North-central Chile Research Articles

Plant Area Index and microclimate underneath shrub species from a Chilean semiarid community

In drylands, environmental conditions under shrub canopy differ from those found in open sites. We should expect that microclimate conditions under shrubs with distinct canopy architecture should also be different. Plant Area Index (PAI) of the three most abundant shrubs species ( Porlieria chilensis, Adesmia bedwellii and Proustia cuneifolia) in Bosque Fray Jorge National Park, north-central Chile was measured using a Plant Canopy Analyzer. During two years (2004–2005), we recorded the Relative Humidity and Air Temperature underneath and away from the canopy of the shrubs. The three shrub species showed significant differences in PAI. Microclimate at 30 cm and 2 m above the soil in the open conditions were drier and warmer than underneath shrub canopies. Vegetation patches generate moderate microclimate conditions. Canopy structure can buffer climatic variability, contributing to high herbaceous productivity as well as shrub recruitment. Reflecting shrub architecture and observed PAI values, the lowest microclimate variations were observed under the canopies of P. chilensis, followed by P. cuneifolia and finally A. bedwellii. We bring a novel approach quantifying the Plant Area Index instead of the Plant cover and using a low cost method that integrates the distribution of leaves and may be derived from remote sensing products.

Climate change impacts on the hydrology of a snowmelt driven basin in semiarid Chile

In this paper we present an analysis of the direct impacts of climate change on the hydrology of the upper watersheds (range in elevation from 1,000 to 5,500 m above sea level) of the snowmelt-driven Limari river basin, located in north-central Chile (30° S, 70° W). A climate-driven hydrology and water resources model was calibrated using meteorological and streamflow observations and later forced by a baseline and two climate change projections (A2, B2) that show an increase in temperature of about 3–4°C and a reduction in precipitation of 10–30% with respect to baseline. The results show that annual mean streamflow decreases more than the projected rainfall decrease because a warmer climate also enhances water losses to evapotranspiration. Also in future climate, the seasonal maximum streamflow tends to occur earlier than in current conditions, because of the increase in temperature during spring/summer and the lower snow accumulation in winter.

Seasonal variation in the range areas of the diurnal rodentOctodon degus

Both breeding activity and abundance and quality of available food are expected to influence daily movements of animals. Animals are predicted to range over large areas to meet high energy demands associated with reproduction (females) or to increase mating success (males). However, animals should expand their range areas whenever food conditions deteriorate. To examine the extent to which breeding activity versus food availability influence space use, we compared the size and location of range areas (home ranges) of the degu (Octodon degus), a diurnal rodent from semiarid environments of north-central Chile, during the austral winter and summer seasons. Degus produce young during the austral spring (September-October) when high-quality food is readily available. In contrast, degus do not breed during the austral summer (January-March) when food is scarce and of low quality. We predicted that degus would range over smaller areas in winter if the availability of food has a greater influence on space than breeding activity. Individuals were radiotracked in winter and the following summer over a 3-year period. Surveys of herbaceous cover were conducted during winter and summer to determine seasonal changes in the abundance and quality of primary food. In summer degus expanded and moved the location of their range areas to locations with available food. Given that preferred food was less abundant in summer than winter, we suggest that degu range areas are strongly influenced by food conditions.

Statistical downscaling of precipitation and temperature in north‐central Chile: an assessment of possible climate change impacts in an arid Andean watershed

Downscaling of atmosphere–ocean general circulation models (AOGCMs) is necessary to transfer predictions of potential climate change scenarios to local levels. This is of special interest in dry mountainous areas, which are particularly vulnerable to climate change due to risks of reduced freshwater availability. These areas play a key role in hydrology, since they usually receive the highest local precipitation amounts, which are then stored in the form of snow and glaciers. The performance and ability to simulate extreme events of a statistical downscaling model (SDSM) were tested in the arid Upper-Elqui watershed, Chile. Thereafter, future temperature and precipitation seasonal trends along with agro-hydrological indices were analysed for the HadCM3 A2a and B2a scenarios. Maximum and minimum temperatures for both linear trends and extreme events were simulated accurately. However, the results show that SDSM was not a very robust method for the simulation of precipitation. Nevertheless, future trends and indices indicate possible strong inter-seasonal perturbations. Citation Souvignet, M., Gaese, H., Ribbe, L., Kretschmer, N. & Oyarzún, R. (2010) Statistical downscaling of precipitation and temperature in north-central Chile: an assessment of possible climate change impacts in an arid Andean watershed. Hydrol. Sci. J. 55(1), 41–57.

