305,431 research outputs found
Identifying plant communities of thermophilous deciduous forest in Greece: Species composition, distribution, ecology and syntaxonomy
No full textThermophilous deciduous forest is widespread in northern mainland Greece and extends in patches further south to Peloponnisos and the bigger islands. In this paper, we provide a phytosociological survey of the plant communities of deciduous oak and mixed forest throughout Greece, based on about 370 releves from the literature and more than 300 personal unpublished ones. Assocation names of the thermophilous deciduous forest are re-evaluated, and syntaxonomic conclusions added. The releves are classified, and 13 associations and several additional subtypes described and presented in synoptic constancy tables. The following associations were recognized, and characterized by species composition, ecology and distribution: 1. Phillyreo-Carpinetum orientalis, 2. Dryopterido pallidae-Ostryetum carpinifoliae, 3. Tilio tomentosae-Castanetum; 4. Genisto carinalis-Quercetum petraeae, 5. Querco frainetto-Castanetum, 6. Cytiso villosi-Castanetum; 7. Lathyro laxiflori-Castanetum; 8. Symphyto ottomani-Quercetum frainetto, 9. Verbasco glabrati-Quercetum frainetto; 10. Huetio cynapioidis-Quercetum frainetto; 11. Digitali viridiflorae-Quercetum frainetto; 12. Geranio asphodeloidis-Quercetum frainetto; 13. Oenantho pimpinelloidis-Quercetum frainetto. Associations 1-2 are assigned to the alliance Fraxino orni-Ostryion, 4-6 and 8-13 to the Quercion frainetto (both Quercetalia pubescentis), 3 interim to the Tilio-Acerion, and 7 to the Quercetalia ilicis. The two Quercetalia pubescentis alliances co-occur in northern Greece; their habitats differ chiefly in terms of soil conditions, bedrock and topography, rather than in overall climatic character
Plant functional traits and diversity in sand dune ecosystems across different biogeographic regions
No full textPlant species of a functional group respond similarly to environmental pressures and may be expected to act similarly on ecosystem processes and habitat properties. However, feasibility and applicability of functional groups in ecosystems across very different climatic regions have not yet been studied. In our approach we specified the functional groups in sand dune ecosystems of the Mediterranean, Hyrcanian and Irano-Turanian phytogeographic regions. We examined whether functional groups are more influenced by region or rather by habitat characteristics, and identified trait syndromes associated with common habitat types in sand dunes (mobile dunes, stabilized dunes, salt marshes, semi-wet sands, disturbed habitats). A database of 14 traits, 309 species and 314 releves was examined and trait-species, trait-plot and species-plot matrices were built. Cluster analysis revealed similar plant functional groups in sand dune ecosystems across regions of very different species composition and climate. Specifically, our study showed that plant traits in sand dune ecosystems are grouped reflecting habitat affiliation rather than region and species pool. Environmental factors and constraints such as sand mobility, soil salinity, water availability, nutrient status and disturbance are more important for the occurrence and distribution of plant functional groups than regional belonging. Each habitat is shown to be equipped with specific functional groups and can be described by specific sets of traits. In restoration ecology the completeness of functional groups and traits in a site may serve as a guideline for maintaining or restoring the habitat. (C) 2016 Elsevier Masson SAS. All rights reserved.Reinhold-und-Johanna-Tuxen-Stiftung Ira
Arzneipflanzenflora im ehemaligen Königreich Hannover laut G.F.W. Meyer (Stand: 1836–1849) und heute
No full textThe diversity of woodland vegetation in Central Albania along an altitudinal gradient of 1300 m
No full textThe woodland vegetation of Central Albania is studied and discussed along an altitudinal gradient in the Dajti National Park (DNP). The plant species combinations recorded in 168 plots were classified and subjected to indirect gradient analysis using environmental variables of geology, soil, topography, disturbance and grazing impact. The transect over more than 1300 m reflects the biogeographically intermediate paramediterranean vegetation zonation and the relatively humid Mediterranean "hygric series" at its eastern margins. It reveals the total range of woodland types known to occur in Central Albania, thus stressing the representativity of the area regarding biodiversity and biogeography, and its importance for nature conservation. Along the elevation gradient, we found three plant communities of the mesomediterranean Quercetalia ilicis, five of the supramediterranean Quercetalia pubescentis and five of the montane or oromediterranean Fagetalia sylvaticae.DAA
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Examining the relationship between total species richness and single island palaeo- and neo-endemics
No full textRecently, Emerson and Kolm (2005) hypothesized that diversity begets speciation (DBS hypothesis). The relationship between total species richness and single island endemic diversity (as a proportion of the total species richness of the island) has been used as evidence for the DBS hypothesis. This relationship has been documented in oceanic archipelagos, but many criticisms have been raised on whether this relationship truly supports the DBS hypothesis. In this study we tested if this hypothesis holds in the Aegean archipelago (a continental archipelago with continuous human presence over millennia). Endemism in the Aegean includes mainly neo-endemic species but also relictual populations of formerly more widespread species (i.e. palaeo-endemics). Contrary to the DBS hypothesis, we found that total species richness was not significantly correlated to single island endemics (neither neo-endemics nor palaeo-endemics) as a proportion of the island flora. Furthermore, we found that neo-endemic diversity (either as species richness or as a proportion of the islands flora) is mainly correlated to island maximum elevation, while area and isolation were less important. So if this ratio is indeed an index of speciation, then an alternative explanation might be that elevation (interpreted as a proxy for habitat heterogeneity) is the driver of speciation in our case. Palaeo-endemics, on the other hand, were present in only six of the largest islands in the Aegean and their diversity was strongly correlated only with island area, perhaps implying that larger islands support larger population sizes that buffer stochastic extinctions risks. (C) 2010 Elsevier Masson SAS. All rights reserved
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