Organic but also low-input conventional farming systems support high biodiversity of weed species in winter cereals.
In recent years, the European Union has been paying particular attention to the problem of biodiversity loss. The possibilities of its assessment and conservation are included in the latest European Union (EU) policies and reflected in the European Biodiversity Strategy. The biodiversity of weeds in winter cereals in organic and conventional low-input farms in Eastern Poland was investigated during a 3-year period. Significantly more species and larger abundance were found in organic than in conventional farming systems. The biodiversity of these communities was described by Shannon's diversity and Simpson's dominance indices, which showed diversity to be well maintained in both farming systems; however, significantly higher Shannon's index and significantly lower Simpson's index values were observed in organic farms. Both farming systems were the mainstay of endangered and rare species, as well as some invasive weed species. Weed communities of organic farms were dominated mostly by Setaria pumila and Elymus repens, while conventional farms were dominated by Juncus bufonius and Setaria pumila. The study showed the importance of organic farming systems for biodiversity conservation. It was also shown that low-input (traditional) conventional farms are also beneficial for biodiversity conservation.