Molecular phylogeny and historical biogeography of Nacella (Patellogastropoda: Nacellidae) in the Southern Ocean

The evolution and the historical biogeography of the Southern Ocean marine benthic fauna are closely related to major tectonic and climatic changes that occurred in this region during the last 55 million years (Ma). Several families, genera and even species of marine organisms are shared between distant biogeographic provinces in this region. This pattern of distribution in marine benthic invertebrates has been commonly explained by vicariant speciation due to plate tectonics. However, recent molecular studies have provided new evidence for long-distance dispersion as a plausible explanation of biogeographical patterns in the Southern Ocean. True limpets of the genus Nacella are currently distributed in different biogeographic regions of the Southern Ocean such as Antarctica, Kerguelen Province, southern New Zealand Antipodean Province, North-Central Chile and South American Magellanic Province. Here, we present phylogenetic reconstructions using two mitochondrial DNA markers (Cytochrome Oxidase I and Cytochrome b) to look into the relationships among Nacella species and to determine the origin and diversification of the genus. Phylogenies were reconstructed using two methods, Maximum Parsimony and Bayesian Inference, while divergence time among Nacella species was estimated following a relaxed Bayesian approach. For this purpose, we collected inter- and subtidal species belonging to four biogeographic regions in the Southern Ocean: Antarctica, Kerguelen Province, Central Chile, and Magellanic Province. Our molecular results agree with previous morphological and molecular studies supporting the monophyly of Nacella and its sister relationship with Cellana. Two rounds of diversification are recognized in the evolution of Nacella. The first one occurred at the end of the Miocene and gave rise to the main lineages, currently distributed in Antarctica, South America or Kerguelen Province. Large genetic divergence was detected among Nacella species from these distant biogeographic provinces emphasizing the significance of trans-oceanic discontinuities and suggesting long-distance dispersal was relatively unimportant. The second diversification round consisted of a more recent Pleistocene radiation in the Magellanic region. In this province, different morphological species of Nacella exhibit extreme low levels of genetic divergence with absence of reciprocal monophyly among them. According to our time estimation, the origin and diversification of Nacella in the Southern Ocean is more recent (<15 MY) than the expected under the hypothesis of vicariant speciation due to plate tectonics. The evolution of this genus seems to be closely related to drastic climatic and oceanographic changes in the Southern Ocean during the middle-Miocene climatic transition. In spite of the high number of species described for the Magellanic Province, molecular results indicate that these species are the most derived ones in the evolution of the genus and therefore that the Magellanic region does not need to correspond to the origin center of Nacella. The absence of genetic divergence among these species supports a very recent radiation process accompanied by rapid morphological and ecological diversification.

Echinococcus granulosus infection in humans and livestock in the Coquimbo region, north-central Chile

