Weed vegetation of arable land in the Czech Republic: environmental a management factors determining weed species composition

This paper reports on the current situation in weed vegetation composition on arable land in selected areas of the Czech Republic, assessment of influence of selected variables: applied management systems (conventional, organic), crops (winter cereals, root crops) and altitude and ranking of the importance of these particular factors. A phytocoenological survey was conducted from 2006 to 2008 during a vegetation period using relev,s that were 100 m(2) in size, placed in the central part of fields. In total, 202 relev,s of agricultural vegetation were recorded. The combined environmental variables explained 10.6% of the variability. Based on the pCCAs, the highest effect was found at altitude, which explains 5.1% of the species composition variability. The second and third most significant factors are crop and management system, which explain 3.3% and 1.8% of the variability, respectively. The lowlands were generally characterised by the thermophilous summer annual weed species. The higher altitudes were populated by species that are typical for colder areas and poor, humid, and acidic soil types, such as cambisoil.