Pål Thorvaldsen
Research Scientist
(+47) 406 21 869
pal.thorvaldsen@nibio.no
Place
Trondheim
Visiting address
Klæbuveien 153, bygg C 1.etasje, 7031 Trondheim
Authors
Charles D. Minsavage-Davis G. Matt Davies Siri Vatsø Haugum Pål Thorvaldsen Liv Guri Velle Vigdis VandvikAbstract
No abstract has been registered
Authors
Melinda D. Smith Kate D. Wilkins Martin C. Holdrege Peter Wilfahrt Scott L. Collins Alan K. Knapp Osvaldo E. Sala Jeffrey S. Dukes Richard P. Phillips Laura Yahdjian Laureano A. Gherardi Timothy Ohlert Claus Beier Lauchlan H. Fraser Anke Jentsch Michael E. Loik Fernando T. Maestre Sally A. Power Qiang Yu Andrew J. Felton Seth M. Munson Yiqi Luo Hamed Abdoli Mehdi Abedi Concepción L. Alados Juan Alberti Moshe Alon Hui An Brian Anacker Maggie Anderson Harald Auge Seton Bachle Khadijeh Bahalkeh Michael Bahn Amgaa Batbaatar Taryn Bauerle Karen H. Beard Kai Behn Ilka Beil Lucio Biancari Irmgard Blindow Viviana Florencia Bondaruk Elizabeth T. Borer Edward W. Bork Carlos Martin Bruschetti Kerry M. Byrne James F. Cahill Dianela A. Calvo Michele Carbognani Augusto Cardoni Cameron N. Carlyle Miguel Castillo-Garcia Scott X. Chang Jeff Chieppa Marcus V. Cianciaruso Ofer Cohen Amanda L. Cordeiro Daniela F. Cusack Sven Dahlke Pedro Daleo Carla M. D'Antonio Lee H. Dietterich Tim S. Doherty Maren Dubbert Anne Ebeling Nico Eisenhauer Felícia M. Fischer Tai G.W. Forte Tobias Gebauer Beatriz Gozalo Aaron C. Greenville Karlo G. Guidoni-Martins Heather J. Hannusch Siri Vatsø Haugum Yann Hautier Mariet Hefting Hugh A.L. Henry Daniela Hoss Oscar Iribarne Forest Isbell Yari Johnson Samuel Jordan Eugene F. Kelly Kaitlin Kimmel Juergen Kreyling György Kröel-Dulay Johannes Ingrisch Alicia Kröpfl Angelika Kübert Andrew Kulmatiski Eric G. Lamb Klaus Steenberg Larsen Julie Larson Cintia V. Leder Anja Linstädter Jielin Liu Shirong Liu Alexandra G. Lodge Grisel Longo Alejandro Loydi Junwei Luan Jason Lawson Frederick Curtis Lubbe Craig Macfarlane Kathleen Mackie-Haas Andrey V. Malyshev Adrián Maturano-Ruiz Thomas Merchant Daniel B. Metcalfe Akira S. Mori Edwin Mudongo Gregory S. Newman Uffe N. Nielsen Dale Nimmo Yujie Niu Paola Nobre Rory C. O'Connor Romà Ogaya Gastón R. Oñatibia Ildikó Orbán Brooke Osborne Rafael Otfinowski Meelis Pärtel Josep Penuelas Pablo L. Peri Guadalupe Peter Alessandro Petraglia Catherine Picon-Cochard Valério D. Pillar Juan Manuel Piñeiro-Guerra Laura W. Ploughe Robert M. Plowes Cristy Portales-Reyes Suzanne M. Prober Yolanda Pueyo Sasha C. Reed Euan G. Ritchie Dana Aylén Rodríguez William E. Rogers Christiane Roscher Ana M. Sánchez Bráulio A. Santos María Cecilia Scarfó Eric W. Seabloom Baoku Shi Lara Souza Andreas Stampfli Rachel J. Standish Marcelo Sternberg Wei Sun Marie Sünnemann Michelle Tedder Pål Thorvaldsen Dashuan Tian Katja Tielbörger Alejandro Valdecantos Liesbeth van den Brink Vigdis Vandvik Mathew R. Vankoughnett Liv Guri Velle Changhui Wang Yi Wang Glenda M. Wardle Christiane Werner Cunzheng Wei Georg Wiehl Jennifer L. Williams Amelia A. Wolf Michaela Zeiter Fawei Zhang Juntao Zhu Ning Zong Xiaoan ZuoAbstract
Climate change is increasing the frequency and severity of short-term (~1 y) drought events—the most common duration of drought—globally. Yet the impact of this intensification of drought on ecosystem functioning remains poorly resolved. This is due in part to the widely disparate approaches ecologists have employed to study drought, variation in the severity and duration of drought studied, and differences among ecosystems in vegetation, edaphic and climatic attributes that can mediate drought impacts. To overcome these problems and better identify the factors that modulate drought responses, we used a coordinated distributed experiment to quantify the impact of short-term drought on grassland and shrubland ecosystems. With a standardized approach, we imposed ~a single year of drought at 100 sites on six continents. Here we show that loss of a foundational ecosystem function—aboveground net primary production (ANPP)—was 60% greater at sites that experienced statistically extreme drought (1-in-100-y event) vs. those sites where drought was nominal (historically more common) in magnitude (35% vs. 21%, respectively). This reduction in a key carbon cycle process with a single year of extreme drought greatly exceeds previously reported losses for grasslands and shrublands. Our global experiment also revealed high variability in drought response but that relative reductions in ANPP were greater in drier ecosystems and those with fewer plant species. Overall, our results demonstrate with unprecedented rigor that the global impacts of projected increases in drought severity have been significantly underestimated and that drier and less diverse sites are likely to be most vulnerable to extreme drought.
Authors
Tilde Hjermann Nikolai Antonsen Bilet Inger Maren Rivrud Erling Meisingset Pål Thorvaldsen Atle MysterudAbstract
Grazing by wildlife on agricultural land is widespread across geographical regions, and can cause human–wildlife conflicts due to reduced crop yield when the grazing pressure is high. Growing red deer (Cervus elaphus) populations in Europe call for an increased understanding of their grazing patterns to mitigate damages. We quantified how red deer grazing pressure (grazing presence and grazing level) on agricultural grass meadows (n = 60) in Norway varied across multiple spatial scales. We used a nested, hierarchical study design transcending from a broad scale (meadows across the landscape) to intermediate (between nearby meadows) and local (within-meadow) scales, allowing us to identify at which scale the variation in grazing pressure was strongest. We estimated how grazing was determined by broad-scale factors influencing forage availability and quality through population density, distance to coastline, and differences between the first versus second harvest, by intermediate-scale factors in terms of meadow management causing differences in botanical composition and quality, and by local-scale factors in terms of perceived predation risk and disturbance. At a broad scale, higher population densities were associated with higher grazing pressure, and more grazing occurred before the first compared to the second harvest. Intermediate-scale factors explained the most variation of grazing pressure from red deer, with higher grazing pressure on newly renewed meadows compared to other nearby meadows. On a local scale, more grazing occurred closer to the forest edge, providing cover, and further away from infrastructure, with increased risk and disturbance. Overall, our study highlights how drivers of grazing pressure on agricultural land vary across spatial scales. Population reductions on a broader scale may have some effect in reducing the grazing pressure, but renewed meadows will nevertheless attract red deer, causing higher grazing pressure compared to neighbouring meadows. This insight is crucial for determining effective mitigation strategies facing rising red deer populations across Europe.