Increasing the floristic diversity of species-poor grassland in FFH areas

Currently, many grassland habitats 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 reason is the very slow 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
• Improving biodiversity 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

• Focus 1 – Systematic attempt to enhance grassland in the “Spieler's Horst” project area

  In the “Spieler’s Horst” project area near Vockerode, four establishment strips (24 m x 80 m) were created in fall 2017 as part of a measure to increase floristic diversity based on a systematic experimental design. Three main influencing factors are being tested:

  • Surface pretreatment,
  • Contribution options,
  • Management.

  Plowing, tilling, and harrowing were used as variants of surface treatment.

  Plowing (possibly followed by harrowing to level the coarse clod structure and thus create an optimal seedbed) represents the most severe and presumably the most lasting disturbance of the existing grassland vegetation due to the deep turning of the turf. This variant should therefore provide the optimal germination and establishment conditions for the diaspores of the target species to be introduced.

  When tilling, the mechanical disturbance does not penetrate as deeply into the soil. In addition, the turf is not turned over consistently as it is when plowing, but rather the above-ground biomass and underground rhizomes are chopped up.

  The third variant, harrowing, is a minimally invasive method used to assess which plant species are capable of reestablishing themselves in existing grassland stands and to what extent.

  The planned experimental design includes the following variants for introducing diaspores: transfer of mown material, sowing of native herbs, a combination of these two variants, and, as a control, a variant in which no diaspores are introduced.

  Three different regimes are to be used for the management variants:

  • Mowing in June,
  • Mowing in June und September,
  • Mowing in September.

  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 (area size: 4 x 4 m). Furthermore, the nutrient supply (C, N, P, K) and the pH value of the soil are examined on the recipient and donor areas.

  

  

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  Results from the first year after trial implementation

  In the first year after the trial was implemented, differences were particularly evident in the number of Category 1 target species with regard to the introduction variant and the soil preparation variant.

  Compared to the untreated control variants (U), a significantly higher number of category 1 target species were recorded on the sowing variants (E and ME) that had been milled (F) or plowed (P) in advance. The differences between the more disturbed variants (F and P) on the one hand and the minimal disturbance intensity (ST) on the other were also evident in the NMDS ordination of the vegetation data. In this experiment on floristic grassland enhancement, the harrowing variants differ only marginally from the untreated control or the resident vegetation. According to a multivariate ANOVA, the introduction variants (F3 = 1.75, P = 0.029) and the soil preparation variant (F3 = 8.08, P = 0.001) had a significant influence on the species composition.

  When looking at the incorporation variants, it is striking that the different variants were similar across the soil preparation variants. The clear dissimilarity between the mown grass variants in combination with plowing and tilling soil preparation and the species spectrum of the donor area is noteworthy. In addition, the vegetation on the recipient area before the measure was implemented differed significantly from the vegetation on the tilling and plowing variants.

  Overall, a significantly higher total number of species was found on the more disturbed variants. The development of non-target species on these variants in the next recording period remains exciting.

  The management variant cannot yet show any effects in the first year, as the vegetation was recorded before the first mowing.

  

  

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• Focus area 2 – Further measures to enhance the value of grassland

  Since a significant proportion of European, German, and Saxony-Anhalt grasslands are in poor condition, urgent action is needed. This applies in particular to the current species composition of grasslands. To address this issue, this research project plans to implement additional measures for the floristic enhancement of grasslands in other project areas. The aim of this focus is to diversify species-poor grassland (LRT 6510 or 6440; EHZ C) in a cost- and time-efficient manner so that a favorable conservation status can be restored in the medium to long term. The findings and experience gained from previous projects will be used to develop the measures in detail and for specific areas.

  It is planned to implement the measures preferably within the FFH area 0067 (“Dessau-Wörlitzer-Elbauen,” area number 4140-304). In addition, measures to improve the flora and structure of grasslands within FFH area 0125 (“Kühnauer Heide and Elbe floodplain between Aken and Dessau,” area number 4138-301) could also be considered.

  

• Focus 3 - Promotion of selected species typical of floodplains

  During the project period, it is planned to examine the possibilities for reintroducing selected Red List species typical of Saxony-Anhalt’s floodplains, as well as species with a declining trend, and to carry out this reintroduction in suitable habitats typical of the location within FFH areas. In consultation with the cooperation partner, the following species have been preselected:

  • Arabis nemorensis (RL LSA 1, Frank et al. 2004; Distribution in Germany),
  • Gentiana pneumonanthe (RL LSA 1, Frank et al. 2004; Distribution in Germany),
  • Iris sibirica (RL LSA 3, Frank et al. 2004; Distribution in Germany),
  • Sanguisorba officinalis (declining inventory trend, Frank & Neumann 1999; Distribution in Germany),
  • Clematis recta (RL LSA 2, Frank et al. 2004; Distribution in Germany).

  The current and historical occurrence of these species along the Elbe River has been documented. With the exception of Clematis recta, all species are mainly found in commercial grassland, mostly in communities of wet and semi-wet meadows.

  

  

  During the project period, seeds will be collected from wild populations and the conservation culture of the Middle Elbe Biosphere Reserve. These will be used to grow young plants, which will then be used to strengthen existing populations or reintroduce new ones.

  

  

  

  

  

  

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• Focus 4 - Continuation of monitoring the success of vegetation development in selected project areas where measures have already been implemented

  In addition to implementing the systematic experiment on grassland enhancement in the “Spieler’s Horst” project area, the project will continue to monitor the success of nature conservation measures in the project areas during the project period.

  • Küchenholzgraben
  • Untere Schwarze Elster
  • Cortenswiese
  • Klieken.

  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 the target species can migrate into the entire area and establish themselves there permanently.

  

  Vegetation development and comparison of variants:  Untere Schwarze Elster

  The introduction of species led to a significant increase in floristic diversity in grassland across all variants over the years. The positive changes were particularly evident in the experimental variants, but an increase in diversity values was also observed in the untreated control areas. However, even after several years, the diversity values are still significantly lower than in the donor areas (see alsoEngst et al. 2016).

  In terms of numbers in particular, an increase in Category 1 target species was recorded after the measures were implemented. In the „Untere Schwarze Elster“ project area, these include species such as Achillea ptarmica, Allium angulosum, Inula britannica, Sanguisorba officinalis, Serratula tinctoria, and Veronica maritima. Compared to the control areas, a significantly higher number of target species was recorded in all introduction variants. There were only minor differences between the different introduction variants of mown grass transfer and meadow threshing. However, variants with additional sowing of native species showed better establishment success. (Baasch et al. 2016, Engst et al. 2016). These trends were also evident in the other project areas.