Invasive plants: predicting regions at risk!

press release of October 2, 2006

A group from the National Centre of Competence in Research (NCCR) Plant Survival is developing a computer model that will help in identifying regions where a potential invasive plant could successfully establish itself. The group will unveil the details of this first during an international symposium of which it is the organiser.  The event is taking place today and tomorrow at the University of Fribourg.

The common trait of invasive species is to come from another region, usually from another continent, than that of where they proliferate. Being able to determine in advance the potential sites that a species could colonise would save a considerable amount of time in the control of these undesirable plants, which are a big threat to biodiversity.  That is the goal that members of the NCCR Plant Survival have fixed for themselves and who also happen to be co-organisers of the symposium: Heinz Müller-Schärer, professor at the Alma Mater in Fribourg and Antoine Guisan, assistant professor at the University of Lausanne.

The former is well versed with respect to spotted knapweed (Centaurea maculosa). This weed, which originated from Europe, colonised the North-American continent at the end of the 19th Century and is today one of the top three most prolific plant species in the USA. As for the latter, he is an expert in the area of biogeographical modelling, competences that he uses to study the evolution of plants over space and time.

A computer model developed by the teams of Antoine Guisan and Heinz Müller-Schärer should help to identify zones that provide the ideal conditions for the proliferation of a species. The research also aims to quantify the ecological and genetic changes that subsequently affect that species in the invaded region. "Our study relies on a comparison of the climatic niches of spotted knapweed  in its place of origin (Europe) and in the invaded place (North America), in other words, all of the climatic factors (temperature, humidity, etc.) in which the species can subsist", explains Antoine Guisan.

Contrary to a widespread hypothesis, the species' niche does not seem to have been conserved in the invaded location. "In fact, adds Antoine Guisan, the spotted knapweed has replaced its original climatic requirements with a drier climate, enabling it to establish itself in the American North-West. Interestingly, this same phenomenon seems to be happening in Europe, with the distribution spreading towards the west. We are observing a drift of the species' climatic niches that is similar in both continents." Based on these conclusions, the members of the NCCR Plant Survival will soon apply their computer model on other invasive plants, such as ragweed (Ambrosia artemisiifolia), an undesirable species that causes considerable public health problems because of its allergenic properties.

The symposium in Fribourg will also be an occasion to listen to other distinguished scientists. Professor Ragan Callaway, from the University of Montana (USA), will talk about plants that develop "new chemical weapons" in their adopted habitat, such as Alliaria petiolata for example, of which the roots secrete a chemical substance that prevents the mycorrhizae from developing. Mychorrhizae are fungal hyphae that live in symbiosis with the roots and provide nutrients that are essential for the survival of certain plants. By proceeding in such a way, Alliaria petiolata eliminates the competition while gaining more terrain.       

Link to the symposium : http://www.unifr.ch/biol/ecology/biolinv/


Prof. Heinz Müller-Schärer
Université de Fribourg
tel + 41 26 300 8835/8850
fax + 41 26 300 9698

Prof. Antoine Guisan
Université de Lausanne
Tel. +41 21 692 42 54/4160
Fax +41 21 692 42 65