CEAZA
Higher plasticity in ecophysiological traits enhances the performance and invasion success of Taraxacum officinale (dandelion) in alpine environments
Molina-Montenegro, M., Peñuelas, J., Munné-Bosch, S., & Sardans, J.
Phenotypic plasticity has long been suggested to facilitate biological invasions in changing environments, allowing a species to maintain a good ecophysiological performance. High-mountain habitats have been particularly useful for evaluation of the relative importance of environmental conditions in the colonization and invasion process, because they have heterogeneous and stressful climatic conditions, inducing photoinhibition. Light intensity is one of the most changing conditions along altitudinal gradients, showing more variability in higher altitudes. In this study, we analyzed the plasticity in photoprotective strategies and performance of the invasive Taraxacum officinale. Additionally, we tested whether higher plasticity enhances competitive ability in an alpine environment We conducted an experiment to evaluate plasticity with a second generation (F2) of T. officinale individuals from 1,600 to 3,600 m, in a greenhouse with variation in light intensity. Treatments consisted of transferring 120 individuals from each altitude to two conditions of light intensity. We then recorded concentrations of photoprotection pigment, de-epoxidation state of the xanthophyll cycle, foliar angles, photochemical efficiency by fluorescence of photosystem II, total dry biomass and flower production. Additionally, we compared plasticity in both photoprotective and performance traits between T. officinale and the co-occurring native species Hypochaeris thrincioides. Finally, we performed a manipulative experiment under two light regimes in order to assess the competitive outcome between the invasive T. officinale and the native H. thrincioides. Individuals from higher altitude showed significantly greater plasticity than individuals from lower altitude. Similarly, individuals under high light intensity showed higher levels of photoprotective pigments, biomass and flower production. On the other hand, the invasive plant species showed significantly greater plasticity than the co-occurring native species, and a strong negative impact on the biomass of the native plant. Phenotypic plasticity seems to be a successful strategy in T. officinale to compete with native species and may be positively associated with the success of invasions, being greater in individuals from more heterogeneous and stressful environments.
Año: 2012
Palabras claves: Altitudinal gradientCompetitionFluorescenceLight intensityPhotoprotective pigmentsXanthophyll cycle
Referencia APA: Molina-Montenegro, M., Peñuelas, J., Munné-Bosch, S., & Sardans, J. (2012). Higher plasticity in ecophysiological traits enhances the performance and invasion success of Taraxacum officinale (dandelion) in alpine environments. Biol Invasions, 14(1), 21-33.
Modelling the Water Sorption Isotherms of Quinoa Seeds (Chenopodium quinoa Willd.) and Determination of Sorption Heats.
Miranda, M., Vega-Gálvez, A., Sanders, M., López, J., Lemus-Mondaca, R., Martínez, E., & Di Scala, K.
Adsorption and desorption isotherms of quinoa seeds (Chenopodium quinoa Willd.) were measured using the static gravimetric method at three temperatures (20, 40 and 60 °C). Water activity ranged from 0.118 to 0.937. The moisture sorption behaviour of quinoa was temperature dependent, as indicated by a decrease in equilibrium moisture content, at all levels of aw, with increasing temperature. Eight mathematical equations available in the literature were used to model the experimental data, namely, GAB, BET, Caurie, Henderson, Oswin, Halsey, Smith and Iglesias–Chirife. All the equations showed generally a good fit; however, the Iglesias–Chirife and Oswin equations were considered the best to predict the experimental data for both isotherms. Effect of temperature on model parameters was analysed and studied through an Arrhenius-type equation. The net isosteric heats of desorption and adsorption were determined by applying the Clausius–Clapeyron equation resulting in 69.24 kJ mol−1 for desorption and 61.26 kJ mol−1 for adsorption. The experimental heat data were satisfactorily modelled by Tsami’s equation.
Año: 2012
Palabras claves: Quinoa, Sorption isotherms, Isosteric sorption heat, Mathematical modelling.
Referencia APA: Miranda, M., Vega-Gálvez, A., Sanders, M., López, J., Lemus-Mondaca, R., Martínez, E., & Di Scala, K. (2012). Modelling the Water Sorption Isotherms of Quinoa Seeds (Chenopodium quinoa Willd.) and Determination of Sorption Heats. Food Bioprocess Technol, 5(5), 1686-1693.
Determinants of the diversity of plants, birds and mammals of coastal islands of the Humboldt current systems: implications for conservation.
Luna-Jorquera, G., Fernández, C., & Rivadeneira, M.
