Biological soil crusts and their microenvironment: Impact on emergence,survival and establishment of seedlings

To elucidate the impact of biological soil crusts (BSCs) on the establishment of habitat-typical vascular plant species, we studied the effects of seed location (surface versus sub-surface), age of crusts (initial versus stable), long rainy periods (continuous versus discontinuous watering) and microenvironment (cracks versus no cracks). In addition, we investigated growth height, phytomass and N-content of one vascular plant species (Phleum arenarium). Initial crusts were compared with older, stable crusts using seven habitat-typical plant species representing different life forms (annuals versus perennials). Our model ecosystem, situated in the temperate zone (but edaphically dry), is characterised by calcareous sand with threatened pioneer vegetation (Koelerion glaucae). We carefully translocated soil monoliths of these crusts and analysed the effects under common garden conditions.