CEAZA
Nurse effect and soil microorganisms are key to improve the establishment of native plants in a semiarid community.
Molina-Montenegro, M., Oses, R., Atala, C., Torres-Díaz, C., Bolados, G., & León-Lobos, P.
Facilitation by the nurse effect can occur through an amelioration of environmental stress. Plant-microorganism interaction, however, is another key facilitation mechanism of the nurse effect, but is by far the least documented. Here we tested if microclimatic mitigation and soil microorganisms isolated from the root-zone of the nurse shrub Porlieria chilensis can increase the establishment of other native plants in a semiarid community. We conducted field and greenhouse experiments to evaluate the direct and indirect effects of the presence of P. chilensis on the survival and growth of three native plants. In the field experiment, we compared the survival and growth of transplanted individuals beneath nurses and outside of them in pots filled with soil from both microsites (beneath and outside nurses). Finally, in the greenhouse experiment we grew native plants in soil taken from both microsites (below and outside nurses) and with and without soil microorganisms (sterilization process). We found a clear and significant nurse effect of P. chilensis on the tested species through of amelioration of climatic (air temperature, soil moisture, and solar radiation) and edaphic (nitrogen availability) conditions, increasing the performance of these native species. Moreover, performance and establishment were enhanced when soil was kept with microorganisms. Thus, nurse effect mediated by microclimatic amelioration, edaphic improvement and presence of soil microorganisms could be key mechanisms to increase the establishment of native plant species in semiarid communities of central Chile.
Año: 2016
Palabras claves: Nurse effect; Facilitation; Chile; Microorganisms; Symbiosis; Positive interactions.
Referencia APA: Oses, R., Atala, C., Torres-Díaz, C., Bolados, G., & León-Lobos, P. (2016). Nurse effect and soil microorganisms are key to improve the establishment of native plants in a semiarid community. Journal Of Arid Environments, 126, 54-61.
3-D surface properties of glacier penitentes over an ablation season, measured using a Microsoft Xbox Kinect.
Nicholson L. I., Pętlicki M., Partan B., and MacDonell S.
In this study, the first small-scale digital surface models (DSMs) of natural penitentes on a glacier surface were produced using a Microsoft Xbox Kinect sensor on Tapado Glacier, Chile (30°08′ S, 69°55′ W). The surfaces produced by the complete processing chain were within the error of standard terrestrial laser scanning techniques, but insufficient overlap between scanned sections that were mosaicked to cover the sampled areas can result in three-dimensional (3-D) positional errors of up to 0.3 m. Between November 2013 and January 2014 penitentes become fewer, wider and deeper, and the distribution of surface slope angles becomes more skewed to steep faces. Although these morphological changes cannot be captured by manual point measurements, mean surface lowering of the scanned areas was comparable to that derived from manual measurements of penitente surface height at a minimum density of 5 m−1 over a 5 m transverse profile. Roughness was computed on the 3-D surfaces by applying two previously published geometrical formulae: one for a 3-D surface and one for single profiles sampled from the surface. Morphometric analysis shows that skimming flow is persistent over penitentes, providing conditions conducive for the development of a distinct microclimate within the penitente troughs. For each method a range of ways of defining the representative roughness element height was used, and the calculations were done both with and without application of a zero displacement height offset to account for the likelihood of skimming air flow over the closely spaced penitentes. The computed roughness values are on the order of 0.01–0.10 m during the early part of the ablation season, increasing to 0.10–0.50 m after the end of December, in line with the roughest values previously published for glacier ice. Both the 3-D surface and profile methods of computing roughness are strongly dependent on wind direction. However, the two methods contradict each other in that the maximum roughness computed for the 3-D surface coincides with airflow across the penitente lineation, while maximum roughness computed for sampled profiles coincides with airflow along the penitente lineation. These findings highlight the importance of determining directional roughness and wind direction for strongly aligned surface features and also suggest more work is required to determine appropriate geometrical roughness formulae for linearized features.
Año: 2016
Palabras claves:
Referencia APA: Nicholson L. I., Pętlicki M., Partan B., and MacDonell S. (2016). 3-D surface properties of glacier penitentes over an ablation season, measured using a Microsoft Xbox Kinect. The Cryosphere, 10(5), 1897.
