Villa Martinez, Rodrigo Patricio

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Villa Martinez, Rodrigo Patricio

Afiliación principal

Centro de Investigación Gaia Antártica

rodrigo.villa@umag.cl

ORCID

0000-0001-6041-4393

Jerarquía académica

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Línea de investigación

Ciencia Antartica y Subantartica

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DOI 10.3389/fevo.2018.00034
Modulation of Fire Regimes by Vegetation and Site Type in Southwestern Patagonia Since 13 ka
2018-4-9
Moreno, Patricio I.
;
Vilanova, Isabel
;
Villa Martinez, Rodrigo Patricio
;
Francois, Jean P.
The degree to which vegetation and site type have influenced fire regimes through the Holocene has not been investigated in detail in the temperate ecosystems of southern Patagonia. Here we present a first attempt using a paired-basin approach to study the evolution of fire regimes in sectors dominated by humid Nothofagus forests and the xeric Patagonian steppe in the Magallanes region of Chilean Patagonia (51 degrees S). We analyzed sediment cores from two small lakes and a bog located within the same climate zone on opposite sides of the forest-steppe ecotone, similar to 28 km apart. The position of this biological boundary east of the Andes is controlled by the strength and position of the southern westerly winds, which constitute the sole source of precipitation throughout western Patagonia. Our results indicate that fires have occurred in the study region repeated times over the last similar to 13,000 years at bi- and tridecadal timescales. Sectors currently dominated by Patagonian steppe feature high frequency and low magnitude of local fires, and vice versa in humid forests. Climate-driven expansion of Nothofagus scrubland/woodland into steppe environments over the last similar to 4,200 years increased the magnitude and lowered the frequency of fire events, culminating with peak Nothofagus abundance, fire magnitude and frequency during the last millennium. We also detect divergences between lake-based vs. bog-based paleofire histories among paired sites located within the Patagonian steppe, similar to 12 km apart, which we attribute to local burning of the bog at times of lowered water table. This divergence suggests to us that bog-based vegetation and fire histories exacerbate a local, azonal, signal blurring extra-local or regional regimes, thus accounting for some discrepancies in the Quaternary paleovegetation/paleoclimate literature of southern Patagonia.
Scopus© Citations 18 2
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DOI 10.3389/feart.2022.817775
Evolution of Glacial Lake Cochrane During the Last Glacial Termination, Central Chilean Patagonia (∼47°S)
2022-1-25
Vasquez, Alicia
;
Flores-Aqueveque, Valentina
;
Sagredo, Esteban
;
Hevia, Rodrigo
;
Villa Martinez, Rodrigo Patricio
;
Moreno, Patricio I.
;
Antinao, Jose L.
Large ice-dammed lakes developed along the eastern margin of the Patagonian Ice Sheet (PIS) during the Last Glacial Termination (T1). Their spatial/temporal evolution, however, remains poorly constrained despite their importance for deciphering fluctuations of the shrinking PIS, isostatic adjustments, and climate forcing. Here we examine the distribution and age of shoreline features deposited or sculpted by Glacial Lake Cochrane (GLC) in the Lago Cochrane/Pueyrredon (LCP) basin, Central Patagonia, following recession of the LCP glacier lobe from its final Last Glacial Maximum (LGM) moraines. GLC drained initially toward the Atlantic Ocean and continuing ice shrinking opened new drainage routes allowing the discharge toward the Pacific Ocean. We identify five clusters of lake terraces, shorelines, and deltas between elevations similar to 600-500 (N5), similar to 470-400 (N4), similar to 360-300 (N3), similar to 230-220 (N2), and similar to 180-170 masl (N1) throughout the LCP basin. The distribution of these clusters and associated glaciolacustrine deposits provide constraints for the evolving position of the damming glacier bodies. Elevation gradients within the landform clusters reveal glacio-isostatic adjustments that enable us to quantify the magnitude of deglacial rebound and construct isostatically corrected surfaces for the different phases in the evolution of GLC. Our chronology, based principally on radiocarbon dates from lake sediment cores and new OSL dating, suggests that these phases developed between similar to 20.7-19.3 ka (N5), similar to 19.3-14.8 ka (N4), similar to 14.8-11.3 ka (N3), and shortly thereafter (N2 and N1). The N3 landforms are the most ubiquitous, well-preserved, and voluminous, attributes that resulted from a similar to 3,500-year long period of glacial stability, enhanced sediment supply by peak precipitation regime, and profuse snow and ice melting during the most recent half of T1. This scenario differs from the cold and dry conditions that prevailed during the brief N5 phase and the moderate amount of precipitation during the N4 phase. We interpret the limited development of the N2 and N1 landforms as ephemeral stabilization events following the final and irreversible disappearance of GLC after N3. This event commenced shortly after the onset of an early Holocene westerly minimum at pan-Patagonian scale at similar to 11.7 ka, contemporaneous with peak atmospheric and oceanic temperatures in the middle and high latitudes of the Southern Hemisphere.
Scopus© Citations 9 2
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DOI 10.1038/s41598-018-21836-6
Onset and Evolution of Southern Annular Mode-Like Changes at Centennial Timescale
2018-2-22
Moreno, P. I.
;
Vilanova, I.
;
Villa Martinez, Rodrigo Patricio
;
Dunbar, R. B.
;
Mucciarone, D. A.
;
Kaplan, M. R.
;
Garreaud, R. D.
;
Rojas, M.
;
Moy, C. M.
;
De Pol Holz, Ricardo Hernán
The Southern Westerly Winds (SWW) are the surface expression of geostrophic winds that encircle the southern mid-latitudes. In conjunction with the Southern Ocean, they establish a coupled system that not only controls climate in the southern third of the world, but is also closely connected to the position of the Intertropical Convergence Zone and CO2 degassing from the deep ocean. Paradoxically, little is known about their behavior since the last ice age and relationships with mid-latitude glacier history and tropical climate variability. Here we present a lake sediment record from Chilean Patagonia (51 degrees S) that reveals fluctuations of the low-level SWW at mid-latitudes, including strong westerlies during the Antarctic Cold Reversal, anomalously low intensity during the early Holocene, which was unfavorable for glacier growth, and strong SWW since similar to 7.5 ka. We detect nine positive Southern Annular Mode-like events at centennial timescale since similar to 5.8 ka that alternate with cold/wet intervals favorable for glacier expansions (Neoglaciations) in southern Patagonia. The correspondence of key features of mid-latitude atmospheric circulation with shifts in tropical climate since similar to 10 ka suggests that coherent climatic shifts in these regions have driven climate change in vast sectors of the Southern Hemisphere at centennial and millennial timescales.
Scopus© Citations 136 1

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