1,721,171 research outputs found
Site information, seedling counts, and microclimate data for: Limited prospects for future alpine treeline advance in the Canadian Rocky Mountains
No full textThese data were produced as part of a study investigating the effects various biotic and abiotic properties on tree seedling germination beyond existing geographic ranges. Engelmann spruce seeds were grown in a seed addition experiment at four study areas in the Canadian Rocky Mountains
Soil properties and seedling growth data for: Soil properties as constraints to seedling regeneration beyond alpine treelines in the Canadian Rocky Mountains
No full textThese data were produced as part of a study investigating the effects of soil properties on tree seedling germination beyond existing geographic ranges. Engelmann spruce seeds were grown in a greenhouse and growth chamber in soils collected from four study areas in the Canadian Rocky Mountains to determine if soils collected beyond treeline constrained or enhanced seedling growth and survival. Various properties of the soil were analyzed to identify possible causes for the observed soil effects
Regional variability in the response of alpine treelines to climate change
No full textThe distributions of many high-elevation tree species have shifted as a result of recent climate change; however, there is substantial variability in the movement of alpine treelines at local to regional scales. In this study, we derive records of tree growth and establishment from nine alpine treeline ecotones in the Canadian Rocky Mountains, characterise the influence of seasonal climate variables on four tree species (Abies lasiocarpa, Larix lyallii, Picea engelmannii, Pinus albicaulis) and estimate the degree to which treeline movement in the twentieth century has lagged or exceeded the rate predicted by recent temperature warming. The growth and establishment records revealed a widespread increase in radial growth, establishment frequency and stand density beginning in the mid-twentieth century. Coinciding with a period of warming summer temperatures and favourable moisture availability, these changes appear to have supported upslope treeline advance at all sites (range, 0.23–2.00 m/year; mean, 0.83 + 0.67 m/ year). However, relationships with seasonal climate variables varied between species, and the rates of treeline movement lagged those of temperature warming in most cases. These results indicate that future climate change impacts on treelines in the region are likely to be moderated by species composition and to occur more slowly than anticipated based on temperature warming alone
Radiocarbon dating, macroscopic charcoal counts, pollen counts, and tree-establishment data from Little Trefoil Lake, Alberta, Canada
No full textThis dataset was developed from a sediment core collected from Little Trefoil Lake in Jasper, AB, Canada, and from tree-cores collected from the surrounding forest. The data includes radiocarbon dating information, sedimentary charcoal counts, pollen counts, and tree establishment dates
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
Radiocarbon dating, macroscopic charcoal counts, pollen counts, and tree-establishment data from Little Trefoil Lake, Alberta, Canada
No full textThis dataset was developed from a sediment core collected from Little Trefoil Lake in Jasper, AB, Canada, and from tree-cores collected from the surrounding forest. The data includes radiocarbon dating information, sedimentary charcoal counts, pollen counts, and tree establishment dates
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
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