Late Holocene environmental changes as recorded in the sediments of high Andean Laguna Chepical, Central Chile (32° S; 3050ma. sl).
Martel-Cea, A., Maldonado, A., Grosjean, M., Alvial, I., de Jong, R., Fritz, S. C., & von Gunten, L.
We present a reconstruction of environmental changes from sediments of high-altitude Laguna Chepical in the subtropical Andes of Central Chile (32°16′S; 70°30′W, 3050 m a.s.l.) for the past 3100 years. Based on subfossil pollen, microscopic charcoal and diatoms, we inferred changes in moisture (related to precipitation) and ice-cover/ice-free season (related to summer temperature) at decadal to millennial scales. Sustained wetter and colder summer temperatures than today prevailed between 1100 BC and ca. AD 1. Afterward, decreasing pollen accumulation rates and increased fire activity suggest drier conditions and possibly enhanced seasonality and/or inter-annual climate variability. Frequent changes between cold and warm summers were observed, particularly for the last 1000 years. About AD 1250 (during the Medieval Climate Anomaly), wet years and early break up of ice-cover occurred in central Chile, which is today typical for El Niño-like mean conditions. Conversely, and with the exception of a few wet pulses, a generally dry period with extended ice-cover (cool summers) was observed between AD 1400 and AD 1850 (Little Ice Age). This can be interpreted as a trend toward more La Niña-like mean conditions. Recent climate change and human disturbances during the last 100 years have prompted changes in diatom and plant communities that are unprecedented in the late Holocene. First, planktonic diatoms increased as a result of hydraulic interventions in the lake during the late 19th century, and secondly, the Andean vegetation shifted upward as result of recent warming, and the frequency of arboreal taxa was significantly reduced. At the same time peaks of fire activity were observed.
Año: 2016
Palabras claves: Late Holocene; ENSO; Pollen; Diatom; Andes; Climate change.
Referencia APA: Martel-Cea, A., Maldonado, A., Grosjean, M., Alvial, I., de Jong, R., Fritz, S. C., & von Gunten, L. (2016). Late Holocene environmental changes as recorded in the sediments of high Andean Laguna Chepical, Central Chile (32° S; 3050ma. sl). Palaeogeography, Palaeoclimatology, Palaeoecology, 461, 44-54.
Dairy slurry application to grasslands and groundwater quality in a volcanic soil.
Huertas, J., Cuevas, J. G., Paulino, L., Salazar, F., Arumí, J. L., & Dörner, J.
Research in volcanic-ash soils has shown that they largely capture the dairy slurry following application to land; however, their hydrological properties would favor nutrient leaching. Our objective was to evaluate the contribution of biogeochemical and hydrological controls on the pollution of groundwater by cattle slurry applied to a permanent grassland growing on a volcanic soil. We sampled groundwater chemistry since 10 months before the fertilization (three samplings), and 16 months after, with samplings 1-2 months after the fertigation. Following fertilization, ammonium, exchangeable potassium, and magnesium soil concentrations increased in the fertilized plots compared to the control plots. In contrast, no effect of slurry on groundwater quality was detected, with the exception of dissolved organic nitrogen, a main component of dairy slurry that increased in the groundwater below the fertilized plots. Despite the fact that biogeochemical controls predominate, hydrological aspects would be important when rainfall is high, evapotranspiration is low, groundwater table level is high, and water movement in the saturated zone increases. We concluded that the application of slurry to pastures under rates comparable to a high fertilization in the short term, does not generally impact the groundwater quality in volcanic ash-derived soils.
Año: 2016
Palabras claves: Andisol; groundwater pollution; hydraulic properties; saturated zone; dissolved organic nitrogen.
Referencia APA: Huertas, J., Cuevas, J. G., Paulino, L., Salazar, F., Arumí, J. L., & Dörner, J. (2016). Dairy slurry application to grasslands and groundwater quality in a volcanic soil. Journal of soil science and plant nutrition, 16(3), 745-762.
Geographic patterns of diversification and the latitudinal gradient of richness of rocky intertidal gastropods: the ‘into the tropical museum’ hypothesis.
Rivadeneira, M., Alballay, A., Villafaña, J., Raimondi, P., Blanchette, C., & Fenberg, P.
The existence of a canonical LGR in rocky intertidal gastropods can be explained by the combined effect of reduced extinction rates in the tropics and the range expansion of taxa from the extra-tropics toward the tropics, in what we have called the ‘into the tropical museum’ hypothesis.
