Artículo de revista
Late Quaternary climate change, relict populations and present-day refugia in the northern Atacama Desert: a case study from Quebrada La Higuera (18° S)
Fecha
2015Registro en:
Journal of Biogeography (J. Biogeogr.) (2015) 42, 76–88
1365-2699
DOI: 10.1111/jbi.12383
Autor
Mujica, María Isabel
Latorre, Claudio
Maldonado, Antonio
González Silvestre, Leticia
Pinto, Raquel
Pol-Holz, Ricardo de
Santoro, Calogero
Institución
Resumen
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.
Results The three oldest middens dated to more than 37 ka (thousand calibrated
14C 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.