1,720,981 research outputs found
Restoring grasslands with arbuscular mycorrhizal fungi around remnant patches
Full text linkEcological restoration of species-rich grasslands remains a priority for conservation of biodiversity. Torrez et al. (Applied Vegetation Science, this issue) determined if plant species recolonization of degraded nutrient-poor grasslands could be increased by adding a local source of arbuscular mycorrhizal fungal (AMF) inoculum at different distances from intact remnant grasslands. They highlight the important role of below-ground processes on restoration success.Fil: Teste, Francois. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; Argentin
Evolutionary dynamics of dispersal during co-invasion of trees and their mycorrhizal symbionts and pathogens
No full textMost invasive trees depend closely on mycorrhizal symbionts to provide required resources, and thus their invasive success depends on the dispersal of these symbionts as well as their own dispersal. Invasive trees may also be negatively impacted by pathogenic fungi in their natural range, and thus benefit from ‘enemy release’ if they spread into new areas faster than these pathogenic fungi. Previous empirical and theoretical work has shown that the dispersal characteristics of organisms can undergo selection pressure and evolution during the course of an invasion or colonization of new areas, but the evolutionary dynamics of dispersal during coinvasion has not been considered. In this work, we use spatially-explicit eco-evolutionary simulation modelling to investigate how the dispersal characteristics of trees and their mycorrhizal symbionts and pathogens evolve over the course of a tree invasion. We find that the selection pressures manifesting during the invasion cause the dispersal characteristics of the different organisms to vary across time and space in complex and interdependent ways that are influenced by human management. For example, dispersal ability of the three organisms increases over time and is higher at the fronts of an invasion, but managing trees through removal of outliers decreases the rate at which increased dispersal ability evolves.Fil: Renton, M.. University of Western Australia; AustraliaFil: Teste, Francois. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; Argentina. University of Western Australia; AustraliaII International Symposium Mycorrhizal Symbiosis in South AmericaSan Carlos de BarilocheArgentinaUniversidad Nacional del Comahu
Plasticity in root symbioses following shifts in soil nutrient availability during long-term ecosystem development
No full textThe vast majority of terrestrial plants form root symbioses with arbuscular mycorrhizal (AM) fungi to enhance nutrient (particularly phosphorus, P) acquisition. However, some plant species also form dual symbioses involving ectomycorrhizal (ECM) fungi, with a subset of those also forming triple symbioses also involving dinitrogen (N 2 )-fixing bacteria. It has been suggested that these plants show plasticity in root symbioses to optimise nutrient acquisition depending on the type and strength of soil nutrient limitation (e.g., N vs. P), yet empirical evidence remains limited. Alternatively, the degree of investment or “preference” in particular root symbioses might simply reflect differences in inoculum potential among soils of contrasting nutrient availability, reflecting adaptations of root symbionts to different edaphic conditions. Here, we grew two co-occurring plant species forming triple (AM/ECM/N 2 -fixing; Acacia rostellifera) or dual (AM/ECM; Melaleuca systena) symbioses in soils of increasing age and contrasting nutrient availability from an Australian long-term soil chronosequence to disentangle the relative importance of abiotic factors (e.g., soil nutrient availability and stoichiometry) and biotic factors (e.g., soil inoculum potential) in determining root colonisation patterns and functional outcomes of these multiple root symbioses. For both plant species, we found clear hump-shaped plant growth patterns along the pedogenesis-driven gradient in soil nutrient availability, with peak growth in intermediate-aged soils, while high levels of mycorrhizal colonisation by the “preferred” root symbionts were maintained across all soils. We found large increases (540%) in foliar manganese concentrations with increasing soil age and declining P availability, suggesting that plants may be relying on the release of carboxylates to help acquire P in the most P-impoverished soils. Finally, we found that soil abiotic properties, such as strong differences in soil nutrient availability, are generally more important than soil inoculum potential in explaining these shifts in our plant and root responses. Synthesis. Our study suggests that plants capable of forming multiple root symbioses show plasticity in their nutrient-acquisition strategies following shifts in soil nutrients during long-term ecosystem development, yet maintain a preference for certain root symbionts despite changes in soil microbial inoculum.Fil: Teste, Francois. University of Western Australia; Australia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Laliberté, Etienne. University of Western Australia; Australia. University of Montreal; Canad
Dual-mycorrhizal plant functional responses following shifts in soil nutrient availability during ecosystem development
