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Forage offering and seasonal intake comparisons to evaluate European rabbit threat in Nothofagus forests of southern Patagonia

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Ecological Processes 2022年第1期11卷 604-617页

作者： Alejandro Huertas Herrera mónica toro‑manríquez Laura Borrelli maría Vanessa Lencinas Guillermo martínez Pastur Centro de Investigación en Ecosistemas de la Patagonia(CIEP) Camino Baguales s/n Km 4CoyhaiqueChile Ulterarius Consultores Ambientales y Científicos Ltda. Ignacio Serrano 420CoyhaiqueChile Instituto Nacional de Tecnología Agropecuaria(INTA) EEA BarilocheModesta Victoria 44508400 San Carlos de BarilocheRío NegroArgentina Laboratorio de Recursos Agroforestales Centro Austral de Investigaciones Científicas(CADIC)Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET)Houssay 2009410 UshuaiaTierra del FuegoArgentina.

Background:The European rabbit(Oryctolagus cuniculus L.1758)was introduced into different regions of the world,generating significant trade‑offs that critically impacted native ***,we evaluate the rabbit’s forage intakes in three vegetation types(forests,shrublands,and grasslands)along the four seasons in a temperate forest landscape in Southern Patagonia and discuss the potential threats over native *** formulated the following questions:(i)what is the forage offer at each vegetation type?(ii)what is the rabbit’s forage intake and how it varied across the seasons along the year?and(iii)which vegetation types and plant life forms were more used according to the rabbit’s forage intakes?methods:We censused understory vegetation to characterize the forage offer at each vegetation type and determined seasonal dietary intakes using microhistological analysis of *** plant species identified in the field were grouped according to life form classes(tree regeneration,shrubs,forbs,graminoids,orchids,ferns,bryophytes,and hemiparasites).Data were analysed through uni‑and multi‑variate analyses,determining relationships between forage offer and the rabbit’s forage ***:Forage intakes revealed changes in plant life form consumption across vegetation types,where intake pressure was considerably different for tree regeneration(p=0.001),graminoids(p=0.001),and hemiparasites(p=0.001).Besides,significant changes in consumption among seasons were detected for shrubs(p=0.001),ferns(p=0.030),and hemiparasites(p=0.002).Although many species play an important role in the rabbit’s forage intake networks(e.g.,Chiliotrichum diffusum,Holcus lanatus),the strongest intake linkages were found in exotic grasses(e.g.,Poa pratensis and Festuca sp.),native hemiparasites(e.g.,misodendrum sp.),native shrubs(e.g.,Empetrum rubrum),and native trees(e.g.,Nothofagus sp.).The summer and autumn seasons presented higher intake compared to the winter and spring seasons.F

关键词： Forest ecology Oryctolagus cuniculus Plant-animal interaction Vegetation type Herbivory Habitat use

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Knowledge arising from long-term research of variable retention harvesting in Tierra del Fuego: where do we go from here?

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Ecological Processes 2019年第1期8卷 318-333页

作者： Guillermo J.martínez Pastur Yamina m.Rosas mónica toro manríquez Alejandro Huertas Herrera Juan A.miller Juan m.Cellini marcelo D.Barrera Pablo L.Peri maría V.Lencinas Centro Austral de Investigaciones Científicas(CADIC) Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET)Houssay 200(9410)UshuaiaTierra del FuegoArgentina Universidad Nacional de la Plata(UNLP) Calle 7 e/47 y 48(1900)La PlataBuenos AiresArgentina Instituto Nacional de Tecnología Agropecuaria(INTA) Universidad Nacional de la Patagonia Austral(UNPA)Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET)cc 332(9400)Río GallegosSanta CruzArgentina

