CEAZA
Estimating Spatial Distribution of Air Temperature from Meteorological Stations Using Atmospheric Model.
Montecinos, S., Bascuñán-Godoy, L., Salinas, P., Astudillo, O., & Lopez, D.
Planning agricultural procedures needs to take into account meteorological conditions. However, because of high associated costs, the density of meteorological stations is often not enough to cover all the cultivated or potentially cultivated areas. In this article we present a methodology to estimate seasonal maximum and minimum mean temperature in cultivated area using data registered in a sole or a few meteorological stations. The procedure is based on mesoscale modeling, which allows meteorological variables to be spatially distributed considering synoptic data and local characteristics.
Simulated daily cycle of temperature was compared with data registered at six meteorological stations located in the cultivated floor of the semiarid Limari Valley (Chile, 31°S). Although in some cases the simulated temperature differs in about 2°C with the observed one, a good fit between model results and experimental data was observed. Using the simulated seasonal minimum and maximum mean temperature fields, maps of temperature differences with respect to a reference station were drawn. In order to observe the influence of the orography on the lapse rate around a station, the methodology was applied for two reference stations located in places with different orographic characteristics. Results for winter and summer seasons are shown.
These generated maps can be used by farmers and agricultural planners to obtain information of seasonal minimum and maximum mean temperature from a station in any site of the cultivated area. This technique is a good alternative to obtain meteorological information at low costs, contributing to territorial planning for climate resilient agriculture sustainability.
Año: 2013
Palabras claves:
Referencia APA: Montecinos, S., Bascuñán-Godoy, L., Salinas, P., Astudillo, O., & Lopez, D. (2013). Estimating Spatial Distribution of Air Temperature from Meteorological Stations Using Atmospheric Model. Journal Of Agricultural Science, 5(2).
Positive interactions between the lichen Usnea antarctica (Parmeliaceae) and the native flora in Maritime Antarctica.
Molina-Montenegro, M., Ricote-Martínez, N., Muñoz-Ramírez, C., Gómez-González, S., Torres-Díaz, C., Salgado-Luarte, C., & Gianoli, E.
Eight out of 13 species were positively associated with cushions of the widespread lichen U. antarctica, while only one species (U. aurantiaco-atra) showed a negative association with U. antarctica. Survival of Deschampsia was enhanced when growing associated with U. antarctica cushions. Our results indicate that cushions ameliorated the extreme conditions of Antarctic islands through increased temperature and soil moisture, decreased radiation and evaporative water loss and increased nutrient availability.
Año: 2013
Palabras claves: Antarctica; Deschampsia antarctica ; Facilitation; Global warming; Lichens; Mosses; Nurse effect.
Referencia APA: Molina-Montenegro, M., Ricote-Martínez, N., Muñoz-Ramírez, C., Gómez-González, S., Torres-Díaz, C., Salgado-Luarte, C., & Gianoli, E. (2013). Positive interactions between the lichen Usnea antarctica (Parmeliaceae) and the native flora in Maritime Antarctica. J Veg Sci, 24(3), 463-472. http://dx.doi.org/10.1111/j.1654-1103.2012.01480.x
Environmental Hypoxia Reduces the Escape Response Capacity of Juvenile and Adult Scallops Argopecten purpuratus.
Brokordt, K., Pérez, H., & Campos, F.
