henry, Gregory H. R., Hollister, Robert D., Bjork, Robert G., Boulanger-Lapointe, Noemie, Cooper, Elisabeth J., Cornelissen, Johannes H. C., Day, Thomas A., Dorrepaal, Ellen, Elumeeva, Tatiana G., Gill, Mike, Gould, William A., Harte, John, Hik, David S., Hofgaard, Annika, Johnson, David R., Johnstone, Jill F., Jonsdottir, Ingibjorg Svala, Jorgenson, Janet C., Klanderud, Kari, Klein, Julia A., Koh, Saewan, Kudo, Gaku, Lara, Mark, Levesque, Esther, Magnusson, Borgthor, May, Jeremy L., Mercado-Diaz, Joel A., Michelsen, Anders, Molau, Ulf, Myers-Smith, Isla H., Oberbauer, Steven F., Onipchenko, Vladimir G., Rixen, Christian, Schmidt, Niels Martin, Shaver, Gaius R., Spasojevic, Marko J., Porhallsdottir, Pora Ellen, Tolvanen, Anne, Troxler, Tiffany, Tweedie, Craig E., Villareal, Sandra, Wahren, Carl-Henrik, Walker, Xanthe, Webber, Patrick J., Welker, Jeffrey M., and Wipf, Sonja

Abstract

Temperature is increasing at unprecedented rates across most of the tundra biome(1). Remote-sensing data indicate that contemporary climate warming has already resulted in increased productivity over much of the Arctic(2,3), but plot-based evidence for vegetation transformation is not widespread. We analysed change in tundra vegetation surveyed between 1980 and 2010 in 158 plant communities spread across 46 locations. We found biome-wide trends of increased height of the plant canopy and maximum observed plant height for most vascular growth forms; increased abundance of litter; increased abundance of evergreen, low-growing and tall shrubs; and decreased abundance of bare ground. Intersite comparisons indicated an association between the degree of summer warming and change in vascular plant abundance, with shrubs, forbs and rushes increasing with warming. However, the association was dependent on the climate zone, the moisture regime and the presence of permafrost. Our data provide plot-scale evidence linking changes in vascular plant abundance to local summer warming in widely dispersed tundra locations across the globe.

Published
2012
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31. Plot-scale evidence of tundra vegetation change and links to recent summer warming

Author

Elmendorf, Sarah C., primary, Henry, Gregory H. R., additional, Hollister, Robert D., additional, Björk, Robert G., additional, Boulanger-Lapointe, Noémie, additional, Cooper, Elisabeth J., additional, Cornelissen, Johannes H. C., additional, Day, Thomas A., additional, Dorrepaal, Ellen, additional, Elumeeva, Tatiana G., additional, Gill, Mike, additional, Gould, William A., additional, Harte, John, additional, Hik, David S., additional, Hofgaard, Annika, additional, Johnson, David R., additional, Johnstone, Jill F., additional, Jónsdóttir, Ingibjörg Svala, additional, Jorgenson, Janet C., additional, Klanderud, Kari, additional, Klein, Julia A., additional, Koh, Saewan, additional, Kudo, Gaku, additional, Lara, Mark, additional, Lévesque, Esther, additional, Magnússon, Borgthor, additional, May, Jeremy L., additional, Mercado-Dı´az, Joel A., additional, Michelsen, Anders, additional, Molau, Ulf, additional, Myers-Smith, Isla H., additional, Oberbauer, Steven F., additional, Onipchenko, Vladimir G., additional, Rixen, Christian, additional, Martin Schmidt, Niels, additional, Shaver, Gaius R., additional, Spasojevic, Marko J., additional, Þórhallsdóttir, Þóra Ellen, additional, Tolvanen, Anne, additional, Troxler, Tiffany, additional, Tweedie, Craig E., additional, Villareal, Sandra, additional, Wahren, Carl-Henrik, additional, Walker, Xanthe, additional, Webber, Patrick J., additional, Welker, Jeffrey M., additional, and Wipf, Sonja, additional

