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Ecological wood anatomy of shrub and tree species that accour naturally in forests under drastic precipitation gradient in northwestern Patagonia, Argentina
No full textA utilização de gradientes ambientais no estudo de comunidades vegetais possibilita a eleição de sítios onde há a predominância de um fator abiótico que determina o sucesso ou o fracasso de espécies ao longo de sua extensão. Entre as inúmeras ferramentas utilizadas no estudo de gradientes climáticos, se destaca a anatomia do lenho, pois, é um ramo da ciência que permite analisar, além dos aspectos espaciais, os aspectos temporais dos sítios por meio dos anéis de crescimento. Além disso, a ampla distribuição das plantas lenhosas ao longo do globo possibilita análises em praticamente todos os tipos de biomas e ecossistemas terrestres. Dentro desse contexto estão os bosques andino-patagônicos de Araucaria araucana (Pehuén) ao norte de sua distribuição na Argentina. Esses bosques ocupam territórios caracterizados por um acentuado gradiente de precipitação, que vai de cerca de 3000 a 100 milímetros anuais, entre a cordilheira do Andes e a estepe patagônica, que os define como bosques mésicos e xéricos, com diferenças ecológicas que condicionam a formação vegetal, dinâmica, estrutura, relações com o clima e vulnerabilidade em cenários de mudanças ambientais. O objetivo do projeto foi descrever e analisar comparativamente a estrutura anatômica do lenho de 33 espécies arbóreas e arbustivas ocorrentes ao longo de um gradiente de precipitação, entre a encosta da cordilheira dos Andes e a estepe Patagônica, para verificar possíveis alterações anatômicas que permitam a determinação de tendências e elucidem os limites de distribuição das espécies. Foram coletadas amostras não destrutivas de lenho durante três expedições para a Patagônia entre 2012 e 2014, seguidas de procedimentos laboratoriais de confeccção de lâminas histológicas, preparo de amostras para análises dendrocronológicas, captura de imagens com câmeras acopladas a microscópios óptico e eletrônico de varredura, mensurações, descrições e análises comparativas com o auxílio de softwares. Foram identificados caracteres anatômicos exclusivos de sítios secos e úmidos que permitiram a caracterização, posicionamento ao longo do gradiente de precipitação e grupamento de espécies xerófitas e mesófitas; A ultra-estrutura das pontoações de traqueídeos de Araucaria araucana apresentou diferenças marcantes na frequência e porosidade de suas membranas, sendo maior e menos porosas em sítios xéricos, e menor e mais porosas nos mésicos; a chave dicotômica microscópica permitiu a identificação das 32 espécies arbustivas, as espécies Chuquiraga oppositifolia e Nothofagus antarctica apresentaram potencial dendrocronológico, e foram identificadas tendências anatômicas latitudinais influenciadas pelo clima nos extremos da América do Sul. A anatomia do lenho se mostrou uma ferramenta confiável no estudo de um gradiente de precipitação na Patagônia argentina, e os resultados apontam para riscos de embolismos e morte induzida por falha no sistema hidráulico de Araucaria araucana ao longo de todo o gradiente, em função do atual cenário climático, e suas projeções em médio e longo prazos.The use of environmental gradients in plant communities studies allows the election of sites with predominance of an abiotic factor that determines the success or failure of species along its length. Among the numerous tools used in the study of climatic gradients, highlights the wood anatomy, which is a branch of biological sciences that allows us to analyze, besides the spatial aspects, the temporal aspects of the sites due to the presence of growth rings. Furthermore, the wide distribution of woody plants throughout the world allows analysis in virtually all terrestrial biomes. Within this context are the Andean-Patagonian forests of Araucaria araucana (Pehuén) in it\'s north distribution in Argentina. These forests occupy territories characterized by a drastic precipitation gradient, ranging from about 3000 to 100 millimeters per year, between the mountain range of the Andes and the Patagonian steppe, which defines them as mesic and xeric forests, with ecological differences that determine the vegetation type, it\'s dynamics, structure, relationships with climate and vulnerability in environmental change scenarios. The aim of the project was to describe and comparatively analyze the wood anatomical structure of 33 tree and shrub species that accours along a precipitation gradient, between the slope of the Andes and the Patagonian steppe, and identify possible anatomical changes that allow the determination of trends and elucidate the species distribution limits. nondestructive wood samples were taken during three expeditions to Patagonia between 2012 and 2014, followed by laboratory