Natural beds and cultures of the scallop Argopecten purpuratus are exposed to hypoxia periodically because they are located near upwelling zones. We evaluated the effects of environmental hypoxia on juvenile and adult scallops' escape responses and recovery capacities using 3 different hypoxic cycle (i.e., a gradual decrease and increase of dissolved oxygen) trials. Trials 1 and 2 consisted of single (1-day) hypoxic cycles; trial 3 included exposure to several consecutive daily hypoxic cycles over 7 days, which occurs in the natural environment. Trial 1 evaluated the combined effects of energy demands from escape responses and metabolism on escape responses. during environmental hypoxia. Trial 2 evaluated only the effect of environmental hypoxia on the escape responses. Before and after the hypoxic cycles, the scallops were exposed to their main predator, the sea star Meyenaster gelatinosus. We evaluated 6 indicators of the scallops' escape response: reaction time, the total number of claps, duration of the clapping response until exhaustion, clapping speed, the proportion of claps, and recovery clapping rate after a recuperation of 5 min or 10 min (for juveniles and adults, respectively). The combined effect of functional and environmental hypoxia (trial 1) affected both juvenile and adult escape responses, with a reduction in their number of claps (15% and 25%, respectively), the clapping rate in juveniles (17%), and the clapping time in adults (19%). However, environmental hypoxia alone (trial 2) affected juvenile escape responses only, with a reduction in their number of claps (18%) and clapping rate (17%). After hypoxic exposure in trial 3, adults only showed a reduced escape capacity (clap number and clapping time of 16% and 17%, respectively), although both adult and juvenile scallops had a reduced capacity to recuperate their initial clap number (18% and 23%, respectively) and clapping rate (21% and 17%, respectively). Recovery capacity was associated with a strong reduction in phasic muscle carbohydrates during this period. Overall, hypoxia reduced the escape capacity of A. purpuratus, which may implicate a higher vulnerability to predation (for natural populations) and a decreased physiological status to support other stress factors (for cultured or natural populations).
Año: 2013
Palabras claves: Hypoxia, scallops, escape response, Argopecten purpuratus.
Referencia APA: Brokordt, K., Pérez, H., & Campos, F. (2013). Environmental Hypoxia Reduces the Escape Response Capacity of Juvenile and Adult Scallops Argopecten purpuratus. Journal Of Shellfish Research, 32(2), 369-376
Wind effects on snow cover in Pascua-Lama, Dry Andes of Chile.
Gascoin, S., Lhermitte, S., Kinnard, C., Bortels, K., & Liston, G.
We present the first application of a distributed snow model (SnowModel) in the instrumented site of Pascua-Lama in the Dry Andes (2600–5630 m above sea level, 29° S). A model experiment was performed to assess the effect of wind on the snow cover patterns. A particular objective was to evaluate the role of blowing snow on the glacier formation. The model was run using the data from 11 weather stations over a complete snow season. First, a cross-validation of the meteorological variables interpolation model (MicroMet submodel) was performed to evaluate the performance of the simulated meteorological forcing. Secondly, two SnowModel simulations were set up: one without and the other with the wind transport submodel (SnowTran-3D). Results from both simulations were compared with in situ snow depth measurements and remotely sensed snow cover data. The inclusion of SnowTran-3D does not change the fact that the model is unable to capture the small-scale snow depth spatial variability (as captured by in situ snow depth sensors). However, remote sensing data (MODIS daily snow product) indicate that at broader scales the wind module produced an improved representation of the snow distribution near the glaciers (2-D correlation coefficient increased from R = 0.04 to R = 0.27). The model outputs show that a key process is the sublimation of blowing snow, which amounts to 18% of the total ablation over the whole study area, with a high spatial variability. The effect of snow drift is more visible on the glaciers, where wind-transported snow accumulates preferentially. Net deposition occurred for 43% of the glacier grid points, whereas it is only 23% of non-glacier grid points located above the minimum glacier altitude (4475 m).
Año: 2013
Palabras claves: Snow; Glacier; Wind; Sublimation; Andes; MODIS.
Referencia APA: Gascoin, S., Lhermitte, S., Kinnard, C., Bortels, K., & Liston, G. (2013). Wind effects on snow cover in Pascua-Lama, Dry Andes of Chile. Advances In Water Resources, 55, 25-39.
Barotropic and baroclinic semidiurnal tidal currents in two contrasting coastal upwelling zones of Chile.
