1,720,984 research outputs found
Large effects of land use conversion on C storage in dry forest ecosystems from Southern South America
Full text linkFil: Conti, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Conti, Georgina. Universidad Nacional de Córdoba; Argentina.Net CO2 land use change emissions represent one of the main drivers of global climatic change. However, the effect of the accelerated deforestation over plant and soil carbon (C) pools from dry Chaco forests from southern South America has been poorly quantified. Including five ecosystem types related to different land uses, we quantified the magnitude and change of total C stocks (including trees, shrubs, herbs, coarse and fine debris, soil organic and inorganic C stocks up to 2 m depth). C stocks in soils represented the largest C stocks in these forest ecosystems (more than 74%), and specifically C stored at deeper layers. Shrubs also comprises a large C stocks not quantified before in detail. The conversion of primary and secondary forest to degraded shrublands and croplands did generate high losses of organic C both in aboveground biomass and in soils up to 30 cm depth with values of c. 45.6 % of C loss. Although deeper soil C is in general stable, land use conversion did also imply changes in soil inorganic C (27.63 Mg C ha-1 of net C loss). Our results indicate that a landscape transformation as the one predicted in the region may lead to a huge reduction of the C stored in these forest, with a consequent net C emission and a reduction in the associated ecosystem services provided to local, regional and global scales by dry Chaco forests.https://scisoc.confex.com/scisoc/2014SES/webprogram/Person510967.htmlFil: Conti, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Conti, Georgina. Universidad Nacional de Córdoba; Argentina.Ecologí
Long-term forest use results in community plant functional trait convergence in a subtropical seasonally dry forest
Full text linkFil: Conti, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Conti, Georgina. Universidad Nacional de Córdoba; Argentina.Fil: Enrico, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Huygens, Dries. Ghent University; Bélgica.Fil: Díaz, Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.A debate exists around the effect of forest use on processes and societal benefits provided by these ecosystems. Functional traits the biological attributes of organisms - is expected to have important effects on these processes and also determine the community responses to environmental factors. Subtropical seasonally dry forest from South America has been experiencing accelerated land-cover changes in the last few decades. Over large areas, forests have been replaced by shrublands, as a result of historic logging and grazing. Here, we analyze changes in plant community functional diversity (including variety and identity) in response to long-term forest use in dry forests of central Argentina. Specifically, we addressed the following questions: (i) How does historic forest use affect plant community functional diversity (in terms of variety and identity)? ( ii) How does historic forest use modify community assembly rules of these communities With that aim, we sampled 8 functional key traits of 30 dominant species across 16 sites resulting from different past and present land-use regimes (mainly selective logging and grazing). Our results showed that functional identity (i.e., the community weighted means of functional traits) remains mostly unchanged, except for architectural traits (height and wood density) that were reduced across sites as a result of historic forest extraction. Although changes in functional identity were not strong, functional variety, in terms of both multivariate indices (RaoQ and FDisp) and univariate indices (FDvar), tracked changes in nutrient availability and forest structure as a result of historic forest use. These results indicate that community functional variety is reduced across the historic forest use gradient, with functional convergence being an important component of community assemblage. Under the assumption (untested in this work) that a wider variety of functional traits should support a higher number of ecosystem benefits to people, our results suggest that forest management at relatively low intensities could provide several ecosystem benefits without risking their long-term provision. We also advocated the inclusion of different components of functional diversity as an important resource in the analysis of the impact of global changes in these subtropical dry forests, at present being seriously transformed.http://iavs2016.org/59th-Annual-Symposium/Program/Abstract-Booklet/AbstractsIAVS2016.aspxFil: Conti, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Conti, Georgina. Universidad Nacional de Córdoba; Argentina.Fil: Enrico, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Huygens, Dries. Ghent University; Bélgica.Fil: Díaz, Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Ecologí
Fast carbon turnover after logging in the Semi-Arid Chaco forest (Argentina)
