Grassland enhancement in FFH areas using new methods for establishing target species

Currently, many grasslands in FFH areas do not have a favorable conservation status as defined by the FFH Directive. Even after many years of extensive management and largely optimal site conditions, they often still lack the species inventory typical of the habitat. This can be attributed primarily to the lack of suitable sources of diaspores in the surrounding area, as species-rich grasslands are rare and often isolated from one another. Another cause is the very low dispersal rate of many target species. In addition, dense, grass-dominated stands lack suitable establishment niches, which delays or completely inhibits the immigration of new species.

As part of this project, various methods for actively introducing target species are being tested on selected areas in FFH areas. To this end, existing species-rich meadow stands are being used as donor areas for seed material. Through mowing transfer, sowing of meadow threshing and regional seed mixtures, the diversity of species-poor grasslands is to be increased in the long term and a characteristic species composition restored.

Project priorities

• Active introduction of target species in FFH areas
• Improvement of species diversity in species-poor grasslands
• Restoration of characteristic species compositions
• Hay transfer, meadow threshing, and sowing of regional seed mixtures

Project region

Landkreis Wittenberg

Further project details

• implementation of measures

  In most areas, the measures were implemented according to a uniform trial design (block design, 4 variants, 6 replicates). In order to create good germination conditions and reduce competition from existing vegetation, six strips approximately 120 m long and 6 m wide are tilled into the restoration areas at the beginning of each measure. The loose soil is then compacted by rolling. Seed-rich material is then applied to each establishment strip in four different variants. First, the species-rich donor areas are mowed and the diaspore-rich mown material is applied fresh to the treatment area. Second: the mown material is threshed on the area with a combine harvester and the threshed material is sown on the recipient area in a dry state. In addition, two trial variants are being set up in which, in addition to the application of mown material or meadow threshing, sowing with seeds of regional origin is carried out. Implementation has so far taken place in autumn 2009 in the FFH areas “Küchenholzgraben bei Zahna” and “Untere Schwarze Elster,” and in late autumn 2010 in the area “Elbaue zwischen Griebo und Prettin.” In the FFH area “Dessau-Wörlitzer Elbauen,” measures have been implemented on two areas: in fall 2011 on the “Cortenswiese” near Dessau and in fall 2014 on a meadow near the village of Klieken. All project areas are located in Landkreis Wittenberg.

  In addition, a 22-hectare field in the Dornburger Aue in the Jerichower Land district, located in the FFH area “Elbaue zwischen Saalemündung und Magdeburg” was converted back to grassland (LRT 6440 with transitions to LRT 6510). These measures were implemented at the end of March/beginning of April 2011.

  

• Monitoring the success of nature conservation measures

  All measures are accompanied by performance reviews. The establishment of all species is documented and compared between the individual variants. To this end, vegetation surveys are carried out once a year on all trial variants and on undisturbed grassland (area size: 4 x 4 m). Furthermore, the nutrient supply (C, N, P, K) and the pH value of the soil are examined on donor and recipient areas.

• Vegetation development on the renaturation areas

  The results of our annual vegetation survey on the now five-year-old renaturation areas “Küchenholzgraben” and “Untere Schwarze Elster” confirmed that all tested introduction methods (mown grass, meadow threshing, and sowing of native species) can successfully enhance the flora of grasslands. The number of target species in category 1 (red list species and species with declining populations) and category 2 (other characteristic species) increased continuously over the years and showed relatively high values with an average of up to 20 species. There was also a positive trend in coverage rates. In the fifth year, the target species in categories 1 and 2 reached approximately 20% in the “Küchenholzgraben,” and together with grassland species in category 3, they even reached up to 60% cumulative total coverage. In the Untere Schwarze Elster project area, the cumulative coverage rates were similarly high at 15% (categories 1 and 2) and 50% (categories 1–3). Overall, there were only minor differences between the mown grass and meadow threshing variants. In contrast, additional sowing had a clearly positive effect. On these plots, the number of species and coverage rates of the target species were significantly higher than in the variants without additional sowing. The use of regional seed is particularly recommended if there are no or only moderately suitable donor areas in the vicinity of the treatment areas. In addition, additional sowing can also be used to introduce species that are difficult to detect with mown grass transfer at the end of September, such as species that scatter seeds in spring.

  

  

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• What happens next?

  Experience gained from the project to date clearly shows that the measures implemented are very well suited to developing the species composition and diversity of grassland areas in a targeted manner. Monitoring will continue in the project areas. This is the only way to determine whether the target species persist on the treated areas and to what extent the changes in species composition observed on the establishment strips affect the adjacent untreated grassland areas, i.e., whether target species can migrate into the entire area and establish themselves there permanently. We see a need for further research with regard to optimizing the methods. In particular, the growing conditions in the first year after implementation of the measures have a decisive influence on the final establishment of the sensitive seedlings. For example, on some areas, dominant populations of certain ruderal and seed bank species or very rapid regeneration of highly competitive grasses were observed, which hindered the optimal development of the introduced target species. More sustainable disturbance of the original vegetation (e.g., by plowing) and/or an optimized maintenance regime could contribute to further improving the establishment conditions. Systematic studies on the influence of additional soil disturbance variants in combination with different mowing variants on vegetation development could generate new insights.

  Monitoring will continue in all areas where measures have already been implemented. This is the only way to determine whether the target species can become permanently established. It remains to be seen whether changes in species composition will be limited to the establishment strips or whether target species will be able to migrate into the entire area. Adapted maintenance management is to be implemented on all areas to support the success of the measures.