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Chapter 11. Soil carbon in sensitive European ecosystems: from science to land management - a summary
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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
On the Sawfly Pristiphora subarctica (Forsslund, 1936) (Hymenoptera: Tenthredinidae) in Spruce Plantations of the Southern Alps
No full textPristiphora subarctica is commonly considered a rare sawfly species feeding on Norway spruce (Picea abies (L.) Karsten) with central and northern European distribution. In this paper the occurrence of a large population of this sawfly species in spruce plantations of the Southern Alps (Asiago Plateau, Venetian Prealps, Italy) is documented. Three plantations were attacked for two subsequent years starting from spring 1998. Although no trees died as a consequence of the defoliation, the crown architecture was compromised by the growth of multiple shoots derived from proventitious
buds. Th e population density of verwintering stages of the sawfly was estimated by searching for cocoons in soil
samples and density of adults was monitored with yellow sticky traps. The damage to the plantations was evaluated by counting the number of trees bearing red defoliated
leaders
Soil organic carbon responses to forest expansion on mountain grasslands
Full text linkGrassland abandonment followed by progressive forest expansion is the dominant land-use change in the European Alps. Contrasting trends in soil organic carbon (SOC) stocks have been reported for mountainous regions following forest expansion on grasslands. Moreover, its effects on SOC properties involved into long-term stability are largely unknown. The aim of this PhD thesis was to explore changes in: (i) SOC stocks; (ii) physical SOC fractions and their sensitivity to SOC changes; and (iii) labile carbon (C) in soil and fractions following forest expansion on mountain grasslands. A land-use gradient located in the Southern Alps (Italy) was examined, comprising managed grassland, two transitional phases in which grassland abandonment led to colonization by Picea abies (L.) Karst., and old forest dominated by Fagus sylvatica L. and P. abies. Organic and mineral soil layers were collected within three plots for each successional stage. Soil samples were fractionated according to: (i) aggregate size fractionation, separating aggregates through wet-sieving, and (ii) size-density fractionation, separating stable aggregates from particulate organic matter (POM) non-occluded within aggregates. Changes in labile soil C were assessed by analysis of carbohydrate monomers and by thermal analysis of soil and size-density fractions.
Our study showed that mineral SOC stocks were lower in early-stage and old forest (-28% in the top 10 cm of mineral soil) than in managed and abandoned grassland. The SOC accumulation within the organic layers following forest establishment could not fully compensate the mineral SOC stock difference between forest and grassland successional stages.
The dimension of aggregates assessed by aggregate size fractionation tended to increase, while SOC allocation to stable aggregates assessed by size-density fractionation decreased following conversion of grassland to forest (e.g from 81 to 59% in the 0-5 cm layer). Higher SOC allocation to POM fraction in the mineral soil, together with changed carbon distribution between mineral and organic soil layers, suggest an overall decrease in physical SOC protection and a concomitant shift to unprotected SOC fractions. The size-density fractions showed higher sensitivity to SOC changes than aggregate size fractions and therefore may be better suited for the detection of SOC changes.
Carbohydrate and thermal analyses indicated higher shares of labile soil C in grassland abandoned since 10 years than in managed grassland and forest successional stages. Ratios of
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microbially to plant-derived carbohydrates decreased from grassland to forest successional stages, and corresponded to decreased SOC allocation to stable aggregates.
Forest expansion on mountain grasslands caused a decrease in SOC stocks within the mineral soil and in physically protected SOC fractions, which can be explained by lower accumulation of binding agents of microbial origin. This can have implications for the accumulation of atmospheric CO2 in soil and for the susceptibility of SOC to external disturbances such as management and environmental changes
Current status, uncertainty and future needs in soil carbon monitoring
No full textThe need for cataloguing global soil carbon was recently highlighted by Gianelle et
al., (2010) in a letter to Science, where the importance of considering soils and
SOM sensitivity to temperature were underscored. Moreover the need to understand
the global distribution of soil carbon is a real concern for climate change
international policy issues. In order to establish the status of our knowledge regarding global soil carbon stocks in relation to climate change problems, an International workshop named G-SCAN (Global Soil Carbon Network) was organized in Florence (20-21, April) by the Edmund Mach Foundation (San Michele All'Adige, Italy). Some of the top scientists working on soil carbon dynamics from Europe and the US discussed the topic according to three working groups: a) Methodological standardization of soil C stocks; b) Detecting changes in Soil C; and c) Long-term experiments. Starting from real situations of soil carbon inventories and databases, the main problems and needs related to monitoring were highlighted and discussed. The results of the workshop will be published soon as an opinion paper in a peer reviewed journal. The unresolved problems still concerning soil carbon monitoring were discussed and could serve as a basis to homogenize current databases,
compare soil inventories and improve global soil mappin
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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