1,720,964 research outputs found
Climate responses of long-lived woody species from the comfort zone to the outposts struggling for life
No full textClimate change is expected to cause profound effects in ecosystem structure, function, and distribution, particularly affecting long-lived woody species and forests, which will have to shift their distribution range to keep pace with relevant environmental changes. To address this challenge, new conservation strategies such as assisted migration must be implemented. However, effectively translocating woody species requires a thorough understanding of how forests respond to climate fluctuations throughout their distribution range.
This thesis aims to advance our knowledge in supporting the development of crucial conservation strategies by investigating growth patterns, ecophysiological strategies for coping with climate variability, and climate-growth relationships of long-lived woody species across their distribution range. The thesis, based on a retrospective approach that combines dendrochronology and dendroanatomy, is divided into three key research lines: i) assessment of the growth performance and climate sensitivity of several species within and outside their natural distribution range, ii) evaluation of climate-growth relationships and xylem structure in target species under optimal conditions, and iii) analysis of the climate responses of long-lived woody species at the edges of their distribution range, while assessing their suitability as proxies for climate reconstruction.
At the edges of the distribution, in Iceland, contrasting responses were found among species (Juniperus communis, Betula nana, Salix lanata, Betula pubescens, Sorbus aucuparia, Picea abies, and Pinus contorta) living under similar environmental conditions, underscoring the importance of species-specific ecological assessment for conservation strategies. Within the comfort zone, Picea mariana, a species native to present-day Canada, was analyzed by applying dendroanatomical techniques. Photosynthesis and carbon allocation were correlated to xylem traits, revealing a strong relationship between these two mechanisms. These dendroanatomical techniques were then analyzed in detail, comparing different approaches for dataset development and highlighting the high similarity between the two main protocols currently used in laboratories. Focusing on common juniper at the edge of its distribution range, this taxon revealed great potential as a paleoclimatic proxy, being identified as the oldest non-clonal shrub ever recorded in the tundra biome. Thanks to this unique characteristic, a reconstruction of July ground frost frequency for the past 1,200 years was possible. It showed a drastic reduction in frost frequency in the last century and, for the first time since the Viking Age, the complete absence of this phenomenon in 2021.
These findings provide a high-resolution, long-term, spatially comprehensive perspective on long-lived woody species’ growth habits. They offer insights into the ecophysiological strategies, and climate sensitivity of these species from the comfort zone to the outposts of their distribution ranges, offering insights into how certain forest woody species may respond to future climate scenarios. This thesis emphasizes the importance of these lines of research for the near future, while providing a sound foundation for crucial management strategies such as assisted migration
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
Review of embedding and non-embedding techniques for quantitative wood anatomy
No full textIn recent decades, xylem anatomical traits have become increasingly important in dendrochronological research, as they offer the unique opportunity to assess eco-physiological drivers of tree growth at intra-annual resolution. However, standard protocols for generating such data are still missing, leading to methodological uncertainty, and complicating data exchange among laboratories. Here, we compare protocols for high-quality permanent slide preparation in dendroanatomy and address effects of paraffin embedding vs. non-embedding approaches. Tests are conducted on both gymnosperm and angiosperm wood types of widely distributed European tree species, considering cell wall thickness (CWT), mean lumen area (MLA), and hydraulic diameter (Dh). Results indicate that non-embedding does not significantly alter the qualitative and quantitative characteristics of permanent slides compared to embedded samples. Whereas the mean chronologies of MLA and Dh and their non-embedded counterparts share substantial high-frequency variance, the CWT chronologies reveal slightly larger discrepancies at inter-annual scale. However, methodological differences do not exceed 11.1% for any parameter. While these results show high similarity between the two approaches, we recommend adopting the non-embedding procedure, since it saves resources and therefore allows to produce larger datasets. Regardless of the protocol used to build wood anatomical datasets, assembling large-scale networks of wood anatomical data could transform our understanding of forest responses to global changes
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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