Reconstrucción de la vegetación posglacial y su relación con el ascenso relativo del nivel del mar en el extremo este del canal Beagle, Tierra del Fuego, Argentina

This paper presents the main palaeoenvironmental results obtained from a site located in the western sector of the Beagle Channel, Isla Grande de Tierra del Fuego, southernmost Argentina. The palynological analysis performed on marine sediments from Aserradero‐Lapataia 2 (latitude 54°51′22.7″S, longitude 68°34′22.8″W) allowed us to document the evolution of palaeoenvironmental conditions during the beginning of the Holocene marine transgression into the Beagle Channel. The results indicate that, prior to the marine incursion, the coastal areas were characterized by the presence of open‐grown shrubs and herbs along with woodland palaeocommunities. The aquatic environments were dominated exclusively by freshwater taxa. Around 8300 cal. a BP, seawater gradually flooded the channel while cold and high effective moisture conditions favoured the development of an arboreal vegetation with dominance of Nothofagus forest and scarcity of shrub and herbaceous communities. Gradually increasing salinities allowed the development of freshwater/marine transitional environments indicated by aquatic palynomorphs able to tolerate stressed conditions under fluctuating salinities. The increasing dinocyst diversification with dominance of heterotrophic taxa corroborates the establishment of a fully marine environment during the middle–late Holocene in the Beagle Channel.

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“…a BP (Borromei et al . ). The oldest marine deposits in the eastern sector of the Beagle Channel are located in the Río Varela mouth area (Fig.…”

Section: Discussionmentioning

confidence: 97%

Early to middle Holocene palaeoenvironmental reconstruction of the Beagle Channel (southernmost Argentina) based on terrestrial and marine palynomorphs

Candel

Borromei

Louwye

2018

Boreas

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“…The second site (from hereon Moat) is located close to Bahía Moat at 54.97 • S and 66.73 • W. The bay is formed by the creek 15 Río Moat that drains towards the south into the Beagle Channel at the south-western edge of Penisula Mitre. Our measurements were conducted in a cushion bog approximately 1 km off the Beagle Channel's northern coast which developed on a series of three glaciofluvial plains elevated between 33.1 m and 40.3 m above mean sea level (Borromei et al, 2014). The bog is limited by Río Moat in the west and a Pleistocene fronto-lateral moraine in the south (Borromei et al, 2014).…”

Section: Vascular Plant-dominated Cushion Bog Moatmentioning

confidence: 99%

“…Our measurements were conducted in a cushion bog approximately 1 km off the Beagle Channel's northern coast which developed on a series of three glaciofluvial plains elevated between 33.1 m and 40.3 m above mean sea level (Borromei et al, 2014). The bog is limited by Río Moat in the west and a Pleistocene fronto-lateral moraine in the south (Borromei et al, 2014). It is sickle-shaped, covers an area of 170 ha and slopes at 0.6 • slightly towards the south-east.…”

Section: Vascular Plant-dominated Cushion Bog Moatmentioning

confidence: 99%

Cushion bogs are stronger carbon dioxide net sinks than moss-dominated bogs as revealed by eddy covariance measurements on Tierra del Fuego, Argentina

Holl¹,

Pancotto²,

Heger³

et al. 2019

Preprint

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Abstract. The near-pristine bog ecosystems of Tierra del Fuego in southernmost Patagonia have so far not been studied in terms of their current carbon dioxide (CO2) sink strength. CO2 flux data from southern hemisphere peatlands is scarce in general. In this study, we present CO2 net ecosystem exchange (NEE) fluxes from two Fuegian bog ecosystems with contrasting vegetation communities. One site is located in a glaciogenic valley and developed as a peat moss-dominated raised bog, the other site is a vascular plant-dominated cushion bog located at the coast of the Beagle Channel. We measured NEE fluxes with two identical eddy covariance (EC) setups at both sites for more than two years. With the EC method, we were able to observe NEE fluxes on ecosystem level and at high temporal resolution. Using a mechanistic modeling approach, we estimated daily NEE models to gap-fill and partition the half-hourly net CO2 fluxes into components related to photosynthetic uptake (gross primary production, GPP) and to total ecosystem respiration (TER). We found a larger relative variability of annual NEE sums between both years at the moss-dominated site. A warm and dry first year led to comparably high TER sums. Photosynthesis was also promoted by warmer conditions but less strong than TER with respect to absolute and relative GPP changes. The annual NEE-C uptake was more than three times smaller in the warm year. Close to the sea at the cushion bog site, the mean temperature difference between both observed years was less pronounced, and TER stayed on similar levels. A higher amount of available radiation in the second observed year led to an increase of GPP (5&#8201;%) and NEE (35&#8201;%) carbon (C) uptake. The average annual NEE-C uptake of the cushion bog (&#8722;122 &#177; 76&#8201;g&#8201;m&#8722;2&#8201;a&#8722;1, n = 2) was more than four times larger than the average uptake of the moss-dominated bog (&#8722;27 &#177; 28&#8201;g&#8201;m&#8722;2&#8201;a&#8722;1, n = 2).