Sound conservation plans for islands require understanding the processes underlying to the patterns of species richness and composition. Larger islands are often the targets of conservation assuming that the island area mainly determines species richness, and that species composition is nested across islands. However, in small-island these patterns could be altered because of stochastic processes, and species assemblages could be disharmonious. In addition, human impact could further modify the distribution pattern and diversity. Here we use the case of seven islands from the coastal system of Coquimbo as a model to address the role of environmental variables and human impacts on species richness and assembly rules of plants, birds, and mammals. We hypothesize (a) the existence of a small-island effect, and the prevalence of habitat diversity and anthropogenic impacts as main drivers of species richness, and (b) the existence of disharmonious assemblages, characterized by a low degree of nestedness and random patterns of species co-occurrence. Our results showed that (a) species richness is mainly correlated with habitat diversity, and only weakly related to island area supporting the ‘small-island effect’ and (b) species composition is highly structured, but that such structure may be the result of anthropogenic activities. Nestedness was observed in plants and landbirds, while co-occurrence patterns were only detected in plants. Assemblages in small-islands departed from the nestedness pattern and maintain rare species. Currently, only three of the seven islands are protected by national regulations, excluding the smaller ones that are subjected to human disturbance and invasive mammals. Our study suggests that it necessary to include all the islands in a major protected area to preserve both richness and species composition of a number of representative islands of the Humboldt current systems. We showed that conservation plans solely based on island area might not be robust.
Año: 2012
Palabras claves: Humboldt, current, Conservation, Small-island effect, Island biogeography.
Referencia APA: Luna-Jorquera, G., Fernández, C., & Rivadeneira, M. (2012). Determinants of the diversity of plants, birds and mammals of coastal islands of the Humboldt current systems: implications for conservation. Biodiversity And Conservation, 21(1), 13-32.
Distribution of Pleuroncodes monodon larvae over the continental shelf of south-central Chile: Field and modeling evidence for partial local retention and transport.
Yannicelli, B., Castro, L., Parada, C., Schneider, W., Colas, F., & Donoso, D.
In situ and modeled spatial distribution of squat lobster (Pleuroncodes monodon) larvae over the continental shelf off south central Chile (35–37°S) was analyzed along with currents and hydrography. We aimed to identify the main larval transport/retention characteristics in the study area, which constitutes the southernmost P. monodon fishing grounds embedded in the Humboldt Current System. We hypothesized that the main contribution to population renewal originates in the two persistent adult aggregations close to the nursery ground that occurs over a continental shelf terrace limited by two submarine canyons. Two extensive bio-physical field campaigns were carried out during the main 2001–2002 upwelling season field data indicated that larvae were released from late austral winter to spring from spots to the north and south of the nursery. Zoea I were found mainly below 50 m depth in southward-flowing waters, whereas older zoea dominated in northward flowing layers above 50 m. Larvae were circumscribed between the coast and the shelf break front and pelagic retention areas were identified over the widest shelf area. Megalopa and juveniles during March, were only found over the nursery area. Individual based simulations coupled to the output of a hydrodynamic model (climatological configuration) for the studied area, showed that the release sites close to the nursery made the largest contribution to recruitment. Sites further north could also contribute to recruitment if hatching occurred later in the upwelling season. The contribution of vertical behavior to larval success was also important, as was the former’s interaction with the site and time of larval release. Our results support the relevance of coastal circulation (affected by topography) on the persistence of P. monodon populations off southern Chile, and the modulation of temporal variability. These results might apply to other abundant species in the area.
Año: 2012
Palabras claves:
Referencia APA: Yannicelli, B., Castro, L., Parada, C., Schneider, W., Colas, F., & Donoso, D. (2012). local Distribution of Pleuroncodes monodon larvae over the continental shelf of south-central Chile: Field and modeling evidence for partial retention and transport. Progress In Oceanography, 92-95, 206-227.
What do we know about high-altitude precipitation in the semi-arid Andes of Chile?
Bourgin P, Andreassian V, Gascoin S, Valery A.
Mapping precipitations on a regular grid is often required for hydrological and ecological modelling. The spatial interpolation methods are generally used to estimate such a distribution from ground-based measurements. In the case of mountainous areas, the estimation of precipitation amounts is still a challenging task and the results of spatial interpolation should be verified as much as possible. Here we describe a three-steps method for the validation of a precipitation map. This is used in the context of a mountainous semi-arid region, the Norte Chico in Chile (26°S-32°S). The implementation of this validation method showed the benefits of an interpolation method developed by Valéry [2010] for mountainous areas. The hydrological balance of the high-altitude watersheds is now more realistic.
Año: 2012
Palabras claves: Precipitation, spatial interpolation method, extrapolation, altitude, altitudinal corrections, validation, water equivalent, water balance.
Referencia APA: Bourgin P, Andreassian V, Gascoin S, Valery A. (2012). Que sait-on des précipitations en altitude dans les Andes semi-arides du Chili?. La Houille Blanche. 2012;(2):12-17.