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1. 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 SA, Blach-Overgaard, Anne, Blok, Daan, Cornelissen, J Hans C, Forbes, Bruce C, Georges, Damien, Goetz, Scott J, Guay, Kevin C, Henry, Gregory HR, HilleRisLambers, Janneke, Hollister, Robert D, Karger, Dirk N, Kattge, Jens, Manning, Peter, Prevéy, Janet S, Rixen, Christian, Schaepman-Strub, Gabriela, Thomas, Haydn JD, 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 MPD, 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 DM, 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, and Magnusson, Borgthor

Subjects
Climate Change Impacts and Adaptation, Biological Sciences, Ecology, Environmental Sciences, Climate Action, Biometry, Geographic Mapping, Global Warming, Humidity, Phenotype, Plant Physiological Phenomena, Plants, Soil, Spatio-Temporal Analysis, Temperature, Tundra, Water, General Science & Technology
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

16. MIGRATORY AGRICULTURAL WORKERS IN THE UNITED STATES.

Author

Grinnell Coll., IA. and JORGENSON, JANET M.

Abstract

FIELD STUDIES WERE CONDUCTED IN 1960 IN THE LOWER RIO GRANDE VALLEY OF TEXAS AND IN IOWA TO AUGMENT INFORMATION ON MIGRATORY WORKERS. FACULTY-STUDENT TEAM FIELD TRIPS FOUND MANY FACTORS TO CONSIDER IN PROVIDING A CONSTRUCTIVE APPROACH TO THE PROBLEMS OF THE MIGRANT WORKER. CHILDREN OF THE MIGRANTS ARE NOT GETTING THE EDUCATION THEY NEED TO BREAK OUT OF THE MIGRANT PATTERN. PREVENTIVE HEALTH CARE LACKS INCENTIVE BECAUSE OF POOR LIVING CONDITIONS. POVERTY PREVENTS CURATIVE MEDICINE. THE MIGRANT SUFFERS FROM PREJUDICE AND DISCRIMINATION. CONSTANT STRAIN TO EARN A LIVING IS THE MAIN CONTRIBUTING FACTOR TO THE PLIGHT OF THE MIGRANT. WAGE INCREASES MIGHT BE DIFFICULT IF FARM ORGANIZATIONS AND GROWERS' ASSOCIATIONS SHOULD OPPOSE LEGISLATION WHICH WOULD INCLUDE FARMERS UNDER THE FAIR LABOR PRACTICES ACT. WAYS TO BETTER THE SITUATION OF THE MIGRANT INCLUDE THE WORK SCHEDULE SYSTEM OF THE ANNUAL WORKERS PLAN, THE WORK OF CHURCH ASSOCIATIONS, AND LEGISLATION. THE PROGRAM IN MUSCATINE, IOWA, ILLUSTRATES HOW COOPERATION BETWEEN INDUSTRY, CHURCH, AND COMMUNITY CAN RESULT IN A COMPARATIVELY SUCCESSFUL MIGRANT COMMUNITY. CROP DIVERSIFICATION COMBINED WITH INDUSTRIAL JOBS WOULD FORM CONTINUOUS EMPLOYMENT OPPORTUNITIES FOR MIGRANTS. REGIONAL PLANNING CAN CONTRIBUTE TO STABLE COMMUNITIES. AN ANNOTATED BIBLIOGRAPHY COMPILED ACCORDING TO GENERAL STUDIES, CIVIL RIGHTS AND LEGAL STATUS, HOUSING AND COMMUNITY RELATIONS, HEALTH AND SAFETY, EDUCATION AND CHILD LABOR, ACTIVITIES OF PRIVATE AGENCIES, STATE PROGRAMS, AND NEWSLETTERS AND PERIODICAL BULLETINS IN INCLUDED.

Published
1960

17. 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

18. 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

19. Recent circum-Arctic ice-wedge degradation and its hydrological impacts

Author

Liljedahl, Anna K., Boike, Julia, Daanen, Ronald P., Fedorov, Alexander N., Frost, Gerald V., Grosse, Guido, Hinzman, Larry D., Iijima, Yoshihiro, Jorgenson, Janet C., Matveyeva, Nadya, Necsoiu, Marius, Raynolds, Martha K., Romanovsky, Vladimir E., Schulla, Jörg, Tape, Ken D., Walker, Donald A., Wilson, Cathy J., Yabuki, Hironori, Zona, Donatella, Liljedahl, Anna K., Boike, Julia, Daanen, Ronald P., Fedorov, Alexander N., Frost, Gerald V., Grosse, Guido, Hinzman, Larry D., Iijima, Yoshihiro, Jorgenson, Janet C., Matveyeva, Nadya, Necsoiu, Marius, Raynolds, Martha K., Romanovsky, Vladimir E., Schulla, Jörg, Tape, Ken D., Walker, Donald A., Wilson, Cathy J., Yabuki, Hironori, and Zona, Donatella

