1,720,981 research outputs found
Beyond nitrogen critical loads – is there a role for the ‘Ecosystem Services’ approach?
No full textThis paper considers the extent to which indicators of critical load exceedance capture the potential
impacts of changes in nitrogen deposition on ecosystem services. It shows that there are significant
links between nitrogen deposition and a large range of ecosystem services. There is potential for
indicators to be adapted to provide more specific qualitative information for Natura 2000 sites of
the implications of critical load exceedance for ecosystem services.
For the provision of ecosystems goods (e.g. food, fuel, fibre) and water quality and erosion
regulation, it is likely that quite specific information can be provided on the effects of nitrogen
deposition. For others, such as pollination and cultural services, the implications for ecosystem
services are likely to depend on the specific changes in species composition that are found in
specific habitats and sites. The issue of climate regulation has been identified as a critical ecosystem
service, but this effect is not currently considered explicitly in setting critical loads, and given the
complexity of the potential effects of nitrogen deposition on different greenhouse gas fluxes, it
seems impractical to include this in any simple assessment of effects of critical load exceedance.
There are ecosystem services where exceedance of the established empirical critical load for
nitrogen input can be a positive outcome, for example, increases in more nitrophilous species
increasing productivity in certain grassland types and increased grass growth stabilising coastal
dunes, and hence enhancing erosion regulation. An ecosystems approach would therefore have
value in informing the prioritization of conservation management practices in areas with high
nitrogen deposition, depending on the ecosystem service that is most valued at any particular site.
However, given that the cause and effect relationships underlying important ecosystem services are
often complex and not sufficiently understood, more data and research is needed to provide specific
guidance on potential conservation priorities
Current and future policy options for tackling nitrogen deposition impacts on Natura 2000 sites (theme 5): Background document
No full textNew science on the effects of nitrogen deposition and concentrations on Natura 2000 sites (theme 3): background documement
No full textThis background paper summarizes established and new science on the effects of nitrogen (N)
deposition on ecosystems and considers the potential for improved assessment of N deposition
impacts on Natura 2000 sites. The key aspects covered are N deposition effects on biodiversity and
on biogeochemistry, links to ecosystem services, the importance of N form, N deposition indicators,
management practices and ecosystem reversibility following decreased N input.
The paper shows that:
• Evidence of N impacts on different vegetation types in Europe exists, but that it is important
that it is translated meaningfully to the target habitats listed under the Habitats Directive.
Evidence for N deposition effects to important ecosystem services, such as carbon
sequestration, also exists but the cause and effect relationships underlying them are often
complex and not sufficiently understood.
• Chemical N form can influence both the rate of ecosystem change, and the extent of impacts
on the short and long-term. Evidence is presented for ammonia causing detrimental plant
physiological effects, probably on the majority of species, whilst ammonium and nitrate
effects will depend on plant species present.
• Plant species composition as well as plant biochemical parameters may be useful
bioindicators for assessment of N deposition effects in Natura 2000 sites, however
“baseline” data are mostly not available for rare species. Ecosystem specific indicators,
that are predictive of further damage, rather than a consequence of already existing adverse
effects (i.e., early warning indicators) are needed.
• Site level management practices can be useful to reduce the impact if N deposition but they
will certainly not be able to mitigate all the impacts of enhanced N deposition and enhances N concentration on Natura 2000 habitats. More knowledge is needed to better understand
where and if management intervention is appropriate to mitigate N effects.
• Studies on the reversibility of N impacts show that some ecosystem parameters may revert
quickly, while other components may show strong inertia. In some cases reversion to the
original state may however be impossible.
• Climatic factors interfere with ecosystem effects of N deposition. It is clear that climate
both can emphasize and mitigate effects of N deposition. Current climate and expected
climatic changes must be included in assessments and predictions of N deposition effects
on ecosystems.
The aim is to provide a broad picture of scientific advancement within the field of N deposition
research, and to provide a starting point for workshop discussions. Workshop discussions addressed
the relevance of new science in assessing N deposition impacts on Natura 2000 sites, and identified
when there is potential to make management adjustments to mitigate such effects
Current and future policy options for tackling nitrogen deposition impacts on Natura 2000 sites (theme 5): Working group report
No full text
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
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