procedures of histological slides confection, sample preparation for dendrocronological analysis, picture capturing with cameras attached to optical and scanning electron microscopes, measurements, descriptions and comparative analysis through software. exclusive characters of wet and dry sites were identified and allowed the characterization, positioning along the precipitation gradient and grouping as xerophytes or mesophytes; Araucaria araucana tracheids pits ultrastructure showed significant differences in frequency and porosity of it\'s membranes, being higher and less porous in xeric sites, and lower and more porous in mesic; microscopic dichotomous key allowed the identification of 32 shrub species, Chuquiraga oppositifolia and Nothofagus antarctica showed dendrocronological potential; Latitudinal anatomical trends were identified influenced by the climate at the extremes of South America. The wood anatomy proved to be a reliable tool in the study of a precipitation gradient in Patagonia, and the results points to potential embolisms followed by death induced by hidraulic system failure in Araucaria araucana throughout the gradient, due to the current climate scenario, and its projections in mid and long terms
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
Knowledge of current vegetation state for land-use management in the foothills and the piedemonte (Mendoza, Argentina)
Full text linkSe realizó el inventario de la vegetación de la Cuenca de los Ríos Chacras y Tejo en la Precordillera y Piedemonte de Mendoza, donde se desarrollan tres subsistemas ambientales: montaña, piedemonte y planicie aluvial, vinculados a través de un gradiente O-E con flujos naturales de energía. Esta interrelación da como resultado la configuración de pisos altitudinales de vegetación y procesos morfodinámicos, en tanto existe otro flujo de intercambio -de origen antrópico- con sentido inverso al natural. Se generan así interfases naturales y sociales, activas y pasivas, que dan lugar a una amplia gama de conflictos y potencialidades. Esta situación determinó la necesidad de alcanzar un conocimiento básico de la vegetación existente a nivel semidetallado, lo cual permitirá conocer las relaciones de la vegetación con la dinámica ambiental. Se definieron distintas unidades de vegetación, vinculadas con las principales geoformas, suelos y clima, en las que se efectuaron relevamientos fisonómicos y estructurales de reconocimiento. Esta descripción fue acompañada con la identificación de especies por estratos, mediante censos florísticos y cálculo de cobertura total. El análisis y comparación de la vegetación permitió obtener unidades homogéneas desde el punto de vista fisonómico, biológico y ecológico. Se confeccionó el mapa de pisos altitudinales, de comunidades de vegetación actual y de cobertura a escala 1:25.000, lo que permitió contar con información básica para orientar el proceso de ordenamiento territorial a través de la propuesta realizada por decreto 1077/95 de Ley Provincial 5804/91.We performed a vegetation inventory of the Basins of the rivers Chacras and Tejo in the Andean foothills and the Piedmonts of Mendoza. Three environment subsystems are developed there: mountain, piedmont and alluvial plains, related to each other through a W-E gradient with natural energy flows. This interaction gives the conformation of altitudinal vegetation levels and morphodynamic processes while there is another flow-anthropogenic exchange, with a natural inverse sense. Thus natural and social, active and passives interfaces are generated, resulting in a wide range of conflicts and potentialities. This situation led to the need to achieve a basic understanding of existing vegetation at a semi-detailed level, allowing understanding the relationship between vegetation and the environmental dynamic. We defined different vegetation units, related to landforms, soils and climate, in which physiognomic and structural surveys of recognition where made. This description was accompanied by the identification of species by strata, through floristic surveys and total coverage calculation. The analysis and comparison of the vegetation allowed getting homogenous units in a physiognomic, biologic and ecological way. The map of altitudinal levels, of current vegetation communities and of coverage at 1:25,000 scale was made, which provided the basic information to guide the process of territorial management through the proposal made by the by decree 1077/95 Provincial Law 5804/91.Fil: Abraham, Elena M..
Instituto Argentino de Investigaciones de las Zonas Áridas Fil: Roig, Fidel Alejandro.
Instituto Argentino de Investigaciones de las Zonas Áridas. Botánica y Fitosociología Fil: Salomón, Mario.
Universidad Nacional de Cuyo. Facultad de IngenieríaFil: Rubio, Cecilia.
Instituto Argentino de Investigaciones de las Zonas Áridas Fil: Pedrozo, Raquel.
