CONICET | Buscador de Institutos y Recursos Humanos

Tall grassland landscapes in the Paraná River floodplainare associated with a particular natural fluctuation, and toanthropic disturbances that determine their floristic assemblages.This paper addresses tall-grasslands of Panicum prionitisand evaluates the relationship between its floristic compositionand the occurrence of fire, hydrological pulses and soiltexture. Fifty-eight plots of tall grasslands of 25m2 each wereanalyzed in eight patches; abundance-cover of each specieswas recorded. Of the plots, 15 were distributed in three of theeight patches. The three patches had different fire histories: 7months, 4 years and 14 years from the last fire event. In theeight patches, sediment samples of 0-20cm depth were collectedand 20 topographic readings were performed. Vegetationwas analyzed by applying classification and indirect ordinationmultivariate techniques. One hundred and eighteen speciesdistributed in four floristic groups were found. No statisticallysignificant differences in diversity and floristic compositionwere identified among tall grasslands with different fire history.Differentiation in floristic groups was mainly associatedwith hydrological pulses and soil texture. Fire does not generatesignificant changes in species richness, diversity or structurein Panicum prionitis tall grasslands. From the conservationperspective, we believe it is appropriate to suggest that tomaintain the permanence of the Panicum prionitis tall grasslandsthe fire events should not be avoided.