Weed vegetation and its conservation value in three management systems of Hungarian winter cereals on base-rich soils

Floristic composition and conservation value of the weed vegetation of winter cereal fields on base-rich soils in western Hungary was compared among three management systems: (i) small, extensively managed fields; (ii) small, intensively managed fields and (iii) large, intensively managed fields. Data were analysed by principal components analysis (PCA) and redundancy analysis (RDA). Most variation in species composition was explained by the differences between the three field types, particularly by the difference between the extensively managed fields and the two types of intensively managed fields and by crop cover. There were several species positively associated with small extensively managed fields, but no species associated with either of the two types of intensively managed fields. Logistic regression was made of the occurrence of species groups important for nature conservation on the first RDA axis, representing the distinction between the extensively and intensively managed fields. This showed that Red List and insect-pollinated plant species occurred more frequently in small extensively managed fields, but there was no difference between fields in the frequency of bird seed-food species.