Cyst echinococcosis (CE) is one of the most important zoonosis in Chile, where studies have focussed mainly in moist southern regions. The present study was conducted to determine the prevalence of cystic echinococcosis (CE) in livestock and humans in the semiarid Coquimbo region in north-central Chile. A review of all surgical cases of CE in humans reported in the Elqui, Limarí and Choapa provinces in Coquimbo region for the period comprising 1995–2006 was obtained. In addition, a retrospective study of CE covering condemnation records from slaughterhouses of these provinces from the same period was carried out. The surgical incidence of CE in humans ranged between 2.3 and 8.5 cases per 10 5 people, with more cases reported in provinces with a higher percentage of rural inhabitants (Limarí and Choapa). A total of 174,034 cattle, 22,208 goats, 35,404 sheep, 25,355 swine and 9391 equines were examined during the period. Higher prevalence of CE was detected in cattle (24%), followed by swine (14%), sheep (11%), goats (6%), and equines (9%). More cases of CE in livestock were also found in provinces with higher rural population. The overall trend of the prevalence of CE for each livestock species across years was a significant downward one, except for swine in Elqui and sheep and swine in Choapa. Cattle showed higher prevalence of CE in liver in Elqui, in kidney in Limarí and in lungs in Choapa. Swine showed similar prevalence by organs in all provinces. Sheep showed higher prevalence of CE in liver in Elqui and Limarí and lower prevalence in Choapa. Goats presented higher prevalence of CE in kidney in all provinces, and equines had higher prevalence of CE in liver in the provinces where animals were slaughtered. Further studied are needed to assess whether these differences are due to different strains affecting these species or due to ecological factors. When analyzing the CE prevalence of each species within each province, a negative correlation between prevalence of CE in goats and rainfall in the Limarí province was found. This could be attributed to changes in management practices and/or ecological factors. This study shows that surveillance of CE at slaughterhouses combined with the analyses of incidence in humans can be used to detect areas with a higher risk of infection. Improvements in record-keeping of infected animals at slaughterhouses are proposed in order to trace back farms where infection was most likely acquired.

Echinococcus granulosus infection in domestic dogs in urban and rural areas of the Coquimbo region, north-central Chile

Hydatidosis is a zoonotic disease caused by the cystic stage of the cestode parasite Echinoccocus granulosus, in which the definitive hosts are mainly domestic dogs. This parasite is regarded mainly as a rural disease, where man is exposed through contact with eggs excreted by definitive hosts; however, some studies have shown that domestic dogs can get infected within urban areas. This study was conducted to assess differences in prevalence of E. granulosus in urban and rural sites in Coquimbo region of Chile. From 2005 to 2006 a cross-sectional household questionnaire survey was conducted in Coquimbo and Ovalle cities, in three towns and in rural sites along two transects from these cities to the Fray Jorge NP in the Coquimbo region. Faecal samples were collected from dogs during the questionnaire survey and tested for Echinococcus coproantigens. Positive dogs were found in urban areas. Analysis of risk factors indicated that dogs inhabiting the borders of urban areas were at greater risk of being coproantigen positive than those in the centre of these areas. These results are likely to be related to the custom of slaughtering livestock at home in urban areas during local celebrations, which could favour the importation of E. granulosus to urban areas by acquiring livestock contaminated with cysts from rural sites. This study shows that surveillance and control measures in livestock and domestic dogs need to be introduced in urban areas as well as rural areas of the Coquimbo region to reduce the public health risk of hydatid disease.

Phytostabilization of massive mine wastes with native phytogenetic resources: potential for sustainable use and conservation of the native flora in north-central Chile

C. Orchard, P. Leon-Lobos, and R. Ginocchio. 2009. Phytostabilization of massive mine wastes with native phytogenetic resources: potential for sustainable use and conservation of the native fl ora in north-central Chile. Cien. Inv. Agr. 36(3):329-352. The mining industry has left an important legacy of inadequately abandoned tailing storage facilities (TSFs) in the north-central area of Chile, and they may pose environmental risks. The Chilean government has recently established new regulations governing the closure of TSFs, and these regulations favor the use of environmentally sustainable technologies. Among these technologies is phytostabilization, which can use native plant species that may also have economic and/or subsistence value. Phytostabilization programs based on sustainably maintained native species could also contribute to the conservation of both local fl ora and regional ecosystems in north-central Chile. The main objective of this study was to use the Coquimbo Region as a case study area to look for added economic value from native plant species that have spontaneously colonized abandoned TSFs and to look for other species that, given their ecological characteristics, may be established on post-operational TSFs by phytostabilization. A review of technical, scientifi c and ethnobotanic literature on traditional uses and recently discovered uses of selected plant species was performed. The results showed that 68 spontaneously colonizing phytostabilization species have at least one known use, while 420 species with potential for use in phytostabilization (28% of the regional native fl ora) have various uses. Ornamentation, cattle forage, mellipherous, medicine, crafts and phytochemicals are the main uses identifi ed for the local native fl ora. Most of the identifi ed species are endemic to Chile (69%). These species are therefore a very valuable phytogenetic resource that can be used in the rehabilitation of massive mine wastes. This unique resource could be lost if these species are not identifi ed and studied in the near future.

