Late Quaternary climate change, relict populations and present‐day refugia in the northern Atacama Desert: a case study from Quebrada La Higuera (18° S)

Abstract

Aim In deserts, past climate change (and particularly past rainfall variability) plays a large role in explaining current plant species distributions. We ask which species were most and which were least affected by changes in rainfall during the late Quaternary in northernmost Chile.Location Quebrada La Higuera (QLH; 18°S), a shallow canyon that cuts east-west through the western Andean precordillera of northern Chile, connecting the Altiplano with the hyperarid Atacama Desert.Methods We collected and dated 22 rodent middens from elevations of 3100-3500 m in QLH. These were analysed for identifiable plant macrofossils and pollen. We also measured chinchilla rat (Abrocoma cinerea) faecal pellets in the youngest middens to explore how they relate to past ecological and climatic change. ResultsThe three oldest middens dated to more than 37 ka (thousand calibrated 14 C years), four middens dated to 14.4-11.6 ka, and fifteen middens spanned the last 650 years. During all the intervals examined, extralocal species (those found today at higher elevations and indicative of positive rainfall anomalies) were present at our midden sites. In the youngest interval, Parastrephia pollen (indicating increased rainfall) increased abruptly at ad 1760 and remained high until the mid-1800s. This increase was also seen in our faecal pellet record.Main conclusions Extralocal species were prevalent in late Pleistocene middens at lower elevations when the climate was wetter. When combined with other regional midden records, we postulate that many species found today in the Altiplano were displaced to lower elevations during the late Pleistocene. The recent large-scale mortality documented among arboreal cactus populations along the present upper margins of the Atacama suggests that these are relict populations that are likely to have flourished during a wetter period in the early 1800s.

The Dry Puna as an ecological megapatch and the peopling of South America: Technology, mobility, and the development of a late Pleistocene/early Holocene Andean hunter-gatherer tradition in northern Chile

“…Moreover, moister conditions promoted significant increases in the availability of plant resources for livestock at lower elevations as evinced by elevational displacements of hillslope vegetation and reconstructed plant-cover for Andean grasslands (Maldonado et al, 2005;Latorre et al, 2006;Quade et al, 2008;Placzek et al, 2009;Mujica et al, 2015).…”

Análisis Tecno-Tipológico De Instrumentos Líticos Del Sitio Arcaico Temprano Ipilla 2 en Los Andes De Arica, Chile

“…Ipilla se localiza en la quebrada La Higuera, a 3.400 msm y a unos 11 km al suroeste del pueblo de Tignamar en el piso ecológico conocido como puna (Mujica et al 2015), al sureste de Arica (Figura 1). Ipilla 2 es un sitio a cielo abierto que abarca una superficie aproximada de 800 m 2 , emplazado sobre una estrecha terraza fluvial adyacente a una paleovertiente (Rech 2001;Ugalde et al 2012).…”

“…La importancia del emplazamiento radica en la surgencia de una vertiente de agua dulce vigente durante el Holoceno Temprano (Rech 2001) y su proximidad a Pampa Oxa, una pradera hacia el norte que en aquella época debió tener mayor cantidad de recursos forrajeros para animales silvestres como guanacos y vicuñas (Mujica et al 2015). Si bien Ipilla y sus inmediaciones no presenta en la actualidad condiciones para actividades agrícolas o pastoriles, los habitantes de Tignamar recordaban que el chacu, ubicado en la ladera sur frente a Ipilla, habría sido utilizado hasta comienzos del siglo veinte para acorralar burros salvajes, lo que coincide con la fase final de un período de mayor pluviosidad en la zona (Mujica et al 2015).…”

“…Si bien Ipilla y sus inmediaciones no presenta en la actualidad condiciones para actividades agrícolas o pastoriles, los habitantes de Tignamar recordaban que el chacu, ubicado en la ladera sur frente a Ipilla, habría sido utilizado hasta comienzos del siglo veinte para acorralar burros salvajes, lo que coincide con la fase final de un período de mayor pluviosidad en la zona (Mujica et al 2015).…”

“…Los circuitos de movilidad podrían haber conectado locaciones ubicadas en la zona de puna como Pampa El Muerto-15 (Osorio et al 2015) y Patapatane (Osorio 2013), dos abrigos con los que podría compartir la misma tecnología lítica. Estos fueron ocupados durante el Arcaico Temprano, cuando las condiciones ambientales eran mejores que las actuales para caza y recolección (Moreno et al 2009;Mujica et al 2015;Rech 2001).…”