Abstract

Vegetation changes during the Holocene in the North Iberá, Corrientes, Argentina. Wetlands are very important sites for palynological studies, since they represent one of the most suitable environments for fossil pollen preservation. The aim of this work was to determine, by palynological analysis of lacustrine sediments, the vegetal communities and the predominant environment during the Holocene in NW of Iberá. Two lagoons were studied: San Sebastián and San Juan Poriahú. Sediment samples were obtained with witness using a "Levingstone square-rod sampler", processed with Faegri e Iversen techniques and dated with C14. The palynological graphs were divided in zones using the Tilia program. The palynological analysis allowed visualizing diverse changes in the vegetation: from 6 140 +/- 50 to 5 170 +/- 100 a. C., the NW of Iberá was characterized by marsh-herbaceous vegetation and arboreal vegetation typical of dry vegetation. From 5 170 +/- 100 to 3 460 +/- 60 a. C., a decrease in the species frequency, typical of wet environments, is produced, and the clogging of the waterbody, from 3460 +/- 60 a. C. onwards, while continuing the dominance of herbaceous vegetation typical of these environments, the arboreal pollen, indicates the beginning of a hygrophilous forest development.

Highlights

  • El Iberá constituye un sistema hídrico alimentado fundamentalmente por lluvias (1 200 a 1 500mm año)

  • Otros antecedentes de estudios palinológicos en el noreste de Argentina fue el realizado por Garralla (1998) en el Norte de la provincia de Santa Fe, señalando el tipo de vegetación y las condiciones paleoambientales predominantes durante el Holoceno Superior

  • En el estrato herbáceo se observan los mayores porcentajes de toda la columna sedimentaria de Bidens sp. (12%) y Baccharis sp. (17%), también se observa la disminución de Poaceae (40%), Triglochin sp. (30%), los periporados Tipo Amaranthus (5%,), Tipo Chenopodium (9%), Senecio sp. (10%) y Apocynaceae (

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Summary

Introduction

El Iberá constituye un sistema hídrico alimentado fundamentalmente por lluvias (1 200 a 1 500mm año). Integrando el estrato herbáceo predominan las poáceas con porcentajes elevados y relativamente estables (70%), periporados del Tipo Amaranthus (60%) y Erymgium campestre con el (50%) que se registra por primera vez a los 50cm de profundidad.

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