Fig. 2 Relationships between the total volume of trees and shrubs in the field margins and overall species richness (A) and percentages of TCCS (B) in vascular plants, bryophytes, birds, and breeding pairs of birds Table 4 Distribution of TCCS species in three types of field margins divided according to the volume of tall vegetation Taxonomic group Parameter Herba-ceous selleck kinase inhibitor (N = 21) Shrubby (N = 29) Tree lines (N = 20) Kruskal–Wallis test Birds Total no. of species 24 37 46   No. of SPECs 5 8 10 H = 4.21; df = 2; p = 0.12 Percentage of SPECs 23.8a 19.1 15.2 H = 5.26; df = 2; p = 0.07

Birds Total no. of pairs 268.3 393.8 501.0   No. of pairs of SPECs 37.5 67.75 45.0 H = 2.44; df = 2; p = 0.29 Percentage of pairs of SPECs 14.0 17.2 b 9.0 b H = 8.65; df = 2; p = 0.01 Vascular plants Total no. of species 366 413 395   No. of Wortmannin cell line threatened species 3 7 4 H = 0.47; df = 2; p = 0.79 Percentage of threatened species at local level 0.16 0.28 0.23 H = 0.30; df = 2; p = 0.86 Bryophytes Total no. of species 56 72 76   No. of threatened species 2 3 3 H = 0.67; df = 2; p = 0.71 Percentage of threatened species at national level 1.16 1.47 1.13 H = 0.45; df = 2; p = 0.80 aThe percentages denote mean weighted values per plot bSignificant difference is marked in bold (nonparametric multiple comparison test) Discussion Field margins as refuges of rare and threatened species We have demonstrated that field margins in Poland regularly support plants and

animals recognized as conservation targets. Threatened birds occurred check details in 12.9 %, plants in 18.6 %, and bryophytes in 20.0 % of field margins, and birds of conservation concern were recorded in 95.7 % plots. These data contradict some earlier results suggesting that contemporary agro-ecosystems seldom host rarities (Manhoudt et al. 2005; Kleijn et al. 2006; Aavik et al. 2008; Liira et al. 2008). We also discovered a large number (78) of plant species listed as being of least concern in the European red list, including 40 CWR (Bilz et al. 2011). CWR are

a major component of plant genetic resources for food and agriculture, providing crucial ecosystem services for humankind (Maxted Fossariinae et al. 2006). The high number of CWR in just a sample of field margins signifies the retained natural features of their vegetation, multifunctionality and importance in preventing loss of biodiversity. The findings suggest that almost every field margin in the Polish farmland provides a habitat for species of conservation importance. More generally, these data emphasize the remarkable heterogeneity of the agricultural landscape in this part of Europe and confirm regional differences in biodiversity patterns (Palang et al. 2006; Batáry et al. 2011; Cogălniceanu and Cogălniceanu 2010; Tryjanowski et al. 2011). Importance of shrubby margins The occurrence of the threatened species in farmland should be considered in a broader context of landscape and vegetation systems.