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Macroecology of global alpine vegetation
Full text linkGli ecosistemi alpini, ossia gli habitat di alta quota al di sopra della linea degli alberi, sono essenziali per il sostentamento umano e sono tra gli ambienti più minacciati dal cambiamento climatico di origine antropica. Nonostante il consenso generale sulla distribuzione e le caratteristiche ecologiche dei biomi terrestri, l'effettiva estensione e le caratteristiche bioclimatiche degli ecosistemi alpini globali sono ancora incerte. Inoltre, i pattern e le cause della diversità vegetale e del funzionamento degli ecosistemi alpini globali sono in gran parte sconosciuti. Questo lavoro rappresenta un punto di partenza per la delineazione dei pattern macroecologici dei biomi alpini globali.
In primo luogo, ho creato una mappa delle aree alpine globali modellando le quote altimetriche regionali della linea degli alberi ad alta risoluzione spaziale, utilizzando dataset globali di copertura forestale. Ho usato questa mappa in combinazione con altri dataset digitali per valutare le caratteristiche climatiche degli ecosistemi alpini e determinarne i pattern di produttività primaria. In secondo luogo, ho analizzato i pattern globali di ricchezza delle specie vegetali negli ecosistemi alpini e l’influenza di fattori ambientali, geografici e storici a diverse scale spaziali. Per fare ciò, ho messo insieme un dataset globale della vegetazione alpina composto da oltre 8.900 plot, ho valutato i pattern latitudinali di ricchezza regionale e a livello di singole comunità vegetali, e li ho modellati rispetto a diversi predittori, stimati utilizzando raster globali. Infine, ho analizzato la variazione funzionale della vegetazione alpina in rapporto alla storia evolutiva e al macroclima. Per fare ciò, ho ulteriormente selezionato il suddetto dataset di plot di vegetazione alpina in base alla disponibilità di tratti funzionali e dati filogenetici. Ho valutato le strategie funzionali delle diverse specie di piante alpine e la dissimilarità funzionale della vegetazione tra grandi unità geografiche caratterizzate da diversa vegetazione planiziale dominante, macroclima e storia evolutiva. Infine, ho modellato la dissimilarità funzionale rispetto alle dissimilarità ambientale e filogenetica.
Dalle analisi effettuate, è emerso che i biomi alpini coprono quasi il 3% delle terre emerse al di fuori dell'Antartide. Nonostante le differenze di temperatura tra le diverse latitudini, questi ecosistemi convergono al di sotto di una soglia di 5,9 °C di temperatura media annua e verso l'estremità più fredda dello spazio climatico globale. Al di sotto di tale soglia di temperatura, gli ecosistemi alpini sono influenzati da un gradiente latitudinale di temperatura media annua e sono differenziati dal punto di vista climatico per stagionalità e continentalità. Questo gradiente distingue lo spazio climatico dei biomi alpini globali da quello dei biomi temperati, boreali e della tundra. Sebbene i biomi alpini siano similmente caratterizzati da aree scarsamente vegetate, le ecoregioni mondiali mostrano forti differenze nella produttività della loro fascia alpina indipendentemente dalle principali zone climatiche. Inoltre, in contrasto con il ben noto gradiente di diversità latitudinale, la ricchezza di specie vegetali alpine di alcune regioni temperate dell'Eurasia è paragonabile a quella degli ecosistemi alpini tropicali. Questo pattern è principalmente spiegato dall'estensione attuale e passata delle aree alpine, dall'isolamento e dalla variazione del pH del suolo tra le diverse regioni, mentre la ricchezza delle comunità vegetali dipende da fattori ambientali locali. Infine, le specie vegetali delle aree alpine sembrano riflettere la variazione funzionale globale di tutte le piante e sono principalmente differenziate per le loro strategie di utilizzo delle risorse. Il macroclima attuale esercita un effetto limitato sulla vegetazione alpina, agendo per lo più a livello delle singole comunità vegetali e in combinazione con la storia evolutiva. Inoltre, la vegetazione alpina globale è funzionalmente indipendente dalle zone di vegetazione in cui è integrata, mostrando una forte convergenza funzionale.
Nel complesso, nonostante la loro distribuzione globale e l'apparente eterogeneità, gli ambienti alpini formano un gruppo distinto di biomi funzionalmente convergenti, fortemente disaccoppiati dagli ambienti di pianura e con una storia biogeografica varia, la cui eredità può ancora essere osservata sugli attuali pattern di diversità che sono ulteriormente rifiniti da fattori locali.Alpine ecosystems, namely high-elevation habitats above the climatic treeline, are essential to human livelihoods and are among the environments with the highest vulnerability to anthropogenic climate change. Despite the overall agreement on the distribution and ecological features of terrestrial biomes, the actual extent and bioclimatic characteristics of alpine ecosystems worldwide are still uncertain. Furthermore, the patterns and drivers of plant diversity and functioning in alpine ecosystems are largely unknown at the global scale. This work represents a novel contribution to the delineation of macroecological patterns of global alpine biomes.
