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In recent decades considerable changes in agricultural practices (especially increased fertilisation, early and increased cutting) have led to the decline of many characteristic grassland species. Formerly widespread species have become rare, and many grassland species are considered to be nowadays threatened and are on Red Lists. The continuous loss of species-rich grassland habitats remains unabated and affects even species that are still relatively widespread and abundant. The associated fragmentation and reduced gene flow will therefore impact the genetic diversity of local populations also of these species. The present study concerns a formerly common grassland species that has experienced a sharp decline in large parts of the study area (Saar-Lor-Lux) within the last decades. Alopecurus rendlei, is an annual grass occurring in fragmented and sometimes very small populations on periodically humid to wet grassland sites with moderate nutrient supply. The aims of the study were to analyse genetic diversity and population genetic structure to study the potential consequences of habitat fragmentation and to determine if there is a relationship between genetic differentiation and geographical distance (IBD pattern). Leaf samples were collected along 25 meter transects and genotyped after DNA extraction using 13 newly designed microsatellite markers. Genetic variation within populations was assessed as NP (private alleles), NAP (alleles per population), NE (effective alleles), HO (observed heterozygosity), uHE (unbiased expected heterozygosity) and FIS (fixation index). Population structure was analysed by principal coordinate analysis (PCoA), AMOVA and STRUCTURE and a Mantel test was performed to analyse the relationship between geographic distance and genetic differentiation. The studied populations showed a high genetic diversity (mean NP = 0.026, NAP = 5.16, NE = 3.17, HO = 0.52, uHE = 0.65) and a weak genetic structure (STRUCTURE analysis). The assumption that at least some effects of genetic drift were already detectable in the studied populations could be confirmed, particularly in the highly isolated and very small population D11 in Germany (uHe = 0.56). Weak genetic differentiation among regions (1%) and a low differentiation of populations within regions (5%) strongly suggest that the populations were only recently fragmented, and that genetic drift remains largely unnoticeable mostly due to very large population sizes. Another non-exclusive explanation for the high genetic diversity and the weak genetic structure could be that there is ongoing gene flow between the extant populations, as shown by the significant isolation by distance pattern. Conservation measures will be necessary to counteract a further decline of A. rendlei and the generally strong species loss in grassland. Ensuring extensive agricultural practices adapted to the species' habitat requirements plays an important role. Likewise, measures to counteract further fragmentation and decline of current population sizes to prevent a reduction of gene flow are needed to assure the long-term conservation of the species. [ABSTRACT FROM AUTHOR]

Colline/submontane acidic grasslands, elements of pre-industrial farming, are declining throughout Central Europe. As they correspond largely to the priority EU habitat type 6230 (Species-rich Nardus grasslands), a syntaxonomically sound delimitation is of importance. In the Rhenish Massif (Western Germany), acidic grasslands form diverse and syntaxonomically intricate vegetation patterns. We studied such grasslands in the Lahn-Dill district near Donsbach based on 292 original relevés from 1987. The dataset was classified into nine clusters. The clusters were aligned with syntaxa according to the proportions of diagnostic species. Four associations (with subunits) and one community specified to alliance were distinguished (in brackets corresponding alliances and classes): Polytricho piliferi-Scleranthetum perennis (Hyperico perforati-Scleranthion perennis, Sedo-Scleranthetea), Airo-Festucetum (Thero-Airion, Sedo-Scleranthetea), Campanulo rotundifoliae-Dianthetum deltoidis and Hypericum perforatum-Gnaphalium sylvaticum community (Violion caninae, Nardetea strictae), Arrhenatheretum elatioris ranunculetosum bulbosi (Arrhenatherion elatioris, Molinio-Arrhenatheretea). The Polytricho piliferi-Scleranthetum perennis and the Campanulo rotundifoliae-Dianthetum deltoidis, to our knowledge, are described for the first time for Germany. By NMDS ordination we detected soil fertility and soil acidity as the main drivers for vegetation differentiation followed by moisture-related variables. On average we found 37.7 vascular plant species, 4.3 bryophyte species, and 0.6 lichen species per plot which was on average 15.6 m² in size. Thirty-five threatened vascular plant species, two bryophyte and eight lichen species of the German Red List indicate the area's eminent conservation value. By our study, we extended the national list of syntaxa by two associations and appreciate the diverse acidic grasslands at the eastern edge of the Rhenish Massif. [ABSTRACT FROM AUTHOR]

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In a field experiment over 7 years the effect of mulching was compared with mowing, through which harvested material is removed from the plot. By mulching the harvest material remains on the field and decomposes. Thereby released nutrients can return to the nutrient cycle. That causes an increase of yields of following forage plants and a higher deprivation of nutrients. Annual mulching over a longer period increased the amount of plant available potassium and phosphorus in the soil. The plant community only slightly changed in its composition during the time. [ABSTRACT FROM AUTHOR]