1,720,972 research outputs found
IMPACT OF AGRICULTURAL PRACTICES ON BIODIVERSITY OF SOIL INVERTEBRATES, ASSESSMENT THROUGH DNA METABARCODING APPROACH
Full text linkIn spite of the increase of the organically farmed areas worldwide, it has been always doubted if the organic farming really enhances the soil biodiversity, as the main component in the agroecosystems. This doubt was a target of many studies, trying to reveal the true impact of the applied agricultural practices in the adopted farming strategies, targeting the soil invertebrates as bioindicators of the impact. Unfortunately, the doubt is still, due to the limitations in the sampling and taxonomy of the soil’s invertebrates communities. In the last years, the molecular approaches represent promising methods to overcome these limitations. Thus, the DNA metabarcoding was applied targeting the COI gene in the DNA extracted from soil samples collected in different farming strategies (organic vs non organic), with a different cropping systems (stable meadow vs barley) and different levels in the field from the margin to center, this sampling was performed in three seasons (May, July and October).
In addition, the soil properties (pH, texture, N%, C% and C/N ratio) were determined for the selected samples. The illumine MiSeq run was performed and the obtained reads were processed
bioinformatically to get the OTU table (Operational Taxonomic Unite). This OTU table was used for the statistical and ecological analysis. Finally, the QBS, a soil quality index depends on the soil
inhibiting microarthropods, was calculated by its classic method and estimated based on the obtained molecular data, to check the correlation between the resulted values. Results showed that the DNA metabarcoding approach represents a promising method for the assessment of soil biodiversity in the agroecosystem, but this approach is not able to detect the seasonal changes of the soil invertebrates’ communities. Regarding the farming strategies, the farming management as organic or non organic (conventional) did not affect significantly the community structure of soil invertebrates and the biodiversity indices Shannon and Pielou’s evenness, while the species richness was significantly lower in the conventional farm. Soil invertebrates’ communities were significantly affected by the crop and the position of the field (as margin or field), and the C/N ratio. For Rotifera and Tardigrada communities’ structure were affected by the farming strategy, while insects’ communities were affected by the pH of the soil. The role of the margin of the field as a reservoir is increased in the cultivated fields (barley), while in the stable meadows the interactions between the margin and the center of
the field are lower. Finally, the soil biological quality is decreased from the margin to the center of the field (of the same field), also decreased in the barley field comparing to the stable meadows.
The obtained molecular index mQBS that is developed based on the QBS-ar is a promising approach for the soil biological quality estimation
Ecological State Evaluation of a Rural Landscape Revealing the Importance of Naturalised and Organic Crop Fields
No full textThis study understood the ecological state of an agrarian landscape, by performing the tools and
indicators proposed by the “Landscape Bionomics” (LB) discipline. The tested principles and methods
offer a systemic approach to study environmental problems at different scales (i.e. crop, field, farm and
landscape) and to promote the rehabilitation of compromised areas. The methodology distinguishes
specific landscape elements according to their functions, which can be exclusive like human habitats (e.g.
productive, residential, subsidiary) and natural habitats (e.g. source, resistant, stabilising, geologic), or in
common between these two (e.g. protective, resilient, connective).
Using LB, we assessed the impact of anthropic factors on a rural area (15km2 in the South Milan
Agricultural Park in Lombardy Region, Italy) in a 62 years timespan (data from 1954, 1999 and 2016).
