Hydroclimate variability in the low-elevation Atacama Desert over the last 2500 yr.

Autores:

Gayo, E., Latorre, C., Santoro, C., Maldonado, A., & De Pol-Holz, R.

Resumen:

Paleoclimate reconstructions reveal that Earth system has experienced sub-millennial scale climate changes over the past two millennia in response to internal/external forcing. Although sub-millennial hydroclimate fluctuations have been detected in the central Andes during this interval, the timing, magnitude, extent and direction of change of these events remain poorly defined. Here, we present a reconstruction of hydroclimate variations on the Pacific slope of the central Andes based on exceptionally well-preserved plant macrofossils and associated archaeological remains from a hyperarid drainage (Quebrada Maní, ∼21° S, 1000 m a.s.l.) in the Atacama Desert. During the late Holocene, riparian ecosystems and farming social groups flourished in the hyperarid Atacama core as surface water availability increased throughout this presently sterile landscape. Twenty-six radiocarbon dates indicate that these events occurred between 1050–680, 1615–1350 and 2500–2040 cal yr BP. Regional comparisons with rodent middens and other records suggest that these events were synchronous with pluvial stages detected at higher-elevations in the central Andes over the last 2500 yr. These hydroclimate changes also coincide with periods of pronounced SST gradients in the Tropical Pacific (La Niña-like mode), conditions that are conducive to significantly increased rainfall in the central Andean highlands and flood events in the low-elevation watersheds at inter-annual timescales. Our findings indicate that the positive anomalies in the hyperarid Atacama over the past 2500 yr represent a regional response of the central Andean climate system to changes in the global hydrological cycle at centennial timescales. Furthermore, our results provide support for the role of tropical Pacific sea surface temperature gradient changes as the primary mechanism responsible for climate fluctuations in the central Andes. Finally, our results constitute independent evidence for comprehending the major trends in cultural evolution of prehistoric peoples that inhabited the region.

Año: 2012

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An Early Holocene task camp (~8.5 ka cal BP) on the coast of the semi-arid north of Chile.

Autores:

Ballester, B., Jackson, D., Carré, M., Maldonado, A., Méndez, C., & Seguel, R.

Resumen:

According to current thinking, the peopling of South America involved a coastal as well as an inland exploitation. Here the authors describe a camp that may denote a transition between the two. As indicated by bifacial tools, the investigation shows that people began to move inland and hunt mammals around 8500 cal BP, perhaps in association with a change in the climate.

Año: 2012

Palabras claves: Chile, peopling of South America, coastal, inland, shell, midden, bifacies

Mid-Holocene mean climate in the south eastern Pacific and its influence on South America.

Autores:

Carré, M., Azzoug, M., Bentaleb, I., Chase, B., Fontugne, M., & Jackson, D., Ledru, M.P., Maldonado, A., et al

Resumen:

The eastern tropical Pacific plays a key role in the tropical atmospheric circulation and in the global carbon cycle, and assessing the sensitivity of this region to global climate changes is a major challenge facing climatologists. Provided here is a synthesis of proxy records of the mean climate of the mid-Holocene (5–8 ka) along the south eastern Pacific margin and four regions of South America. These regions were selected for the strength and stability of ENSO teleconnections, and located outside the direct influence of the intertropical convergence zone or the southern westerlies in order to avoid the overprinting signal of their insolation-related variations and focus on the relationship between the eastern tropical Pacific and South America. This study is based on a review of published multiproxy data as well as new isotopic data from the Peruvian and Chilean coast. The available evidence indicates that sea-surface temperatures were ∼1–4 °C cooler from the Galapagos to the southern Peruvian coast as a result of increased coastal upwelling forced by changes in longshore windfields. The mean La Niña-like conditions in the eastern South Pacific were associated to aridity in southern Brazil and along the whole South American Pacific coast from central Chile to the Galapagos, and to wetter conditions on the western central Andes. This regional synthesis provides a coherent picture of the South American mean climate that is very similar to the modern precipitation pattern observed during La Niña conditions, suggesting that atmospheric teleconnections linking the South Eastern Pacific to these continental areas were similar in the middle Holocene.