Bravo, L., Ramos, M., Sobarzo, M., Pizarro, O., & Valle-Levinson, A.
Current velocity observations from the continental shelves of Coquimbo (~30°S) and Concepcion (~36°30'S), central Chile, were analyzed to evaluate the role of water column stratification and shelf width on baroclinic semidiurnal tidal currents. Semidiurnal barotropic currents off both zones were typically < 5 cm/s, but depth-dependent semidiurnal flows could exceed 10 cm s-1 during stratified conditions. Both zones are recognized as pronounced upwelling centers, with maximum upwelling-favorable winds in spring and summer, respectively. At the northern zone, stratification was mainly controlled by temperature differences between surface and bottom waters with maximum stratification during summer. The southern zone showed more stratification during winter because of freshwater input from local rivers. Consequently, greater variability in the baroclinic semidiurnal currents was observed during summer at the northern continental shelf and in winter at the south. In both regions, much of the semidiurnal variability was consistent with an internal wave's first baroclinic mode of wavelengths of ~10–13 km. Nevertheless, during the period of maximum energy fluxes off the north, the second baroclinic mode (wavelength ~7 km) was also important and matched periods of low upwelling index (relaxation of upwelling favorable winds). Typical energy fluxes during summer integrated in the water column, related to the semidiurnal internal tides were 0.12 W/m of the northern site and 0.1 W/m off the southern site. Possible sites of internal wave generation off the south were the Biobío submarine canyon and the slope/shelf break, while off the north, the generation site was the slope/shelf break.
Año: 2013
Palabras claves: Baroclinic waves; semidiurnal; energy flux.
Referencia APA: Bravo, L., Ramos, M., Sobarzo, M., Pizarro, O., & Valle-Levinson, A. (2013). Barotropic and baroclinic semidiurnal tidal currents in two contrasting coastal upwelling zones of Chile. J. Geophys. Res. Oceans, 118(3), 1226-1238
Within-population genetic diversity of climbing plants and trees in a temperate forest in central Chile.
Torres-Díaz, C., Ruiz, E., Salgado-Luarte, C., Molina-Montenegro, M., & Gianoli, E.
The climbing habit is a key innovation in angiosperm evolution: climbing plant taxa have greater species richness than their non-climbing sister groups. It is considered that highly diversified clades should show increased among-population genetic differentiation. Less clear is the expected pattern regarding within-population genetic diversity in speciose lineages. We tested the hypothesis of greater within-population genetic diversity in climbing plants compared to trees in a temperate forest in central Chile. The assumption underlying this hypothesis is that higher among-population differentiation in climbers compared to trees should reflect higher genetic diversity as well. AFLP markers from 167 individual plants from 14 species (seven climbers and seven trees) were used to estimate the following indices of within-population genetic diversity: mean unbiased expected heterozygosity (He), percentage of polymorphic loci (PPL), Shannon information index (I), and the effective number of alleles (Ne). Overall, within-population genetic diversity did not differ between climbing plants and trees. The He for climbing plants was slightly higher than that of trees (0.247 vs. 0.231), and PPL was higher in trees (93.6) than in climbers (81.8), but these differences were not statistically significant. Both I and Ne were very similar for both groups. The expected greater genetic diversity in climbers might have been counterbalanced by tree-related ecological factors that turned to be relevant in the species assemblages studied. Results of this preliminary study should be further confirmed with a broader approach including several forest sites and larger sample sizes.
Año: 2013
Palabras claves: AFLP, climbers, evolution, genetic variability, key innovation.
Referencia APA: Torres-Díaz, C., Ruiz, E., Salgado-Luarte, C., Molina-Montenegro, M., & Gianoli, E. (2013). Within-population genetic diversity of climbing plants and trees in a temperate forest in central Chile. Gayana Bot., 70(1), 36-43
Different photoprotective responses under drought conditions of two predominant Chilean swamp forest species.