Published
2012
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32. Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time

Author

Elmendorf, Sarah C., primary, Henry, Gregory H. R., additional, Hollister, Robert D., additional, Björk, Robert G., additional, Bjorkman, Anne D., additional, Callaghan, Terry V., additional, Collier, Laura Siegwart, additional, Cooper, Elisabeth J., additional, Cornelissen, Johannes H. C., additional, Day, Thomas A., additional, Fosaa, Anna Maria, additional, Gould, William A., additional, Grétarsdóttir, Járngerður, additional, Harte, John, additional, Hermanutz, Luise, additional, Hik, David S., additional, Hofgaard, Annika, additional, Jarrad, Frith, additional, Jónsdóttir, Ingibjörg Svala, additional, Keuper, Frida, additional, Klanderud, Kari, additional, Klein, Julia A., additional, Koh, Saewan, additional, Kudo, Gaku, additional, Lang, Simone I., additional, Loewen, Val, additional, May, Jeremy L., additional, Mercado, Joel, additional, Michelsen, Anders, additional, Molau, Ulf, additional, Myers-Smith, Isla H., additional, Oberbauer, Steven F., additional, Pieper, Sara, additional, Post, Eric, additional, Rixen, Christian, additional, Robinson, Clare H., additional, Schmidt, Niels Martin, additional, Shaver, Gaius R., additional, Stenström, Anna, additional, Tolvanen, Anne, additional, Totland, Ørjan, additional, Troxler, Tiffany, additional, Wahren, Carl-Henrik, additional, Webber, Patrick J., additional, Welker, Jeffery M., additional, and Wookey, Philip A., additional

Published
2011
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40. Changes in high arctic tundra plant reproduction in response to long-term experimental warming.

Author

KLADY, REBECCA A., HENRY, GREGORY H. R., and LEMAY, VALERIE

Subjects
*TUNDRA plants, *CLIMATE change, *BOTANY, *PLANT reproduction, *PLANT communities, *BIOTIC communities, *WOODY plants, *FROZEN ground, *PLANT ecology
Abstract

We provide new information on changes in tundra plant sexual reproduction in response to long-term (12 years) experimental warming in the High Arctic. Open-top chambers (OTCs) were used to increase growing season temperatures by 1-2 °C across a range of vascular plant communities. The warming enhanced reproductive effort and success in most species; shrubs and graminoids appeared to be more responsive than forbs. We found that the measured effects of warming on sexual reproduction were more consistently positive and to a greater degree in polar oasis compared with polar semidesert vascular plant communities. Our findings support predictions that long-term warming in the High Arctic will likely enhance sexual reproduction in tundra plants, which could lead to an increase in plant cover. Greater abundance of vegetation has implications for primary consumers - via increased forage availability, and the global carbon budget - as a function of changes in permafrost and vegetation acting as a carbon sink. Enhanced sexual reproduction in Arctic vascular plants may lead to increased genetic variability of offspring, and consequently improved chances of survival in a changing environment. Our findings also indicate that with future warming, polar oases may play an important role as a seed source to the surrounding polar desert landscape. [ABSTRACT FROM AUTHOR]

Published
2011
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41. The effect of experimental warming on the root-associated fungal community of Salix arctica.

Author

Fujimura, Kei E., Egger, Keith N., and Henry, Gregory H. R.

