Succession in two plots at "Kungsmarken" between 1952 and 2005 with different historical management

Abstract: Abstract The main influences on growing conditions in pastures and hayfields are grazing and mowing, which regulate the species struggle for space and resources. If the management ceases, this will contribute to a change of the vegetation. A succession starts where the plant cover gradually will change according to a specific pattern. After some time a few competitive species, previously disfavoured by management regime, will be dominant. My aim with this study was to reinventory two already existing plots at ?Kungsmarken?, in an attempt to examine how succession has proceeded in the plots since management regime stopped in 1952. One of the plots, plot A, had been grazed and the other, plot B, had been mown and then grazed. Prior inventories have been done at ?Kungsmarken? in 1952, 1955, 1968 and 1976. During my inventory in the summer of 2005, the same plots were inventoried and the same method was used as has been used in the area since 1952. Eight lines 11 meters apart were put up in each plot. Fourteen subplots of one square meter were placed on each line 6 meters apart, starting with the first subplot 5 meters from the starting point. The number of species has continuously decreased between 1952 and 2005 in both plots. The decrease of vascular plants was 30 % in plot A and 26 % in plot B. Almost half of the species went extinct and a considerable number immigrated in both plots between 1952 and 1976 as well as 1976 and 2005, indicating that the turnover of species was large. The species? frequency and diversity have decreased in both plots between 1976 and 2005, implying that the within-patch spatial heterogeneity of species has decreased. Both the proportion and composition of indicator species differed between the inventories of 1976 and 2005. Besides that, the percentage of indicator species was higher in both plots in the inventory of 1976 than 2005, as well as all species noted at the inventory of 1976 are typical for pastures and hayfields found in unfertilized and managed areas. Furthermore, a big part of the indicator species found in 2005 are either ruderal species, mostly occurring in disturbed fields, or forest species. When categorizing all species found at the inventories in 1952, 1976 and 2005 in succession connected groups, there seems to be a trend. Late successional species has, in accordance with the ?intermediate disturbance hypothesis?, to some extent gradually replaced early successional species in both plots A and B between 1952 to 1976, and 1976 to 2005.