Plant community patterns in a gypsum area of NE Spain. II. Effects of ion washing on topographic distribution of vegetation

A model, based on the physico-chemical properties of gypsum, is postulated in order to interpret the regular distribution of plant communities associa ted with the topography and the main environmental stresses to which each v egetation type is subjected in a landscape unit. The leaf chemical composition of 28 representative plant species supports t he main predictions of the model: species from low areas present large conc entrations of Na, N and ash but low contents of Ca. It is demonstrated that the strong nutrient and salt downwashing in the hilly terrain is an import ant cause of the vegetation segregation observed on a large spatial scale. (C) 1999 Academic Press.