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Angélica Casanova-katny - One of the best experts on this subject based on the ideXlab platform.
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Competition between native Antarctic vascular plants and invasive Poa annua changes with temperature and soil nitrogen availability
Biological Invasions, 2017Co-Authors: Lohengrin A. Cavieres, Ana Karen Sanhueza, Gustavo Torres-mellado, Angélica Casanova-katnyAbstract:Over the last decades human have introduced non-native organisms to Antarctica, including the grass species Poa annua. This non-native grass under constant growth temperatures has been shown negatively affect the growth of the only two native Antarctic vascular plants, Deschampsia antarctica and Colobanthus quitensis, under constant growth temperatures. However, whether there are changes in the interaction between these species under warmer conditions is an important question. In cold ecosystems, soil nutrient status directly affects plant responses to increases in temperature and Antarctic soils are highly variable in nutrient supply. Thus, in this study we experimentally assessed the interaction between the non-native Poa with the two native Antarctic vascular plant species at two different temperatures and levels of nutrient availability. Individual mats of the study species were collected in King George Island, and then transported to Concepcion where we conducted competition experiments. In the first experiment we used soil similar to that of Antarctica and plants in competition were grown at two temperatures: 5°/2° and 11°/5 °C (day/night temperature). In a second experiment plants were grown in these two temperature regimes, but we varied nitrogen (N) availability by irrigating plants with Hoagland solutions that contained 8000 or 300 µM of N. Overall, Poa exerted a Competitive Effect on Deschampsia but only at the higher temperature and higher N availability. At 5°/11 °C the Competitive response of Deschampsia to Poa was of similar magnitude to the Competitive Effect of P. Deschampsia, and the Competitive Effect was greater with at low N. The Competitive Effect of Poa was similar to the Competitive response of Colobanthus to Poa at both temperatures and N levels. Thus, at low temperatures and N soil content the native Antarctic species might withstand Poa invasion, but this might change with climate warming.
Lohengrin A. Cavieres - One of the best experts on this subject based on the ideXlab platform.
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Competition between native Antarctic vascular plants and invasive Poa annua changes with temperature and soil nitrogen availability
Biological Invasions, 2017Co-Authors: Lohengrin A. Cavieres, Ana Karen Sanhueza, Gustavo Torres-mellado, Angélica Casanova-katnyAbstract:Over the last decades human have introduced non-native organisms to Antarctica, including the grass species Poa annua. This non-native grass under constant growth temperatures has been shown negatively affect the growth of the only two native Antarctic vascular plants, Deschampsia antarctica and Colobanthus quitensis, under constant growth temperatures. However, whether there are changes in the interaction between these species under warmer conditions is an important question. In cold ecosystems, soil nutrient status directly affects plant responses to increases in temperature and Antarctic soils are highly variable in nutrient supply. Thus, in this study we experimentally assessed the interaction between the non-native Poa with the two native Antarctic vascular plant species at two different temperatures and levels of nutrient availability. Individual mats of the study species were collected in King George Island, and then transported to Concepcion where we conducted competition experiments. In the first experiment we used soil similar to that of Antarctica and plants in competition were grown at two temperatures: 5°/2° and 11°/5 °C (day/night temperature). In a second experiment plants were grown in these two temperature regimes, but we varied nitrogen (N) availability by irrigating plants with Hoagland solutions that contained 8000 or 300 µM of N. Overall, Poa exerted a Competitive Effect on Deschampsia but only at the higher temperature and higher N availability. At 5°/11 °C the Competitive response of Deschampsia to Poa was of similar magnitude to the Competitive Effect of P. Deschampsia, and the Competitive Effect was greater with at low N. The Competitive Effect of Poa was similar to the Competitive response of Colobanthus to Poa at both temperatures and N levels. Thus, at low temperatures and N soil content the native Antarctic species might withstand Poa invasion, but this might change with climate warming.
Antonella Rossi - One of the best experts on this subject based on the ideXlab platform.
