<i>DESCRIPTION OF HALOPHYTIC PLANT COMMUNITIES: COMPARING VEGETATION GROUPS OBTAINED BY MULTIVARIATE ANALYSIS AND SYNTAXA</i>

Abstract

Six vegetation groups (A-F) had been defined in the salt steppes of the Guadalentín (Murcia) by means of multivariate methods. Each of them is characterized by the dominance of certain halophytic or subhalophytic species. In the present paper, ordination techniques (correspondence analysis and canonical correspondence analysis) are used to compare four of these groups (A-D) with syntaxa –associations or subassociations described in Southeastern Spain or, more generally, in the Mediterranean region. The affinities and disagreements between each group and supposedly related syntaxa are shown and discussed. In general terms, there is not a good correspondence between vegetation groups and syntaxa, specially in the cases of group B (characterized by dominance ofFrankenia corymbosa or Limonium caesium) and group D (characterized by dominance of Halocnemum strobilaceum). The differences can be attributed to the particular conditions of the salt steppes of the Guadalentín, also to vegetation changes that are taking place in them or the presence of certain species which are scarce or absent in other mediterranean salt marshes and salt steppes. Sometimes a vegetation group can be related to an association but, within its range of variation, the group represents certain form linked to local or particular circumstances. This shows that the variation which exists within an association (or subassociation) can be very outstanding ecologically, and that there are difficulties to extrapolate environmental parameters from one representation of an association to another.