Threatened flora of semi-natural grasslands: preservation and restoration

Abstract

Semi-natural grasslands play an important role in the modern environments, serving as refuges for a number of threatened plant and animal species. In this thesis I concentrate on the problems of identifying, maintaining and recreating plant communities typical of these grasslands. First I used field data to study whether the most species-rich grasslands were characterised by common variables describing land use and environment. However, these variables proved to be of little use. No shortcut was found to discovering the individual grasslands with the richest flora or a set of sites with the highest total species-richness. Instead, comprehensive species inventories are necessary when searching and monitoring the floristically valuable areas. Besides semi-natural grasslands, the occurrence and success of grassland species were also studied on a restored meadow and in alternative habitats that they invade spontaneously. Grassland plants were regularly found bordering roads and railways, and they even appeared capable of using such routes as dispersal corridors. They thrived especially on the verges of small, unpaved roads in open environments. However, entire plant communities similar to those on semi-natural grasslands were not identified, probably due to excessive disturbance and an unfavourable management regime. An appropriate mowing frequency and avoidance of the use of de-icing salt may, nevertheless, increase the number of grassland species along roads and railways. As an example, a rare grassland species Campanula cervicaria succeeded equally well on roadsides as on meadows, provided that the vegetation remained open. Its population sizes decreased with shading, and small populations had an elevated risk of losing all fertile plants. For preservation of C. cervicaria and other rare, short-living grassland species, recreating a grassland failed to be a viable alternative. 1herefore, in the protection of grassland communities the importance of preservation and management of existing semi-natural grasslands cannot be over-emphasised.