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Université de Fribourg

Unpalatable plants facilitate tree sapling survival in wooded pastures

Smit, Christian ; Den Ouden, Jan ; Müller-Schärer, Heinz

In: Journal of Applied Ecology, 2006, vol. 43(2), p. 305

1. In endangered wooded pasture ecosystems established tree saplings are frequently found in spatial association with protective structures, suggesting nurse effects. This associational resistance is thought to be a driving force behind tree regeneration in wooded pastures. Experimental evidence for associational resistance is, however, scarce. We studied the effects of unpalatable plants on tree...

Université de Fribourg

Time to cut: population models reveal how to mow invasive common ragweed cost-effectively

Lommen, Suzanne T. E. ; Jongejans, Eelke ; Leitsch-Vitalos, Melinda ; Tokarska-Guzik, Barbara ; Zalai, Mihály ; Müller-Schärer, Heinz ; Karrer, Gerhard

In: NeoBiota, 2018, vol. 39, p. 53–78

Roadsides are an important habitat for invasive common ragweed, Ambrosia artemisiifolia L., by facilitating seed dispersal. Reducing the size of roadside populations is therefore essential for confining this highly allergenic species. Here, we aim to determine the cost-effectiveness of mowing regimes varying in frequency and timing, by analysing population-level effects and underlying...

Université de Fribourg

Testing the Evolution of Increased Competitive Ability (EICA) hypothesis in a novel framework

Handley, Richard J. ; Steinger, Thomas ; Treier, Urs A. ; Müller-Schärer, Heinz

In: Ecology, 2008, vol. 89, no. 2, p. 407–417

The “evolution of increased competitive ability” (EICA) hypothesis proposes that escape from natural enemies, e.g., after transcontinental introductions, alters the selection regime because costly defenses no longer enhance fitness. Such an evolutionary loss of defenses enables resources to be directed toward growth or other traits improving performance. We tested the EICA hypothesis in a...

Université de Fribourg

Testing population differentiation in plant species – how important are environmental maternal effects

Bischoff, Armin ; Müller-Schärer, Heinz

In: Oikos, 2010, vol. 119, no. 3, p. 445-454

The maternal environment may contribute to population differentiation in offspring traits if growing conditions of mother plants are different. However, the magnitude of such environmental maternal effects compared with genetic differentiation is often not clear. We tested the importance of environmental maternal effects by comparing population differentiation in parental seed directly collected...

Université de Fribourg

Sympatric diploid and tetraploid cytotypes of Centaurea stoebe s.l. do not differ in arbuscular mycorrhizal communities and mycorrhizal growth response

Sudová, Radka ; Kohout, Petr ; Kolaříková, Zuzana ; Rydlová, Jana ; Voříšková, Jana ; Suda, Jan ; Španiel, Stanislav ; Müller-Schärer, Heinz ; Mráz, Patrik

In: American Journal of Botany, 2018, vol. 105, no. 12, p. 1995–2007

Genome duplication is associated with multiple changes at different levels, including interactions with pollinators and herbivores. Yet little is known whether polyploidy may also shape belowground interactions.Methods: To elucidate potential ploidy‐specific interactions with arbuscular mycorrhizal fungi (AMF), we compared mycorrhizal colonization and assembly of AMF communities in roots of...

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

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

Seed provenance matters — Effects on germination of four plant species used for ecological restoration

Bischoff, Armin ; Vonlanthen, Beatrice ; Steinger, Thomas ; Müller-Schärer, Heinz

In: Basic and Applied Ecology, 2006, vol. 7, no. 4, p. 347-359

The use of local seed provenances is often recommended in restoration and habitat creation because they are thought to be better adapted to local habitat conditions. However, spatial scales and the degree of population differentiation are not well known and germination is often not included in comparisons between provenances. We analysed germination as a key trait of plant development in five...

Université de Fribourg

Seed bank persistence of clonal weeds in contrasting habitats : implications for control

Hesse, Elze ; Rees, Mark ; Müller-Schärer, Heinz

In: Plant Ecology, 2007, vol. 190, no. 2, p. 233-243

The ability of weeds to form a seed bank is important for their population dynamics and management because it provides a refuge enabling reinvasion after established target plants have died. However, knowledge of the differential seed behaviour of individual species over multiple years and varying environmental conditions is surprisingly rare but necessary for effective control of diverse...