Dry calcareous grasslands are considered to be the most species-rich habitats in Germany and are protected via the European Fauna-Flora-Habitat Directive 92/43/EEC and on the basis of the BNatschG. They are currently threatened by the climate-induced and/or management-induced massive spread of the Bromus erectus, resulting in a loss of characteristic, less competitive species of this extremely valuable habitat. However, as this spread has just begun in Central Germany, it is still possible to take countermeasures through adaptations in management. The aim of the project is to investigate different management strategies that can successfully control the spread of Bromus erectus at a still early stage of expansion. For this purpose, we will observe and analyze the vegetation on different sites in Central Germany within six model regions.  Selected sites should undergo continuous management for at least five years. The following management variants will be evaluated: grazing with cattle and/or horses, sheep, goats, mowing, and abandonment.

The upright brome (Bromus erectus W. Hudson 1762) is a perennial grass species that reaches growth heights of 30 to 90 cm. The species grows in loose to dense clumps and forms a rhizome with roots up to 60 cm deep (intensive rooter). The flowering period is from May to October.

Bromus erectus is native to dry, base-rich sites in southern and southwestern Europe (Sutkowska et al. 2013). In Central Europe, the species only appeared in modern times (Poschlod & WallisDeVries 2002), where it was further spread, especially by hay seeding. Since then, this perennial species has continued to migrate northeast from southwestern Germany. In Central Germany, Bromus erectus was probably first sown and thus introduced in the mid to late 19th century (Heinrich 2010). Currently, a strong spread of the species can be observed in the Central German dry calcareous grasslands, which leads to a loss of characteristic but less competitive species of this extremely valuable habitat.

For a long time, the problem of the immigration of the upright brome was only noticed sporadically, as the species is described as a characteristic grass species of semi-dry grasslands (Schubert 2001). However, in addition to Thuringia (Heinrich 2010), Lower Saxony and North Rhine-Westphalia, the species has also been classified as a neophyte in Saxony-Anhalt since 2016 (Frank 2016).

In a relatively short time, the Bromus erectus can become dominant if sites are managed inappropriately or are abandoned (Bornkamm 2006). The original vegetation structure of the dry grasslands is significantly altered, especially more homogeneous, by the relatively large tufts and the strong litter accumulation. The increased litter accumulation also promotes nitrogen availability in the soil through increased moisture. Recently, a massive increase of Bromus erectus is observed in the dry calcareous grasslands in Central Germany (Meier et al. 2021), leading to suppression of the predominantly low-competitive characteristic dry grassland species. As a result, sites become both floristically and faunistically deficient (Poniatowski et al. 2018).

Bornkamm, R. (2006) Fifty years vegetation development of a xerothermic calcareous grassland in Central Europe after heavy disturbance. Flora-Morphology, Distribution, Functional Ecology of Plants, 201(4), 249-267.
Frank, D. (2016) Gefäßpflanzen (Tracheophyta: Lycopodiophytina, Pteridophytina, Spermatophytina) Bestandsentwicklung. – In: Frank, D. & Schnitter, P. (Eds.): Pflanzen und Tiere in Sachsen-Anhalt: Ein Kompendium der Biodiversität. Natur+Text, Rangsdorf: 192–318.
Heinrich, W. (2010) Zum Indigenat der Aufrechten Trespe (Bromus erectus) in Thüringen. Haussknechtia, 12, 101-126.
Meier, T., Hensen, I. & Partzsch, M. (2021) Floristic changes of xerothermic grasslands in Central Germany: A resurvey study based on quasi-permanent plots. Tuexenia, 41, 203-226.
Poniatowski, D., Hertenstein, F., Raude, N., Gottbehüt, K., Nickel, H. & Fartmann, T. (2018) The invasion of Bromus erectus alters species diversity of vascular plants and leafhoppers in calcareous grasslands. Insect Conservation and Diversity, 11(6), 578-586.
Poschlod, P. & WallisDeVries, M.F. (2002) The historical and socioeconomic perspective of calcareous grasslands—lessons from the distant and recent past. Biological Conservation, 104, 361–376.
Schubert, R. (2001) Prodomus der Pflanzengesellschaften Sachsen-Anhalts. – Mitteilungen zur floristischen Kartierung Sachsen-Anhalt: 688 pp.
Sutkowska, A., Pasierbinski, A., Warzecha, T., Mandal, A. & Mitka, J. (2013) Refugial pattern of Bromus erectus in Central Europe based on ISSR fingerprinting. Acta Biologica Cracoviensia Series Botanica, 55, 107–119.

The search for suitable sample areas was carried out in six model regions in central Germany (Lower Saale Valley, Saale-Unstrut region, Biosphere Reserve Karstlandschaft Südharz, Kyffhäuser Nature Park, Gothe/Ilm district, Hainich National Park).