Bascuñán-Godoy, L., Alcaíno, C., Carvajal, D., Sanhueza, C., Montecinos, S., & Maldonado, A.
Myrceugenia exsucca (DC.) O.Berg (Myrtaceae) and Luma chequen (Molina) A. Gray (Myrtaceae) are two predominants species from swamp forests of Chile. These species present differential microhabitat distribution across soil moisture and north-south precipitation gradients, with only L. chequen being commonly found in lower moisture sites. It is hypothesized that L. chequen has greater plasticity than M. exsucca in the attributes involved in photoprotection under drought conditions. To test this hypothesis: both species were exposed to short term drought treatment. A group of individuals was maintained irrigated (with of -0.58 and -0.73 MPa for M. exsucca and L. chequen, respectively), while another group was exposed to drought treatment with around -1.4 MPa ( D). High relationship was founded between relative water content (RWC) and water potential () forM. exsucca (r2= 0.74) more than for L. chequen (r2= 0.46), indicating thatM. exsucca experienced larger dehydration during the drought treatment. As functional attributes of photosynthetic apparatus, amount of total chlorophyll and chlorophyll a fluorescence parameter levels were studied in both species. The results show that L. chequen reduced total content of chlorophylls and maximum efficiency of PSII (Fv / Fm) related to decrease of energy capture increasing significantly the thermal dissipation (qN). On the other hand, M. exsucca does not change these parameters, but significantly reduced the level of photochemical processes (qL), indicating an energy imbalance. The results indicate M. exsucca has less plasticity than L. chequen under drought conditions. It is believed that these differences may be crucial in the establishment period and may be influencing the limited distribution ofM. exsucca in sites with lower water availability.
Año: 2013
Palabras claves: Thermal dissipation, water potential, native plants, Myrtaceae family, wetland plants.
Referencia APA: Bascuñán-Godoy, L., Alcaíno, C., Carvajal, D., Sanhueza, C., Montecinos, S., & Maldonado, A. (2013). Different photoprotective responses under drought conditions of two predominant Chilean swamp forest species. Gayana Bot., 70(2), 267-274.
Meteorological drivers of ablation processes on a cold glacier in the semi-arid Andes of Chile.
MacDonell, S., Kinnard, C., Mölg, T., Nicholson, L., & Abermann, J.
Meteorological and surface change measurements collected during a 2.5 yr period are used to calculate surface mass and energy balances at 5324 m a.s.l. on Guanaco Glacier, a cold-based glacier in the semi-arid Andes of Chile. Meteorological conditions are marked by extremely low vapour pressures (annual mean of 1.1 hPa), strong winds (annual mean of 10 m s−1), shortwave radiation receipt persistently close to the theoretical site maximum during cloud-free days (mean annual 295 W m−2; summer hourly maximum 1354 W m−2) and low precipitation rates (mean annual 45 mm w.e.). Snowfall occurs sporadically throughout the year and is related to frontal events in the winter and convective storms during the summer months. Net shortwave radiation provides the greatest source of energy to the glacier surface, and net longwave radiation dominates energy losses. The turbulent latent heat flux is always negative, which means that the surface is always losing mass via sublimation, which is the main form of ablation at the site. Sublimation rates are most strongly correlated with net shortwave radiation, incoming shortwave radiation, albedo and vapour pressure. Low glacier surface temperatures restrict melting for much of the period, however episodic melting occurs during the austral summer, when warm, humid, calm and high pressure conditions restrict sublimation and make more energy available for melting. Low accumulation (131 mm w.e. over the period) and relatively high ablation (1435 mm w.e.) means that mass change over the period was negative (−1304 mm w.e.), which continued the negative trend recorded in the region over the last few decades.
Año: 2013
Palabras claves:
Referencia APA: MacDonell, S., Kinnard, C., Mölg, T., Nicholson, L., & Abermann, J. (2013). Meteorological drivers of ablation processes on a cold glacier in the semi-arid Andes of Chile. The Cryosphere, 7(5), 1513-1526. http://dx.doi.org/10.5194/tc-7-1513-2013
Major hydrological regime change along the semiarid western coast of South America — Response to comments by Maldonado and Moreiras [page number in this issue].
