1,720,958 research outputs found
Old coppice versus high forest: The impact of beech forest management on plant species diversity in central Apennines (Italy)
No full textAims: Silvicultural management plays a major role in shaping understory diversity through its action on stand structure. In many parts of Europe, recent socioeconomic changes have led to the progressive abandonment of coppicing in favor of high forest (HF) management. In order to examine how this change impacts understory species, we compared old coppice-with-standards and HF stands in terms of structural features and understory richness and composition, also taking into account the diagnostic species pool of the habitat. Since the management systems for coppices and HFs differ in cutting regime, we expect that they would cause different changes in floristic composition and richness. Methods: The study area was the Montagne della Duchessa massif, in central Italy. Structural differences and floristic richness were compared, and the diagnostic species diversity was analyzed using rarefaction curves and Rényi diversity profiles. Differences in understory composition were analyzed through indicator species analysis. Important Findings: Our results showed that, though the old coppices have a slightly higher number of understory species in general, the HF stands have greater mean species richness in both understory and diagnostic species, the latter being more evenly distributed inside the community. These finding were related to the cut regime, which favor a constant canopy cover over time and thus the maintenance of more stable microclimatic conditions, promoting the higher abundance and evenness of shade-tolerant and vernal species. Conversely, the dense canopy of the old coppice appears to affect the understory richness by reducing the presence of light-demanding species, but still without a complete recolonization of the shade-tolerant species. Overall, our findings provide the first insights supporting that, in a Mediterranean montane context, old coppice conversion to HF could over time improve the species diversity in these habitats and help maintain good conservation status of the typical mature beech forests
Understory functional response to different management strategies in Mediterranean beech forests (central Apennines, Italy)
No full textThe aim of this paper was to investigate the functional composition of the understory of Mediterranean beech forest stands that have been managed in two different ways, namely, coppicing and tree by tree harvesting. In particular, we used a trait-based approach to characterize old coppice and high forest stands, analyzing their differences and evaluating the status of old coppices by considering their conversion towards high forest stands. The study area was the Montagne della Duchessa massif in central Italy, which lies at the center of the Apennine chain. Sixty-six plots were laid out and their species abundance and structural parameters were recorded. Data on plant traits were collected using both European databases and the literature available. Redundancy analysis was performed to assess the relationship between trait states and management, and forward selection was used to identify the structural parameters with a significant effect on trait variability. A Wilcoxon Rank-Sum test was done to assess differences in trait states between the management types. High forests proved to be more related to traits typical of mature forest conditions, while old coppices seemed not to have a clear trait association, except for some trait states related to open habitats, and showed the same âmature forestâ trait composition, even if with lower abundances. This indicates that, despite the higher initial disturbance pressure, once abandoned, old coppices tend over time to evolve naturally towards mature forest functional conditions
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
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
Floristic and structural variability of the central apennines beech forests in relation to natural and anthropogenic determinants
No full textForests are complex ecosystems, in which the floristic composition is the result of the combined effect of several factors, acting at different levels. Climate, lithology, geomorphology act at a broader scale, driving the forest's communities differentiation while, at a finer scale, the understory species composition is shaped by the forest stand structure that directly influences the environmental conditions (light, temperature, moisture) at the ground level. Fagus sylvatica forests are the most abundant broadleaved communities in central and southern Europe; in Italy they represent the typical montane vegetation in the Apennine chain, where these coenoses reach the highest elevations of their whole distributional range. Beech forests have been managed for centuries, prevalently as coppice, or coppice-with-standards (CWS), and high forest (HF). However, in recent decades deep socio-economical changes have led to the progressive abandonment of coppice cut and its conversion to high forest management. These two systems differ in cut intensity and severity (both higher in CWS): given that forest management impacts upon overstory structure and therefore determines the understory composition, management changes are likely to affect understory species composition and diversity.
In this thesis I have analyzed the effect of the main environmental drivers on beech forests communities: I then focused on the management effects on understory species and 9210* Habitat diagnostic species richness and composition (sensu Habitat Directive 92/43 EEC), in order to understand the possible implications of the old CWS conversion on the floristic composition.
The study was conducted in central Apennines, on the Montagne della Duchessa massif, where beech forests occupy a surface of more than 1200 ha; these forests have ceased to be managed since '60s, so the CWS have become older, and are destined to be converted to the HF cut.
I studied the role of the environmental factors in differentiating the beech forests communities by using a dataset of 40 relevés randomly selected. The dataset obtained has been analyzed through a cluster analysis and a Indicator Species Analysis (ISA), in order to obtain groups of relevés and to characterize them in floristic terms; the groups obtained were then compared in terms of environmental and topographic variables, Ellenberg indicator values, life forms, Social Behaviour Types (SBT) and structural parameters. Results showed that the floristic and coenological variability is shaped by a climatic and edaphic gradient, that both contribute to define two main communities: a microthermal one, placed at higher altitudes and cooler aspects (Cardamino kitaibelii - Fagetum sylvaticae), and a termophilous one, lying at lower altitudes and warmer aspects (Lathyro veneti - Fagetum sylvaticae). Social Behaviour Types and structural parameters were useful for detecting the effects of the progressive reforestation process occurring inside the microthermal community at higher elevation.
In order to investigate the differences between old CWS and HF stands in terms of understory richness and composition, I used 66 relevés, selected through a random-stratified method, so as to have a comparable number of relevés for each management category; old CWS and HF stands were compared in terms of structural attributes and floristic richness through a U Mann-Whitney test: the II results showed how management is the main factor responsible for differences in the tree layer's spatial aggregation pattern and vertical layering, and that therefore determines the amount of surface available for understory species. HF stands showed a higher mean richness of both understory and diagnostic species, these latter being more evenly distributed (higher species equitability) inside the community. This leads to the consideration that in HF stands the cut regime provided a constant canopy cover over time, and then maintained more stable microclimatic conditions favoring a higher abundance and evenness of the shade-tolerant and vernal species. Conversely, in old CWS the dense canopy negatively affected the understory richness by reducing the light-demanding species pool, while the shade-tolerant species have not yet had time to spread.
In order to understand the implications of the old CWS conversion on beech forests ecosystem's ecological functions, the same dataset was analyzed through plant functional traits, by creating a relevés x traits matrix. A Redundancy Analysis (RDA) was performed to assess the relationship between traits states and management, while a U Mann-Whitney test was used to assess differences in traits states richness between the management types. The results were consistent with the previous findings based on habitat diagnostic species, as HF stands showed a higher affinity to traits typical of mature forests, while old CWS were more related to traits related to managed stands. Moreover, HF stands showed a higher abundance of those traits related to the natural forest's seasonal change, this indicating a good species distribution among the functional niches. Even in this case, old CWS was shown to be in a transitional stage, still represented by some traits related to management, where the mature forest traits are also present, but with lower abundance.
Finally, given that in a forest ecosystem understory represent more than 90% of species richness, and is the most sensitive to disturbance, the modern silvi-cultural strategies should take into account the management effects on forest biodiversity, and adopt sustainable interventions able to favor the typical biodiversity of the ecosystems we want to manage. This thesis provides useful information for management purposes, as our findings show that, in the forests studied, the old CWS conversion to HF could be a good management strategy if our aim is the conservation over time of the species typically related to mature forest conditions
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