Cambios en la vegetación durante el Holoceno en la región Norte del Iberá, Corrientes, Argentina

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 C 14. 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. Rev.

Paleoenvironmental interpretation of the mid‐late Holocene of Corrientes province, Argentina

“…The objective of our study was to recognize and reconstruct the predominant plant communities and their variations during the Holocene in the Corrientes province from pollen analyses, in order to infer changes in regional past climatic conditions, and thereby contribute to our understanding of paleodiversity and paleoenvironmental evolution in northeastern Argentina. This palynological study adds to preliminary results previously documented by Fernandez Pacella et al (2011), who palynologically analyzed sediments of two lakes located in the northwest of the Iberá Wetland to infer paleoclimatic conditions during the mid and late Holocene in the northern Corrientes province.…”

“…2), namely San José (27°45′47″S, 57°13′20″W), 'C' (28°10′41″S,57°55′42″W), Rodeo Porá (28°30′30″S, 58°02′36″W) and San Ignacio (28°62′32″S, 58°28′27″W) lakes. Additional information from San Juan lake (27°40′03″S, 57°11′53″W) and San Sebastián lake (27°52′58″S, 57°20′34″W), located in the northwest of the Iberá Wetland, analyzed and published previously was included (Fernandez Pacella et al 2011). The sedimentary cores were obtained with a Livingston-type sampler in the central and deepest part of the lakes, with about 85 cm length in San José lake, 110 cm length in 'C' lake, 120 cm length in Rodeo Porá and 145 cm length in the San Ignacio lakes.…”

“…Taxa were grouped as arboreal, shrub, herbaceous and aquatic. The palynological data in the San Juan and Sebastian lakes (Fernandez Pacella et al 2011) were reworked, excluding algae and spores from the pollen diagrams.…”

“…There is a substantial number of Holocene palynological investigations from the northwestern lowlands and the Pampas region in Argentina (Fernández and Romero 1984, Prieto 1989, 1996, 2016, Cuadrado and Anzótegui 1992, Paez and Prieto 1993, Quattrocchio et al 1993, 2008, Grill 1994, Grill and Quattrocchio 1996, Mautino et al 1997, Mautino and Anzótegui 1998, 2002a, b, Borel et al 2001, Garralla et al 2001, Garralla 2002, Prieto et al 2004, Caria and Garralla 2006, Tonello and Prieto 2010, Vilanova et al 2010 and we aimed to compare the results of our with these regional studies (Iriondo 1994, Orfeo 2000, Fernandez Pacella et al 2011, as well as with studies from southern Brazil (Sandi et al 2001), in order to carry out a paleoclimatic evaluation for the Holocene of the Corrientes.…”

“…(Fernandez Pacella et al 2011).Zone XVII: (75-65 cm) 3484-3700 cal BP (according to the age-depth model). Arboreal and shrubby taxa are observed: Tecoma sp.…”