Loss of biological diversity is one of the greatest challenges that our civilization must face nowadays. Reaction to the diminishing biodiversity of agricultural landscapes is various measures promoting free-living organisms. The study deals with the vegetation composition and structure of agro-environmental-climatic measures applied on arable land in operating conditions (intensively farmed regions of the Czech Republic). Additional study focus was applied to a popular measure of the feeding bio-belts. Bio-belts are not only hiding places for free-living animals but can provide them a rich food offer in the period from the harvest of main crops until winter. Thanks to the bio-belts, the landscape gains in biodiversity, and sloping sites can be protected from soil erosion. The vegetation of land parts used as bio-belts was assessed using phytocoenological relevés. Dominant plant species sown in the bio-belts were Avena sativa, Panicum miliaceum, Brassica oleracea var. acephala, Fagopyrum esculentum, Phacelia tanacetifolia, and Pisum arvense. Apart from the sown plants, there were also weeds occurring in the bio-belts, of which the most abundant were Chenopodium album, Amaranthus retroflexus, Setaria verticillata, Cirsium arvense, Equisetum arvense, etc. Risks connected with the realization of feeding bio-belts in respect of weeds occurring on arable land are negligible. Weeds from bio-belts have only a limited potential to spread to adjacent arable land. A potential spreading of weeds from the bio-belts to adjacent arable land was not demonstrated. On the contrary, thanks to its composition, the vegetation of bio-belts has the potential to extend the food offer for animals. Thus, bio-belts are useful for supporting biodiversity in regions intensively used for agriculture.