Vegetation changes in restored semi-natural meadows in the Turku Archipelago of SW Finland

Abstract

In the Turku Archipelago of SW Finland the traditional animal husbandry dramatically decreased in 1950s after which the unused semi-natural pastures and meadows began to develop into less species rich shrub and tree communities. Restoration of some semi-natural meadows and pastures started in the late 1970s. Removing trees and shrubs, grazing, mowing, and pollarding deciduous trees were used as restoration of practises. Vegetation changes were followed from forty-one permanent sample plots established on restored areas. In this paper the data before restoration and 7–8 years after the first monitoring was analysed with parametric tests. The sample plots were divided into three restoration groups where the main restoration practises were: group 1. grazing, group 2. thinning (clearing plots from shrubs and removing some trees), group 3. thinning, mowing, and grazing (old wooded meadows). The results showed that: (1) The vegetation changed during analysed time. The number of species increased in all restored areas even though the changes were more pronounced in grazed areas and wooded meadows than in thinned areas. During restoration many common herb and grass species immigrated into the sample plots, but very few new indicator species of meadows were recorded. Most of the new species were found in few numbers in a sample plot which led to the significant increase in the number of sparse species (percentage cover < 1) in all restoration groups. The grasses benefited more from the restoration than herbs increasing their percentage cover significantly in grazed areas and in wooded meadows. In thinned areas the total percentage cover of the ten most dominant herb and grass species increased significantly. (2) The different restoration groups changed vegetation quite similarly. In grazed areas and in wooded meadows significant changes were slightly more numerous than in thinned areas. (3) The differences between the islands in vegetation changes were not pronounced. The added variance components among islands increased during restoration which probably indicated that the restoration practises as well as the species pool of the islands influenced the success of restoration.