First, I created a map of global alpine areas by modelling regional treeline elevations at high spatial resolution using global forest cover data. I used this map in combination with global digital datasets to assess the climatic characteristics of alpine ecosystems and to evaluate patterns of primary productivity. Second, I assessed the global patterns of plant species richness in alpine ecosystems and the relative effect of environmental, geographical and historical factors at different spatial scales. To do so, I compiled a global dataset of alpine vegetation consisting of more than 8,900 plots, evaluated latitudinal patterns of regional and community richness and modelled them against different predictors estimated using global raster layers. Third, I assessed the functional variation of alpine vegetation and its relationship with evolutionary history and macroclimate. I filtered the abovementioned dataset of alpine vegetation plots based on the availability of functional trait and phylogenetic data. I assessed the functional trade-offs of alpine plant species and the functional dissimilarity of alpine vegetation across large geographic units with different dominant lowland vegetation, macroclimate, and evolutionary history. Finally, I modelled functional dissimilarity against environmental and phylogenetic dissimilarity.
I found that alpine biomes cover almost 3% of land outside Antarctica. Despite temperature differences across latitudes, these ecosystems converge below a sharp threshold of 5.9 °C and towards the colder end of the global climatic space. Below that temperature threshold, alpine ecosystems are influenced by a latitudinal gradient of mean annual temperature and are climatically differentiated by seasonality and continentality. This gradient delineates a climatic envelope of global alpine biomes. Although alpine biomes are similarly dominated by poorly vegetated areas, world ecoregions show strong differences in the productivity of their alpine belt irrespectively of major climate zones. Furthermore, in contrast with the well-known latitudinal diversity gradient, plant species richness of some temperate alpine regions in Eurasia is comparable to that of hyper-diverse tropical alpine ecosystems. This pattern is mainly explained by the current and past alpine area, isolation, and variation in soil pH among regions, while community richness depends on local environmental factors. Finally, plant species in alpine areas seemingly reflect the global variation of plant function and are mainly differentiated for their resource-use strategies. The current macroclimate exerts a limited effect on alpine vegetation, mostly acting at the community level in combination with evolutionary history. Alpine vegetation is also functionally independent from the vegetation zones in which it is embedded, exhibiting strong functional convergence at the global scale.
Overall, despite their global distribution and apparent heterogeneity, alpine environments form a distinct group of functionally convergent biomes, strongly decoupled from lowland environments, and with a varied biogeographic history, whose legacy can still be observed on current diversity patterns which are locally refined by fine-scale factors
Simulating diverse forest management options in a changing climate on a Pinus nigra subsp. laricio plantation in Southern Italy
Full text linkMediterranean pine plantations provide several ecosystem services but are vulnerable to climate change. Forest management might play a strategic role in the adaptation of Mediterranean forests, but the joint effect of climate change and diverse management options have seldom been investigated together. Here, we simulated the development of a Laricio pine (Pinus nigra subsp. laricio) stand in the Bonis watershed (southern Italy) from its establishment in 1958 up to 2095 using a state-of-the-science process-based forest model. The model was run under three climate scenarios corresponding to increasing levels of atmospheric CO2 concentration and warming, and six management options with different goals, including wood production and renaturalization. We analysed the effect of climate change on annual carbon fluxes (i.e., gross and net primary production) and stocks (i.e., basal area, standing and harvested carbon woody stocks) of the autotrophic compartment, as well as the impact of different management options compared to a no management baseline. Results show that higher temperatures (+3 to +5 °C) and lower precipitation (-20 % to -22 %) will trigger a decrease in net primary productivity in the second half of the century. Compared to no management, the other options had a moderate effect on carbon fluxes over the whole simulation (between -14 % and +11 %). While standing woody biomass was reduced by thinning interventions and the shelterwood system (between -5 % and -41 %), overall carbon stocks including the harvested wood were maximized (between +41 % and +56 %). Results highlight that management exerts greater effects on the carbon budget of Laricio pine plantations than climate change alone, and that climate change and management are largely independent (i.e., no strong interaction effects). Therefore, appropriate silvicultural strategies might enhance potential carbon stocks and improve forest conditions, with cascading positive effects on the provision of ecosystem services in Mediterranean pine plantations
Table_1_Simulations reveal climate and legacy effects underlying regional beta diversity in alpine vegetation.docx
Full text linkIntroductionWhether the distribution and assembly of plant species are adapted to current climates or legacy effects poses a problem for their conservation during ongoing climate change. The alpine regions of southern and central Europe are compared to those of the western United States and Canada because they differ in their geographies and histories.MethodsIndividual-based simulation experiments disentangled the role of geography in species adaptations and legacy effects in four combinations: approximations of observed alpine geographies vs. regular lattices with the same number of regions (realistic and null representations), and virtual species with responses to either climatic or simple spatial gradients (adaptations or legacy effects). Additionally, dispersal distances were varied using five Gaussian kernels. Because the similarity of pairs of regional species pools indicated the processes of assembly at extensive spatiotemporal scales and is a measure of beta diversity, this output of the simulations was correlated to observed similarity for Europe and North America.ResultsIn North America, correlations were highest for simulations with approximated geography and location-adapted species; those in Europe had their highest correlation with the lattice pattern and climate-adapted species. Only SACEU correlations were sensitive to dispersal limitation.DiscussionThe southern and central European alpine areas are more isolated and with more distinct climates to which species are adapted. In the western United States and Canada, less isolation and more mixing of species from refugia has caused location to mask climate adaptation. Among continents, the balance of explanatory factors for the assembly of regional species pools will vary with their unique historical biogeographies, with isolation lessening disequilibria.</p
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
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