Refine my results

Document type

Specific Collection

Language

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

Aboveground environment type, soil nutrient content and arbuscular mycorrhizal fungi explain establishment success of Centaurea jacea on ex-arable land and in late-successional grasslands

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

In: Plant and Soil, 2009, vol. 322, no. 1-2, p. 115-123

We studied the relative importance of the aboveground and belowground environment for survival and growth of emerged seedlings of Centaurea jacea to better understand the general difficulty of establishing late-successional species at restoration sites on ex-arable land. Potted seedlings growing on soil from six late-successional grasslands and from six ex-arable (restoration) sites were...

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

Classical biological control : exploiting enemy escape to manage plant invasions

Müller-Schärer, Heinz ; Schaffner, Urs

In: Biological Invasions, 2008, vol. 10, no. 6, p. 859-874

Practitioners of classical biological control of invasive weeds are confronted with a dual expectation: to achieve successful control of plant invaders and to avoid damage to nontarget plants and adverse indirect effects. In this paper we discuss key issues that we consider to be crucial for a safe, efficient, and successful classical biological control project, and that have also caused some...

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...

Université de Fribourg

Evolution in invasive plants: implications for biological control

Müller-Schärer, Heinz ; Schaffner, Urs ; Steinger, Thomas

In: Trends in Ecology and Evolution, 2004, vol. 19, p. 417-422

Evidence is increasing that invasive plants can undergo rapid adaptive evolution during the process of range expansion. Here, we argue that evolutionary change during invasions will also affect plant–antagonist inter-actions and, thus, will have important implications for biological control programmes targeted at invasive plants. We explore how altered selection in the new range might influence...