Abstract

Ice-wedges are common permafrost features formed over hundreds to thousands of years of repeated frost cracking and ice vein growth. We used field and remote sensing observations to assess changes in areas dominated by ice-wedges, and we simulated the effects of those changes on watershed-scale hydrology. We show that top melting of ice-wedges and subsequent ground subsidence has occurred at multiple sites in the North American and Russian Arctic. At most sites, melting ice-wedges have initially resulted in increased wetness contrast across the landscape, evident as increased surface water in the ice-wedge polygon troughs and somewhat drier polygon centers. Most areas are becoming more heterogeneous with wetter troughs, more small ponds (themokarst pits forming initially at ice-wedge intersections and then spreading along the troughs) and drier polygon centers. Some areas with initial good drainage, such as near creeks, lake margins, and in hilly terrain, high-centered polygons form an overall landscape drying due to a drying of both polygon centers and troughs. Unlike the multi-decadal warming observed in permafrost temperatures, the ice-wedge melting that we observed appeared as a sub-decadal response, even at locations with low mean annual permafrost temperatures (down to −14 °C). Gradual long-term air and permafrost warming combined with anomalously warm summers or deep snow winters preceded the onset of the ice-wedge melting. To assess hydrological impacts of ice-wedge melting, we simulated tundra water balance before and after melting. Our coupled hydrological and thermal model experiments applied over hypothetical polygon surfaces suggest that (1) ice-wedge melting that produces a connected trough-network reduces inundation and increases runoff, and that (2) changing patterns of snow distribution due to differential ground subsidence has a major control on ice-wedge polygon tundra water balance despite an identical snow water equivalent at the landscape-scale

Published
2016

20. Pan-Arctic ice-wedge degradation in warming permafrost and its influence on tundra hydrology

Author

Liljedahl, Anna K., Boike, Julia, Daanen, Ronald P., Fedorov, Alexander N., Frost, Gerald V., Grosse, Guido, Hinzman, Larry D., Iijma, Yoshihiro, Jorgenson, Janet C., Matveyeva, Nadya, Necsoiu, Marius, Raynolds, Martha K., Romanovsky, Vladimir E., Schulla, Jörg, Tape, Ken D., Walker, Donald A., Wilson, Cathy J., Yabuki, Hironori, Zona, Donatella, Liljedahl, Anna K., Boike, Julia, Daanen, Ronald P., Fedorov, Alexander N., Frost, Gerald V., Grosse, Guido, Hinzman, Larry D., Iijma, Yoshihiro, Jorgenson, Janet C., Matveyeva, Nadya, Necsoiu, Marius, Raynolds, Martha K., Romanovsky, Vladimir E., Schulla, Jörg, Tape, Ken D., Walker, Donald A., Wilson, Cathy J., Yabuki, Hironori, and Zona, Donatella

Abstract

Ice wedges are common features of the subsurface in permafrost regions. They develop by repeated frost cracking and ice vein growth over hundreds to thousands of years. Ice-wedge formation causes the archetypal polygonal patterns seen in tundra across the Arctic landscape. Here we use field and remote sensing observations to document polygon succession due to ice-wedge degradation and trough development in ten Arctic localities over sub-decadal timescales. Initial thaw drains polygon centres and forms disconnected troughs that hold isolated ponds. Continued ice-wedge melting leads to increased trough connectivity and an overall draining of the landscape. We find that melting at the tops of ice wedges over recent decades and subsequent decimetre-scale ground subsidence is a widespread Arctic phenomenon. Although permafrost temperatures have been increasing gradually, we find that ice-wedge degradation is occurring on sub-decadal timescales. Our hydrological model simulations show that advanced ice-wedge degradation can significantly alter the water balance of lowland tundra by reducing inundation and increasing runoff, in particular due to changes in snow distribution as troughs form. We predict that ice-wedge degradation and the hydrological changes associated with the resulting differential ground subsidence will expand and amplify in rapidly warming permafrost regions.

Published
2016

21. Spatiotemporal remote sensing of ecosystem change and causation across Alaska.

Author

Pastick, Neal J., Jorgenson, M. Torre, Goetz, Scott J., Jones, Benjamin M., Wylie, Bruce K., Minsley, Burke J., Genet, Hélène, Knight, Joseph F., Swanson, David K., and Jorgenson, Janet C.

Subjects
ECOSYSTEMS, CHANGE, CLIMATE change, SPATIOTEMPORAL processes, LANDSAT satellites, REMOTE-sensing images, TAIGAS
Abstract

