RELATIONSHIPS BETWEEN VEGETATION ZONATION AND ALTITUDE IN A SALT-MARSH SYSTEM IN NORTHWEST SPAIN

Vegetation zonation in salt marshes has traditionally been attributed largely to altitudinal differences, since altitude determines the temp oral pattern of tidal flooding and is thus closely related to proximat e determinants of the distribution of species and plant communities. W e investigated the distribution of vascular plants and plant communiti es along a series of altitudinal transects in two salt marshes in the northwestern Iberian Peninsula. Our results indicate that altitudinal range varies significantly both among species and among communities, a nd confirm that salt-marsh vegetation characteristics (species cover a nd composition) can be predicted on the basis of altitude, particularl y at the lower levels of the profile.