ABOVE-GROUND AND SEED BANK WEED BIODIVERSITY COMPARISON IN CONVENTIONAL AND ORGANIC FARMING SYSTEMS IN POLAND.

The assessment and conservation of agricultural biodiversity is one of the current goals of European Union policies, which is reflected in European Biodiversity Strategy. The biodiversity of soil seed bank and above-ground weed flora were investigated in spring cereals in organic and conventional farming system. The study was carried out between 2012 and 2014. Species of above-ground wild flora were counted on a surface of 1m2 in the field. Soil for seed bank evaluation was taken from the field and evaluated by seedling emergence method in a greenhouse. There were no significant differences in number of species between two communities. Biodiversity of weed community, described by Shannon's diversity index and Simpson's dominance index, was significantly better maintained in the soil seed bank than in above-ground flora in both farming systems. A strong, positive correlation between the number of species, Shannon's diversity index, Simpson's dominance index of soil seed bank and above-ground weed species was found in both farming systems, while abundance of seeds and above-ground weeds was significantly, positively correlated only in the conventional farming system. Qualitative composition of weed flora depended more on the type of community (soil seed bank or above-ground weed communities) than the farming system. [ABSTRACT FROM AUTHOR]