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Influence of Major Anions on As(V) Adsorption by Synthetic 2-line Ferrihydrite. Kinetic Investigation and XPS Study of the Competitive Effect of Bicarbonate
Water Air and Soil Pollution, 2009Co-Authors: Franco Frau, D. Addari, Davide Atzei, Riccardo Biddau, Rosa Cidu, Antonella RossiAbstract:The potential Competitive Effect of background electrolytes (Na2HPO4·2H2O, NaHCO3, Na2SO4 and NaCl solutions) on arsenate adsorption onto synthetic 2-line ferrihydrite has been studied by means of kinetic batch experiments conducted at pH values from 4.0 to 10.0 and at anionic concentrations of 0.01 and 0.1 M. The results indicate that the adsorptive capacity of ferrihydrite for arsenate decreases strongly in the presence of phosphate species at pH in the range of 4–10 and in the presence of bicarbonate at pH 8.3 as a consequence of their Competitive Effect. Analogously to phosphate, a surface interaction of inner-sphere type between ferrihydrite and bicarbonate is suggested. Chloride has negligible Effects on arsenate adsorption processes, confirming it as an outer-sphere ion that does not compete with the inner-sphere binding peculiar to arsenate onto ferrihydrite. Sulphate exhibits an intermediate behaviour; at 0.01 M concentration, the Competitive Effect of sulphate is similar to that of chloride, whereas at 0.1 M concentration sulphate shows a moderate influence on arsenate adsorption. The results of the kinetic studies can be summarised by the following order of Competitive capacity: phosphate > carbonate > sulphate > chloride. The process of arsenate adsorption follows pseudo-second order kinetics and the reaction half-time notably increases in the presence of strong competitor anions such as phosphate and carbonate with respect to an inEffective competitor anion such as chloride. Modelling of arsenate adsorption with PHREEQC, according to the Generalized Two-Layer Model, confirms that the pH Effect is notably less important than the Competitive Effect of carbonate species in determining the amount of arsenate adsorbed onto ferrihydrite at pH 8.3 in 0.1 M NaHCO3 solution, whereas the model greatly underestimates the Competitive Effect of carbonate species at pH 8.3 in 0.01 M NaHCO3 solution. The results of the batch experiments in 0.1 M NaHCO3 solution are substantiated by XPS analyses of ferrihydrite after immersion in the same solution, both with and without dissolved arsenate. XPS confirms the interaction between ferrihydrite surface and arsenate; the binding energy of As3d shifts towards higher binding energies after adsorption with respect to the pure compound Na2HAsO4·7H2O taken as reference standard. In presence of carbonate species, the As3d binding energy is found at intermediate values. XPS quantitative analysis shows a depletion of arsenate on ferrihydrite surface, providing further evidence of the competition of the two species (i.e. arsenate and bicarbonate) for the ferrihydrite adsorption sites. Important environmental implications concerning arsenic mobility, as well as possible application in various fields (e.g. irrigation agriculture, soil decontamination, water treatment), might derive from these findings.
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Influence of Major Anions on As(V) Adsorption by Synthetic 2-line Ferrihydrite. Kinetic Investigation and XPS Study of the Competitive Effect of Bicarbonate
Water Air and Soil Pollution, 2009Co-Authors: Franco Frau, D. Addari, Davide Atzei, Riccardo Biddau, Rosa Cidu, Antonella RossiAbstract:The potential Competitive Effect of background electrolytes (Na(2)HPO(4) center dot 2H(2)O, NaHCO(3), Na(2)SO(4) and NaCl solutions) on arsenate adsorption onto synthetic 2-line ferrihydrite has been studied by means of kinetic batch experiments conducted at pH values from 4.0 to 10.0 and at anionic concentrations of 0.01 and 0.1 M. The results indicate that the adsorptive capacity of ferrihydrite for arsenate decreases strongly in the presence of phosphate species at pH in the range of 4-10 and in the presence of bicarbonate at pH 8.3 as a consequence of their Competitive Effect. Analogously to phosphate, a surface interaction of inner-sphere type between ferrihydrite and bicarbonate is suggested. Chloride has negligible Effects on arsenate adsorption processes, confirming it as an outer-sphere ion that does not compete with the inner-sphere binding peculiar to arsenate onto ferrihydrite. Sulphate exhibits an intermediate behaviour; at 0.01 M concentration, the Competitive Effect of sulphate is similar to that of chloride, whereas at 0.1 M concentration sulphate shows a moderate influence on arsenate adsorption. The results of the kinetic studies can be summarised by the following order of Competitive capacity: phosphate > carbonate > sulphate > chloride. The process of arsenate adsorption follows pseudo-second order kinetics and the reaction half-time notably increases in the presence of strong competitor anions such as phosphate and carbonate with respect to an inEffective competitor anion such as chloride. Modelling of arsenate adsorption with PHREEQC, according to the Generalized Two-Layer Model, confirms that the pH Effect is notably less important than the Competitive Effect of carbonate species in determining the amount of arsenate adsorbed onto ferrihydrite at pH 8.3 in 0.1 M NaHCO(3) solution, whereas the model greatly underestimates the Competitive Effect of carbonate species at pH 8.3 in 0.01 M NaHCO(3) solution. The results of the batch experiments in 0.1 M NaHCO(3) solution are substantiated by XPS analyses of ferrihydrite after immersion in the same solution, both with and without dissolved arsenate. XPS confirms the interaction between ferrihydrite surface and arsenate; the binding energy of As3d shifts towards higher binding energies after adsorption with respect to the pure compound Na(2)HAsO(4)center dot 7H(2)O taken as reference standard. In presence of carbonate species, the As3d binding energy is found at intermediate values. XPS quantitative analysis shows a depletion of arsenate on ferrihydrite surface, providing further evidence of the competition of the two species (i.e. arsenate and bicarbonate) for the ferrihydrite adsorption sites. Important environmental implications concerning arsenic mobility, as well as possible application in various fields (e.g. irrigation agriculture, soil decontamination, water treatment), might derive from these findings
Elsa E. Cleland - One of the best experts on this subject based on the ideXlab platform.