Universidad Nacional de Cuyo. Facultad de Filosofía y Letras. Departamento de Aplicación Docent
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
Landform heterogeneity drives multi-stemmed Neltuma flexuosa growth dynamics. Implication for the Central Monte Desert forest management
Full text linkDrylands represent the main earth biome, providing ecosytemic services to a large number of people. Along these environments, woodlands are often dominated by multi-stemmed trees, which are exploited by local inhabitants to obtain forest products for their livelihood. In central-west Argentina, Neltuma flexuosa (algarrobo) woodlands are distributed across different landform units, varying in topographical and soil characteristics. This research aimed to reconstruct stem-growth time until harvestable diameter was achieved, and biological rotation age according to topo-edaphic variability in three algarrobo forests using dendrochronological methods. Results indicated that landform heterogeneity modulated species radial growth, influencing stem increments and cutting cycle period. In this sense, a decreasing trend in tree productivity emerged along a loamy-to-sandy textured soil gradient. These findings provide useful novel information for N. flexuosa forest management, suggesting the need to account for spatial landform/soil heterogeneity when examining desert forest dynamics.
Highlights:
Neltuma flexuosa provides forest product (poles) to Central Monte Desert (Argentina) local inhabitants.
N. flexuosa wood productivity was assessed for different topo-edaphic landforms.
Cutting cycle was reached at younger ages at river and paleo-river landforms.
Wood extraction must consider landscape heterogeneity.Drylands represent the main earth biome, providing ecosytemic services to a large number of people. Along these environments, woodlands are often dominated by multi-stemmed trees, which are exploited by local inhabitants to obtain forest products for their livelihood. In central-west Argentina, Neltuma flexuosa (algarrobo) woodlands are distributed across different landform units, varying in topographical and soil characteristics. This research aimed to reconstruct stem-growth time until harvestable diameter was achieved, and biological rotation age according to topo-edaphic variability in three algarrobo forests using dendrochronological methods. Results indicated that landform heterogeneity modulated species radial growth, influencing stem increments and cutting cycle period. In this sense, a decreasing trend in tree productivity emerged along a loamy-to-sandy textured soil gradient. These findings provide useful novel information for N. flexuosa forest management, suggesting the need to account for spatial landform/soil heterogeneity when examining desert forest dynamics.
Highlights:
Neltuma flexuosa provides forest product (poles) to Central Monte Desert (Argentina) local inhabitants.
N. flexuosa wood productivity was assessed for different topo-edaphic landforms.
Cutting cycle was reached at younger ages at river and paleo-river landforms.
Wood extraction must consider landscape heterogeneity
Landform heterogeneity drives multi-stemmed Neltuma flexuosa growth dynamics. Implication for the Central Monte Desert forest management
Full text linkDrylands represent the main earth biome, providing ecosytemic services to a large number of people. Along these environments, woodlands are often dominated by multi-stemmed trees, which are exploited by local inhabitants to obtain forest products for their livelihood. In central-west Argentina, Neltuma flexuosa (algarrobo) woodlands are distributed across different landform units, varying in topographical and soil characteristics. This research aimed to reconstruct stem-growth time until harvestable diameter was achieved, and biological rotation age according to topo-edaphic variability in three algarrobo forests using dendrochronological methods. Results indicated that landform heterogeneity modulated species radial growth, influencing stem increments and cutting cycle period. In this sense, a decreasing trend in tree productivity emerged along a loamy-to-sandy textured soil gradient. These findings provide useful novel information for N. flexuosa forest management, suggesting the need to account for spatial landform/soil heterogeneity when examining desert forest dynamics.
Highlights:
Neltuma flexuosa provides forest product (poles) to Central Monte Desert (Argentina) local inhabitants.
N. flexuosa wood productivity was assessed for different topo-edaphic landforms.
Cutting cycle was reached at younger ages at river and paleo-river landforms.
Wood extraction must consider landscape heterogeneity.Drylands represent the main earth biome, providing ecosytemic services to a large number of people. Along these environments, woodlands are often dominated by multi-stemmed trees, which are exploited by local inhabitants to obtain forest products for their livelihood. In central-west Argentina, Neltuma flexuosa (algarrobo) woodlands are distributed across different landform units, varying in topographical and soil characteristics. This research aimed to reconstruct stem-growth time until harvestable diameter was achieved, and biological rotation age according to topo-edaphic variability in three algarrobo forests using dendrochronological methods. Results indicated that landform heterogeneity modulated species radial growth, influencing stem increments and cutting cycle period. In this sense, a decreasing trend in tree productivity emerged along a loamy-to-sandy textured soil gradient. These findings provide useful novel information for N. flexuosa forest management, suggesting the need to account for spatial landform/soil heterogeneity when examining desert forest dynamics.
Highlights:
Neltuma flexuosa provides forest product (poles) to Central Monte Desert (Argentina) local inhabitants.
N. flexuosa wood productivity was assessed for different topo-edaphic landforms.
Cutting cycle was reached at younger ages at river and paleo-river landforms.
Wood extraction must consider landscape heterogeneity
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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