Vegetation establishment after restoration measures in calcareous sandy grasslands

Abstract

ABSTRACT

Calcareous sandy grasslands are among the most threatened habitats in Europe, primarily because of abandonment, acidification, eutrophication and fragmentation. Much of the biodiversity found in calcareous sandy grasslands depend on the availability of calcareous sand in the topsoil layer. As this sand is naturally depleted of CaCO3 heavy disturbances such as erosion or use of military vehicles is essential to preserve high species richness and avoiding degeneration of the habitat. For calcareous sandy grasslands different methods have proven successful in restoration and management, such as grazing, liming, topsoil removal and soil perturbation. The aim with this study was to test the hypothesis that the restoration methods topsoil removal and soil perturbation can restore calcareous sandy grasslands. An inventory of the vegetation composition and collection of soil samples were carried out in eight locations in eastern Scania, all treated with topsoil removal or soil perturbation. The treatments resulted in significantly higher pH and partly lower levels of nutrients compared to control plots. Species richness and species diversity were higher in control plots, whereas number and proportion of target species was higher in plots treated with topsoil removal. Since the main restoration target is the specialist species, the rather drastic treatment of topsoil removal and soil perturbation described in this study could be considered a success due to the increase of target species and thereby altering the habitat towards calcareous sandy grasslands. The treatment reduces plant-available N, increases pH and creates disturbance. From this study it seems that high pH might be the most important factor to establish target species in calcareous calcareous sandy grasslands in southeast Sweden. This study strengthens the perspective that restoration of sandy calcareous grasslands is a complicated long-term process, which generally includes restoration of both biotic and abiotic conditions.

Popular science summary:

Restoration measures in calcareous sandy grasslands

Sandy grasslands are one of the most threatened habitats in Europe. As many other systems in Europe the habitat is threatened by abandonment and agricultural intensification, leading to acidification and eutrophication. Furthermore, most of the remaining areas are strongly fragmented and often so small that it poses further threat to the rarest and most specialized species. For calcareous sandy grasslands different methods have proven successful in restoration and management, such as grazing, liming, topsoil removal and soil perturbation.

In Sweden calcareous sandy grasslands occurs fragmentary in the eastern part of Scania and in some small areas on Öland. The habitat covers only about 30-50 hectares and exhibits a unique composition of rare species under Swedish conditions. Today many of the sandy grasslands in Sweden are degenerated due to acidification and eutrophication, and in need of rather drastic restoration measures. Much of the biodiversity found in calcareous sandy grasslands depend on the availability of calcareous sand in the topsoil layer. As this sand is naturally depleted of lime, heavy disturbance such as erosion or use of military vehicles is essential to preserve high species richness and avoiding degeneration of the habitat. Topsoil removal and soil perturbation is done in order to restore a lime-rich, nutrient-poor habitat and induce vegetation succession towards calcareous sandy grasslands.

Aim and methods
The aim with this study was to test if topsoil removal and soil perturbation can restore calcareous sandy grasslands. This was done by investigating the vegetation composition and by comparing soil characteristics, such as levels of phosphorus, nitrogen and pH, between treated plots and non-treated control plots. An inventory of the vegetation composition and collection of soil samples were carried out in eight locations in eastern Scania, all treated with topsoil removal or soil perturbation.

Results
The treatments resulted in significantly higher pH and partly lower levels of nutrients compared to control plots. Species richness and species diversity were higher in control plots, whereas number and proportion of target species was higher in plots treated with topsoil removal. Since the main restoration target is the specialist species, the rather drastic treatment of topsoil removal and soil perturbation described in this study could be considered a success due to the increase of target species and thereby altering the habitat towards calcareous sandy grasslands. The treatment reduces plant-available N, increases pH and creates disturbance. From this study it seems that high pH might be the most important factor to establish target species in calcareous calcareous sandy grasslands in southeast Sweden. This study strengthens the perspective that restoration of sandy calcareous grasslands is a complicated long-term process, which generally includes restoration of both biotic and abiotic conditions.

Supervisor: Pål Axel Olsson
Master’s Degree Project 45 credits in Nature Conservation 2012
Department of Biology, Lund University

• author: Alexandersson, Sara
• supervisor: Pål Axel Olsson
• organization: Degree Projects in Biology
• course: BION24 20121
• year: 2012
• type: H2 - Master's Degree (Two Years)
• subject: Biology and Life Sciences
• language: English
• id: 3616122
• date added to LUP: 2013-03-22 14:41:43
• date last changed: 2013-03-22 14:41:43