1,720,970 research outputs found
Recovering a small part of the early work of Holmes & LaMarche and collaborators in South America
No full textOne of the most widespread dendrochronological samplings ever conducted in South America was performed by La Marche and collaborators during 1973 -1978. However, the entire species and/or sites sampled had no robust chronology either because there were not enough materials collected, or simply because the materials were never processed. Here, I process and analyze all Nothofagus dombeyi samples collected during LaMarche and collaborators? field sampling in South America. Tree-ring chronology was developed for Alto Vilches site. For the other sites sampled by LaMarche and collaborators there were not enough samples, or series were not sufficiently long in order to build a chronology or to provide adequate information about tree growth. The Alto Vilches (VIL) developed chronology extended into the early 1800s, and showed high mean sensitivity values, and a strong common signal. As expected, VIL chronology evidenced narrow rings for several years that correspond with low precipitation periods in Patagonia. Making available the information kept in unprocessed tree-ring samples reinforces the dendrochronological potential of this species and strengthens chronology networks developed for ecological studies in northern Patagonia. Finally, this study will honor the initial work of LaMarche and collaborators and provide a conclusion to a small part of it.Fil: Suarez, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentin
La aplicación del análisis de los anillos de crecimiento a interrogantes ecológicos: Un breve repaso de la Dendroecología en Hispanoamérica
Full text linkLa dendrocronología es la ciencia que utiliza la datación anual de los anillos de crecimiento de las plantas arbóreas y arbustivas leñosas para analizar los patrones temporales y espaciales de los procesos en las ciencias físicas y culturales. A pesar que el estudio de los anillos de crecimiento data del siglo XIX, se le atribuye a A. E. Douglass, fundador del Laboratory of Tree-Ring Research en la Universidad de Arizona, el desarrollo de la dendrocronología como ciencia. Dependiendo del uso y la aplicación de la serie de anillos, la dendrocronología reconoce diferentes subdisciplinas que varían según los autores. Entre ellas se encuentran la dendroarqueología, la dendroclimatología, la dendroecología y la dendrogeomorfología.Fil: Amoroso, Mariano Martin. Universidad Nacional de Rio Negro. Sede Alto Valle. Escuela de Produccion, Tecnologia y Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte; ArgentinaFil: Suarez, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentin
Age-size-habitat relationships for Polylepis australis: Dealing with endangered forest ecosystems
Full text linkAssessing tree ages is important for the understanding of forest recruitment patterns and tree growth. However, little experience exists in the subtropics and accurate aging usually involves potentially damaging techniques such as tree coring or even the use of entire cross sections, which is not recommendable in endangered species or ecosystems. We provide an example of how age may be predicted on the basis of tree size and site conditions, using Polylepis australis of Central Argentina. Our study was conducted in two entire river basins where 96 independent trees were successfully cored for age analysis. Site and tree characteristics were registered and tree age determined through standard dendrochronological techniques. The multiple regression procedure selected tree circumference and proportion of rock under the tree canopy as significant variables explaining 48% of the variation in number of growth rings. Trees surrounded by rock clearly grew slower than those surrounded by a higher proportion of soil and vegetation. A comparison with a one site study shows that the ability to predict P. australis age is clearly reduced when geographical range is extended but the explanatory power of our model is still high enough for certain applications and within the range of other one site studies. We suggest that tree size and site characteristics may be used to predict age in other subtropical mountain forests with a well marked growth season.Fil: Suarez, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; ArgentinaFil: Renison, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Diversidad Biológica y Ecológica. Cátedra de Ecología; ArgentinaFil: Marcora, Paula Inés. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Diversidad Biológica y Ecológica. Cátedra de Ecología; ArgentinaFil: Hensen, Isabell. Martin-Luther-University Halle-Wittenberg; Alemani
Insect herbivory in climber-host shrubs associations: Benefit or detriment?