Año: 2015
Palabras claves: Biodiversity; dispersal; diversification dynamics; extinction; fossil record; origination.
Referencia APA: Rivadeneira, M., Alballay, A., Villafaña, J., Raimondi, P., Blanchette, C., & Fenberg, P. (2015). Geographic patterns of diversification and the latitudinal gradient of richness of rocky intertidal gastropods: the ‘into the tropical museum’ hypothesis. Global Ecology And Biogeography, 24(10), 1149-1158.
Mid Holocene radiocarbon ages in the Subtropical Andes (∼29°–35° S), climatic change and implications for human space organization.
Méndez, C., Gil, A., Neme, G., Nuevo Delaunay, A., Cortegoso, V., & Huidobro, C., Durán, V., Maldonado, A.
This article discusses the distribution of radiocarbon age signatures obtained from archeological sites between 29° and 35° S in Central Chile and Midwest Argentina. The goal of this analysis is to establish bases from which to interpret regional trends in the distribution of the archaeological record that connect these areas, which have been traditionally considered to be geographically decoupled. We propose a standardized methodology for selecting ages that provide a reliable human signature. Variations in date frequencies in a regional scale are discussed with the use of summed probability distributions. Radiocarbon voids at the regional level previously identified in Midwest Argentina are explored. Regional chronological information is compared to the available paleoenvironmental records, thereby emphasizing the possible role of climate pulses in the spatial organization of human populations. Significant arid conditions between 7800 and 5700 cal BP are coincidental with a focused occupation of the Andes Mountains, an area which may have offered stable resources and thus was more effectively occupied than other environmental bands.
Año: 2015
Palabras claves: Radiocarbon dates; Climate change; Human paleoecology; Hunter–gatherers; Mid-Holocene; Subtropical Andes.
Referencia APA: Méndez, C., Gil, A., Neme, G., Nuevo Delaunay, A., Cortegoso, V., Huidobro, C., Durán, V. & Maldonado, A. (2015). Mid Holocene radiocarbon ages in the Subtropical Andes (∼29°–35° S), climatic change and implications for human space organization. Quaternary International, 356, 15-26.
Positive interactions by cushion plants in high mountains: fact or artifact?.
Molina-Montenegro, M., Oses, R., Acuña-Rodríguez, I., Fardella, C., Badano, E., & Torres-Morales, P. et al.
Positive interactions are defined as non-trophic interactions where at least one of the interacting species is benefited in terms of fitness and the other remains unaffected. Nevertheless, the bidirectional feedbacks between species may be positive, neutral or negative. Thus, if facilitated species induce negative effects on their ‘nurses’, the assumed definition of positive interactions could be reconsidered.
Año: 2015
Palabras claves: Cushion plants, facilitation, nurse effect, positive interactions, stress gradient hypothesis.
Referencia APA: Molina-Montenegro, M., Oses, R., Acuña-Rodríguez, I., Fardella, C., Badano, E., & Torres-Morales, P. et al. (2015). Positive interactions by cushion plants in high mountains: fact or artifact?. Journal Of Plant Ecology, 9(2), 117-123
Reproduction reduces HSP70 expression capacity in Argopecten purpuratus scallops subject to hypoxia and heat stress.
Brokordt, K., Pérez, H., Herrera, C., & Gallardo, A.
In scallops, gonad production is highly demanding energetically, and reproduction usually occurs during spring-summer, a period of strong environmental changes. The synthesis of heat-shock proteins (HSPs) is a major mechanism of stress tolerance in animals, including scallops, and HSP expression contributes considerably to cellular energy demand. Therefore, reproductive investment may limit the availability of energy (in terms of ATP) for the expression of HSP in organisms exposed to environmental stress. We evaluated the stress response capacity of adult Argopecten purpuratus scallops to high temperature and hypoxia. Stress response capacity was assessed through gene expression (for temperature stress) and protein induction of 70 kD HSP at 3 reproductive stages: immature, mature and spawned. We also evaluated the effect of reproductive status on the cellular ATP provisioning capacity through citrate synthase activity. Immature scallops exposed to thermal stress showed 1.3- and 1.5-fold increases in hsp70 mRNA and HSP70 protein levels, respectively, and those exposed to hypoxia doubled their level of HSP70 compared to non-stressed immature scallops. However, following gonad maturation and spawning, hsp70 mRNA increased by only 0.49- and 0.65-fold, respectively, after thermal stress and HSP70 protein levels of scallops exposed to thermal and hypoxia stressors did not differ from those of non-stressed animals. In parallel, citrate synthase showed its highest level in immature scallops, declined with gonad maturation, and was lowest in spawned scallops. These results suggest that reproductive investment reduces the stress response capacity of A. purpuratus and that mature and spawned scallops could be more vulnerable to environmental stressors than immature individuals.