Ortega, C., Vargas, G., & Rutllant, J.
Based on the sedimentology, geomorphology and geochronology of eolian and alluvial deposits at Quebrada Santa Julia (QSJ, 31°50′S) site, in a small coastal watershed in the semiarid central Chile, Ortega et al. (2012) interpreted a regional arid climate setting concomitantly with high local humidity due to reinforced coastal fog development between 13,000 and 8600 cal yr BP. Together with other continental proxies and paleo-SST records off central Chile, Ortega et al. (2012) proposed La Niña-like conditions during the latest Pleistocene‒early Holocene along this semiarid coast. A major hydrologic regime shift shortly after 8600 cal yr BP resulted in higher frequency of torrential rainfall episodes still under an arid climate setting, before the onset of El Niño at ~ 5500 cal yr BP (e.g., Rodbell et al., 1999). This hypothesis differs from that of Maldonado and Moreiras (2013) based on pollen records, who suggest humid conditions associated with precipitation around 13,000 and 10,500 cal yr BP (e.g., Maldonado et al., 2010).
Año: 2013
Palabras claves: Early Holocene; Coastal fog; Rainfall; Hydrologic change; Lifting condensation level; Sea level.
Referencia APA: Ortega, C., Vargas, G., & Rutllant, J. (2013). Major hydrological regime change along the semiarid western coast of South America — Response to comments by Maldonado and Moreiras [page number in this issue]. Quaternary Research, 80(1), 140-142.
Ecophysiological plasticity and local differentiation help explain the invasion success of Taraxacum officinale (dandelion) in South America.
Molina-Montenegro, M., Palma-Rojas, C., Alcayaga-Olivares, Y., Oses, R., Corcuera, L., Cavieres, L., & Gianoli, E.
Plasticity and local adaptation have been suggested as two main mechanisms that alien species use to successfully tolerate and invade broad geographic areas. In the present study, we try answer the question if the mechanism for the broad distributional range of T. officinale is for phenotypic plasticity, ecotypic adaptation or both. For this, we used individuals of T. officinale originated from seeds collected in five localities along its latitudinal distribution range in the southern-hemisphere. Seedlings were acclimated at 5 and 25°C for one month. After the acclimation period we evaluated ecophysiological and cytogenetic traits. Additionally, we assessed the fitness at each temperature by recording the seed output of individuals from different localities. Finally, we performed a manipulative experiment in order to assess the tolerance to herbivory and competitive ability between T. officinale from all origins and Hypochaeris scorzonerae a co-occurring native species. Overall, individuals of T. officinale showed high plasticity and ecotypic adaptation for all traits assessed in this study. Changes both in physiology and morphology observed in T. officinale from different origins were mostly correlated, enhancing their ecophysiological performance in temperatures similar to those of their origin. Additionally, all localities showed the same chromosome number and ploidy level. On the other hand, all individuals showed an increase the seed output at 25°C, but those from northern localities increased more. T. officinale from all origins was not significantly affected by herbivory while native showed a negative effect. On the other hand, T. officinale exerted a strong negative effect on the native species, but this former not effected significantly to the invasive T. officinale. High plasticity and local adaptation in all ecophysiological traits, seed-set and the low cytogenetic variability in T. officinale suggests that both strategies are present in this invasive plant species and are not mutually exclusive. Finally, higher tolerance to herbivory and competitive ability suggests that T. officinale could perform successfully in environments with different climatic conditions, and thus colonize and invade South-America.
