 replacement of Sphagnum mosses with ‘brown mosses’ such as Drepanocladus, Scorpidium, and Campylium (Elveland, 1983; Moen, 1976). The shorter vegetation also allowed more sun to reach the ground surface. This allowed the low-statured, heliophytic plants such as Parnassia palustris and the currently red-listed Saxifraga hirculus to thrive (Elveland, 1983) and also favored several species of invertebrates (Sjöberg, 1982). Thanks to these effects, past haymaking is not considered a negative impact when wetlands are assessed according to the criteria for natural habitats of European interest in the sense of the EU Habitats Directive (Gardfjell and Hagner, 2016). On the contrary, continued or reintroduced harvest is recommended to preserve both ecological and cultural values of the last remaining mire meadows (Svensson and Moreau, 2012; Tenning, 2015). In our study area, however, no mires are currently used as meadows. In general, mire meadows in northern Sweden were abandoned in the 1920s and 1930s (Elveland, 1983), and this area probably followed the general pattern because the mires that were reclaimed as arable land in the early 1900s could produce much higher volumes of hay. When haymaking ceased, many of the abovementioned effects were reversed naturally. Sphagnum species came back to replace the brown mosses (Moen, 1976), tussocks formed, and bushes and trees started to colonize the area (Elveland, 1983). A manmade habitat of importance for biodiversity was thus lost.
Second, management through damming also affected the biodiversity of the mires in the region. In some cases dams such as the one at Renbergstjärnen in our study area were abandoned in the 1930s and thus, those mires have not since been subjected to annual flooding. In other locations, such as Bergtjärnen, the timber-floating dams were used until the 1960s, and later beavers (Castor fiber) moved in and sustained the flooding by building supplementary dams. As a result, these new water surfaces became important nesting habitats for ducks (Sjöberg, 1982) and have increased the biodiversity of tree species in the area now that the lake’s immediate surroundings have been colonized by deciduous trees, mostly Betula pubescens. In a forest landscape otherwise dominated by conifers, deciduous stands offer attractive habitats for a number of species (Berg et al., 1994). Ultimately, these habitats are likely to be colonized by Picea abies, but not as long as flooding continues. Thus, damming that was originally introduced for haymaking has become long-lasting due to other needs, first of timber floaters and then of beavers, all of which has been important for promoting local and landscape biodiversity.
Other kinds of management were less beneficial for biodiversity. Actions to reclaim arable land were introduced in the late 1800s and ultimately affected 3% of the total mire area. The common procedure was to ditch and then to prepare the soil with spades and ploughs and add fertilizer (Osvald, 1937). When a mire was turned into arable land, the natural ecosystem was destroyed as opposed to when it was just modified by haymaking. In our study area, we could see that the mires selected for cultivation were in most cases mire meadows, and generally among the most productive ones. Although reclamation was only performed on a small part of the total mire area, a relatively large proportion of the productive mires habitats were thus lost.
As hay from natural meadows became less valuable, foresters increasingly tried to turn mires into productive forest land using ditches. Regarding the real effects of these ditches, our results are ambiguous, because the conversion from mire to forest does not closely follow the presence of ditches. The part of the total mire area that is now covered with forest is as large as the area located close to ditches, 106 ha, or 39%. Although the size is the same, however, the two areas do not overlap, as only 61 ha of the former mires that are today covered with forest is located within 60 m of a ditch. One reason for this mismatch could be met