Full text linkFil: Kowaljow, Esteban. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Kowaljow, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Conti, Georgina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Conti, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Pérez Harguindeguy, Natalia. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Pérez Harguindeguy, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Díaz, Sandra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Díaz, Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Although the effect of forest logging on soil organic C (SOC) has been studied across different ecosystems, there is no consensus on the general resulting pattern, showing increases, decreases or not net changes in comparison with the former forest. A reduction on SOC content is expected as a result of disturbance activities promoting C loss or removal from the surface organic matter. Increased litter inputs resulting from a higher net primary productivity of young stands relative to mature stands could also being expected, increasing the SOC content of the logged sites, coupled with the deeper effect of an increased decomposition of dead roots from the removed woody biomass. A balance between these factors could also be resulting in no net C change on soils after logging. We aim to test the change on SOC up to 2 m depth in the semiarid Chaco of Central Argentina where an increased selective logging as result of extended silvopastoral activities is increasingly common. Using a paired sampling design we aim to compare the effect of selective logging of four different ages (3, 7, 9 & 22 years after logged, n=4) over the SOC content through the soil profile up to 2 m depth. SOC between forests have shown no significant differences indicating the homogeneity in climatic and soil variables under the study area. SOC under selective logging showed significant differences between them and with the correspondent former forest not only at surface but also at depth. SOC content had significantly increased after 22 years of forest logging showing a similar pattern that the model proposed by Covington and others, although the results showed on this study need to be replicated including selective logging on a broader range of times since logging has taken place. Our results seems to indicate a net decrease in SOC during the first years after disturbance (1.64 kg m-2 to a 2 m depth) followed by an increase during the following 22 years in the SOC content reaching a maximum of a net increase of 4.65 kg m-2 to a 2 m depth after 22 years of disturbance. A better understanding of the direction and magnitude of these changes is important for predicting the effect of land use change on soil fertility at regional level as well as its consequences for the global C cycle.https://scisoc.confex.com/scisoc/2014SES/webprogram/Person510967.htmlFil: Kowaljow, Esteban. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Kowaljow, Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Conti, Georgina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Conti, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Pérez Harguindeguy, Natalia. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Pérez Harguindeguy, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Díaz, Sandra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Díaz, Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Ecologí
Efecto de los hongos micorrícicos arbusculares en el carbono orgánico del suelo en sistemas agrícolas: una aproximación meta-analítica
No full textIncreasing soil organic carbon (SOC) stocks in agroecosystems is a major goal to maintain agricultural sustainability and mitigate climate change. Arbuscular mycorrhizal fungi (AMF) can increase crop growth and yield, but studies in agricultural soils have shown that their effects on SOC stocks can be either positive (through soil aggregation and inputs) or negative (through increased mineralization or “priming”). We conducted a meta-analysis to quantitatively evaluate the role of AMF on SOC stocks across several crop species and conditions. We used a dataset comprising 62 trials from 19 studies including field or pot experiments that directly manipulated the mycorrhizal status of plants. We found a strong effect of AMF on SOC stocks, with an average increase of 21.5%. The positive effect of AMF on SOC stocks was consistently observed across a wide range of conditions, including different soil types, crop species, or AMF inoculation sources (single o mixed AMF species). Our results suggest a higher contribution of AMF mediated mechanisms leading to SOC accretion rather than carbon losses. Future studies should evaluate the effects of AMF on SOC fractions to clarify the mechanisms behind its overall contribution to SOC accrual.Fil: Conti, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Piñeiro, Gervasio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin
Plant functional diversity and carbon storage- an empirical test in semiarid forest ecosystems
