The importance of ecological farming for biodiversity is shown for weed communities and for birds. Also for carabids, the importance as a reservoir of species is shown. The ecological farmers have to regard the sustainability of their agricultural practice. The reduction of nitrogen- and insecticide-input since 1993, ecologically positive, is shown for Northern Germany. With the species number of predatory arthropods in Hesse it is shown, that all agricultural intensities contribute to biodiversity. So none should be omitted, so far. The importance of structures like hedges etc. for biodiversity is pointed out. Should herbicide-resistant, genetically-manipulated crops be introduced to middle European agriculture, the ecological value of these fields would be drastically reduced, and the ecological importance of eco-farming would rise sharply.