Movement patterns of the seastar Heliaster helianthus in central Chile: relationship with environmental conditions and prey availability

The rates and patterns of feeding and displacement of predators constitute two of the most important plastic behavioral responses that allow individuals to respond quickly to changes in abundance of their prey, predation risks and to rapid alterations in environmental conditions. In this study, we quantified seasonal and spatial variation in displacement (net changes in location in 12 or 24 h periods) and prey consumed of marked individuals of the keystone seastar Heliaster helianthus at six sites spanning 600 km along the coast of north-central Chile. We evaluated the hypotheses that: (1) at sites with low availability (cover) of the main prey, the mussel Perumytilus purpuratus, Heliaster displays larger displacements and consumes a greater proportion of other prey (e.g. mobile species) than at sites with high mussel cover, (2) daily displacements will be correlated with sea surface temperature (SST) and (3) increased wave action will reduce seastar daily displacement. Our results show that Heliaster displacement is higher at sites with lower availability of P. purpuratus; and at these sites, a larger proportion of Heliaster individuals are observed feeding, mostly on other prey (e.g. limpets), which could offset the higher costs associated with increased movement. In addition, wave forces affected the activity of Heliaster negatively. Contrary to our expectations, the daily displacements did not show any relationship with SST measured on the day or the previous days of the surveys, despite the fact that average displacement was generally higher in summer than in winter months. Future studies should examine Heliaster movement during single foraging excursions and determine whether these responses affect the growth and reproductive output of individuals. Such information is vital to understand how changes in prey abundance and environmental conditions alter the behavior and energy budget of this predator and its ability to control prey populations.

Interaction of water components in the semi-arid Huasco and Limarí river basins, North Central Chile

Abstract. For sustainable water resource management in semi-arid regions, sound information is required about interactions between the different components of the water system: rain/snow precipitation, surface/subsurface run-off, groundwater recharge. Exemplarily, the Huasco and Limarí river basins as water stressed river catchments have been studied by isotope and hydrochemical methods for (i) the origin of water, (ii) water quality, (iii) relations of surface and groundwater. Applying the complex multi-isotopic and hydrochemical methodology to the water components of the Huasco and Limarí basins, a differentiation of water components concerning subsurface flow and river water along the catchment area and by anthropogenic impacts are detected. Sulphate and nitrate concentrations indicate remarkable input from mining and agricultural activities along the river catchment. The 2H-18O relations of river water and groundwater of both catchments point to the behaviour of river waters originated in an arid to semi-arid environment. Consequently, the groundwater from several production wells in the lower parts of the catchments is related to the rivers where the wells located, however, it can be distinguished from the river water. Using the hydrological water balance and the isotope mixing model, the interaction between surface and subsurface flows and river flow is estimated.

Foraging Behavior of Tufted Tit-Tyrants (Anairetes parulus) in Semiarid Northcentral Chile

Abstract We studied foraging behavior of Tufted Tit-Tyrants (Anairetes parulus) in Matorral (shrubland) habitat of northcentral Chile. This species is a generalist insectivore feeding in most shrubs of Matorral habitat at our study site, although they favored three of the dominant plant species. Their foraging is typical of small tyrannid flycatchers, using rapid perch gleans coupled with hover gleans and supplemented by flycatching. They use relatively long search periods (3–5 sec) followed by rapid gleans, which is typical for small tyrannids. Their active foraging (3.1 ± 1.8 prey attacks/min) coupled with a longer search time distinguishes them from parids or regulids of the Holarctic with which they often are compared. They generally forage singly or in pairs and aggressively defend what appears to be foraging territories in winter and summer. Densities of Tufted Tit-Tyrants at our study site were higher than reported in other studies from Chile and Argentina, presumably reflecting resource availability.

