Middle- to late-Holocene environmental changes in Bajo de la Quinta, NE Patagonia, inferred by palynological records and their relation to human occupation

Marcos, Maria Alejandra; Mancini, María Virginia; Dubois, Cristian Mario Favier

doi:10.1177/0959683612437862

Cited by 21 publications

(32 citation statements)

References 46 publications

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“…For example, many reconstructions of the SWWs are based on biological proxies, in particular palynological records (e.g. Fontana and Bennett, 2012;Marcos et al, 2012;Moreno et al, 2012;Echeverria et al, 2014;Strother et al, 2015). It is not clear, however, whether reconstructed changes in vegetation are always due to fluctuations in precipitation and/or temperature (Moreno et al, 2012), although approaches using wind blown exotic pollen are potentially more reliable (e.g.…”

Section: Introductionmentioning

confidence: 99%

A diatom–conductivity transfer function for reconstructing past changes in the Southern Hemisphere westerly winds over the Southern Ocean

Saunders

Hodgson

Mcmurtrie³

et al. 2015

J Quaternary Science

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Sub-Antarctic islands are ideally placed to reconstruct past changes in Southern Hemisphere westerly wind behaviour. They lie within their core belt (50-60˚S) and the strong winds deliver sea salt ions to the islands resulting in a west to east conductivity gradient in their water bodies. This means that the stronger (or weaker) the winds, the higher (or lower) the conductivity values measured in the water bodies. A survey of the water chemistry and diatom assemblages of lakes and ponds on sub-Antarctic Campbell Island (52˚32 0 S, 169˚8 0 E) revealed that, similar to other sub-Antarctic islands, conductivity was the most important, statistically significant ecological variable explaining turnover in diatom community structure. Based on this, a diatom-conductivity transfer function was developed (simple weighted averaging with inverse deshrinking: R 2 ¼ 0.86, R 2 jack ¼ 0.66, RMSEP ¼ 0.25 log 10 mS cm À1 ). This transfer function will be applied to lake sediment cores from the western edge of the Campbell Island plateau to reconstruct past conductivity/sea spray and therefore directly reconstruct changes in Southern Hemisphere westerly wind strength within their core belt.

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Section: Introductionmentioning

confidence: 99%

A diatom–conductivity transfer function for reconstructing past changes in the Southern Hemisphere westerly winds over the Southern Ocean

Saunders

Hodgson

Mcmurtrie³

et al. 2015

J Quaternary Science

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“…The similar paleohydric balance of Bajo de la Quinta ( Fig. 2e) at the Atlantic coast to those of forest environments suggest that between 400 and 200 cal yrs BP, Atlantic humid air masses reached the continent probably under weak SWW (Marcos et al, 2012a in northern Patagonia between 1600 and 750 cal yrs BP and winter-like conditions between 750 and 200 cal yrs BP. During the last 200 cal yrs BP, there is a remarkable decrease in the Northern Patagonia pollen based index suggesting higher than before precipitation seasonality toward present day conditions between 40 and 45…”

Section: Controls Over Hydric Balance In Northern and Southern Patagoniamentioning

confidence: 62%

“…We constructed past pollen-based paleohydric balance indices. Main pollen taxa were considered suggesting above/below hydric availability at every site, following paleoecological and modern pollen-vegetation calibrations highlighted on previous published works ( Bamonte and Mancini, 2011;Bamonte et al, 2014;Bianchi and Ariztegui, 2012;Echeverria et al, 2014;Iglesias, 2013;Iglesias et al, 2012Mancini, 2007Mancini, , 2009Mancini et al, 2012;Marcos and Mancini, 2012;Marcos et al, 2012a;Paez et al, 2001;Sottile et al, 2012;Sottile, 2014). Each paleohydric balance was calculated as the standardized ratio between the sum (in percentages) of positive hydric availability taxa and the sum of negative hydric availability taxa (see Supplement, Sect.…”

Section: Methodsmentioning

confidence: 99%

Eastern Andean environmental and climate synthesis for the last 2000 years BP from terrestrial pollen and charcoal records of Patagonia