Contemporary climate change in Alaska has resulted in amplified rates of press and pulse disturbances that drive ecosystem change with significant consequences for socio‐environmental systems. Despite the vulnerability of Arctic and boreal landscapes to change, little has been done to characterize landscape change and associated drivers across northern high‐latitude ecosystems. Here we characterize the historical sensitivity of Alaska's ecosystems to environmental change and anthropogenic disturbances using expert knowledge, remote sensing data, and spatiotemporal analyses and modeling. Time‐series analysis of moderate—and high‐resolution imagery was used to characterize land‐ and water‐surface dynamics across Alaska. Some 430,000 interpretations of ecological and geomorphological change were made using historical air photos and satellite imagery, and corroborate land‐surface greening, browning, and wetness/moisture trend parameters derived from peak‐growing season Landsat imagery acquired from 1984 to 2015. The time series of change metrics, together with climatic data and maps of landscape characteristics, were incorporated into a modeling framework for mapping and understanding of drivers of change throughout Alaska. According to our analysis, approximately 13% (~174,000 ± 8700 km2) of Alaska has experienced directional change in the last 32 years (±95% confidence intervals). At the ecoregions level, substantial increases in remotely sensed vegetation productivity were most pronounced in western and northern foothills of Alaska, which is explained by vegetation growth associated with increasing air temperatures. Significant browning trends were largely the result of recent wildfires in interior Alaska, but browning trends are also driven by increases in evaporative demand and surface‐water gains that have predominately occurred over warming permafrost landscapes. Increased rates of photosynthetic activity are associated with stabilization and recovery processes following wildfire, timber harvesting, insect damage, thermokarst, glacial retreat, and lake infilling and drainage events. Our results fill a critical gap in the understanding of historical and potential future trajectories of change in northern high‐latitude regions. Arctic and boreal landscapes have experienced unprecedented changes in recent decades that have significant consequences for socio‐environmental systems. Despite a legacy of studies that have documented the heightened sensitivity of northern landscapes to change, characterization and prognosis of ecosystem change has remained elusive. Here, we combine remote sensing and climate reanalysis data into an integrated modeling framework to fingerprint the historical (1984–2015) sensitivity of Alaska's ecosystems to changing environmental conditions and disturbances. Our results fill a critical gap in the understanding of the historical and potential future trajectories of change in Alaska, with direct relevance to other northern high‐latitude regions. [ABSTRACT FROM AUTHOR]

Published
2019
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22. Pan-Arctic ice-wedge degradation in warming permafrost and its influence on tundra hydrology

Author

Liljedahl, Anna K., primary, Boike, Julia, additional, Daanen, Ronald P., additional, Fedorov, Alexander N., additional, Frost, Gerald V., additional, Grosse, Guido, additional, Hinzman, Larry D., additional, Iijma, Yoshihiro, additional, Jorgenson, Janet C., additional, Matveyeva, Nadya, additional, Necsoiu, Marius, additional, Raynolds, Martha K., additional, Romanovsky, Vladimir E., additional, Schulla, Jörg, additional, Tape, Ken D., additional, Walker, Donald A., additional, Wilson, Cathy J., additional, Yabuki, Hironori, additional, and Zona, Donatella, additional

Published
2016
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23. Ice wedge degradation: Why Arctic lowlands are becoming wetter and drier

Author

Liljedahl, Anna K., Boike, Julia, Daanen, R. P., Fedorov, A., Frost, Gerald, Grosse, Guido, Hinzman, L., Iijima, Yoshihiro, Jorgenson, Janet, Matveyeva, N. V., Necsoiu, M., Raynolds, Martha K., Romanovsky, V. E., Schulla, J., Tape, Ken, Walker, Donald A., Wilson, Cathy, Yabuki, H, Liljedahl, Anna K., Boike, Julia, Daanen, R. P., Fedorov, A., Frost, Gerald, Grosse, Guido, Hinzman, L., Iijima, Yoshihiro, Jorgenson, Janet, Matveyeva, N. V., Necsoiu, M., Raynolds, Martha K., Romanovsky, V. E., Schulla, J., Tape, Ken, Walker, Donald A., Wilson, Cathy, and Yabuki, H

Abstract

Top melting of ice-wedges and subsequent ground subsidence is now a widespread phenomenon across the Arctic domain. We show field and remote sensing observations that document extensive ice-wedge degradation, which initially has resulted in increased wetness contrast across the landscape (i.e. both a drying and a wetting), a shift in pond type and an overall drying in later stages. The differential ground subsidence at cold continuous permafrost regions appear to be linked to press and pulse climate forcing. Here, the process of crossing the local threshold for ice-wedge stability may be favored by a press occurrence such as long-term, gradual increases in summer air temperature, mean annual air temperature and/or possibly winter precipitation, but our observations suggest it is most likely initiated by pulse atmospheric forcing such as extreme summer warmth and/or winter precipitation. Field measurements of water levels, frost tables and snow accumulation across the main ice-wedge polygon types and their respective features support dramatic shifts in the hydrologic regime with altered topography and a complexity that ultimately affect the larger-scale hydrologic system. For example, our numerical model experiments show that a connected trough-network reduces inundation and increases runoff and that changing patterns of snow distribution due to the differential ground subsidence play a crucial role in altering lowland tundra water balance. These fine-scale (10’s cm) geomorphic changes are expected to further expand and amplify in rapidly warming permafrost regions and likely will dramatically modify land-atmosphere and land-ocean fluxes and exchange of carbon, water, and energy.

Published
2015

24. 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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25. 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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26. 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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