10.2.2004: Forschung CH

Säume als Ausgleichsflächen?




Sabine Güsewell, Claude Théato, Andreas Bosshard

Säume sind potenzielle ökologische Ausgleichsflächen, doch bisher als solche nicht anerkannt. Ihre Artenvielfalt und Artenzusammensetzung zeigen deutlich regionale Unterschiede. Landwirte stehen der Anlage von Säumen als ökologische Ausgleichsfläche skeptisch gegenüber


1) Agricultural intensification has led to a considerable loss of species in the cultural landscape, mainly due to the disappearance of specific landscape features. As a countermeasure, Swiss agricultural policy offers various types of ecological compensation areas since 1993.
2) Field margins, i.e. herbaceous strips along fields and meadows, are a potential element of ecological compensation, but not yet recognised as such. Herbaceous strips are defined here as species-rich permanent vegetation types between crop fields, along meadows, pastures, lanes, ditches and wood. Once established, these strips are mowed only once each year or every second year, and no fertilisers or pesticides are applied. The project „Species-rich field margins in the lowlands of Switzerland“ was set up to assess the contribution of herbaceous strips along fields to enhancing the ecological value of the cultural landscape.
3) In this thesis, a floristic survey of existing strips along crop fields and meadows was carried out to establish a reference for the evaluation of sown strips. Differences between strips as well as the factors determining species richness were investigated. In addition, qualitative interviews were conducted with farmers to investigate their attitude towards strips.
4) Species composition and species richness varied strongly among geographic regions, and many species were recorded in only one of the regions. The total species number per strip correlated positively with the length and width of the strips and negatively with the average nutrient indicator value of the vegetation. Species richness in strips along fields was lower than in those along meadows. Species-rich strips were characterised by a higher cover, biomass and diversity of legumes (Fabaceae) than species-poor ones.
5) The interviewed farmers viewed strips rather negatively. The margins of large fields were the only place where they could conceive establishing strips. Farmers were concerned about practical issues and about problems with weeds or pests. They disliked the idea of taking valuable ground out of production and questioned the ecological value of herbaceous strips.
6) Several recommendations for the successful integration of strips in the cultural landscape can be derived from this study. First, it is important that the vegetation of strips does not include problematic weeds that might disperse into adjacent farmland. Second, strips should not be compared to fallows as regards their ecological function, but rather to hedge margins, which are also narrow linear landscape features in the intensively cultured farmland. Third, the mowing date should not be fixed, but adapted to the vegetation development, so that farmers can use the hay and get some benefit from the strips.

Keywords:
Ecological compensation areas, botanical diversity, regional differences

Art der Publikation:
Diplomarbeit

Literatur:
Théato C. (2001): Säume als ökologische Ausgleichsflächen? Diplomarbeit, Geobotanisches Institut ETH Zürich.

Kontaktadresse:
Dr. Sabine Güsewell, Geobotanisches Institut, Dept. Umweltnaturwissenschaften (D-UMNW), ETH Zürich, Zürichbergstrasse 38, CH-8044 Zürich
sabine.guesewell@env.ethz.ch
Tel: +41 (0) 1 632 43 07
Fax: +41 (0) 1 632 12 15

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