1,720,996 research outputs found
Birch (Betula pubescens Ehrh.) Encroachment Alters Contribution of Plant Functional Groups to Ecosystem Carbon Cycling in a Rewetted Bog
Get PDFABSTRACT Rewetted bogs with high water levels (WL) and mire‐specific vegetation are crucial carbon (C) sinks, but their function might be threatened by tree encroachment, a phenomenon widespread in the northern hemisphere that often coincides with low WL. This might impact C cycling both at the ecosystem and microform scale in multiple ways, but so far, data are lacking. We established two sites in the same former peat extraction area, one showing permanently high WL and mire‐specific vegetation (open site, OS), while the other one has more fluctuating WL and a dense birch (Betula pubescens Ehrh.) population (tree site, TS). We measured the carbon dioxide (CO2) exchange at ecosystem (eddy covariance) and plot scale (chamber measurements) for 1 year to clarify the differences between the sites and the impact of birch encroachment on the contribution of the different bog‐specific microforms and the trees to the ecosystem's CO2 balance. Overall, the OS had a CO2 balance of −262.4 ± 7.8 g CO2‐C m−2 year−1 indicating CO2 uptake, while the TS was close to neutral (−28 ± 5.1 g CO2‐C m−2 year−1). The smaller uptake at the TS was caused by higher (151%) ecosystem respiration, while gross primary production was 14% higher. However, the microform contributions to C uptake strongly differed: At the OS, both hummocks and hollows showed net uptake, while at the TS, most C (52%) was assimilated by the birches and the understory was a net CO2 source. This indicates a loss of peat C from the TS, while the successfully rewetted site was accumulating new peat. Accounting for plot‐scale CH4 fluxes, both sites were a weak source of greenhouse gases, but a distinctly stronger C sink occurred at the OS. Our data show the possibility of increasing C removal from the atmosphere by full rewetting and the establishment of mire‐specific vegetation
Drought influence on carbon and water cycling in a Mediterranean Quercus suber L. woodland during the drought year 2012
No full textDrought impact on carbon and water cycling in a Mediterranean Quercus suber L. woodland during the extreme drought event in 2012
No full textStable oxygen isotope analysis reveal vegetation influence on soil water movement and ecosystem water fluxes in a semi-arid oak woodland
No full textThe EGU General Assembly 2015 will be held at the ACV centre in Vienna, Austria, from 12 to 17 April 2015. The event will bring together geoscientists from all over the world to one meeting covering all disciplines of the Earth, Planetary and Space Sciences. The EGU aims to provide a forum where scientists, especially early career researchers, can present their work and discuss their ideas with experts in all fields of geoscienc
The FACCE-ERA-Net Plus project “Climate smart Agriculture on Organic Soils” (CAOS)
No full textThe FACCE-ERA-Net Plus project “Climate smart Agriculture on Organic Soils” (CAOS) focuses on farmed organic soils, hotspots of vulnerability and GHG emissions in Europe. We propose to use wet organic soils as risk insurance in dry periods on farm/regional level, while water and soil management assures trafficability in wet conditions. Wet management systems abate peat degradation and therefore foster higher infiltration rates and ease subirrigation. Economically, wetness-adapted crops with stable yield quantity/quality for food, feed and bioenergy are needed. Convincing farmers and decision makers of profitable and resilient wet management systems on organic soils under climate change needs proof by on-farm experiments, historical evidence and bi-directional involvement.Overall, we aim to generate knowledge of climate smart agricultural system design on organic soils adapted to regional European conditions. CAOS will provide and distribute evidence that active management with control of groundwater levels, improved trafficability and alternative high productivity crops improves yield stability/quality and climate change resilience while mitigating GHG emissions and improving soil/water quality. We hypothesize that the strong potential for adaptation to increased climatic variability on farmed organic soil will facilitate mitigation of the largest GHG source from agriculture in Central/Northern Europe. At MACSUR conference, we present the project concept and first results
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
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