Nothofagus pumilio forests in Tierra del Fuego are the southernmost forests in the world,where extreme climate conditions represent a challenge to attain sustainable forest *** forestry was proposed as an alternative to increase the species conservation in managed ***,we synthetized results related to the implementation of a variable retention harvesting based on a combination of aggregate patches and dispersed retention during the last 18 years comparing with other silviculture proposals(e.g.,shelterwood cuts)and control treatments(primary unmanaged forests).We summarized the results for(i)sawmill operations,(ii)timber yield,(iii)overstory stability,(iv)forest structure,(v)microclimate and natural cycles,(vi)natural regeneration dynamics(flowering,seeding,foraging,recruitment,growth,and mortality),and(vii)biodiversity(mammals,understory plants,mistletoes,birds,arthropods,mosses,lichens,and fungi).In general,aggregate patches maintained forest structure and micro-environmental variables,and slightly increased biodiversity and forest reproduction variables compared to unmanaged primary *** the contrary,dispersed retention decreased forest structure variables and greatly increased biodiversity(richness and abundance)when it was compared to unmanaged primary *** conditions are influenced by variable retention harvesting,but direction and magnitude of the effect depend and differ according to retention *** this,biodiversity taxa greatly differed among groups depending on retention *** general,the species assemblages in aggregate patches were similar to those found in primary unmanaged forests,while they were significantly modified in the dispersed *** occurred due to(i)local extinction of some original species,(ii)the introduction of native species from the surrounding environments,or(iii)the invasion of exotic *** silvicultural method has been a useful tool to conserve biodiversity and ec

关键词： Aggregate patches Dispersed retention Biodiversity conservation Long-term sustainability Timber production

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Suitable conditions for natural regeneration in variable retention harvesting of southern Patagonian Nothofagus pumilio forests

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Ecological Processes 2019年第1期8卷 240-251页

作者： mónica D.R.toro manríquez Juan m.Cellini maría V.Lencinas Pablo L.Peri Karen A.Peña Rojas Guillermo J.martínez Pastur Centro Austral de Investigaciones Científicas(CADIC) Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET)Houssay 200(9410)UshuaiaTierra del FuegoArgentina Laboratorio de Investigaciones en maderas(LImAD) Universidad Nacional de la Plata(UNLP)Diagonal 113 n°469(1904)La PlataBuenos AiresArgentina Instituto Nacional de Tecnología Agropecuaria(INTA) Universidad Nacional de la Patagonia Austral(UNPA)Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET)cc 332(9400)Río GallegosSanta CruzArgentina Departamento de Silvicultura y Conservación de la Naturaleza Facultad de Ciencias Forestales y de Conservación de la NaturalezaUniversidad de Chilecc 9206SantiagoChile.

Background:Variable retention(aggregated and dispersed retention)harvesting proposed for Nothofagus pumilio was designed for timber purposes and biodiversity *** by opening canopy generates different microenvironments and creates contrasting conditions for seedling establishment,growth,and eco-physiology performance due to synergies(positives or negatives)with biotic and abiotic *** study evaluated the regeneration in different microenvironment conditions within managed stands during 5 years after *** forest structure after harvesting and different microenvironments were characterized in managed stands,where 105 regeneration plots were measured(3 stands×7 microenvironments×5 replicas).We characterized the seedling bank,as well as growth and ecophysiology performance of the *** and multivariate analyses were conducted for the ***:microenvironments offered different environmental conditions for natural regeneration(soil moisture and light availability).Seedling under debris and dicot plants showed better eco-physiological performance,establishment,and growth than plants growing under monocots or located in the dispersed retention without the protection of other understory *** most unfavorable microenvironment conditions were high canopy cover of remnant trees(inside the aggregates or close to trees in the dispersed retention)and heavily impacted areas(skidder extraction roads).Conclusions:Favorable microenvironments in the harvested areas will improve the natural recruitment,growth,and eco-physiology performance of the natural regeneration after *** is necessary to develop new silvicultural practices that decrease the unfavorable microenvironments(e.g.,road density or excessive woody accumulation),to assure the success of the proposed silvicultural method.

