Weed communities of cereal crops grown on differently revegetated cut-over peatland sites.
Spring cereals (oats and barley) were grown during 1984-86 on abandoned cut-over peatland sites with different amounts of vegetation in central Finland. The relationship between the structure of the vegetation before ploughing and that of the subsequent weed communities was studied. The sites were abandoned in 1976, 1982 and 1983, and in 1983 supported an above-ground biomass of 318, 42 and 0 g DM/m2, resp. Total weed biomass progressively decreased in the 2 partially revegetated sites, but increased on the previously bare site. Species composition changed markedly at the latter site during the 3 years of cultivation, and the species composition changed least at the longest-abandoned site. Similarity between communities at the same site generally increased during the 3 years of cultivation, but decreased between communities at different sites.