Subjects
MYCORRHIZAS, DNA, GENETIC polymorphisms, FUNGAL communities, TUNDRA ecology, BIOMASS
Abstract

The effect of experimental warming on the root-associated fungal community of arctic willow (Salix arctica) was studied in three distinct habitats at a tundra site in the Canadian High Arctic. Plots were passively warmed for 5–7 years using open-top chambers and compared to control plots at ambient temperature. Fungal communities were assessed using terminal restriction fragment length polymorphisms. We found the following: (1) the root-associated fungal community in these high arctic tundra habitats is highly diverse; (2) site and soil characteristics are the most important drivers of community structure and (3) warming increased the density of different genotypes on individual root sections but has not (yet) affected the composition, richness or evenness of the community. The change in genotype density in the warmed plots was associated with an increase in PCR amplification efficiency, suggesting that increased C allocation belowground is increasing the overall biomass of the fungal community.The ISME Journal (2008) 2, 105–114; doi:10.1038/ismej.2007.89; published online 25 October 2007 [ABSTRACT FROM AUTHOR]

Published
2008
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42. Sex- and habitat-specific responses of a high arctic willow, salix arctica, to experimental climate change

Author

Macdonald, S. Ellen, Jones, Michael H., and Henry, Gregory H. R.

Subjects
CARBON dioxide, HABITATS, ECOLOGY, CLIMATE change
Abstract

Dioecious plant species and those occupying diverse habitats may present special analytical problems to researchers examining effects of climate change. Here we report the results from two complementary studies designed to determine the importance of sex and habitat on gas exchange and growth of male and female individuals of a dioecious, circumpolar willow, Salix arctica, in the Canadian High Arctic. In fieldstudies, male and female willows from dry and wet habitats were subjected to passively enhanced summer temperature (~1.3 deg. C) using small open-top chambers over three years. Peak season gas exchange varied significantly by willow sex and habitat. Overall net assimilation was higher in the dry habitat than in the wet, and higher in females than in males. In the dry habitat, net assimilation of females was enhanced by experimental warming, but decreased in males. In the wet habitat, net assimilation of females was substantially depressed by experimental warming, while males showed an inconsistent response. Development and growth of male and female catkins were enhanced by elevated temperature more than leaf fascicles, but leaf fascicle developmentand growth varied more between the two habitats, particularly in males. In a controlled environment study, male and female willows from these same wet and dry habitats were grown in a 2 x 2 factorial experiment including 1x or 2x ambient [CO2] and 5 or 12 deg. C. The sexes responded very differently to the experimental treatments, but we found no effect of original habitat. Net assimilation in maleswas affected by the interaction of temperature and CO2, but in females by CO2 only. Our results demonstrate (a) significant intraspecific and intersexual differences in arctic willow physiology and growth, (b) that these differences are affected by environmental conditions expected to accompany global climate change, and(c) that sex- and habitat-specific responses should be explicitly accoun [ABSTRACT FROM AUTHOR]

Published
1999

43. Long-term deepened snow promotes tundra evergreen shrub growth and summertime ecosystem net CO 2 gain but reduces soil carbon and nutrient pools.

Author

Christiansen CT, Lafreniére MJ, Henry GHR, and Grogan P

Subjects
Carbon analysis, Northwest Territories, Nutrients analysis, Seasons, Carbon Dioxide metabolism, Plant Development, Snow, Soil chemistry, Tundra
Abstract

Arctic climate warming will be primarily during winter, resulting in increased snowfall in many regions. Previous tundra research on the impacts of deepened snow has generally been of short duration. Here, we report relatively long-term (7-9 years) effects of experimentally deepened snow on plant community structure, net ecosystem CO 2 exchange (NEE), and soil biogeochemistry in Canadian Low Arctic mesic shrub tundra. The snowfence treatment enhanced snow depth from 0.3 to ~1 m, increasing winter soil temperatures by ~3°C, but with no effect on summer soil temperature, moisture, or thaw depth. Nevertheless, shoot biomass of the evergreen shrub Rhododendron subarcticum was near-doubled by the snowfences, leading to a 52% increase in aboveground vascular plant biomass. Additionally, summertime NEE rates, measured in collars containing similar plant biomass across treatments, were consistently reduced ~30% in the snowfenced plots due to decreased ecosystem respiration rather than increased gross photosynthesis. Phosphate in the organic soil layer (0-10 cm depth) and nitrate in the mineral soil layer (15-25 cm depth) were substantially reduced within the snowfences (47-70 and 43%-73% reductions, respectively, across sampling times). Finally, the snowfences tended (p = .08) to reduce mineral soil layer C% by 40%, but with considerable within- and among plot variation due to cryoturbation across the landscape. These results indicate that enhanced snow accumulation is likely to further increase dominance of R. subarcticum in its favored locations, and reduce summertime respiration and soil biogeochemical pools. Since evergreens are relatively slow growing and of low stature, their increased dominance may constrain vegetation-related feedbacks to climate change. We found no evidence that deepened snow promoted deciduous shrub growth in mesic tundra, and conclude that the relatively strong R. subarcticum response to snow accumulation may explain the extensive spatial variability in observed circumpolar patterns of evergreen and deciduous shrub growth over the past 30 years., (© 2018 John Wiley & Sons Ltd.)