Sottile

Echeverria

Mancini

et al. 2015

Preprint

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Abstract. The Southern Hemisphere Westerly Winds (SWW) constitute an important zonal circulation system that dominates the dynamics of Southern Hemisphere mid-latitude climate. Little is known about climatic changes in the Southern South America in comparison to the Northern Hemisphere due to the low density of proxy records, and adequate chronology and sampling resolution to address environmental changes of the last 2000 years. Since 2009, new pollen and charcoal records from bog and lakes in northern and southern Patagonia at the east side of the Andes have been published with an adequate calibration of pollen assemblages related to modern vegetation and ecological behaviour. In this work we improve the chronological control of some eastern Andean previously published sequences and integrate pollen and charcoal dataset available east of the Andes to interpret possible environmental and SWW variability at centennial time scales. Through the analysis of modern and past hydric balance dynamics we compare these scenarios with other western Andean SWW sensitive proxy records for the last 2000 years. Due to the distinct precipitation regimes that exist between Northern (40–45° S) and Southern Patagonia (48–52° S) pollen sites locations, shifts on latitudinal and strength of the SWW results in large changes on hydric availability on forest and steppe communities. Therefore, we can interpret fossil pollen dataset as changes on paleohydric balance at every single site by the construction of paleohydric indices and comparison to charcoal records during the last 2000 cal yrs BP. Our composite pollen-based Northern and Southern Patagonia indices can be interpreted as changes in latitudinal variation and intensity of the SWW respectively. Dataset integration suggest poleward SWW between 2000 and 750 cal yrs BP and northward-weaker SWW during the Little Ice Age (750–200 cal yrs BP). These SWW variations are synchronous to Patagonian fire activity major shifts. We found an in phase fire regime (in terms of timing of biomass burning) between northern Patagonia Monte shrubland and Southern Patagonia steppe environments. Conversely, there is an antiphase fire regime between Northern and Southern Patagonia forest and forest-steppe ecotone environments. SWW variability may be associated to ENSO variability especially during the last millennia. For the last 200 cal yrs BP we can concluded that the SWW belt were more intense and poleward than the previous interval. Our composite pollen-based SWW indices show the potential of pollen dataset integration to improve the understanding of paleohydric variability especially for the last 2000 millennial in Patagonia.

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“…Previous studies suggest a more arid climate during the mid‐Holocene and increased precipitation during the late Holocene in comparison with the modern rainfall regime in the Pampas, and the mid‐latitude region on the leeside of the Andes between 37 and 42°S (e.g. Grimm et al ., ; Schäbitz, ; Mancini et al ., ; Marcos et al ., ; Razik et al ., ). North‐eastern and central Patagonian palynological records dating to the middle Holocene indicate low precipitation values and arid climatic conditions, in agreement with the general trends recorded at AC.…”

Section: Discussionmentioning

confidence: 99%

“…Both changes fostered climatic variability, including intensification of precipitation and variable hydrological conditions reflected in the post-4370 cal a BP record at AC. In north-eastern Patagonia most of the palynological records suggest a weakening of westerly winds and the penetration of moist Atlantic air from the north-east and greater local moisture availability (Schäbitz, 2003;Marcos et al, 2012). In northwestern Patagonia present-day mixed Nothofagus dombeyi and Austrocedrus chilensis forests developed at ca.…”

Section: Palaeoclimatic Evolution In a Regional And Extraregional Conmentioning

confidence: 99%

A multi-proxy study of Holocene environmental change recorded in alluvial deposits along the southern coast of the Pampa region, Argentina

et al. 2014

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Analyses of fossil records of molluscs, stable isotopes of carbon and oxygen, diatoms and palynomorphs from alluvial deposits at Arroyo Claromecó, in the southern Pampa region of Argentina, provide an integrated reconstruction of rapid Holocene environmental change related to marine and palaeoclimate influences. The major events recorded include: (i) disturbances produced by marine influences in close proximity to the coast before ca. 7700 cal a BP; (ii) a short‐term decrease in salinity associated with freshwater influx between ca. 7700 and 7400 cal a BP in response to eustatic adjustment as sea level rose; (iii) an increasing input of marine water related to the Holocene sea‐level highstand and greater evaporative conditions between 7400 and 6450 cal a BP; and (iv) evaporative processes linked to a pronounced climatic variability that triggered changes in water chemistry during the last ca. 6000 cal a BP concurrently with the late Holocene sea‐level fall. A comparison of coastal and continental stable isotope records from the Pampa region reveals that evaporation and a negative precipitation/evaporation (P/E) ratio balance strongly influenced water chemistry in the coastal region, and was as important an influence as marine water during the period of maximum sea‐level highstand.

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Middle- to late-Holocene environmental changes in Bajo de la Quinta, NE Patagonia, inferred by palynological records and their relation to human occupation

Cited by 21 publications

References 46 publications

A diatom–conductivity transfer function for reconstructing past changes in the Southern Hemisphere westerly winds over the Southern Ocean

A diatom–conductivity transfer function for reconstructing past changes in the Southern Hemisphere westerly winds over the Southern Ocean

Eastern Andean environmental and climate synthesis for the last 2000 years BP from terrestrial pollen and charcoal records of Patagonia

A multi-proxy study of Holocene environmental change recorded in alluvial deposits along the southern coast of the Pampa region, Argentina

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