Pål Thorvaldsen
Forsker
(+47) 406 21 869
pal.thorvaldsen@nibio.no
Sted
Trondheim
Besøksadresse
Klæbuveien 153, bygg C 1.etasje, 7030 Trondheim
Forfattere
Even Unsgård Erling Meisingset Inger Maren Rivrud Gunn Randi Fossland Pål Thorvaldsen Vebjørn Veiberg Atle MysterudSammendrag
In Europe, over a third of the agricultural area is grass meadows used for livestock grazing and fodder production. Grass meadows provide a food source for wild ungulates causing human-wildlife conflicts due to forage removal. Few experimental studies have quantified biomass loss with enough replicates to determine how surrounding environments influences level of biomass removal. Using an exclosure experiment on 57 grassland meadows over five years at the northwest coast of Norway covering 10 650 km2, we quantified biomass removal by red deer (Cervus elaphus L.) and how environmental factors impacted biomass loss (Study 1). Furthermore, we examined development of biomass loss and crude protein concentration in five fields throughout the growing season (Study 2). The average predicted biomass loss to red deer grazing was 16% for the first harvest, and 7.3% for the second harvest (Study 1). Biomass loss increased with red deer density from 0% at the lowest density (0.6 red deer harvested/km2) to 31% at the highest density (4 red deer harvested/km2). Biomass loss increased from 12% to 32.8% as terrain ruggedness index (TRI) rose from 2.1 to 7.1. Absolute biomass loss increased towards time of grass harvest (Study 2). Crude protein concentration was higher in unfenced plots during the period before first harvest, but not between first and second harvest (Study 2). The quantification of biomass removal at a large spatial scale over several years in this study provides a better understanding of factors causing variation in losses.
Forfattere
Charles D. Minsavage-Davis G. Matt Davies Siri Vatsø Haugum Pål Thorvaldsen Liv Guri Velle Vigdis VandvikSammendrag
Northern European heathlands and moorlands dominated by Calluna vulgaris are internationally recognized for their conservation importance while also supporting traditional, low-intensity agriculture and game hunting. Managed burning plays an important role in maintaining these ecosystems but climate and land-use changes, including planned or unplanned transitions to forest and woodland, are now resulting in concerns about increasing wildfire frequency, intensity and severity. In combination with rapidly-changing regulations surrounding managed burning, this has highlighted the need to understand current and potential future fuel structures to effectively model fire behaviour and develop evidence-based regulations surrounding managed burning. We developed standardized heathland fuel descriptions and modeled associated fire behaviour for heathlands in the UK (England, Scotland) and Norway. Utilizing existing fuel and biomass data, we used cluster analysis to identify five distinct fuel models and assessed how they were represented across C. vulgaris life-stages, geographic locations and EUNIS habitat-types. We validated their independence by examining predicted fire rates of spread based across three representative fire weather scenarios. Fire rates of spread differed between C. vulgaris life stages, regardless of EUNIS community or country. Mature stage and taller building stage fuels produced the highest fire rates of spread and early, shorter building and pioneer stage fuels produced the lowest. Moss and litter fuel loads proved to be important determinants of fire rate of spread in a high-risk fire weather scenario. An understanding of links between fuel types and potential fire behaviour can be used to inform management and policy decisions. To aid in this, we used classification tree analysis to link fuel types to easily-observable characteristics. This will facilitate pairing the fuel models with fire behaviour prediction software to make evidence-based assessments of management fire safety and wildfire risk.
Forfattere
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 ZuoSammendrag
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.
Divisjon for skog og utmark
Reinbeiting på dyrka mark
Intensiv beiting av husdyr påvirker avling og plantenes opplagsnæring, og har negativ effekt på overvintringsevne og spiringsegenskapene om våren. Avlingsreduksjonen er avhengig av beitetidspunkt, nedbeitingsgrad, artssammensetning i enga, samt lokalt klima og værforhold det aktuelle året mm. Det er få presise og omfattende studier på avlingstap grunnet graveskader og beiting av rein på innmark.
Divisjon for matproduksjon og samfunn
RESTORE: Restaurering av økosystemfunksjoner og biodiversitet i semi-naturlige naturtyper under sterkt arealpress
I RESTORE skal vi utvikle nye løsninger for restaurering av semi-naturlige natur som er i fare for tap og forringelse på grunn av endringer i arealbruk. Resultatene skal gi grunnlag for en bedre ivaretagelse av det biologiske mangfoldet og de økologiske funksjonene som finnes i semi-naturlig natur.