title: Plants living on gypsum: beyond the specialist model.
abstract: OBJECTIVE
  Plants from gypsum habitats are classified as gypsophiles and gypsovags. The former include both narrow endemics limited to small gypsum areas and regionally dominant gypsophiles growing in gypsum areas of large regions, whereas gypsovags are plants that can grow both in gypsum and non-gypsum soils. Factors controlling the distribution of gypsum plants are still not fully understood.
  
  
  METHODS
  To assess how the different types of gypsum plants deal with the stressful conditions of gypsum substrates, comparisons were made of the leaf chemical composition of four gypsovags, five regionally dominant gypsophiles and four narrow gypsum endemics growing in two massive gypsum areas of the Iberian Peninsula.
  
  
  RESULTS
  The chemical composition of gypsovags was clearly different from regionally dominant gypsophiles, while the chemical composition of narrow-gypsophile endemics was more similar to the chemical composition of gypsovags than to that of regionally dominant gypsophiles. Regionally dominant gypsophiles showed higher concentrations of ash, Ca, S, N, Mg P and Na, whereas gypsovags and local gypsophile endemics displayed higher concentrations of C and greater C : N ratios.
  
  
  CONCLUSIONS
  Such differences suggest that the three groups of gypsum plants follow diverse ecological strategies. It is suggested that regionally dominant gypsophiles might fit the 'specialist' model, being species specifically adapted to gypsum, whereas both gypsovags and narrow-gypsophile endemics might fit the 'refuge' model, being stress-tolerant species that find refuge on gypsum soils from competition. The analysis of the leaf chemical composition could be a good predictor of the degree of plants specialization to gypsum soils.
authors.affiliation: Pyrenean Institute of Ecology (CSIC), Av. Montañana 1005, Apdo. 202, 50192 Zaragoza, Spain. sarap@ipe.csic.es
authors.forename: Sara
authors.initials: S
authors.lastname: Palacio
authors.forename: Adrián
authors.initials: A
authors.lastname: Escudero
authors.forename: Gabriel
authors.initials: G
authors.lastname: Montserrat-Martí
authors.forename: Melchor
authors.initials: M
authors.lastname: Maestro
authors.forename: Rubén
authors.initials: R
authors.lastname: Milla
authors.forename: María J
authors.initials: MJ
authors.lastname: Albert
mesh_terms: D002118:Calcium / Q000032:analysis / Q000378:metabolism; D002133:Calcium Sulfate / Q000737:chemistry* / Q000378:metabolism*; D008274:Magnesium / Q000032:analysis / Q000378:metabolism; D010944:Plants / Q000737:chemistry* / Q000378:metabolism*; D012987:Soil / Q000032:analysis*; D013030:Spain
chemical_list: D012987:Soil; D008274:Magnesium; D002118:Calcium; D002133:Calcium Sulfate