Full text linkSummary 1. Carbon storage in vegetation and soil underpins climate regulation through carbon sequestration. Because plant species differ in their ability to capture, store and release carbon, the collective functional characteristics of plant communities (functional diversity) should be a major driver of carbon accumulation in terrestrial ecosystems. 2. Three major components of plant functional diversity could be put forward as drivers of carbon storage in ecosystems: the most abundant functional trait values, the variety of functional trait values and the abundance of particular species that could have additional effects not incorporated in the rst two components. 3. We tested for associations between these components and carbon storage across 16 sites in the Chaco forest of Argentina under the same climate and on highly similar parental material. The sites differed in their plant functional diversity caused by different long-term land-use regimes. 4. We measured six plant functional traits in 27 species and weighted them by the species abundance at each site to calculate the community-weighted mean (CWM) and the functional divergence (FDvar) of each single trait and of multiple traits (FDiv). We also measured plant and soil carbon storage. Using a stepwise multiple regression analysis, we assessed which of the functional diversity components best explained carbon storage. 5. Both CWM and FDvar of plant height and wood-specic gravity, but no leaf traits, were retained as predictors of carbon storage in multiple models. Relationships of FDvar of stem traits and FDiv with carbon storage were all negative. The abundance of ve species improved the predictive power of some of the carbon storage models. 6. Synthesis. All three major components of plant functional diversity contributed to explain carbon storage. What matters the most to carbon storage in these ecosystems is the relative abundance of plants with tall, and to a lesser extent dense, stems with a narrow range of variation around these values. No consistent link was found between carbon storage and the leaf traits usually associated with plant resource use strategy. The negative association of trait divergence with carbon storage provided no evidence in support to niche complementarity promoting carbon storage in these forest ecosystems.Fil: Conti, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); ArgentinaFil: Diaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); 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
Shrub biomass estimation in the semiarid Chaco forest: a contribution to the quantification of an underrated carbon stock
Full text linkAbstract & Context The quantification of biomass of woody plants is at the basis of calculations of forest biomass and carbon stocks. Although there are well-developed allometric models for trees, they do not apply well to shrubs, and shrub-specific allometric models are scarce. There is therefore a need for a standardized methodology to quantify biomass and carbon stocks in open forests and woodlands. & Aims To develop species-specific biomass estimation models for common shrubs, as well as a multispecies shrub model, for the subtropical semiarid Chaco forest of central Argentina. & Methods Eight shrub species (Acacia aroma, Acacia gilliesii, Aloysia gratissima, Capparis atamisquea, Celtis ehrenbergiana, Larrea divaricata, Mimozyganthus carinatus, and Moya spinosa) were selected, and, on average, 30 individuals per species were harvested. Their total individual dry biomass was related with morphometric variables using regression analysis. & Results Crown area as well as crown-shaped variables proved to be the variables with the best performance for both species-specific and multispecies shrub models. These allometric variables are thus recommended for standardized shrub biomass assessments. & Conclusion By accounting for the shrub component of the vegetation, our models provide a way to improve the quantification of biomass and carbon in semiarid open forest and woodlands.Abstract & Context The quantification of biomass of woody plants is at the basis of calculations of forest biomass and carbon stocks. Although there are well-developed allometric models for trees, they do not apply well to shrubs, and shrub-specific allometric models are scarce. There is therefore a need for a standardized methodology to quantify biomass and carbon stocks in open forests and woodlands. & Aims To develop species-specific biomass estimation models for common shrubs, as well as a multispecies shrub model, for the subtropical semiarid Chaco forest of central Argentina. & Methods Eight shrub species (Acacia aroma, Acacia gilliesii, Aloysia gratissima, Capparis atamisquea, Celtis ehrenbergiana, Larrea divaricata, Mimozyganthus carinatus, and Moya spinosa) were selected, and, on average, 30 individuals per species were harvested. Their total individual dry biomass was related with morphometric variables using regression analysis. & Results Crown area as well as crown-shaped variables proved to be the variables with the best performance for both species-specific and multispecies shrub models. These allometric variables are thus recommended for standardized shrub biomass assessments. & Conclusion By accounting for the shrub component of the vegetation, our models provide a way to improve the quantification of biomass and carbon in semiarid open forest and woodlands.Fil: Conti, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); ArgentinaFil: Conti, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); ArgentinaFil: Enrico, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); ArgentinaFil: Enrico, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); ArgentinaFil: Casanoves, Fernando. Biometric Unit,; Costa RicaFil: Casanoves, Fernando. Biometric Unit,; Costa RicaFil: Diaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); ArgentinaFil: Diaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentin
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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