Vegetation invasions into absolute desert: A 45;th000 yr rodent midden record from the Calama–Salar de Atacama basins, northern Chile (lat 22°–24°S)

Abstract

Research Article| March 01, 2002 Vegetation invasions into absolute desert: A 45;th000 yr rodent midden record from the Calama–Salar de Atacama basins, northern Chile (lat 22°–24°S) Claudio Latorre; Claudio Latorre 1Laboratorio de Palinología, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago, Chile Search for other works by this author on: GSW Google Scholar Julio L. Betancourt; Julio L. Betancourt 2Desert Laboratory, U.S. Geological Survey, 1675 West Anklam Road, Tucson, Arizona 85745, USA Search for other works by this author on: GSW Google Scholar Kate A. Rylander; Kate A. Rylander 2Desert Laboratory, U.S. Geological Survey, 1675 West Anklam Road, Tucson, Arizona 85745, USA Search for other works by this author on: GSW Google Scholar Jay Quade Jay Quade 3Desert Laboratory, Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Claudio Latorre 1Laboratorio de Palinología, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago, Chile Julio L. Betancourt 2Desert Laboratory, U.S. Geological Survey, 1675 West Anklam Road, Tucson, Arizona 85745, USA Kate A. Rylander 2Desert Laboratory, U.S. Geological Survey, 1675 West Anklam Road, Tucson, Arizona 85745, USA Jay Quade 3Desert Laboratory, Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA Publisher: Geological Society of America Received: 14 Nov 2000 Revision Received: 02 Aug 2001 Accepted: 18 Sep 2001 First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2002) 114 (3): 349–366. https://doi.org/10.1130/0016-7606(2002)114<0349:VIIADA>2.0.CO;2 Article history Received: 14 Nov 2000 Revision Received: 02 Aug 2001 Accepted: 18 Sep 2001 First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Claudio Latorre, Julio L. Betancourt, Kate A. Rylander, Jay Quade; Vegetation invasions into absolute desert: A 45;th000 yr rodent midden record from the Calama–Salar de Atacama basins, northern Chile (lat 22°–24°S). GSA Bulletin 2002;; 114 (3): 349–366. doi: https://doi.org/10.1130/0016-7606(2002)114<0349:VIIADA>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Plant macrofossils, percentage abundance of grass taxa, fecal-pellet δ13C, and plant-cuticle contents from 49 fossil rodent middens dated by 14C record changes in local vegetation and precipitation since 45 ka (calibrated or measured to thousands of calendar years before present) in the central Atacama Desert (lat 22°–24°S) of northern Chile. The midden sites are along the hyperarid upper margin (2400–3100 m) of the “absolute desert,” in an extreme environment sparsely vegetated by annual herbs and halophytic shrubs. Conditions between 40 and 22 ka may have been at least intermittently dry, and possibly cooler, as implied by four middens with low species richness. We infer a large increase in summer rainfall between 16.2 and 10.5 ka on the basis of the lowering of steppe grasses by as much as 1000 m, prominence of C4 grasses and summer annuals, high species richness, and displacement of northern species at least 50 km south of their modern ranges. The precipitation increase was greatest for a cluster of middens between 11.8 and 10.5 ka. Abrupt drying, evident in a dramatic decrease in grass abundance, occurred after 10.5 ka at all four midden localities. Increased percentages of grass, higher species richness, and extralocal taxa record slightly wetter conditions between 7.1 and 3.5 ka. The present hyperarid conditions were established after 3 ka.Present-day variability of summer precipitation in the central Atacama Desert and adjacent Altiplano is related to the intensity and position of upper air circulation anomalies, which in turn respond to Pacific sea-surface temperature anomalies. Summer insolation over the central Andes (lat 20°S) was at its minimum during the latest glacial to early Holocene transition, so regional insolation forcing cannot account for intensified pluvial conditions in the central Atacama. Summer precipitation collapsed abruptly between 10.5 and 10 ka, indicating either nonlinear relationships with seasonal insolation or a change in intensity of upper air circulation over the Altiplano, effectively blocking moisture transport to the Atacama Desert. Here, we suggest that precipitation variations on millennial time scales in the central Atacama are the result of extraregional forcing of the South American Summer Monsoon through intensified Walker Circulation (stronger easterlies) and La Niña–like conditions operating through insolation anomalies (i.e., departures in insolation values) directly over central Asia and the equatorial Pacific. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.