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“…Many studies of Late Quaternary palaeoecological conditions from Isla Grande de Tierra del Fuego, southernmost Patagonia, were largely based on palynological records from terrestrial sediments Rabassa, 1987, 1995;heusser, 1989, 1998, 2003Markgraf, 1993;Borromei, 1995;Quattrocchio and Borromei, 1998;Mauquoy et al, 2004;Borromei et al, , 2010Borromei et al, , 2014Borromei and Quattrocchio, 2008;Markgraf and huber, 2010;Musotto, 2013;Waldmann et al, 2014;Musotto et al, 2016a, in press; among others works). Studies on dinocyst assemblages and palynofacies from Late Quaternary deposits of the southern South america are still limited to a few contributions (Borromei andQuattrocchio, 2001, 2007;Grill et al, 2002;Candel et al, 2009Candel et al, , 2011Candel et al, , 2012Rabassa et al, 2009;Candel, 2010;Fernández et al, 2014).…”

Section: Resumen Revisión De La Reconstrucción Paleoambiental De Secmentioning

confidence: 99%

Review of the Palaeoenvironmental Reconstruction of Late Quaternary Marine Sequences, Tierra Del Fuego (Argentina)

Candel

Borromei

2016

PEAPA

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Abstract. This work is an updated review of the knowledge on the evolution and development of palaeoenvironments during the holocene marine ingression and posterior regressive event in Tierra del Fuego. During the beginning of the marine transgression, ca. 8,000 cal yr BP, the vegetation in the southern coastal areas along the Beagle Channel was mainly arboreal with dominance of Nothofagus forest and scarcity of shrub and herbaceous communities, while in the northeastern atlantic coast, the treeless steppe was replaced by a relatively open Nothofagus forest. The early-Middle holocene aquatic assemblages were characterized by a scarce occurrence of marine components, especially dinoflagellate cysts, suggesting the development of low energy estuarine environments with low-salinities caused by glacier meltwater discharge. after 6,000 cal yr BP, an increase in the number of aquatic species was observed with dominance of Peridiniales dinoflagellate cysts, indicating the establishment of marginal marine environments with low to moderate salinities and high nutrient levels. During the last 1,000 cal yr BP, the littoral vegetation along the Beagle Channel showed an open Nothofagus forest and the development of peatlands, while in the northeastern atlantic coast the steppe vegetation developed under less humid environmental conditions related to the marine regressive event. These assemblages have a similar composition to those observed in modern sediments of the Beagle Channel and suggest palaeoenvironmental conditions comparable to today.

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Reconstrucción de la vegetación posglacial y su relación con el ascenso relativo del nivel del mar en el extremo este del canal Beagle, Tierra del Fuego, Argentina

Cited by 20 publications

References 28 publications

Early to middle Holocene palaeoenvironmental reconstruction of the Beagle Channel (southernmost Argentina) based on terrestrial and marine palynomorphs

Early to middle Holocene palaeoenvironmental reconstruction of the Beagle Channel (southernmost Argentina) based on terrestrial and marine palynomorphs

Cushion bogs are stronger carbon dioxide net sinks than moss-dominated bogs as revealed by eddy covariance measurements on Tierra del Fuego, Argentina

Review of the Palaeoenvironmental Reconstruction of Late Quaternary Marine Sequences, Tierra Del Fuego (Argentina)

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