Año: 2012

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Evaluation of sediment trace metal records as paleoproductivity and paleoxygenation proxies in the upwelling center off Concepción, Chile (36°S)

Autores:

Muñoz, P., Dezileau, L., Lange, C., Cardenas, L., Sellanes, J., Salamanca, M., & Maldonado, A.

Resumen:

This study analyzes the records of several trace metals sensitive to redox conditions in continental shelf sediments off Concepción, Chile (36°S). The continental margin off Concepción (36°S; 73°W) lies beneath an important upwelling center characterized by high primary production rates and, consequently, high fluxes of organic matter. In spring and summer, this material settles to the seafloor where it decays, producing periods of very low oxygen content in bottom waters (<1 mL L−1). In addition, an oxygen minimum zone develops at ∼100–400 m water depth, where dissolved oxygen levels are <0.5 mL L−1. This situation changes during strong El Niño events, when dissolved oxygen at the bottom increases drastically (>1 mL L−1).

Año: 2012

Palabras claves:

Rodent middens reveal episodic, long-distance plant colonizations across the hyperarid Atacama Desert over the last 34,000 years.

Autores:

Díaz, F., Latorre, C., Maldonado, A., Quade, J., & Betancourt, J.

Resumen:

Five middens span the last glacial period (34–21 ka) and three middens are from the last glacial–interglacial transition (19–11 ka). The remaining 13 middens span the last 7000 years. Coastal hyperarid sites exhibit low taxonomic richness in middens at 19.3, 1.1, 1.0, 0.9, 0.5 ka and a modern sample. Middens are also dominated by the same plants that occur today. In contrast, middens dated to 28.1, 21.3, 17.3, 3.7 and 0.5 ka contain more species, including Andean extralocals. Precordillera middens (c. 2700 m) show a prominent increase in plant macrofossil richness, along with the appearance of Andean extralocals and sedges at 34.5 and 18.9 ka. Six younger middens dated to 6.1–0.1 ka are similar to the modern local vegetation.

Año: 2012

Palabras claves: Abrocoma;aridland palaeoecology;Atacama Desert;fog oases;hyperarid environments;late Quaternary;Lomas vegetation;Phyllotis;rodent middens

Combining information from benthic community analysis and social studies to establish no-take zones within a multiple uses marine protected area

Autores:

Rojas-Nazar, Ú., Gaymer, C., Squeo, F., Garay-Flühmann, R., & López, D.

Resumen:

A decision support tool was used to determine priority sites for marine conservation within the Isla Grande de Atacama multiple uses marine protected area (MUMPA) in northern Chile, based on both biological and social information. Scuba diving, and an unweighted paired-group method using arithmetic average (UPGMA) analyses were used to determine the main benthic communities found in the shallow rocky and soft-sediment subtidal.

Año: 2012

Palabras claves: Chile;coastal marine conservation;conservation costs;multiple uses marine protected area;benthic ecology;social ecology

The ecology, distribution and conservation status of Myrcianthes coquimbensis : a globally endangered endemic shrub of the Chilean Coastal Desert

Autores:

García-Guzman, P., Loayza, A., Carvajal, D., Letelier, L., & Squeo, F.

Resumen:

The current distribution of M. coquimbensis extends along 82.8 km of the Chilean coast, where the species is mainly threatened by habitat loss. Only 13% of the individuals flowered during 2010, and 66% of these plants lost their entire flower crop due to desiccation. Few seeds (7.5%) were lost to post-dispersal seed predation. The populations are composed mainly of adult plants (70% of the individuals), and little to no recruitment was observed.

