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- Agropyro-Rumicion crispi (1)
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Einige Pflanzengesellschaften der schwedischen Ostsee-Inseln Gotland, Öland und Stora Karlsö werden besprochen und mit Tabellen erläutert. Sie beziehen sich auf "Änge" (Komplexe von Laubwald und Wiese), Nadelwälder auf Kalkboden bzw. auf Sand, Saumgesellschaften, Alvar (Helianthemo-Globularion und Alysso-Sedion), feuchte Wiesen und Weiden (Molinion und Lolio-Potentillion), Sümpfe und Gewässer (Caricion davallianae und Littorellion), Salzwiesen (Armerion maritimae), Stranddünen (Ammophiletalia und Festuco-Sedetalia), feuchte Dünentäler und Schwalben-Guano unter Felsrändern.
This paper describes the reaction of Pulegium vulgare and a number of species from the same locality upon the different flooding regimes of four consecutive years. These species mainly belong to the Lolio-Cynosuretum and the Ranunculo-Alopecuretum. The results show that the effect of a flood on the vegetation strongly depends on the month (the date of the year) during which the inundation occurs. A flood of shorter duration in late summer has a stronger impact than a longer inundation in spring and early summer.
Pulegium vulgare strongly decreased after being flooded in July and August and did not recover in the subsequent year. On account of the behaviour of the species after a summer inundation, seven groups were broadly distinguished.
Between 1996 and 2006 the vegetation succession in drift sands and in blown-out gravel-rich depressions, located in the nature reserve Hulshorsterzand in the central Netherlands, was studied. Within this Natura 2000 habitat (type 2330: inland dunes with open Corynephorus and Agrostis grasslands) so-called lichen steppes are included, famous for their biodiversity, both in flora (cryptogams), and in fauna. With multivariate analysis, the relation between the primary succession, the species composition of the vegetation and the soil quality was studied in three different biotopes i.e. 1. drift sand, 2. blownout gravel-rich depressions and 3. drift sand after management. With a total of up to 34 species, lichen diversity in the study area appeared to be high. Biotope 1, i.e. the pioneer vegetation with Corynephorus canescens on blowing sand, is rather scarce in lichens. Between 1996 and 2006 green algae, C. canescens and Polytrichum piliferum appeared, with the result that much of the former open drift sand area was covered by pioneer stages of the Spergulo-Corynephoretum. If sand stopped blowing in, a combination of P. piliferum with the neophyte Campylopus introflexus occurred. The terminal stages of lichen succession on drift sand, a vegetation with mainly Festuca ovina s.l., Deschampsia flexuosa and reindeer lichens (Cladonia subgen. Cladina), proved to be rather stable. Since 1996 the lichen steppes occurring in biotope 2 were increasingly grass-encroached. Where some sand was still blowing in, lichen diversity did not change much, but gradually C. introflexus increased. However, without sand blowingin, a decreasing lichen cover and loss of some Red List lichens occurred. In general, in this grass-rich vegetation Calluna vulgaris will germinate and gradually a dry heath might develop. However, where dynamics had stopped and Pinus sylvestris seedlings established, succession to a young forest started. Vegetation change from open sand to lichen-rich vegetation is clearly related to a decrease in pH, an increase in organic matter, in % total N and in % total P. The lichen composition is clearly related to this gradient. The applied restoration measures on steep sand dunes in the eastern area, both of cutting pine trees and removing topsoil down to the mineral soil layer, proved to be successful. The sand kept drifting and the pioneer community thriving, including the lichen Stereocaulon condensatum characteristic of pioneer conditions, while the neophytic moss hardly increased between 1996 and 2006.