1,720,985 research outputs found
Post-drought organic carbon mineralization leads to high productivity and nutrient uptake efficiency of perennial grassland after rewetting
Full text linkGrasslands often recover well from drought, with some even surpassing non-drought-stressed controls in productivity long after drought release. However, the mechanisms responsible for such post-drought productivity outperformance remain unclear. In this study we examine how rewetting after drought influences important short- and longer-term soil microbial processes (i.e. nitrogen mineralization, potential enzyme activities) and consequent plant nutrient availability and uptake. For this, a field experiment was set up where an established perennial ryegrass sward under different N-fertilization levels was subjected to either a 2-month experimental summer drought followed by rewetting or to rainfed control conditions. Rewetting after drought led to an immediate pulse in gross N-mineralization and NH4-consumption rates. Both rates increased by >230% and >430% in formerly drought-stressed subplots compared to controls in plots not N-fertilized and N-fertilized during drought, respectively. Importantly, gross N mineralization rates correlated significantly with extractable soil organic carbon contents at the end of drought. Concurrently, drought and rewetting significantly increased NO3–N, P, K, S, Fe, Zn, and Mn availability during the 1st but not the 2nd month after rewetting, except for K. Aboveground productivity of perennial ryegrass responded positively to NO3–N availabilities during the 1st month after rewetting, leading to productivity outperformance of formerly drought-stressed plots compared to controls. These results suggest that short-term productivity outperformance of perennial grasslands in the 1st month after rewetting is driven by an increase in NO3–N availability caused by a rewetting-induced pulse in N-mineralization of organic substrates accumulated during drought. Although effects of drought and rewetting on nutrient availability were only observed in the 1st month after rewetting, grassland productivity outperformance persisted in the 2nd month after rewetting. This indicates that soil drought legacy increased plant nutrient uptake efficiency, explaining longer-term outperformance effects when effects of drought and rewetting on nutrient availability were no longer apparent
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
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
Predicting soil microbial responses to drought: a laboratory analysis
Full text linkopenSoils are fundamental components of terrestrial ecosystems, sustaining plant productivity, nutrient cycling, and carbon storage. Microbial communities play a central role in these processes through decomposition and nutrient mineralization, but their activity is highly sensitive to drought, an increasingly frequent climatic stressor.
This study aims to assess how soil microbial activity responds to varying degrees of water stress across sites differing in soil properties and climatic regimes. Soil samples were collected from five Italian grassland sites spanning a gradient of mean annual precipitation (MAP), organic matter content, and pH. Controlled laboratory incubations were conducted at five moisture levels (10 - 80% water holding capacity) to measure soil respiration, eight extracellular enzymatic activities, microbial biomass carbon (MBC) and nitrogen (MBN), and available nutrients.
We hypothesized that microbial communities from drier sites would be more resistant to water stress than those from wetter regions. In agreement to this expectation, sites with higher MAP showed stronger reductions in respiration under low moisture, but all sites converged to similar relative respiration rates at the lowest moisture levels, even after normalization by soil organic matter. Microbial communities exhibited two contrasting nutrient-acquisition strategies under drought - either increasing or decreasing enzyme production - yet these shifts did not translate into differences in CO2 efflux, indicating that drought imposes a dominant physiological constraint regardless of community strategy or climatic origin. Respiration rates were strongly and positively associated with dissolved nitrogen, revealing a tight coupling of microbial C and N cycling and a potential role for available N in mediating drought effects on soil metabolic activity.
Overall, our results demonstrate that microbial functional responses to drought are governed more by intrinsic moisture limitation than by long-term climatic adaptation, providing mechanistic insights into how soil carbon losses may accelerate in a drying world.Soils are fundamental components of terrestrial ecosystems, sustaining plant productivity, nutrient cycling, and carbon storage. Microbial communities play a central role in these processes through decomposition and nutrient mineralization, but their activity is highly sensitive to drought, an increasingly frequent climatic stressor.
This study aims to assess how soil microbial activity responds to varying degrees of water stress across sites differing in soil properties and climatic regimes. Soil samples were collected from five Italian grassland sites spanning a gradient of mean annual precipitation (MAP), organic matter content, and pH. Controlled laboratory incubations were conducted at five moisture levels (10 - 80% water holding capacity) to measure soil respiration, eight extracellular enzymatic activities, microbial biomass carbon (MBC) and nitrogen (MBN), and available nutrients.
We hypothesized that microbial communities from drier sites would be more resistant to water stress than those from wetter regions. In agreement to this expectation, sites with higher MAP showed stronger reductions in respiration under low moisture, but all sites converged to similar relative respiration rates at the lowest moisture levels, even after normalization by soil organic matter. Microbial communities exhibited two contrasting nutrient-acquisition strategies under drought - either increasing or decreasing enzyme production - yet these shifts did not translate into differences in CO2 efflux, indicating that drought imposes a dominant physiological constraint regardless of community strategy or climatic origin. Respiration rates were strongly and positively associated with dissolved nitrogen, revealing a tight coupling of microbial C and N cycling and a potential role for available N in mediating drought effects on soil metabolic activity.
Overall, our results demonstrate that microbial functional responses to drought are governed more by intrinsic moisture limitation than by long-term climatic adaptation, providing mechanistic insights into how soil carbon losses may accelerate in a drying world
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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