Incidence of thermophilic, grass and rare arable weeds in cereal fields in the Czech and Slovak Republic

Our objectives were to characterise arable weeds of the Czech and Slovak Republic in cereals, especially considering important groups of species: thermophilic, weedy grasses, and rare and endangered species. The three-year phytocoenological survey was conducted from 2006 to 2008 in five climatic regions and eight different soil types. 379 relevés were recorded, and 281 weed species were found. The effects of both the climatic region and soil type were found to be statistically significant. Species richness increased with altitude. Several species were distinctly associated with soil type, from fertile chernozems to less fertile cambisols, while fluvisols were strongly associated with e.g. Calystegia sepium (L.) R. Br. The incidence of species outside their expected regions generally fit two categories: the most pervasive weeds found almost in all climate regions, such as Echinochloa crus-galli (L.) P. Beauv., or rare weeds in higher altitudes than expected, such as Lolium temulentum L. Rare and endangered species were more likely to be found in a colder climate and poorer soils, and this is linked to less intensive management; however, not all endangered arable species can tolerate such conditions. Even though this data is not recently collected, this is still valuable information on the distribution of weedy species, especially concerning the current interest in maintaining biodiversity.