Criteria for selecting sample areas within the model areas:
• FFH-LRT 6210(*) and/or 6240*
• At least 5 - 10 years of continuous management
• Minimum area size > 0.5 ha
• Southerly exposure if possible
• Vegetation data as old as possible available
• Either already colonized with upright brome or at least potentially colonizable (species occurring in the area)

Management variants:
• Temporary grazing with large grazing animals (cattle, equines, mixed grazing)
• Year-round grazing with large grazing animals (cattle, equines, mixed grazing)
• Grazing with sheep (paddock and herding)
• Grazing with goats
• Mowing (extensive, single-cut)
• Fallow land without management

For each of the six management variants, six suitable sample areas were randomly selected. A total of 36 sample areas were recorded. The occurrence of upright brome is recorded at two study levels. At a large-scale level, the question of distribution and the degree of settlement on the respective total area is being investigated at a grid level. At a small-scale level, changes in the calcareous dry grassland vegetation are to be documented through vegetation surveys. In addition to the species composition, representative vitality parameters of Bromus erectus were recorded within each vegetation survey in order to determine the fitness of the respective population.

The sample site that has been best examined over a long period of time is the year-round horse grazing on the Rödel in the NSG and Natura 2000 area “Tote Täler”. The analyzes of the vegetation data as part of this project revealed a very good condition of the calcareous grasslands, which were heavily grass-encroached by dominant stocks of Upright brome (Bromus erectus) before grazing began in 2009. The dominant stands were lighted up and the diversity, particularly of characteristic plant species, increased significantly. This process was made possible in particular by the structures that are created on year-round stocked areas through permanent, but extensive and patch-like grazing. Compared to short-term, intensive grazing, year-round grazing develops a three-dimensional vegetation structure through high selection possibilities for the grazing animals.

Horses in particular play an important role in this process. Compared to other grazing animal species such as cattle, sheep or goats, equids can compensate for poor quality fodder by increasing their feed intake almost continuously. Grass species that are almost indigestible for many herbivores due to silicate deposits in the cells and woody fibers can be digested by equids due to their digestive system geared towards fiber utilization and their high-crowned teeth that protect against abrasion (coevolution of grasses and grazing animals from the Tertiary period). As grazers, equids selectively feed on grasses, thus directly reducing Bromus erectus and indirectly promoting herbaceous plants. Bromus erectus was selectively fed on in all growth phases and in all seasons. Winter grazing plays an important role, since Bromus erectus, as a sub-Mediterranean species, benefits significantly from the milder winters and earlier springs of recent times.

Site characteristics
Location: 51° 13‘ N; 11° 46‘ E
Height: approx. 250 m above sea level
Climate: moderate to slightly continental
Average annual temperature: 8.3°C
Average annual precipitation: 565 mm
Soil and geology: Loess-Luvisols on Middle Muschelkalk
Nitrogen N(total): 0.31%
Phosphorus: 0.26 mg/ 100 g soil
Potassium: 19.05 mg/ 100 g soil
Deposition of atmospheric nitrogen: 13 kg ha-1 a-1

Management
Pasture type: year-round permanent pasture
Pasture start: 2009
Pasture size: approx. 90 ha
Grazing animals: approx. 16 horses of the robust Konik polski breed (approx. 0.2 LU/ha/a)
Agricultural support: voluntary nature conservation services (FNL)
Pasture infrastructure: two-strand, game-permeable fence, drinking trough, low winter feeding (straw)

Vegetation
Habitat type: Semi-natural dry grasslands and scrubland facies on calcareous substrates 6210(*)
Begin of horse grazing in 2009: highly grass-encroached with Arrhenatherum elatius, Brachypodium pinnatum and especially Bromus erectus

Grazing effects
Dynamic, mosaic-like use of space by grazing animals
Reduction of cover of litter layer from 50% (± 18.7) in 2009 to 14.38% (± 9.04) in 2024
Increase of bare soil patches from 1.09% (± 1.65) in 2009 to 7% (± 5.63) in 2024
Habitat-characteristic floristic species increased
Average number of species on vegetation surveys increased from 31.38 (± 10.24) in 2009 to 42.63 (± 9.68) in 2024
Four orchid species newly immigrated
Significant increase in the population of Ophrys apifera: increase in sterile individuals on 1/3 of the pasture area from 1,239 in 2013 to 4,652 in 2024

More information can be found here.

The long-term goal of the project is to develop a manual for dealing with Bromus erectus, to raise awareness among land users and to establish demonstration plots. A further training program for practitioners will be integrated at the Anhalt University of Applied Sciences.