The Humboldt Current System: Ecosystem components and processes, fisheries, and sediment studies

In the Humboldt Current System (HCS), biological and non-biological components, ecosystem processes, and fisheries are known to be affected by multi-decadal, inter-annual, annual, and intra-seasonal scales. The interplay between atmospheric variability, the poleward undercurrent, the shallow oxygen minimum zone (OMZ), and the fertilizing effect of coastal upwelling and overall high primary production rates drive bio-physical interactions, the carbon biomass, and fluxes of gases and particulate and dissolved matter through the water column. Coastal upwelling (permanent and seasonally modulated off Peru and northern Chile, and markedly seasonal between 30°S and 40°S) is the key process responsible for the high biological productivity in the HCS. At present, the western coast of South America produces more fish per unit area than any other region in the world ocean (i.e. ∼7.5 × 10 6 t of anchoveta were landed in 2007). Climate changes on different temporal scales lead to alterations in the distribution ranges of anchoveta and sardine populations and shifts in their dominance throughout the HCS. The factors affecting the coastal marine ecosystem that reverberate in the fisheries are crucial from a social perspective, since the economic consequences of mismanagement can be severe. Fish remains are often well-preserved in sediment settings under the hypoxic conditions of the OMZ off Peru and Chile, and reveal multi-decadal variability and centennial-scale changes in fish populations. Sediment studies from the Chilean continental margin encompassing the last 20,000 years of deposition reveal changes in sub-surface conditions in the HCS during deglaciation, interpreted to include: a major reorganization of the OMZ; a deglacial increase in denitrification decoupled from local marine productivity; and higher deglacial and Holocene paleoproductivities compared to the Last Glacial Maximum in central-south Chile (35–37°S) while this scheme is reversed for north-central Chile. Multi-scale, interdisciplinary approaches and focused research groups are needed to understand air–sea interactions, plankton dynamics, biomass removal by fisheries, and the transformation and fluxes of matter across the different HCS components. In this paper, we present a multidisciplinary synthesis of the HCS that covers its physics, atmosphere, primary and secondary production, medium and high trophic levels, fisheries including management aspects, and relevant sedimentary studies.

Population dynamics of two sympatric rodents in a variable environment: rainfall, resource availability, and predation

Precipitation plays an important role in the dynamics of species found in arid and semiarid environments. However, population fluctuations generally are driven by a combination of multiple factors whose relative contribution may vary through time and among species. We monitored fluctuations of species in three trophic levels for >17 years at a semiarid community in north-central Chile. The region is strongly affected by the El Niño Southern Oscillation, resulting in high variation in rainfall that triggers dramatic changes in food resource availability, with strong effects on upper trophic levels. We focused our analyses on the role played by endogenous and exogenous (climatic) factors on the dynamics of two important rodent species in the community, Octodon degus and Phyllotis darwini. We documented population fluctuations of several orders of magnitude in response to wet and dry episodes of different strength and duration. P. darwini reached similar maximum densities, regardless of the duration of high-rainfall events, whereas O. degus showed additive effects of multiple wet years. Time series diagnostic tools revealed oscillations with a 5-year periodicity in rainfall, which may be the cause of the same periodicity and a weak second-order signal observed in the rodent dynamics. However, the dynamics of both rodent species were dominated by strong first-order processes, suggesting an important role of direct density dependence. Intraspecific competition, expressed as the ratio of rodent density/rainfall (or food resources) explained more than two-thirds of the variation in the population rate of change, whereas less than one-third was explained by lagged rainfall (or food resources). We detected no significant effects of predation. Our results contribute to a growing number of examples of dynamics governed by the combined effect of density dependence and climatic forcing. They also reveal strong bottom-up regulation that may be common in other arid environments.

