1,720,962 research outputs found
Effect of phenology, nutrient availability and windthrow on flowering of Allium ursinum – results from long-term monitoring and experiments
No full textAllium ursinum, a dominant herb layer species in nutrient rich, deciduous forests of Central Eu-rope, has considerably expanded in the past decades. As this species mainly relies on regeneration by seeds, we wanted to analyse if and how the timing of phenological phases, climatic factors and resource availability correlated with flowering intensity as a potential factor for its success. We rec-orded annual inflorescence numbers in a population of the Göttinger Wald from 1981 until 2017 and conducted phenological observations across the same time span. In addition, inflorescences were counted in a fertilization experiment contrasting a control with a nitrogen, a phosphorus and a nitro-gen + phosphorus fertilization variant from 2010 to 2017. To investigate the effect of disturbance, inflorescence numbers were counted two to four years after a local summer storm in the southwest-ern foothills of the Harz Mountains in different disturbance categories after windthrow. Our results demonstrate that the length of the growing period for A. ursinum was a strong predic-tor of the number of inflorescences produced in the following year from 1981 to 2017. Climatic factors that had a significant effect on inflorescence numbers were all linked to growing period length. The effect of an increasing trend in growing period length on inflorescence numbers of A. ursinum, was, however, not directly obvious through an increasing flowering intensity with time. Instead, an exceptionally long growing period in 1991 synchronized the flowering behaviour of the population leading to years with a very high flowering intensity. These recurrent high flowering years may have facilitated the expansion of A. ursinum e.g., by increasing the probability of successful seedling establishment or of an accidental dispersal by ungulates. Results of the fertilization experi-ment indicate that atmospheric nitrogen deposition alone does not lead to an increase in inflorescence numbers. Highest numbers were recorded with a combined application of nitrogen and phosphorus. Inflorescence numbers also benefited from an increase in light availability after windthrow but de-creased in the third year after disturbance. Nevertheless, the high reproductive effect after disturb-ance might enable the persistence of this closed forest specialist against other competitors. Overall our results indicate that recurrent high flowering years induced by long growing periods and a high resource availability including light, phosphorus and nitrogen may have influenced the successful expansion of A. ursinum in the past decades and can explain new occurrences and the efficient gap filling in already A. ursinum-rich stands
The north-eastern distribution range of European beech a review
No full textToday, European beech (Fagus sylvatica L.) seems to be a markedly successful tree species in the north-east of its distribution range. The distribution area may be larger than originally assumed; past forest management is probably the main cause of the contraction in the postglacial European beech range. Numerous attempts consistently have failed to locate a distinct distribution edge for European beech. Therefore, we de. ne northern and eastern Poland and the southern regions of the Baltic States as margins of European beech distribution. Ecophysiological approaches have identified the drought constraints for European beech in terms of (1) the critical limit for xylem cavitation and loss of hydraulic conductivity, reached at a shoot water potential of -1.9 MPa, and (2) a reduction in gross primary production and total ecosystem respiration when relative extractable soil water reaches 40 and 20 per cent, respectively. However, it is difficult to correlate European beech distribution margins with single macro-climatic factors. Moreover, the adaptation of European beech populations and provenances to drought and frost varies. The phenotypic plasticity and evolutionary adaptability of European beech appear to be underestimated. These characteristics may counteract a further contraction of the European beech range arising from climate change in the future
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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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