The overall results highlighted that anthropic activity impacts are more strongly on landscape functions:
A. The productive (Crop Fields)
B. The resistant (Woods)
C. The protective (Tree Rows)
Moreover, the temporal reconstruction described an altered ecological state in the entire timespan, with
further degradation in the last 17 years. However, at the farm scale, we observed that the resistant, the
protective and some productive apparatuses (In particular permanent meadows and organic fields) play
an ecological role of potential compensation for landscape fragmentation and urbanisation
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
Regenerating Villa Fortuna (RVF) - An experimental Mediterranean complex agroforestry system
No full text“Syntropic agroforestry”, also known as “Successional Agroforestry” (SA), is a well-known approach in
agroforestry. Developed in Latin America, it imitates the natural succession and stratification of the
ecosystem. In this complex system, crops and trees are planted in “consortia” communities that cover the
whole sequence of natural successional steps (from pioneer species to primary forest species), and which
become increasingly harmonious over time. Despite the growing interest among practitioners and
scientists, in Europe and Latin America, there is a lack of data and large-scale research on such complex
agroforestry systems.
In this respect, RVF (Regenerating Villa Fortuna) represents a great opportunity, as an experimental system
focusing on SA in San Salvatore Monferrato (province of Alessandria, Piedmont, Italy). The RVF research
aims to monitor the SA processes starting from day 0 of the regeneration of approx' 20 ha of abandoned,
previously cultivated, land (Figure 1), and continuing the experiment long-term (min 10 yrs).
The research aims to study how successful SA is as an eco-efficient farming system in the Mediterranean
area. The main goals are to recover the local biodiversity and to provide more ecosystem services. RVF
will investigate the environmental, social and economic aspects of this farming approach, and compare
the results with other agroecosystems in the study area.
The research will start by selecting the plant communities to be cultivated, imitating the natural succession
in the Mediterranean area, and then will move on to monitoring the biodiversity, the physiological
status of the plants, yield, and the socio-economic impacts, in order to arrive at an integrated
environmental socio-economic report of the whole approach.
The parameters and indicators that have been chosen are very diverse, due to the huge number of
desired variables; these include: traditional soil Physico-chemical parameters, flora, the stress tolerances
of the cultivated plants, nutrient efficiency, the frequency of the presence of pollinator insects, and yield
in terms of quantity and quality. Moreover, a molecular approach will be implemented through the
application of DNA metabarcoding on the soil environmental DNA, in order to study the progressive
development of the soil communities and their interactions (Bacteria, Fungi and Metazoans).
In addition, raw materials will be used efficiently in order to assess the energy consumed and the inputoutput
balance of the system; for this step, life-cycle assessment analysis will be applied to the whole
system
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
DNA Metabarcoding as a tool for soil’s biodiversity assessment in organic and conventional agroecosystems
No full textElucidating how agricultural practices affect soil invertebrate communities is of relevant importance. In
the present study, using DNA metabarcoding, soil invertebrate communities of selected farms in the Po
Valley (Italy) were assessed in order to address the following questions: i) is the structure of soil
invertebrates’ communities different between organic and conventional farms? ii) To which extent are
field use (crop vs stable meadow) and field margins affecting these communities? Soil samples were
collected from organic and conventional farms in different periods of the year, covering the margins and
three levels towards the centre of fields of stable meadow and barley of both farms. DNA was extracted
from soil samples and a fragment of the cox1 gene amplified using three different pairs of primers;
amplicons were sequenced using Illumina Miseq. Raw sequences were analysed using Qiime and
ecological and statistical analyses were performed with R in order to address the above-mentioned
questions. The recovered invertebrate’s communities were dominated by Arthropoda (~ 80% of the OTUs
in each sample), a total of 831 OTUs (Insecta 51%, Arachnida 18% and Mollusca 14%) formed the core
diversity present in all the analysed samples. α-diversity indices were not significantly different between
the two farming strategies in terms of OTUs richness, Shannon index and Pielou’s evenness. β-diversity
analyses showed the field margins invertebrate communities were different from the inner field
communities. In conclusion, DNA metabarcoding represented a suitable method for soil invertebrates’
biodiversity estimation. The recovered communities are significantly affected by the crop and the
localization in the field (margin vs center). In addition, the role of field margins as a diversity reservoir is
increased in cultivated fields (barley), while in stable meadows fields, the interactions between the
margins and the center of the field are lower
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