Question: To which extent do external ecological factors effect Corynephorus grassland vegetation?

Location: Central Netherlands.

Methods: We implemented different treatments (sand deposition, litter deposition, nitrogen input, mechanical disturbance, control) in permanent plots representing different successional phases in Corynephorus grassland. Plots were recorded just before the treatments and during the subsequent two years. Vegetation changes were analysed by Redundancy Analysis for repeated measurements and Correspondence Analysis, changes in single species abundances by ANOVA.

Results: Species composition hardly changed during the observation period. Several single species abundances showed significant responses to different treatments, most often decrements as direct effects of cover, removal, or dieback. However, Corynephorus canescens and Polytrichum piliferum benefited from sand deposition, the exotic moss Campylopus introflexus from litter deposition. In the colonization phase Polytrichum, Campylopus and Cladonia diversa increased irrespective treatment. Therophytes such as Spergula morisonii showed the strongest negative response to drought, grasses (e.g. Corynephorus canescens) and bryophytes (e.g. Polytrichum piliferum) were less susceptible. Most lichens did not respond at all.

Conclusions: The experiment confirms the high stability of Corynephorus grassland vegetation. Most vegetation changes are in accordance with the hypothetical series of successional phases. In contrast, changes in abundance of single species express considerable dynamics within the vegetation. Species responses also depend on extreme weather conditions as well as on the successional phase of the grassland vegetation and therefore on the competition situation.

Abbreviations: CA = Correspondence Analysis; RDA = Redundancy Analysis.

Nomenclature: Wisskirchen & Haeupler (1998) for vascular plants; Koperski et al. (2000) for bryophytes; van Herk & Aptroot (2004) for lichens; Ettl & Gärtner (1995) for algae.