Plant Palaeocommunities of Central Tierra del Fuego during the Early and Late Holocene

Abstract

Plant Palaeocommunities of Central Tierra del Fuego during the Early and Late Holocene.This study presents new data for the history of vegetation of central Tierra del Fuego. The goal is to identify the vegetation types before and after the middle Holocene, having in mind previous studies proposing a forest expansion started in early Holocene times following a SW-NE precipitation gradient. Two segments of a Sphagnum peat bog profile (R-2: 54°32'S, 67°04'W), now surrounded by the Nothofagus pumilio (Poepp et Endl.) deciduous forest, were analyzed. The following results were obtained through the modern analogs method: steppe and woodland were found in the older segment and open and closed forest in the younger segment. We concluded that an asynchronous establishment of the involved plant communities occurred. In fact, ca. 7000 years BP, while in other sites of the central island forests were already established, in R-2, located eastwards from those sites, the steppe-woodland ecotone dominated. On the other hand, from ca. 2000 years AP to modern times both open and closed forests covered the central area. The humidity carried by the Southern Westerlies could have influenced the late development of Nothofagus. This study represents an advancement in the knowledge of the vegetation history, and provides new data about the asynchrony in the establishment of communities.

Late Holocene wet/dry intervals from Fuegian steppe at Laguna Carmen, southern Argentina, based on a multiproxy record

“…Postglacial palaeoecological data have been reported along the Beagle Channel area (Heusser, 2003;Markgraf and Huber, 2010;Borromei et al, 2014), on the low inner Fuegian Andes valleys (Borromei, 1995;Borromei et al, 2007Borromei et al, , 2016Mauquoy et al, 2004), and high-elevation Andean valleys (Markgraf, 1993;Borromei et al, 2010;Markgraf and Huber, 2010). Several palynological studies focused on central area of the archipelago (Markgraf, 1983;Heusser and Rabassa, 1995;Burry et al, 2007;Musotto et al, 2013Musotto et al, , 2016Musotto et al, , 2017aMusotto et al, , 2017bWaldmann et al, 2014). Despite the substantial number of palaeoclimate studies, records from the northern region of Tierra del Fuego are few (Markgraf, 1980;Heusser et al, 1989Heusser et al, -1990Heusser, 1993).…”

Micromamíferos, tafonomía y paleoambientes del cuaternario tardío en Tierra del Fuego: Los roedores de tres arroyos 1

“…Todos coinciden en un entorno hostil, con temperaturas y condiciones de humedad más bajas que las actuales, quizás también bajo una menor influencia de los "westerlies" australes. El norte de la isla comenzaría a mostrar una expansión del bosque de Nothofagus a partir del Holoceno temprano-medio (Heusser, 1993;Markgraf, 1993;Burry et al 2006). Dos secuencias continuas aparecen en particular relevantes para inferir las condiciones ambientales imperantes en cerro de Los Onas durante el límite Pleistoceno-Holoceno: Onamonte y laguna Azul.…”

Integrated reconstruction of Holocene millennial-scale environmental changes in Tierra del Fuego, southernmost South America

“…Co-variability of our palynological dataset with the δ 13 C and C/N record from Lago Fagnano, probably represent evidence for an increase of runoff erosion in the watershed due to higher local precipitation. The increase in moisture availability is also evidenced by the development of a dense Nothofagus forest around Lago Fagnano (Heusser, 2003), Lago Yehuin (Markgraf, 1993), Estancia Río Claro (Burry et al, 2006), and also by the migration of the forest-steppe ecotone to the northwest of the Fagnano lake at the Onamonte site after ~5800 cal a BP (Heusser, 1993). Since moisture mainly arrives from the Pacific Ocean carried by the SHW, intensification of the regional wind activity during the mid-Holocene is likely linked to an increase in rain frequency, as identified in other archives as well (Tonello et al, 2009; Fig.…”

“…1A and B). Yet, studies completed on the northern and central parts of the archipelago are still scarce (Markgraf, 1980;Heusser, 1993;Heusser and Rabassa, 1995;Burry et al, 2006). The current contribution presents palynomorph analysis (pollen, spores and algae) and associated palynofacies, combined with additional identification of diatom flora obtained from sedimentary cores retrieved at different locations and water depths from Lago Fagnano (Fig.…”