2005). For example, in farmlands
where grasslands are the matrix, extensive wet meadows play an important role in maintaining threatened plants (Liira et al. 2008). In extensively cultivated landscapes fields may also host plant species of conservation importance, however threatened arable floras consist mainly of annual species, and their occurrence is rare and ephemeral (Wilson and Aebischer 1995). In the outermost zone of crops adjoining the 70 studied filed margins HSP inhibition we noted 223 species of vascular plants, but only one species, the Rye Brome Bromus secalinus, was recognized as threatened (classed VU in the national and local red lists). Our data were collected within an arable production system, representative of many Central European landscapes (see Study area), where residuals of natural vegetation along edges are particularly common. Of them,
woody edge habitats, such as tree lines and hedgerows, are of exceptional importance for biodiversity, for example being the most consistent predictor of bird species richness on Polish farmland (Sanderson et al. 2009; Wuczyński et al. 2011). In the present study overall species richness of birds, vascular plants and bryophytes also increased with the volume of trees and shrubs, although the TCCSs were most abundant (in percentage terms) in field margins with an intermediate volume. This tendency was common to each of the studied taxa, probably in response to the ecological characteristics of the focal species. Most of the TCCS are associated
with open GSK1904529A or mixed landscapes. These constituted 80 % of the threatened vascular plants, representative of different types of grasslands, thermophilous saum communities and threatened segetal weeds. Four of the Urease threatened bryophytes are associated with agricultural plant communities, and the fifth species, the Marble Screw-moss (Syntrichia papillosa) is an obligate epiphyte growing on solitary, old trees. Seven of the eleven bird species of conservation concern are classified as being typical of agricultural and grassland habitats (Tucker and Evans 1997). Our findings suggest that shrubby margins can act as centers of endangered species in agro-ecosystems. Herbaceous margins, particularly strongly subject to agricultural impact, are usually poor in diversity and deprived of priority species, especially when dominated by common reed Phragmites australis, whereas dense tree lines are dominated by common species associated with forests. With regard to vascular plants, margins with an intermediate cover of tall vegetation represent successional stages in which species associated with open habitats are still able to occur, whereas shade-tolerant plants also appear. Pykälä et al.