Mallines en la Sierra de Comechingones, Sierras Pampeanas, Argentina. Caracterización geológico-geomorfológica y reconstrucción paleoambiental durante el Holoceno

Abstract

Wet-meadows are wetlands of high environmental value and common in the Patagonia, Cordillera de los Andes and Pampean Ranges of Argentina. Particularly, the studies about the functioning and dynamics of wet-meadows are still insufficient and partials in Pampean Ranges. In this paper we analyze the geological-geomorphological factors that influenced the origin, distribution, morphometry and dynamics of wet-meadows in highlands of the southern Comechingones Range (Pampean Ranges of Córdoba, Argentina). A paleoenvironmental reconstruction from sedimentological, palynological, diatomological and chronological records of one of these systems is also proposed. The study area is located at an erosion paleosurface developed previously to the andean orogeny, on an igneous-metamorphic basement rocks. This paleosurface is preserved in the eastern slope of the Comechingones Range and shows different degree of fluvial incision. Most wetmeadows are linked to geomorphological environments with low morphodynamic activity, especially in the granitic rocks and loessic/loessoid deposits preserved in summit plains. The main source of sediments for wet-meadows is the reworking of Quaternary loessic/loessoide sequences. The wetmeadow paleorecords suggests the persistence of wetlands in the Comechingones Range highlands during most of the Holocene, with contractions and expansions in response to environmental variability. The Holocene climate conditions were variable, mainly related to changes in water availability and temperature. A drier period than the current, at least temporarily, took place between ca. 7,000 and 4,700 cal. years BP (6,400 and 4,100 14C years BP). Climatic conditions similar to the current ones were likely established since 4,700 cal. years BP (4,326 14C years BP). During the last centuries, incision and drainage networks integration processes, promote the removal of several wetlands, especially since 1,970s due to precipitation increasing and, subordinately, frequent wildfires.

Estudio comparativo de la composición florística, diversidad y productividad de vegas o mallines de Tierra del Fuego, Chile

“…No obstante, algunos estudios en el hemisferio norte han mostrado efectos beneficiosos sobre la riqueza de especies vegetales al realizar un pastoreo racional (Dupré & Diekmann, 2001;Pykälä, 2005). Por otra parte, la mayoría de los estudios en Patagonia especialmente en Argentina, sobre las vegas o mallines se han focalizado en los aspectos geológicos, edáficos, sedimentológicos, topográficos, hídricos, mapeos y procesamiento de imágenes satelitales y sobre la distribución espacial de las comunidades vegetales (Gandullo & Schmid, 2001;Gaitán et al 2011;Mazzoni & Rabassa;Vázquez et al 2013;Gaitán et al 2015;Grima et al 2015;Andreazzini et al 2020). Los dos únicos trabajos en Magallanes a una escala regional sobre la variabilidad de tipos de suelo y clasificación de vegetación en vegas, corresponde a los estudios realizados por Filipová et al 2010y Filipová et al 2013, y un reciente estudio de caso sobre la caracterización de la composición y estructura florística en las geoformas asociadas a una vega, acotado a una estancia de uso ganadero (Domínguez & Ivelic-Sáez, 2020).…”