Fragmentation is one of the largest threats to biodiversity today. For plants, the semi- natural grasslands is one of the most species rich habitats in Sweden, and also one subjected to fragmentation. The effect of fragmentation and landscape history on plant richness is unclear, with conflicting reports. Some plant species show a slow response to changes in their habitat, creating an extinction debt. In a fragmented landscape, some species will go extinct in some patches while still persisting in other, species with relatively low colonization rates might never recolonize these areas and eventually the species will go completely extinct. Thirty semi-natural grassland areas in Östergötland in the south of Sweden were analyzed, and the amount of semi-natural grassland at three different points in time (1870, 1940 and 2002-2004) and at seven different spatial scales was calculated. Generally, the amount of semi-natural grasslands had decreased, but in varying degree depending on spatial scale: from 15% to 1% grassland left. Despite the large variation of habitat loss in the areas, three point in time and seven spatial scales, our study was unable to reveal any evidence of an influence of past landscape history on present species composition. Hence, present day habitat management seems more important for plant species richness than historical land use. This has positive implications on conservation biology and the managing of nature preserves. Areas with high species richness will, with the right management, keep that richness and no species will go extinct. This might also change the distribution of financial support, to better support the current management plans and focusing on the areas with the highest species richness today.
Maps from three different time periods were investigated (1870, 1940 and 2000), these maps were used to identify semi-natural grassland during these time periods.
30 areas were chosen in the county of Östergöland, and the amount of grassland loss within a 3 km radius were noted.
The field work was conducted in the late summer of 2010 and 100 squares were evenly distributed across the area though avoiding stones and wet patches.
All the plants within each square were categorized to species, some of the species were categorized as grassland specialist and some to grassland species.
None of the two types of odds, for neither the grassland specialists nor the grassland species, were a significantly affected by any of the parameters at any of the spatial scales. So, despite making 630 tests, involving seven spatial scales, two types of classification of grassland species, two types of odds and specialist/species richness, there were no significant cases.
• Our result show that history does not affect species richness of grassland plants, or the odds of a plant being a grassland species.
• This show that there is no extinction debt or that it already has been paid of.
• This has optimistic implications on conservation planning and habitat management since we can expect that current species richness will remain with correct management and no further species will go extinct.
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Last updated: 06/03/11