Año: 2015
Palabras claves: Reproductive cost, HSP70, hsp70 mRNA, Stress response, Thermal stress, Hypoxia stress, Scallops, Argopecten purpuratus.
Referencia APA: Brokordt, K., Pérez, H., Herrera, C., & Gallardo, A. (2015). Reproduction reduces HSP70 expression capacity in Argopecten purpuratus scallops subject to hypoxia and heat stress. Aquat. Biol., 23(3), 265-274.
Estudio de la relación polen-vegetación actual en el Norte de Chile, en el transecto Pozo Almonte-Salar de Huasco (20º15’S/69º06’O).
Collao-alvarado, K., Maldonado, A., González, L., Sandoval, A., De Porras, M., Zamora, A., & Arancio, G.
La diversidad vegetal de la zona andina del Norte Grande de Chile ha sido estudiada desde diversos puntos de vista (florísticos, fisonómicos, etnobotánicos, conservacionistas, etc.); sin embargo, hasta ahora no se ha estudiado desde un punto de vista palinológico. Así, este trabajo tiene como objetivo aportar al conocimiento de la vegetación y su señal polínica en los distintos pisos altitudinales del Norte Grande de Chile, aportando además a la identificación de los principales tipos polínicos presentes. Este estudio presenta la relación entre lluvia de polen y vegetación actual en un transecto altitudinal entre Pozo Almonte y el Salar de Huasco, en el norte de Chile, junto con fotografías y descripciones de 12 morfotipos polínicos representativos de la zona. Los resultados de los muestreos de vegetación corroboran las tendencias descritas en trabajos previos identificándose los principales pisos de vegetación descritos anteriormente (piso prepuneño, puneño, altoandino y subnival). De igual manera los resultados de la lluvia de polen muestran una clara relación con los ensambles de vegetación que la produce, siendo posible diferenciar cada uno de los pisos de vegetación a partir de su señal polínica. Así, los resultados pueden ser de gran interés para la interpretación de registros polínicos fósiles o para estudios de carácter ecológico.
Año: 2015
Palabras claves: Palinología, lluvia de polen, pisos altitudinales, diversidad vegetal.
Referencia APA: Collao-alvarado, K., Maldonado, A., González, L., Sandoval, A., De Porras, M., Zamora, A., & Arancio, G. (2015). Estudio de la relación polen-vegetación actual en el Norte de Chile, en el transecto Pozo Almonte-Salar de Huasco (20º15’S/69º06’O). Gayana Bot., 72(1), 125-136.
A 700-year record of climate and environmental change from a high Andean lake: Laguna del Maule, central Chile (36 S).
Carrevedo, M., Frugone, M., Latorre, C., Maldonado, A., Bernardez, P., & Prego, R. et al.
Central Chile is heavily exploited for mineral and water resources, with agriculture and large urban populations all creating intensive landscape use. Few records of past environmental and climate change are available that afford a broader context. To aid in this assessment, we present a 700-year reconstruction from Laguna del Maule (LdM) in the high Andes of central Chile based on sedimentological, geochemical, diatom and pollen analyses. The age model is based on 210Pb/137Cs and 14C dating tied into known volcanic eruptions. Sedimentology consists of organic-rich sediments and diatom oozes with several interspersed volcanic-rich facies and two tephra deposits. Sediment geochemistry exhibits increased productivity (high Br/Ti, biosilica) and more dominant oxic conditions (high Fe/Mn) from AD 1300 to 1400 and from AD 1650 to 1850, likely during periods of relatively lower lake levels and better development of littoral environments. However, during this later period, high elevation vegetation was dominant, indicative of regional cooler/wetter conditions. In contrast, sediments deposited from AD 1850 to 1930 evidence decreased productivity and increased anoxic lake bottom conditions. The ‘Little Ice Age’ (LIA) in LdM is characterized by significant variations in lake dynamics and hydrology with cooler/wetter conditions (AD 1570–1700), major environmental changes in the 18th century and ending at ca. AD 1850. LdM record documents the impact of the LIA in the southern hemisphere and stresses the global nature of this climate period. Large changes in lake dynamics and diatoms assemblages during the 20th century could be related to anthropogenic impacts, but recent changes in climate patterns cannot be excluded.
