Relationship between vegetation of levee’s neo-ecosystems and environmental heterogeneity in the Lower Delta of the Paraná River, Argentina.

KALESNIK, F; P. ACEÑOLAZA; M. HURTADO Y J. MARTÍNEZ

River Research and Applications

Jhon Wiley & Sons

Año: 2007

1535-1459

ABSTRACT The relationship between environmental heterogeneity and the levee deposits neo-ecosystem in the islands of the lower Paraná delta has been analyzed. Ninety-seven surveys were carried out in which the vegetation was classified in three environmental units. Classification and, direct and indirect ordination techniques were used. Edaphic and hydrologic variables were analyzed. Three environmental units were identified. Unit A vegetation was different from the vegetation in units B and C. In Unit A there are similarities among its neo-ecosystems due to the Hymenachne grumosa dominance. The neo-ecosystems in B and C were grouped according to their management history instead of their origin. In areas called as ‘short-term abandonment’ environments two exotic species predominate, Lonicera japonica y Rubus spp;, whereas in ‘medium-term and long-term abandonment’ ecosystems the predominant ones were two exotic species of trees (privet, Ligustrum sinense, ash tree, Fraxinus pennsylvanica) as well as two native species of trees: Myrsine spp. and Blepharocalyx tweediei. The categorization of these environments corresponds to the fluvial – tidal gradient that at the same time may affect some of the edaphic variables that were studied (pH and slime content). KEY WORDS Wetlands; levee deposits, Paraná River Delta; neo-ecosystems; secondary forest; Paraná River; exotic plants.