PRIMARY NATURAL AND SECONDARY ANTHROPOGENIC SUCCESSIONAL DYNAMICS OF WETLAND VEGETATION IN "CIÉNAGAS DEL NAME" (CENTRAL CHILE): A CONCEPTUAL MODEL

The dynamics of wetland vegetation in “Laguna del Name”, Cauquenes province, Maule Region, Chile was studied, including aquatic and swamp vegetation as well as surrounding terrestrial areas. By applying the Bray-Curtis similarity index, the first cluster put together the swamp communities, while the second cluster corresponded to terrestrial and aquatic communities; this ordination analysis was used to make equal the first two axes to temperature and moisture gradients. The plant geographical origin of the species allowed distinguishing primary native communities with few introduced species, as well as secondary and tertiary anthropogenic communities with several introduced species. A conceptual model of the potential vegetation dynamics was developed, identifying a natural succession (filling of the lagoon) and an anthropogenic succession, which corresponds to the degradation of the primitive sclerophyllous forest through logging, grazing, farming and ruderalization; this allowed determining the course followed in both cases. The aquatic succession may correspond to a natural hydrosere that would cause the filling of the lagoon, starting with submerged aquatic species, followed by floating leaf communities and leading to a reed bed that may end up in a native swamp forest. Today, this aquatic series stops at the reed-bed stage with Schoenoplectus californicus, which in turn can be replaced by anthropogenic wet meadow/pasture communities. The succession of land degradation transforms sclerophyllous native forest into a grazing “espinal” with Acacia caven, which can permanently invade the wet meadows, connecting both series.