Año: 2015
Palabras claves: Chile, diatoms, geochemistry, Late Holocene, Little Ice Age, pollen.
Referencia APA: Carrevedo, M., Frugone, M., Latorre, C., Maldonado, A., Bernardez, P., & Prego, R. et al. (2015). A 700-year record of climate and environmental change from a high Andean lake: Laguna del Maule, central Chile (36 S). The Holocene, 25(6), 956-972.
Isolation and Characterization of 12 Microsatellite Loci in Soapbark, Quillaja saponaria (Quillajaceae).
Letelier, L., Harvey, N., Valderrama, A., Stoll, A., & González-Rodríguez, A.
Premise of the study: Microsatellite primers were developed for the endemic Chilean tree Quillaja saponaria (Quillajaceae), a common member of the sclerophyllous Mediterranean forest, to investigate intraspecific patterns of genetic diversity and structure.
Methods and Results: Using an enriched library, 12 polymorphic microsatellite loci were developed in Q. saponaria. All loci consisted of dinucleotide repeats. The average number of alleles per locus was 5.3 (2–13), with a total of 64 alleles recorded in 39 individuals from three populations.
Conclusions: The microsatellite markers described here are the first characterized for Q. saponaria. The polymorphic loci will be useful in studies of genetic diversity and genetic population differentiation in natural populations of this species.
Año: 2015
Palabras claves: Chile, microsatellites, Quillaja saponaria, Quillajaceae, soapbark.
Referencia APA: Letelier, L., Harvey, N., Valderrama, A., Stoll, A., & González-Rodríguez, A. (2015). Isolation and Characterization of 12 Microsatellite Loci in Soapbark, Quillaja saponaria (Quillajaceae). Applications In Plant Sciences, 3(5), 1500024.
Effects of wind-driven spatial structure and environmental heterogeneity on high-altitude wetland macroinvertebrate assemblages with contrasting dispersal modes.
Bertin, A., Alvarez, E., Gouin, N., Gianoli, E., Montecinos, S., & Lek, S. et al.
Dispersal is a major determinant of connectivity between communities that may modulate the importance of environmental and spatial processes on taxonomic composition. While wind is likely to influence transport distance, rate and direction for numerous species, its effects on community composition remain poorly understood.
Using eigenvector-based spatial analyses, we investigated the influence of wind flows, estimated by mesoscale models, on the spatial structure of benthic macroinvertebrate assemblages with contrasting flying abilities in high Andean wetlands (26–32°S). We further quantified the relative importance of local and regional processes through a variation partitioning approach.
The influence of environmental heterogeneity was prevalent and of relatively similar amplitude in both flying and non-flying assemblages. Significant spatial structure more strongly driven by wind flows than by Euclidean schemes was detected for both assemblages. As expected, the highest levels of spatial structure were observed for the flying macroinvertebrate assemblage and they occurred at a much larger spatial scale in this group, suggesting a greater dispersal aptitude of the flying taxa.
Our results show that environmental effects are predominant in shaping the spatial structure of macroinvertebrate communities in high Andean wetlands, as generally found in other systems. They also demonstrate the significance of wind flows in regulating high-altitude wetland macroinvertebrate communities and illustrate the importance of considering adequate spatial models and biological characteristics of species to advance our understanding of community patterns.
Año: 2015
Palabras claves: Benthic macroinvertebrates; dispersal; eigenvector maps; wetlands; wind.
Referencia APA: Bertin, A., Alvarez, E., Gouin, N., Gianoli, E., Montecinos, S., & Lek, S. et al. (2015). Effects of wind-driven spatial structure and environmental heterogeneity on high-altitude wetland macroinvertebrate assemblages with contrasting dispersal modes. Freshwater Biology, 60(2), 297-310.