Its effects depend on despite all of the form it takes

"We are in the stages of the ecological engineering", recognizes Thierry Dutoit. As colleagues ecologists, the researcher has exhibited in Paris, during a recent symposium on the report between science and conservation, the magnitude of the challenge of biodiversity. Little by little, scientists are developing tools to meet the needs of managers of natural areas or "users" of nature. The complexity of the operation of the ecosystems makes difficult the identification of the mechanisms that cause the disappearance of wildlife species. Human action is always in the front line, but ecology gradually says the abuse, and even benefits. Because we find today that landscapes shaped for millennia by humans can seriously suffer the disappearance of this partnership.

On the causse Méjean, Lozère, the struggle between the invasion of the pines and the abandonment of sheep ranching led the team of Paul Caplat, CNRS, to simulate several scenarios in a European programme. His results show that the best case for biodiversity and socio-economic future of farmers is a principled zone management. The worst in the medium term would be abandoned to nature.

Down South, in the pic Saint-Loup, Clélia Sirami, functional and Evolutionary Ecology Centre analyzed data of twenty-five years of observation of evolution of the biodiversity in this shared area between sections of Oaks, livestock and crops. The decline of agriculture there causes a closure of the landscape classic, woody species are gaining ground, plant structure reconciles. Twenty-five years, Clélia Sirami shows that seven endemic species have suffered from this situation. Forest bird communities are progressing on the contrary, as the alouette lulu. "These are the changes of land use to ensure the maintenance of biodiversity." "We recommend to maintain these activities," explains the researcher. Under the Natura 2000 programme, managers of these spaces are therefore considering the installation of a shepherd on the Piedmont.

"Since the end of the 1990s, we realize that biodiversity can take advantage of the pasture", explains Muriel Tichit, agronomist at the Inra. It simulated the effect on the dynamics of populations of birds of the grazing land management strategies in the Poitevin. By playing on the density of cattle and grazing periods, the farmers can improve the quality of the habitats of different species.

Urbanization, a chance

The preservation of biodiversity may sometimes depend on little. Thierry Dutoit explains that the Arles region has an original ecosystem that intensive agriculture failed to kill. This zone of steppe vegetation, which has experienced three thousand years of sheep grazing, has undergone post-war inadequate fruit crops in the field who are arrested in the 1980s. Since then, the stress-tolerant species endemic resumed their colonization, but at the slow pace of 1 metre in ten years. The ecologists have found that it is sufficient to place stones dating back to the basement to enhance habitat fragile plants. A decision which contradicts a centuries-old practice of destoning.

The ecologists can also prevent or lessen disturbance to an environment threatened by anthropogenic project such as construction of a motorway. It is studied by Pierre Joly and his team focused their work on the modeling of the "roughness" of the habitat of amphibians. At the request of an association, they studied the case of the hot point of the Isle Crémieux, a Mecca of biodiversity in Rhône-Alpes expects the A48 motorway cross blithely. This plateau is teeming with 80 ponds where the green tree frog breeds. To assess its ability to travel, they were assigned a coefficient each obstacle (pond, prairie, highway, hedge...) with result card of friction. Their work shows a strong interconnection of populations which therefore would be undermined if the highway destroyed their communications.

Scientists have shown to the contrary that the construction of the line Rhine-Rhone TGV does not disrupt some fragile ecological niches on its route. Réseau Ferré de France (RFF) has assigned to the CPEPESC association an impact study on the proximity of a large reserve of bats. Its scientists have followed the lives of 17 individuals in this population and measured hunting radii greater than 50 kilometres. RFF has adapted passages for fauna to take into account the recommendations of the ornithologists.

The ecologists also galvanized interest in urban areas, which is not the desert one might think. "This is not a hotspot of biodiversity but this medium is richer than a field of beets", causes Fabienne Van Rossum of the University of Brussels.

This scientist has evaluated the effectiveness of the corridors urban to artificially recreate the continuity of the community. They are rivers, parks or grassy strips, these biodiversity corridors to connect different ecological niches. In insects, they increase the reproductive success, limit inbreeding and increase the flow of genes. The movement of insects and birds also fosters the pollen and thus of the vegetation.

For some, urbanization is a chance for biodiversity, since it concentrated populations and frees space. Its effects depend on despite all of the form it takes. Alex Baumel models inevitable urban sprawl of the Côte d'Azur, which will be covered pavilions within twenty years to accommodate its 1 million additional people. His work there is little hope on the future of the beautiful endemic species of the Provence arenaria, a flower which suffers from a "narrow" distribution because of its dependence on a habitat very protected in the limestone massifs.

Failures of ecology are not. Stéphanie rowing the Agroscope draws a balance mixed on the effectiveness of the surfaces of compensation introduced in 1993 by the Switzerland. This principled management of agricultural parcels system failed its most ambitious goal: to safeguard threatened species.