Manganese nodules in the Miocene Bahía Inglesa Formation, north-central Chile: Petrography, geochemistry, genesis and palaeoceanographic significance

Manganese nodules recovered from two stratigraphic horizons of Tortonian–Messinian (late Miocene) age in the Bahía Inglesa Formation of north-central Chile were studied using XRD, SEM and geochemical analysis. The dominant mineral in the nodules is todorokite, which suggests a diagenetic, marine environment. This is supported by field observations of nodules replacing Ophiomorpha burrows. Preliminary, traditional statistical analysis of the nodule geochemistry, including single element, binary and ternary ratios, suggests that the nodules are of the supergene, deep marine type, as also indicated by the presence of foraminifers typical of the upper continental slope, as well as debris flow and turbidity current deposits in an associated submarine palaeocanyon. However, abnormally low Cu concentrations seem to contradict this interpretation, so that additional analyses were carried out. This included multiple discriminant analysis (MDA), as well as a new technique applied for the first time to manganese nodules, namely artificial neural network analysis (ANN). In both methods central log-ratio (CLR) normalization was applied to the raw data. The results, in particular those of the ANN analysis, suggest that the Bahia Inglesa nodules present a chemical signature distinct from that of nodules described to date. A new class is therefore proposed, namely supergene intermediate marine (partially restricted basin).

Structural overprint of a late Paleozoic accretionary system in north-central Chile (34°-35°S) during post-accretional deformation

En la Cordillera de la Costa de Chile, de 36° a 35°S, se encuentra expuesta la arquitectura coherentemente preservada de un prisma de acrecion del Paleozoico tardio, en cercana vecindad a un area entre los 34° y 35°S, donde el mismo esta fuertemente modificado por procesos postacrecionales. Estudiando las desviaciones de la arquitectura original, en esta region pueden ser perfectamente distinguidas estructuras sin- y post acrecionales. Al sur de los 35° se observa un contacto transicional entre dos unidades mayores, el cual refleja un cambio continuo en el modo de acrecion de la cuna acrecional antes de -305 Ma: las metagrauvacas estructuralmente suprayacentes de las series orientales muestran estructuras tipicas de una acrecion frontal, pliegues chevron subverticales de planos de estratificacion con una foliacion de plano axial S . Con el aumento de la deformacion finita hacia su base, se desarrollan pliegues abiertos F2 asociados con una foliacion S , la cual se va tornando cada vez mas achatada y subhorizontal. En las series occidentales estructuralmente subyacentes, S2 es la foliacion de transposicion penetrativa que afecta a las metagrauvacas derivadas de un continente e intercalaciones de metabasitas de origen oceanico. Las estructuras fueron formadas durante acrecion basal. Esta evolucion principal del sistema acrecionario pone firmes restricciones sobre la arquitectura original, tambien en regiones donde este fue destruido luego de la acrecion. La acrecion finalizo cerca de los 225 Ma, cuando ocurrio un cambio mayor en las condiciones geodinamicas hacia un regimen ex-tensional. Aunque el desarrollo del margen en el centro de Chile esta ampliamente caracterizado por extension durante el Mesozoico y Cenozoico, dos episodios pronunciados que involucran acortamiento del antearco afectaron las series orientales al norte de 35°S: 1. Las expresiones de actividad de deslizamiento de rumbo durante el Jurasico son planos empinados de foliacion penetrativa S2, rotacion local de la lineacion de estiramiento L2 a una direccion norte-sur, ple-gamiento apretado vertical de la foliacion principal y replegamiento alrededor de ejes empinados, con zonas de cizalla verticales, semifragiles y sinistrales asociadas. 2. La falla inversa Pichilemu-Vichuquen, levemente sinistral, en el limite entre ambas unidades, es una prominente estructura fragil formada hace cerca de 100 Ma, concomitante con el cierre de cuencas y aceleracion de la exhumacion en el antearco. Estructuras compresivas similares ocurren a lo largo de la costa hacia el norte, donde ambas unidades desaparecieron parcialmente por subduccion, probablemente durante estos eventos de deformacion. La transicion entre sistemas acrecionales casi sin afectar y sistemas afectados, parcialmente subductados al norte, ocurre a los 35°S.

