Diversity of current weed vegetation on arable land in selected areas of the Czech Republic

This paper reports on the within-habitat (alpha) and on the between-habitat (beta) diversity of weed vegetation on arable land in the Czech Republic, influenced by management systems, crops grown and altitude. A phytocoenological survey was conducted from 2006 to 2008 during a vegetation period using releves that were 100 m(2) in size, placed in the central part of fields. The species richness and the mean Sorensen dissimilarity were calculated. The statistically significant effects of the type of farming and altitude on species richness were recorded. The average species numbers in one releve reached 9.17 and 21.17 in conventional and organic farming, respectively. In both management systems, an increasing number of species was recorded with increasing altitude. Statistically significant effects of all the variables were observed when evaluating beta-diversity. Higher beta-diversity was found in conventional farming.