Año: 2013
Palabras claves:
Referencia APA: Molina-Montenegro, M., Palma-Rojas, C., Alcayaga-Olivares, Y., Oses, R., Corcuera, L., Cavieres, L., & Gianoli, E. (2013). Ecophysiological plasticity and local differentiation help explain the invasion success of Taraxacum officinale (dandelion) in South America. Ecography, 36(6), 718-730.
Is Physiological Performance a Good Predictor for Fitness? Insights from an Invasive Plant Species.
Molina-Montenegro, M., Salgado-Luarte, C., Oses, R., & Torres-Díaz, C.
Is physiological performance a suitable proxy of fitness in plants? Although, several studies have been conducted to measure some fitness-related traits and physiological performance, direct assessments are seldom found in the literature. Here, we assessed the physiology-fitness relationship using second-generation individuals of the invasive plant species Taraxacum officinale from 17 localities distributed in five continents. Specifically, we tested if i) the maximum quantum yield is a good predictor for seed-output ii) whether this physiology-fitness relationship can be modified by environmental heterogeneity, and iii) if this relationship has an adaptive consequence for T. officinale individuals from different localities. Overall, we found a significant positive relationship between the maximum quantum yield and fitness for all localities evaluated, but this relationship decreased in T. officinale individuals from localities with greater environmental heterogeneity. Finally, we found that those individuals from localities where environmental conditions are highly seasonal performed better under heterogeneous environmental conditions. Contrarily, under homogeneous controlled conditions, those individuals from localities with low environmental seasonality performed much better. In conclusion, our results suggest that the maximum quantum yield seem to be good predictors for plant fitness. We suggest that rapid measurements, such as those obtained from the maximum quantum yield, could provide a straightforward proxy of individual’s fitness in changing environments.
Año: 2013
Palabras claves: Plant physiology, Photosynthesis, Seeds, Physiological adaptation, Chlorophyll, Rain, Invasive species, Ecophysiology.
Referencia APA: Molina-Montenegro, M., Salgado-Luarte, C., Oses, R., & Torres-Díaz, C. (2013). Is Physiological Performance a Good Predictor for Fitness? Insights from an Invasive Plant Species. Plos ONE, 8(10), e76432. http://dx.doi.org/10.1371/journal.pone.0076432
Internal structure and composition of a rock glacier in the Andes (upper Choapa valley, Chile) using borehole information and ground-penetrating radar.
Monnier, S. & Kinnard, C.
This study uses boreholes, ground temperature monitoring and ground-penetrating radar (GPR) in order to understand the internal structure and composition of a rock glacier in the upper Choapa valley, northern Chile. The rock glacier is a small valley-side feature, 200 m long and ranging between 3710 and 3780 m a.s.l. Two boreholes were drilled down to depths of 20 and 25 m, respectively, using the diamond drillhole technique. An ice–rock mixture was encountered in the boreholes, with heterogeneous ice content averaging 15–30%. Data from common-midpoint (CMP) and constant-offset (CO) GPR surveys acquired, respectively, near the boreholes and across the whole rock glacier were processed to highlight the internal stratigraphy and variations in the radar-wave velocity. The GPR profiles depict a rock glacier constituted of stacked and generally concordant layers, with a thickness ranging from 10 m in its upper part to ∼30 m towards its terminus. The CMP analysis highlights radar-wave velocities of 0.13–0.16 m ns–1 in the first 20 m of the structure. Larger vertical and lateral velocity variations are highlighted from CO data, reflecting the heterogeneous composition of the rock glacier and the likely presence of unfrozen water in the structure. Given the average air temperature registered at the site (+0.5°C), the near-melting-point temperature registered in the boreholes over more than a year and the presence of locally high water content inferred from GPR data, it is thought that the permafrost in the rock glacier is currently degrading.
Año: 2013
Palabras claves:
Referencia APA: Monnier, S. & Kinnard, C. (2013). Internal structure and composition of a rock glacier in the Andes (upper Choapa valley, Chile) using borehole information and ground-penetrating radar. Annals Of Glaciology, 54(64), 61-72.