No full textThe majority of terrestrial plants form root symbioses with arbuscular mycorrhizal (AM) fungi to enhance nutrient (particularly phosphorus, P) acquisition. However, some of these plant species also form dual symbioses involving ectomycorrhizal (ECM) fungi. The factors driving plants to form dual-mycorrhizal symbioses is poorly understood. It has been suggested that these plants show plasticity in root symbioses to optimize nutrient acquisition depending on the type and strength of soil nutrient limitation (e.g., N vs. P). Alternatively, the degree of investment or ?preference? in particular root symbioses might simply reflect differences in inoculum potential among soils of contrasting nutrient availability, reflecting adaptations of root symbionts to different edaphic conditions. To better understand the ecology of dual-mycorrhizal plants, we grew two co‐occurring plant species forming AM and ECM (Acacia rostellifera and Melaleuca systena) symbioses in soils of increasing age and contrasting nutrient availability from an Australian long‐term soil chronosequence. Specifically, we aimed to disentangle the relative importance of abiotic factors (e.g., soil nutrient availability) and biotic factors (e.g., soil inoculum potential) in determining root colonization patterns and functional outcomes of these multiple root symbioses. For both plant species, we found clear hump‐shaped plant growth patterns along the strong gradient in soil nutrient availability, with peak growth in intermediate‐aged soils, while high levels of mycorrhizal colonization by the ?preferred? root symbionts were maintained across all soils. We found large increases (540%) in foliar manganese concentrations with increasing soil age and declining P availability, suggesting that plants may be relying on the release of carboxylates to help acquire P in the most P‐impoverished soils. Finally, we found that soil abiotic properties, such as strong differences in soil nutrient availability, are generally more important than soil inoculum potential in explaining these shifts in our plant and root responses. Our study suggests that plants capable of forming dual-mycorrhiza root symbioses show plasticity in their nutrient‐acquisition strategies following shifts in soil nutrients during long‐term ecosystem development, yet maintain a preference for certain root symbionts despite changes in soil microbial inoculum.Fil: Teste, Francois Philippe. University of Western Australia; Australia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; ArgentinaFil: Laliberté, E.. University of Western Australia; AustraliaII International Symposium Mycorrhizal Symbiosis in South AmericaSan Carlos de BarilocheArgentinaUniversidad Nacional del ComahueUniversidad Austral de ChileUniversidad Nacional del Comahue. Instituto Andino Patagónico de Tecnologías Biológicas y GeoambientalesUniversidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambient
Dual‐mycorrhizal plants: their ecology and relevance
Full text linkDual-mycorrhizal plants are capable of associating with fungi that form characteristic arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) structures. Here, we address the following questions: (1) How many dual-mycorrhizal plant species are there? (2) What are the advantages for a plant to host two, rather than one, mycorrhizal types? (3) Which factors can provoke shifts in mycorrhizal dominance (i.e. mycorrhizal switching)? We identify a large number (89 genera within 32 families) of confirmed dual-mycorrhizal plants based on observing arbuscules or coils for AM status and Hartig net or similar structures for EM status within the same plant species. We then review the possible nutritional benefits and discuss the possible mechanisms leading to net costs and benefits. Cost and benefits of dual-mycorrhizal status appear to be context dependent, particularly with respect to the life stage of the host plant. Mycorrhizal switching occurs under a wide range of abiotic and biotic factors, including soil moisture and nutrient status. The relevance of dual-mycorrhizal plants in the ecological restoration of adverse sites where plants are not carbon limited is discussed. We conclude that dual-mycorrhizal plants are underutilized in ecophysiological-based experiments, yet are powerful model plant–fungal systems to better understand mycorrhizal symbioses without confounding host effects.Fil: Teste, Francois. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; Argentina. University of Western Australia; AustraliaFil: Jones, Melanie D.. University of British Columbia; CanadáFil: Dickie, Ian. University of Canterbury; Nueva Zeland
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
Root phosphomonoesterase activity as dependent on soil phosphorus availability of common herbaceous plant species of Río de la Plata grasslands
No full textRío de la Plata natural grasslands harbor a high diversity of plant species on soils spanning a wide gradient of phosphorus (P) concentration. Half of the total soil P concentration is organic P (Hernandez et al., 1995). Although plant diversity is high, most of the herbaceous communities share the same matrix of species, leading to the question: do common species increase their root phosphomonoesterase activity as the resin P concentration of the soils decreases?Fil: Michelini, Diego. Universidad de la República; UruguayFil: Rodríguez, Andrea. No especifíca;Fil: del Pino, Amabelia. No especifíca;Fil: Lambers, Hans. No especifíca;Fil: Teste, Francois. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi"; Argentina6th Symposium on Phosphorus in Soils and Plants : from molecular scale to ecosystemsBélgicaKatholieke Universiteit Leuve
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
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