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Different traits predict Competitive Effect versus response by Bromus madritensis in its native and invaded ranges
Biological Invasions, 2018Co-Authors: Chandler E. Puritty, Margaret M. Mayfield, Francisco M. Azcárate, Elsa E. ClelandAbstract:Community assembly and coexistence theories predict that both fitness and plant functional traits should influence Competitive interactions between native and invasive species. The evolution of the increased Competitive ability hypothesis predicts that species will grow larger (a measure of fitness) in their invaded than native range; hence we hypothesized that species might exert greater Competitive Effects in their invaded range, lessening the importance of functional traits for Competitive outcomes. In a greenhouse experiment we compared traits and Competitive interactions between Bromus madritensis (an annual grass) and resident species from its native range in Spain, and its invaded range in Southern California. As predicted, B. madritensis collected in California grew larger and had a greater Competitive Effect on resident species than B. madritensis collected in Spain. However, residents from California also suppressed the growth of B. madritensis more than species from its native range in Spain. Competitive interaction strengths were predicted by different suites of traits in the native versus invaded range of B. madritensis; surprisingly, however, size of the resident species (fitness), did not predict variation in Competitive interactions. This study shows that different suites of traits may aid in identifying those native species likely to strongly compete with invaders, versus those that will be Competitively suppressed by invaders, with important implications for the design of restoration efforts aimed at promoting native species growth and preventing invasion. More generally, our study shows that fitness differences may not be as important as traits when predicting Competitive outcomes in this system.
Ana Karen Sanhueza - One of the best experts on this subject based on the ideXlab platform.
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Competition between native Antarctic vascular plants and invasive Poa annua changes with temperature and soil nitrogen availability
Biological Invasions, 2017Co-Authors: Lohengrin A. Cavieres, Ana Karen Sanhueza, Gustavo Torres-mellado, Angélica Casanova-katnyAbstract:Over the last decades human have introduced non-native organisms to Antarctica, including the grass species Poa annua. This non-native grass under constant growth temperatures has been shown negatively affect the growth of the only two native Antarctic vascular plants, Deschampsia antarctica and Colobanthus quitensis, under constant growth temperatures. However, whether there are changes in the interaction between these species under warmer conditions is an important question. In cold ecosystems, soil nutrient status directly affects plant responses to increases in temperature and Antarctic soils are highly variable in nutrient supply. Thus, in this study we experimentally assessed the interaction between the non-native Poa with the two native Antarctic vascular plant species at two different temperatures and levels of nutrient availability. Individual mats of the study species were collected in King George Island, and then transported to Concepcion where we conducted competition experiments. In the first experiment we used soil similar to that of Antarctica and plants in competition were grown at two temperatures: 5°/2° and 11°/5 °C (day/night temperature). In a second experiment plants were grown in these two temperature regimes, but we varied nitrogen (N) availability by irrigating plants with Hoagland solutions that contained 8000 or 300 µM of N. Overall, Poa exerted a Competitive Effect on Deschampsia but only at the higher temperature and higher N availability. At 5°/11 °C the Competitive response of Deschampsia to Poa was of similar magnitude to the Competitive Effect of P. Deschampsia, and the Competitive Effect was greater with at low N. The Competitive Effect of Poa was similar to the Competitive response of Colobanthus to Poa at both temperatures and N levels. Thus, at low temperatures and N soil content the native Antarctic species might withstand Poa invasion, but this might change with climate warming.
