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Université de Fribourg

Biological Flora of the British Isles: Ambrosia artemisiifolia

Essl, Franz ; Biró, Krisztina ; Brandes, Dietmar ; Broennimann, Olivier ; Bullock, James M. ; Chapman, Daniel S. ; Chauvel, Bruno ; Dullinger, Stefan ; Fumanal, Boris ; Guisan, Antoine ; Karrer, Gerhard ; Kazinczi, Gabriella ; Kueffer, Christoph ; Laitung, Beryl ; Lavoie, Claude ; Leitner, Michael ; Mang, Thomas ; Moser, Dietmar ; Müller-Schärer, Heinz ; Petitpierre, Blaise ; Richter, Robert ; Schaffner, Urs ; Smith, Matt ; Starfinger, Uwe ; Vautard, Robert ; Vogl, Gero ; Lippe, Moritz von der ; Follak, Swen

In: Journal of Ecology, 2015, vol. 103, no. 4, p. 1069–1098

This account presents information on all aspects of the biology of Ambrosia artemisiifolia L. (Common ragweed) that are relevant to understanding its ecology. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral...

Université de Fribourg

New protocols to assess the environmental impact of pests in the EPPO decision-support scheme for pest risk analysis

Kenis, Marc ; Bacher, Sven ; Baker, R. H. A. ; Branquart, E. ; Brunel, S. ; Holt, J. ; Hulme, Philip E. ; MacLeod, A. ; Pergl, Jan ; Petter, F. ; Pyšek, Petr ; Schrader, G. ; Sissons, A. ; Starfinger, U. ; Schaffner, Urs

In: EPPO Bulletin, 2012, vol. 42, no. 1, p. 21–27t

Assessing the potential environmental impact of alien plants and plant pests is notoriously difficult. New protocols have been developed in the framework of the EC project PRATIQUE to provide guidance on environmental impact assessment in the EPPO pest risk analysis (PRA) decision-support scheme and enhance consistency between risk assessors and risk ratings for different pests. A set of...

Université de Fribourg

Plant invasions, generalist herbivores, and novel defense weapons

Schaffner, Urs ; Ridenour, Wendy M. ; Wolf, Vera C. ; Bassett, Thomas ; Müller, Caroline ; Müller-Schärer, Heinz ; Sutherland, Steve ; Lortie, Christopher J. ; Callaway, Ragan M.

In: Ecology, 2011, vol. 92, no. 4, p. 829-835

One commonly accepted mechanism for biological invasions is that species, after introduction to a new region, leave behind their natural enemies and therefore increase in distribution and abundance. However, which enemies are escaped remains unclear. Escape from specialist invertebrate herbivores has been examined in detail, but despite the profound effects of generalist herbivores in natural...

Université de Fribourg

Is there rapid evolutionary response in introduced populations of tansy ragwort, Jacobaea vulgaris, when exposed to biological control ?

Rapo, Carole ; Müller-Schärer, Heinz ; Vrieling, Klaas ; Schaffner, Urs

In: Evolutionary Ecology, 2010, vol. 24, no. 5, p. 1081-1099

Differences in the herbivore community between a plant’s native (specialists and generalists) and introduced range (almost exclusively generalists) may lead to the evolution of reduced allocation to defences against specialist herbivores in the introduced range, allowing for increased allocation to competitive ability and to defences against generalist herbivores. Following this logic, the...

Université de Fribourg

Evidence for a combination of pre-adapted traits and rapid adaptive change in the invasive plant Centaurea stoebe

Henery, Martin L. ; Bowman, Gillianne ; Mráz, Patrik ; Treier, Urs A. ; Gex-Fabry, Emilie ; Schaffner, Urs ; Müller-Schärer, Heinz

In: Joural of Ecology, 2010, vol. 98, no. 4, p. 800–813

1. Introduced plants have the potential to rapidly evolve traits of ecological importance that may add to their innate potential to become invasive. During invasions, selection may favour genotypes that are already pre-adapted to conditions in the new habitat and, over time, alter the characteristics of subsequent generations. 2. Spotted knapweed (Centaurea stoebe) occurs in two predominantly...

Université de Fribourg

Shift in cytotype frequency and niche space in the invasive plant Centaurea maculosa

Treier, Urs A. ; Broennimann, Olivier ; Normand, Signe ; Guisan, Antoine ; Schaffner, Urs ; Steinger, Thomas ; Müller-Schärer, Heinz

In: Ecology, 2009, vol. 90, no. 5, p. 1366-1377

Polyploidy is often assumed to increase the spread and thus the success of alien plant species, but few empirical studies exist. We tested this hypothesis with Centaurea maculosa Lam., a species native to Europe and introduced into North America approximately 120 years ago where it became highly invasive. We analyzed the ploidy level of more than 2000 plants from 93 native and 48 invasive C....

Université de Fribourg

Sawdust addition reduces the productivity of nitrogen-enriched mountain grasslands

Spiegelberger, Thomas ; Müller-Schärer, Heinz ; Matthies, Diethart ; Schaffner, Urs

In: Restoration Ecology, 2008///10.1111/j.1526-100X.2008.00424.x

Anthropogenic nutrient enrichment of mountain grasslands has boosted grasses and fast-growing unpalatable plants at the expense of slow-growing species, resulting in a significant loss in biodiversity. A potential tool to reduce nutrient availability and aboveground productivity without destroying the perennial vegetation is carbon (C) addition. However, little is known about its suitability...

Université de Fribourg

Carbon addition alters vegetation composition on ex-arable fields

Eschen, René ; Mortimer, Simon R. ; Lawson, Clare S. ; Edwards, Andrew R. ; Brook, Alex J. ; Igual, José M. ; Hedlund, Katarina ; Schaffner, Urs

In: Journal of Applied Ecology, 2007, vol. 44, no. 1, p. 95–104

1. Recent changes in European agricultural policy have led to measures to reverse the loss of species-rich grasslands through the creation of new areas on ex-arable land. Ex-arable soils are often characterized by high inorganic nitrogen (N) levels, which lead to the rapid establishment of annual and fast-growing perennial species during the initial phase of habitat creation. The addition...

Université de Fribourg

Scale-dependent effects of land use on plant species richness of mountain grassland in the European Alps

Spiegelberger, Thomas ; Matthies, Diethart ; Müller-Schärer, Heinz ; Schaffner, Urs

In: Ecography, 2006, vol. Volume 29, p. 541-548

Traditionally managed mountain grasslands in the Alps are species-rich ecosystems that developed during centuries of livestock grazing. However, changes in land use including fertilisation of well accessible pastures and gradual abandonment of remote sites are increasingly threatening this diversity. In five regions of the Swiss and French Alps we assessed the relationship between land use, soil...

Université de Fribourg

Soil carbon addition affects plant growth in a species-specific way

Eschen, René ; Müller-Schärer, Heinz ; Schaffner, Urs

In: Journal of Applied Ecology, 2006, vol. 43, no. 1, p. 35-42

1. Restoration of ex-arable land to species-rich habitats has become common practice in Europe as a result of Agri-Environment Regulations. The results, however, are highly variable and often disappointing. Competition from weedy species as a result of high soil inorganic nitrogen levels can negatively affect the establishment and growth of desirable grassland plant species. One method...