1,720,955 research outputs found
Thinning affects water use efficiency of hardwood saplings naturally recruited in a Pinus radiata D. Don plantation.
No full textPlantations for timber production combine the productive to the nursery function for natural regeneration of native species. Thinning plays a crucial role in recruitment and establishment of native species, by modifying the irradiance regime beneath the canopy cover. It also promotes the secondary succession towards a more stable forest, which is a main goal in protected areas. The present study was carried in a timber plantation of Pinus radiata D. Don, located in the National Park of Cilento and Vallo di Diano (Southern Italy). The ecophysiological responses of saplings of two hardwood species, Quercus cerris L. and Fraxinus ornus L., according to two contrasting (low and high) relative irradiance (RI) regimes were analysed. Leaf and tree ring d13C values were employed as indicators of water use efficiency (WUE) to explore plant responses to light regime. A preliminary methodological comparison between bulk wood and extracted holocellulose showed no significant differences in d13C between the two materials. Results indicate lower d13C values, thus suggesting a lower WUE, at higher RI regimes (corresponding to heavy thinning) for both the studied species. Furthermore, Q. cerris d13C values are lower than those of F. ornus. These results suggest that, under the same light conditions, the mesophile Q. cerris exhibits a weaker stomatal control than the xerophile F. ornus, which keeps higher WUE. In the mesic environment studied, Q.cerris may overcome F. ornus in the long run, owing to a heavy thinning
Response of Pinus leucodermis to climate and anthropogenic activity in the National Park of Pollino (Basilicata, Southern Italy)
No full textPinus leucodermis (=P. heldreichii var. leucodermis) is widespread in the Balkan Peninsula and is present as a post-glacial relict in Southern Italy. The oldest Italian populations of this species are located at high elevation in the National Park of Pollino, where grazing and logging had endangered their survival, especially during the 20th century. In 1993 the National Park was founded and anthropogenic activities were restricted. To understand the response of P. Leucodermis at the upper tree-line to climatic and anthropogenic activity variations, we developed a tree-ring width chronology (1464–2003). For the period 1804–2003 separate chronologies for the earlywood and latewood were built, and resin duct density was assessed on total ring, earlywood and latewood. Age structure of saplings was also determined. After 1950 a steep decline in tree-ring width was followed by a recovery since 1981. During the 20th century radial growth response to climate was not strong and not stable. In the period 1953– 2000 P. leucodermis radial growth seemed to take advantage of high temperatures and low precipitation. Resin duct density chronologies were not a reliable dendroecological variable, but they documented a metabolic trade-off between growth and differentiation processes. The gap in the age structure between long-lived trees (over 200 years old) and saplings around 40 years old, which mainly grow in protected microsites between rocks, could indicate a negative influence of grazing and related human activities. We suggest that the protection strategies introduced by the National Park could play a positive role in the recruitment of new saplings and in the ring growth recovery of old trees of P. leucodermis
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
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
Using environmental geostatistics for the geochemical characterization of soils from the polluted site of national interest of Tito (PZ - Italy)
No full textThe aim of this work was to provide information concerning the distribution of heavy metals in soils of a polluted ecosystem, in order to predict potential environmental risks and to provide a tool for the decision maker. This paper focuses on characterizing the industrial area of Tito (PZ, southern Italy), a site included among national interest sites to decontaminate, according to D.M. 8/7/2002. Soil contamination was monitored by means of a chemical-physical evaluation, coupled with a modelling approach using geostatistic techniques. A multistep sequential acid extraction technique was used to determine partitioning and levels of heavy metals in soil samples. Results showed that concentrations of analyzed elements are high in the whole area and above legislative admissible limits. A high spatial variation of heavy metals was observed in the studied area, with higher levels of heavy metals beside active and abandoned industrial areas. The adopted approach highlighted that anthropogenic industrial pressure may have detrimental repercussions on the surrounding environment and that recovering contaminated areas by implementing decontamination or permanent making safe interventions becomes necessary
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
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