关键词： Aggregated retention Dispersed retention microenvironments Environmental variables Biometric values Biomass allocation Eco-physiology

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modeling Operational Parameters for Uranium Dioxide Production Reactor through Uranium Trioxide Reaction Using Hydrogen

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World Journal of Nuclear Science and Technology 2016年第3期6卷 131-139页

作者： Pedro Orrego José Hernández Jorge manríquez Sección de Geología y minería Departamento de Materiales Nucleares Comisión Chilena de Energía Nuclear Santiago Chile Ingeniería Civil metalurgia Universidad de Santiago de Chile Santiago Chile

This article shows the modeling of a uranium dioxide production reactor using COmSOL multiphysics software program in its 4.3b version. The model was made using 3 kinds of studies: momentum, heat and mass transport, in order to determine the influence of the most important operational parameters: UO3 reaction rate, composition and flow of the reduction gas, the initial temperature reactor and the reducing gas. The operational parameters evaluated were the followings: constant gas flow of2.5 L/min, initial hydrogen concentration of 0.25, 0.50 and0.75 m, and initial temperature of 400°C. The obtained results allow to conclude that under these working conditions, uranium dioxide is obtained virtually instantaneous and, with concentrations close to 0.5 m H2 in the reducing gas, the process can operate continuously and autogenously, without applying additional energy and temperatures around 600°C.

关键词： Uranium Trioxide Uranium Dioxide Conversion modeling

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Construction of a Potentiostat to Perform Electrochemical Impedance Spectroscopy (EIS) Tests

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modern Instrumentation 2017年第2期6卷 15-27页

作者： Francisco Sepúlveda José Hernández Andrés manríquez Departamento de Ingeniería mecánica Universidad de Santiago de Chile Santiago Chile Departamento de materiales Avanzados Comisión Chilena de Energía Nuclear Santiago Chile

In this work, it was developed the construction of a potentiostat for the execution of Electrochemical Impedance Spectroscopy (EIS) experiments, using an Agilent 33220a signal generator, a RIGOL 1064b oscilloscope and a protoboard for the connection of operational amplifiers to an electrochemical cell. The coordination of the global operation, in addition to data acquisition, was performed using a code generated in the LabVIEW program. The system analyzed was the corrosion of an 1100 aluminum plate in water, in order to compare the results obtained by other authors. The data acquisition consisted in obtaining the values of amplitude, RmS voltage and phase angle between the generated power signals and the current output, in order to obtain the impedance of the system, for different signal frequencies. Finally, the values obtained were plotted on a Nyquist diagram. In this way, the objective of this article is to demonstrate that with conventional laboratory equipment it is possible to implement an experimental device, capable of delivering results similar to those obtained by commercial equipment.

关键词： EIS Impedance LabVIEW

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Effects of UV radiation on the RNA/DNA ratio of Copepods from Antarctica and Chile

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Advances in Polar Science 2015年第2期26卷 147-157页

作者： Paulo F.Lagos m.Jesús Valdés Karen manríquez Faculty of Ecology and Natural Resources School of Marine ScienceMarine Research CenterQuintay (CIMARQ)ValparaísoChile

The effect of ultraviolet （UV） radiation on marine organisms has been an important focus of recent research, with depletion of the ozone layer resulting in increased UV radiation at high latitudes. Several studies have identified negative impacts of UV radiation on the biology of zooplanktonic organisms. This study used the RNA/DNA ratio as a measure of stress in copepod assemblages from Fildes Bay in Antarctica and Quintay Bay on the central coast of Chile, two areas with high UV radiation but different photobiologic histories. Controlled time-light experiments were performed with copepods from the two locations, exposing them to white light, UV light, or darkness. The results showed different responses to UV radiation. Copepods from Fildes Bay showed a slow metabolic response to UV radiation after 4 and 8 h of exposure. Copepods from Quintay Bay showed a fast metabolic response after 4 h of exposure （4 orders of magnitude higher than that for Fildes Bay copepods） followed by a rapid return toward baseline after 8 h of exposure. These different responses probably reflect the time the eopepod assemblages have been exposed to increased UV radiation and the extent of adaptive stress responses to cope with that increased UV radiation. The results of this study show that the RNA/DNA ratio is a useful indicator of the physiologic status of marine organisms and is a useful tool to measure the effects of changing environmental conditions on marine ecosystems, such as those associated with global climate change.