Año: 2012

Palabras claves: Atacama Desert, Chile, conservation biology, habitat loss, Myrtaceae, restricted-range species,

Towards the creation of an integrated system of protected areas in Chile: achievements and challenges

Autores:

Squeo, F., Estévez, R., Stoll, A., Gaymer, C., Letelier, L., & Sierralta, L.

Resumen:

Chile is committed to extending its National System of Protected Areas (NSPA), focusing on eco-regions whose ecosystems are currently under-represented in the NSPA. A newly proposed law aims to create a Service of Biodiversity and Protected Areas that would unify the terrestrial and marine systems. The proposed law would allow the inclusion of private protected areas.

Año: 2012

Palabras claves: biodiversity, GAP analysis, eco-regional planning, marine and terrestrial protected areas, private protected areas, public tenure,

Integrating Ecology and Environmental Ethics: Earth Stewardship in the Southern End of the Americas

Autores:

Rozzi, R., Armesto, J.J., Gutiérrez, J.R., Massardo, F., Likens, G.E., Anderson, C.B., Poole, A., Moses, K.P., Hargrove, E., Mansilla, A.O., Kennedy, J.H., Willson, M., Jax, K., Jones, C.G., Callicott,J.B., and Arroyo, M.T.K.

Resumen:

The South American temperate and sub-Antarctic forests cover the longest latitudinal range in the Southern Hemisphere and include the world's southernmost forests. However, until now, this unique biome has been absent from global ecosystem research and monitoring networks. Moreover, the latitudinal range of between 40 degrees (°) south (S) and 60° S constitutes a conspicuous gap in the International Long-Term Ecological Research (ILTER) and other international networks. We first identify 10 globally salient attributes of biological and cultural diversity in southwestern South America. We then present the nascent Chilean Long-Term Socio-Ecological Research (LTSER) network, which will incorporate a new biome into ILTER. Finally, we introduce the field environmental philosophy methodology, developed by the Chilean LTSER network to integrate ecological sciences and environmental ethics into graduate education and biocultural conservation. This approach broadens the prevailing economic spectrum of social dimensions considered by LTSER programs and helps foster bioculturally diverse forms of Earth stewardship.

Año: 2012

Palabras claves: conservation, temperate forests, sub-Antarctic ecoregion, long-term ecological research, field stations

Seasonal and Multiannual Patterns in Avian Assemblage Structure and Composition in Northern Chilean Thorn-Scrub

Autores:

Douglas A. Kelt, Andrew Engilis Jr., Juan Monárdez, Robert Walsh, Peter L. Meserve, And Julio R. Gutiérrez.

Resumen:

The species composition of the Chilean avifauna is well-defined taxonomically but is not well known ecologically. We sampled avian communities at a biosphere reserve in coastal north-central Chile in three seasons over six years (18 surveys total) and characterized them in terms of community structure and composition. The avifauna (S = 56 species) was dominated by insectivores (S = 20), carnivores (S = 14), and granivores (S = 13), with lesser contributions by omnivores (S = 5), nectarivores (S = 2), folivores (S = 1), and one vagrant piscivore. The fauna varied greatly between summer and winter, and in most years the breeding season also was distinct. Eighteen species constituted a core group of residents observed in nearly all surveys, but at least 15 species were nomadic or migratory. Our site supported more insectivorous species in winter but more granivores and omnivores in the breeding season, although this observation may be confounded by species' detectability. The structure of the set of species was nested temporally, but this was not clearly caused by seasonal influx supplementing a core fauna of residents. Ordination clearly segregated all three seasons, except for one survey that was explained by very dry conditions in that year. Further research will quantify productivity and demographic responses to long-term climatic variation to compare avian and mammalian patterns with respect to extrinsically generated pulses in resources (e.g., El Niño/Southern Oscillation).

Año: 2012

Palabras claves: avian community structure, avian diversity, biosphere reserve, Chile, migration, seasonality, semiarid thorn scrub