The Aquatic Warbler (Acrocephalus paludicola) is a song bird breeding in fen mires and similarly structured other wetlands with a water depth of 1-10 cm. Widespread in central-European wetlands at the beginning of the 20th century, the species is now globally threatened. The westernmost and genetically distinct Pomeranian population is even on the verge of extinction. The major challenge in the conservation of remaining habitat is the costefficient removal of biomass. About 50% of the Pomeranian population survives in a valley fen near Rozwarowo in Northwest Poland, where between 1993 and 2007 a conspicuous change in breeding habitat has taken place from summer grazed sedge meadows to commercial winter cut reed beds. We compared vegetation structure, site conditions, and potential prey abundance with the distribution and abundance of Aquatic Warblers in Rozwarowo Marshes and studied temporal changes and the compatibility of conservation and reed cutting interests. Aquatic Warblers now occur almost exclusively in sparsely growing, low reed with abundant Thelypteris palustris, Carex elata, and Lysimachia vulgaris. This vegetation type provides more potential prey for Aquatic Warblers than the higher productive tall reed, whereas the patches of sedge vegetation have become too small following succession after abandonment. Currently, commercial reed cutting maintains suitable Aquatic Warbler breeding habitat. Considering the impending changes in the reed market, there is a need for flexible agri-environmental schemes (AES) to ensure that stripes are left uncut and to prevent eutrophication by high and long flooding of the site.

The Aquatic Warbler is the only globally threatened passerine bird species in Europe. Around 1900, it was one of the most abundant birds in European fen mires. The population severely decreased as a consequence of extensive wetland drainage. In recent years, it has been rather stable in key breeding sites but has decreased sharply in its westernmost occurrence Pomerania. Conservation of the Pomeranian birds is of key importance for conserving the intraspecific diversity of the species. Throughout 2004-2006 we studied all current breeding sites of the species in Pomerania. Two areas have been studied in more detail: Rozwarowo Marshes, the largest breeding site in Pomerania, and Lower Oder Valley National Park, the last breeding site in Germany. Data on vegetation composition and height, water level, site conditions, and land use were analysed. The sites near the coast and in small river valleys are characterised by sparse and low Phragmites australis stands with a well-developed lower sedge and herb layer. The sites in the Lower Oder Valley are more nutrient-rich and dominated by Carex acuta, Phalaris arundinacea, and other meadow grasses. In Rozwarowo Marshes, the birds inhabit sparse, short Phragmites australis and Thelypteris palustris vegetation that is maintained by winter reed cutting. In the Lower Oder Valley National Park, Aquatic Warblers shifted from Caricetum gracilis to other plant communities that continued to be mown frequently. Similar to the Lithuanian Aquatic Warbler habitats in the Nemunas Delta and in contrast to the predominantly mesotrophic habitats of the core population, the Pomeranian habitats are eutrophic and more influenced by inundation. Various rare and threatened plant communities occur here. The Aquatic Warbler can be regarded as an umbrella species for mesotrophic and slightly eutrophic peatlands for which this bird is a specialist. Conservation activities should focus on a site-specific management and the prevention of further eutrophication.

There are several thousand different cultivars of apple trees but only a limited number are cultivated on an industrial scale. Old cultivars can be useful, for example, in the processing industry due to their different composition. In many cases, they have higher organic acid content. The content of mineral components, colour, and polyphenols in the fruit of 7 old apple tree cultivars, growing in the Wolinski National Park, was studied. The changes that occurred in the fruit after freeze-drying were also evaluated. The trees from which the fruit was picked for analysis, despite the lack of chemical protection, were fruiting and the apples had only a few symptoms of damage caused by pests or diseases. The fruit was characterised by a high soluble solids content (14.4-16.4%), in which sugars and especially fructose dominated. The number of organic acids varied greatly and ranged from 0.27 (Oberlander Himbeerapfel) g to 1.07 g/100 g (Winter Goldparmane). The content of polyphenols in fresh apples ranged from 186 mg (Horneburger Pfannkuchenapfel) to 354 mg/100 g (Winter Goldparmane) and increased after freeze-drying from 666 mg (Weisser Winterkalvill) to 1486 mg/100 g (Winter Goldparmane). The dominant group of polyphenolic compounds was phenolic acid. The freeze-drying process caused unfavourable changes in the colour of the pulp. The fruits of Oberlander Himbeerapfel cultivar were most susceptible to these changes. However, the least darkened fruit of Horneburger Pfannkuchenapfel.