关键词： copepods RNA/DNA ratio physiology ultraviolet radiation

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modeling Operational Parameters of a Reactive Electro-Dialysis Cell for Electro-Refining Anodic Scrap Copper

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American Journal of Analytical Chemistry 2014年第15期5卷 1011-1019页

作者： Gerardo Cifuentes José Hernández Jorge manríquez Nicolas Guajardo Department of metallurgical Engineering Universidad de Santiago de Chile Santiago Chile

This work will create an electro-dialysis cell model that has the purpose of refining anodic scrap copper—an element that currently must be returned to the copper conversion process. The cell modeling is based on Ohm’s Law, while the resulting copper deposit morphology is studied through the thickness of the layer deposited on the surface and the electric current lines traced from the anode to the cathode. The use of the model demonstrated that it is possible to effectively predict the specific energy consumption required for the refinement of the anodic scrap copper, and the morphology of the cathode obtained, with a margin of error of 9%.

关键词： Electro-Refining modeling Copper Scrap Reactive Electro-Dialysis Specific Consumption

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Dissolution Behavior of Gold in Alkaline media Using Thiourea

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International Journal of Nonferrous metallurgy 2019年第1期8卷 1-8页

作者： Cristian Vargas Patricio Navarro Daniel Espinoza Jorge manríquez Erica mejía Departamento de Ingeniería metalúrgica Universidad de Santiago de Chile Avda Libertador Bernardo O′Higgins Santiago Chile Grupo de Investigación GIIAm Facultad de Ingeniería Institución Universitaria Pascual Bravo Medellín Colombia

In this work the dissolutive behavior of gold in alkaline medium using thiourea (TU), under different variables, was studied in a theoretical and experimental way, in order to determine the conditions under which it is feasible to dissolve gold in thiourea-alkaline medium. A thermodynamic study was conducted by chemical speciation using the method of Ro-jas-Hernández, together with an electrochemical study where the electric potential was swept in the anodic direction. The main results of the thermodynamic study were that formamidine disulfide (FDS) and sulfinic compounds (S.C.) prevail at alkaline pH;by increasing the initial concen-tration of thiourea at alkaline pH, the presence of the gold complex is al-most zero for any initial concentration of thiourea. By including sodium sulfite in the gold-thiourea system, it was possible to obtain the Au(I)-TU complex at alkaline pH, with a presence of 95.13%. Electrochemical tests allowed verifying that in the absence of sodium sulfite the dissolution of gold in an alkaline medium is very slow but adding sodium sulfite im-provements become evident in the dissolution of the metal. Therefore, sodium sulfite catalyzes the gold dissolution process and stabilizes the thiourea. With this study it was possible to establish the feasibility of using thiourea in an alkaline medium for the dissolution of gold, and the conditions under which it is possible to dissolve the gold in that medium. With these fundamentals and conditions, it is now possible to move forward to test this system for minerals and/or concentrates containing gold.

关键词： Gold Alkaline Thiourea Dissolution Behavior Sodium Sulfite

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Bismuth Oxide Carbonate Structures Synthesized by microwave—Assisted Solvothermal Approach and Its Use as Catalyst for the Degradation of Azo Dye in a Solution

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Journal of minerals and materials Characterization and Engineering 2019年第6期7卷 468-479页

作者： m. A. Luna-Alvarado m. Estrada-Flores m. E. manríquez-Ramírez C. m. Reza-San Germán Departamento de Ingeniería Química Industrial Escuela Superior de Ingeniería Química e Industrias Extractivas Instituto Politécnico Nacional Ciudad de México México

Because the textile industry wastewater is polluted with azo dyes, and in order to improve a process of wastewater remediation, the synthesized sample was evaluated in the photocatalysis of methylene blue and compared with commercial Bi2O3 and anatase TiO2. Structures of bismuth oxide carbonate (Bi2O2CO3) were successfully synthesized using a solution at 0.03 m concentration of sodium bismuthate as precursor and ethylene glycol as dissolvent by solvothermal microwave-assisted approach. The semiconductor catalyst samples were characterized by X-ray diffraction (XDR), scanning electron microscope (SEm) and Brunauer-Emmett-Teller analysis (BET). The application of the synthesized sample as catalyst, obtained a 68% of degradation. This result is better than the commercial Bi2O3 and close to the anatase TiO2 degradation. This sample shows a variation in the formula (with the presence of carbonates) but also shows an acceptable degradation percentage according to TiO2 results, making Bi2O2CO3 a possible substitute of TiO2.

关键词： Carbonate Bismuth Oxide Photocatalysis microwave-Solvothermal Synthesis methylene Blue Degradation

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