title: Is Erica tetralix abundance on wet heathlands controlled by nitrogen deposition or soil acidification?
abstract: Erica tetralix is the key species on NW European wet heathlands, where it is often found to be the dominating plant species. Consequently, it is of considerable concern that the species has decreased significantly in cover from 28% to 18% over a six-year period. In order to understand the underlying causes, a structural equation modeling (SEM) approach was applied on ecological data from 1130 wet heathland plots. Both atmospheric N deposition and soil acidification were included in the SEM. The most important causal effect revealed by the SEM was a significant negative effect of N deposition on the cover of E. tetralix, whereas soil acidity tended to have a negative effect of relatively less importance. There was no significant effect of N deposition on soil pH, which indicates that there are no major indirect effects of N deposition on the cover of E. tetralix mediated by soil acidification.
authors.affiliation: Department of Bioscience, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark. Electronic address: cfd@dmu.dk.
authors.forename: Christian
authors.initials: C
authors.lastname: Damgaard
authors.forename: Morten
authors.initials: M
authors.lastname: Strandberg
authors.forename: Søren Munch
authors.initials: SM
authors.lastname: Kristiansen
authors.forename: Knud Erik
authors.initials: KE
authors.lastname: Nielsen
authors.forename: Jesper L
authors.initials: JL
authors.lastname: Bak
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000378:metabolism; D004463:Ecology; D004777:Environment; D029791:Ericaceae / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen / Q000032:analysis* / Q000378:metabolism; D010944:Plants / Q000187:drug effects; D012987:Soil / Q000737:chemistry*
chemical_list: D000393:Air Pollutants; D012987:Soil; D009584:Nitrogen
keywords: Atmospheric N deposition; Ecosystem processes; Erica tetralix; Soil acidification; Wet heathlands