Full text linkSpatial proximity between different plant species could modify the sign (positive or negative) of plant-herbivore interaction. The chance of a plant being detected and colonized by herbivorous insects depends not only on the plant's own traits but also on the identity of the neighbouring plants that grow with it. The closest proximity between plants occurs in climbers and their host. We conducted a field experiment to assess the effect of spatial association between a climber plant, Vicia nigricans (Fabaceae), and two host shrubs, Berberis buxifolia (Berberidaceae) and Schinus patagonica (Anacardiaceae), on insect herbivory levels, reproductive output and growth. The presence and identity of the host shrubs affected the herbivory levels of the climber V. nigricans, but not the reproductive output. For the climber, the probability of being attacked by insects could depend on the characteristics of the host shrub. Taking the opposite perspective, climber association affected different traits of the host shrubs. The association with the climber decreased leaf damage (positive), tended to decrease leaf production (negative) and did not affect reproductive output (neutral). Our findings suggest that spatial association between plant species could change the sign of the interactions between plants and insects affecting different traits. By taking into account the perspective of both plants involved in the association, this study shows and emphasizes that plant-animal interactions strongly depend on the community context.Fil: Sasal, Yamila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Suarez, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin
Drought-induced mortality affects understory vegetation: release after death
Full text linkIn recent decades, severe droughts have become an important cause of canopy disturbance in forests, and have shown potential to cause rapid and pronounced vegetation shifts. Under dead canopy, undamaged understory could influence the nature of resource limitation for seedling growth and survival, limiting forest regeneration. We assessed the release response of understory vegetation after a severe drought event in temperate forests of northern Patagonia. Growth trends of dominant tree saplings, and changes in vegetation biodiversity and cover were compared between drought-dead and unaffected canopy. Nothofagus dombeyi undergo growth release after the climatic event in affected forests, and the response was evidenced immediately after the disturbance. For Austrocedrus chilensis, the growth release response was less evident, due mainly to a difference in age structure. In the understory the release response was barely discernable for some components. There was a tendency towards higher cover of the shrub layer in the understory of drought-affected forests, and an important presence of the exotic shrub Rosa rubiginosa. However, the clearest biotic response following drought mortality was the release in growth of understory dominant tree component. Those results strongly suggest that the environment under drought-dead canopy, and the die-off in woody sapling cohorts in a self-thinning process, could favor crown expansion and growth release of understory species that could help predict future forest trajectories in the context of the influence of climatic extreme events. © 2012 The Ecological Society of Japan.Fil: Suarez, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Sasal, Yamila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Agua, clima y crecimiento del Calafate y Chacay : dos arbustos que aportan valiosos productos y servicios en la Patagonia
Full text linkEn regiones áridas y semiáridas de la Patagonia, el calafate y el chacay representan dos especies arbustivas de gran interés ecológico, medicinal, alimenticio y económico para las poblaciones locales. La información almacenada en los anillos de crecimiento de estas especies puede contribuir a conocer cómo crecen y orientarnos sobre sus respuestas ante cambios ambientales.Estación Experimental Agropecuaria BarilocheFil: Weigandt, Mariana Noemi. Instituto Nacional de Tecnologia Agropecuaria (INTA). Estacion Experimental Agropecuaria Bariloche. Area Forestal. Grupo de Ecologia Forestal; ArgentinaFil: Weigandt, Mariana Noemi. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Suarez, Maria Laura. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Diez, Juan Pablo. Instituto Nacional de Tecnologia Agropecuaria (INTA). Estacion Experimental Agropecuaria Bariloche. Area Forestal. Grupo de Ecologia Forestal; ArgentinaFIl: Silva, Carmelina De Las Nieves. Instituto Nacional de Tecnologia Agropecuaria (INTA). Estacion Experimental Agropecuaria Bariloche. Area Forestal. Grupo de Ecologia Forestal; ArgentinaFil: Varela, Santiago Agustin. Instituto Nacional de Tecnologia Agropecuaria (INTA). Estacion Experimental Agropecuaria Bariloche. Area Forestal. Grupo de Ecologia Forestal; Argentin
- …