Importance of water quality on plant abundance and diversity in high-alpine meadows of the Yerba Loca Natural Sanctuary at the Andes of north-central Chile

Los megadepositos de porfidos de Cu-Mo han influido sobre la calidad de las aguas superficiales en las zonas altoandinas del centro-norte de Chile desde el Mioceno. Estas alteraciones en la calidad de las aguas podrian afectar negativamente a la vegetacion presente en las vegas altoandinas, ya que las aguas acidas y ricas en metales son altamente toxicas para las plantas. En este estudio se evaluo el efecto de la calidad de las aguas en la abundancia y diversidad floristica de las vegas altoandinas del Santuario de la Naturaleza Yerba Loca (SNYL), en Chile central (33° 15' S, 70° 18' O). Se realizaron prospecciones hidroquimicas y botanicas en las vegas de Piedra Carvajal, Chorrillos del Plomo y La Lata, durante las estaciones de crecimiento de 2006 y 2007. Se realizo un analisis directo de gradiente a traves del Analisis de Correspondencia Canonica (CCA) para buscar relaciones entre los parametros quimicos del agua y los parametros botanicos. Se encontro una alta variabilidad quimica del agua tanto dentro como entre las vegas, particularmente en cuanto a pH, sulfatos, conductividad electrica, dureza y contenidos totales disueltos de Cu, Zn, Cd, Pb y Fe. Los datos de abundancias especificas y los parametros quimicos del agua sugieren que el pH y el contenido de Cu total disuelto son factores importantes en determinar los cambios en la abundancia y la diversidad de las especies vegetales en las vegas estudiadas. Por ejemplo, Festuca purpurascens, Colobanthus quitensis y Arenaria rivularis son abundantes en ambientes de aguas con altos contenidos de Cu, mientras que Festuca magellanica, Patosia clandestina, Plantago barbata, Werneria pygmea y Erigeron andicola son abundantes en lugares de aguas con bajos contenidos de Cu.

Interannual variability of the coastal fog at Fray Jorge relict forests in semiarid Chile

The coastal mountains of semiarid Chile are punctuated by patches of fog‐dependent evergreen forests. Fog episodes often occur when the prominent coastal topography intercepts a well developed deck of stratocumulus (Sc) off north central Chile. A 22‐year record of ground‐based fog observations at Fray Jorge Biosphere Reserve (FJBR, 30°S), atmospheric reanalysis and satellite derived low cloud amount are used to document the annual cycle and interannual variability of fog frequency there. The number of foggy days minimizes during austral winter and then increases rapidly to reach a maximum in spring (the growing season of FJBR trees). The mean annual cycle of the fog‐frequency follows closely the annual cycle of the nearby marine Sc amount and lower tropospheric stability (LTS). The springtime fog frequency, nearby marine cloud amount and LTS are also well correlated at interannual timescales. Colder than normal sea surface temperatures and warmer than normal air temperatures aloft near 30°S strengthen the temperature inversion and lead to a more persistent cloud deck and higher than normal fog frequency at FJBR. La Niña years produce temperature anomalies very similar to the pattern described before and consequently they are associated with higher than normal springtime fog frequency at FJBR. Conversely, El Niño years are associated with less foggy conditions at FJBR. Interestingly, El Niño–Southern Oscillation (ENSO) related rainfall anomalies in north central Chile are opposite to ENSO‐related anomalies in fog‐frequency. We discuss the overall impact of ENSO in FJBR ecosystems as well as the prospects of FJBR in future climate scenarios driven by increased greenhouse gases.

