Restoration of species-rich mesophilous meadows by hay transfer:
which results do we have after four years?
Rainer Buchwald1, Tim Roßkamp2, Luisa Steiner3
1AG Vegetationskunde und Naturschutz, Institut für Biologie und Umweltwissenschaften, Carl von Ossietzky Universität, D – 26111 Oldenburg
2Büro für Biologie und Umweltplanung, Steinweg 52, D – 26121 Oldenburg
3Institut für Ökosystemforschung, Kandelstr. 26, D – 79106 Freiburg
In the five-years-project „Restoration and creation of species-rich meadows by hay transfer – a contribution to nature conservation in intensively used landscapes“ (supported by the Deutsche Bundesstiftung Umwelt) up to now 21 measures have been carried out, from these 3 in 2004, 14 in 2006 and 4 in 2007 (furthermore a few planned for summer 2008). The restitution areas are situated in SW- (Upper Rhine Valley, Black Forest; with rich or poor mineral soils) and NW-Germany (Weser-Ems-Region, with sand and peat soils); they are abandoned or actual fields or have been managed as intensive or extensive, but species-poor grassland. The donor areas include a wide spectrum of meadow types with great variety of soil types and humidity and nutrient level, as well as floristic composition and structure of the vegetation and the altitude (from 0 to 1200 m s.l.).
Four years after the transfers of 2004 we found on the three recipient areas (former fields) at the Tüllinger Berg (SW-Germany, near Basel) the floristic composition and vegetation structure of a meadow with Arrhenatheretum salvietosum, already very similar to the ones of the donor meadows nearby. The species number and cover of weeds and nitrophytic ruderals decrease from one year to the next, while the typical grassland species disperse into and inside the permanent plots and show higher species numbers and densities.
In accordance with the results of Bosshard (Switzerland; mainly by seed sowing), on former fields the initial character of a mesophilous meadow is discernable already one year after the transfer, while on some former meadows a clear enrichment of typical meadow species has not taken place after 1-2 years. However, in special cases we do not aim at the enrichment of species on former meadows, but on structural changes (vegetation structure, relative cover of the dominant species; e.g. Belchen-Hohtann). In the preliminary comparison of the variants (with or without former soil opening of the meadows; without hay or application of hay in simple or double layer) we found on former fields no differences of species number and cover of the grassland species between the simple and double hay layer, but clearly to the variant without hay; in former meadows, however, the application of the double layer shows better restoration success.
We resume that problems in restoration measures arised mainly by the small interest of a few farmers or the lack of appropriate donor sites or bad whether conditions in the planned transfer period. We found good results in those measures, where the hay had been transported from a very species-rich donor meadow to a very species-poor restitution area and where the soil management and the consecutive application of hay had been carried out very carefully; additionally is important the time of mowing the donor meadow as well as the time of cutting the restitution area in the months and years after the hay transfer.