Establishment of vegetation in broadened field boundaries in agricultural landscapes

Three field experiments with broadened permanent field boundaries were established in agricultural landscapes near Uppsala (southern Sweden). One aim was to test methods for increasing the amount of non-cultivated areas with high plant species diversity and at the same time suppressing the occurrence of weeds. The treatments consisted of re-establishing or broadening boundary strips, sowing a mixture of ley grasses and clover, of wild meadow species, or planting bushes. All treatments were managed by yearly mowing and taking away of the plant material. The vegetation was examined on two occasions during a 10-year period. At the second occasion, a set of untreated field boundaries (reference boundaries) in the vicinity of each experiment was examined for comparison. Sowing meadow species changed the species composition substantially compared to untreated boundaries. Out of 32 sown species, 22 remained after 10 years. These species are normally found in well-managed meadows or pastures. Species that did not establish or disappeared tended to be either adapted to moist or to dry conditions. Sowing meadow species kept the abundance of weeds on a lower level than sowing clover and grasses or free regeneration at one site and kept weed abundance lower or at least not higher than in reference boundaries.