Topsoil removal in degraded open sandy grasslands: can we restore threatened vegetation fast?

Abstract

Natural open inland sandy grasslands are a highly threatened habitat in Europe. The originally nutrient-poor habitats have been affected by increased aerial N-deposition and the spread of competitively strong plants. We investigated the restoration of degraded psammophilous vegetation in the southeastern part of the Czech Republic, central Europe, where the competitively strong grass Calamagrostis epigejos had formed a compact cover over many hectares formerly dominated by valuable psammophilous grasslands. To expose nutrient-poor sand, the upper nutrient-rich layer was scraped off down to a depth of 10–30 cm. Vegetation was recorded by phytosociological relevés annually in a total of 15 permanent plots (5 × 5 m) established between 2012 and 2014 (five plots in each consecutive year). Reference sites with target psammophilous vegetation and degraded sites were also sampled. The target psammophilous species colonized the open sand areas immediately from the adjacent well-preserved vegetation fragments. Out of 101 vascular plant species recorded in total in restored sites, 34 species were classified as target species, out of which 25 species were classified as threatened. After 6 years, the species richness and number of threatened species in the restored plots approached those of the reference sites. The results of multivariate analyses revealed that spontaneous development of restored plots run fast towards psammophilous vegetation. The optimal restoration strategy of eutrophicated open sandy grasslands should consist in creating a mosaic of topsoil removal patches followed by disturbance after some time and preservation of still existing fragments of target vegetation.