Glacial to Holocene changes in sea surface temperature and coastal vegetation in north central Chile: high versus low latitude forcing

North central Chile is located at an important climatic transition zone between humid conditions under the influence of the Southern Hemisphere Westerly Winds in the south and the extremely dry climate of the Atacama Desert in the north. Offshore, equatorward flowing cold waters of the Peru–Chile Current converge with relatively warmer waters coming from the low latitudes. Based on terrestrial and marine proxies from the same archive (GeoB 7139-2) (30°12′S; 71°59′W), we show that during the Glacial (between ∼33 and 19 kyr) cold sea surface temperatures paralleled enhanced humidity with high terrestrial input and abundant vegetation on the adjacent land, suggesting a stronger influence of cold waters from the Antarctic Circumpolar Current and the Westerly Winds. While the deglacial sea surface temperature warming started at ∼19 kyr, the humidity decrease occurred around 17–16 kyr BP. The early to mid-Holocene is characterized by extremely warm and dry conditions. We suggest that climate changes were driven by fluctuations in Antarctic sea-ice extent and the circulation of the Hadley cell, both ultimately linked to insolation changes. Our records further imply warm and dry conditions in north central Chile during the Northern Hemisphere Heinrich events.

Climate signals in high elevation tree-rings from the semiarid Andes of north-central Chile: Responses to regional and large-scale variability

In South America, the arid and semiarid subtropical regions through the Atacama Desert and north-central Chile between 19° and 32°S are currently a gap in the tree-ring chronology network. Only a short tree-ring chronology has been published for this vast region and little is known about the suitability of many woody species for tree-ring analysis and dendroclimatology. In this paper we present the first detailed analysis of the climate responses and influences of the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) on the tree-rings of three species new to dendrochronology and that typically occur at high elevations in the Andes of central and north-central Chile. Three well-replicated tree-ring chronologies of Kageneckia angustifolia, Proustia cuneifolia and Fabiana imbricata are compared with century-long regional records of precipitation and temperature, and with the N3.4 SST and PDO indices in both time and frequency-domains using correlation and wavelet analysis. The radial growth of these species is controlled by winter precipitation and is also positively correlated with temperature during most of the rainy season from April to September (autumn–spring). The regional climate as well as tree growth is strongly modulated by ENSO and ENSO-like conditions in the equatorial Pacific at both interannual and interdecadal timescales. The decadal and interdecadal variability is not correlated with PDO and appears to be related to the Interdecadal Pacific Oscillation (IPO), a Pacific-wide ENSO-like mode of climate variability. Despite their relatively short lifespans, these three new species have a high potential for dendrochronological and dendroclimatic studies in the semiarid region of Chile over the last two centuries.

Effect of the degree of autotomy on feeding, growth, and reproductive capacity in the multi-armed sea star Heliaster helianthus

The term autotomy refers to the process by which some species lose limbs or parts of limbs in response to adverse biotic or abiotic conditions, as for example, predation or abnormally high temperatures. The multi-armed sea star Heliaster helianthus is a key predator of the intertidal and the shallow rocky subtidal communities of north-central Chile. Natural populations of this sea star have been found with up to 60% of the individuals showing some degree of autotomy. The present study evaluated the effects of autotomy on feeding rate and growth of juvenile and adult H. helianthus after experimentally induced autotomy of 17% and 33% of their arms, as well as on the energy content of the pyloric caeca and gonads of adults during the reproductive period. Experimental juvenile sea stars were maintained and fed in the laboratory over a period of five months and adult sea stars for one month, Intact individuals were maintained as parallel controls. The results showed that juveniles undergoing 33% autotomy decreased their feeding rates, and as a consequence showed lowered net individual growth. In contrast, adults with 17% and 33% autotomy showed marked reductions in feeding. The results showed that autotomized adults had between five and seven times lower contents of carbohydrates, lipids, and proteins (and thus energetic content) in their pyloric caeca and gonads. The loss of the arms not only decreased the capacity for feeding in sea stars, but also allocated energy away from growth and reproduction into the process of regeneration of arms. This suggests that autotomy reduces the fitness of H. helianthus. Growth was reduced in the juveniles, while adults became limited in their ability to store energy which then limited their reproductive potential. Finally, based on the important effect of autotomy on reducing the feeding capacity of H. helianthus, the role of this sea star as a predator in the environment may be strongly affected.