Published
2018
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44. Reproduction and seedling establishment of Picea glauca across the northernmost forest-tundra region in Canada.

Author

Walker X, Henry GHR, McLeod K, and Hofgaard A

Abstract

The northern boundary of boreal forest and the ranges of tree species are expected to shift northward in response to climate warming, which will result in a decrease in the albedo of areas currently covered by tundra vegetation, an increase in terrestrial carbon sequestration, and an alteration of biodiversity in the current Low Arctic. Central to the prediction of forest expansion is an increase in the reproductive capacity and establishment of individual trees. We assessed cone production, seed viability, and transplanted seedling success of Picea glauca (Moench.) Voss. (white spruce) in the early 1990s and again in the late 2000s at four forest stand sites and eight tree island sites (clonal populations beyond present treeline) in the Mackenzie Delta region of the Northwest Territories, Canada. Over the past 20 years, average temperatures in this region have increased by 0.9 °C. This area has the northernmost forest-tundra ecotone in North America and is one of the few circumpolar regions where the northern limit of conifer trees reaches the Arctic Ocean. We found that cone production and seed viability did not change between the two periods of examination and that both variables decreased northward across the forest-tundra ecotone. Nevertheless, white spruce individuals at the northern limit of the forest-tundra ecotone produced viable seeds. Furthermore, transplanted seedlings were able to survive in the northernmost sites for 15 years, but there were no signs of natural regeneration. These results indicate that if climatic conditions continue to ameliorate, reproductive output will likely increase, but seedling establishment and forest expansion within the forest-tundra of this region is unlikely to occur without the availability of suitable recruitment sites. Processes that affect the availability of recruitment sites are likely to be important elsewhere in the circumpolar ecotone, and should be incorporated into models and predictions of climate change and its effects on the northern forest-tundra ecotone., (© 2012 Blackwell Publishing Ltd.)

Published
2012
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45. Global assessment of experimental climate warming on tundra vegetation: heterogeneity over space and time.

Author

Elmendorf SC, Henry GH, Hollister RD, Björk RG, Bjorkman AD, Callaghan TV, Collier LS, Cooper EJ, Cornelissen JH, Day TA, Fosaa AM, Gould WA, Grétarsdóttir J, Harte J, Hermanutz L, Hik DS, Hofgaard A, Jarrad F, Jónsdóttir IS, Keuper F, Klanderud K, Klein JA, Koh S, Kudo G, Lang SI, Loewen V, May JL, Mercado J, Michelsen A, Molau U, Myers-Smith IH, Oberbauer SF, Pieper S, Post E, Rixen C, Robinson CH, Schmidt NM, Shaver GR, Stenström A, Tolvanen A, Totland O, Troxler T, Wahren CH, Webber PJ, Welker JM, and Wookey PA

Subjects
Arctic Regions, Biodiversity, Models, Biological, Adaptation, Biological, Ecosystem, Global Warming, Plant Development
Abstract

Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation - and associated ecosystem consequences - have the potential to be much greater than we have observed to date., (© 2011 Blackwell Publishing Ltd/CNRS.)

Published
2012
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