1,720,974 research outputs found
Spatial phylogenetic diversity of pteridophytes in Latium (Central Italy): a tool for conservation planning at regional scale
No full textThe spatial phylogenetic metrics of pteridophyte diversity and endemism may provide use ful information to prioritize protected areas for conservation planning. We analysed spatial
patterns of phylogenetic diversity (PD) and phylogenetic endemism (PE) of native pterido phytes across Latium, to recognise diversity and endemism centres. and to discuss impli cations for conservation in the region. We identified the main PD and PE centres that
should be considered as valuable biodiversity hotspots, due to their high evolutionary and
conservation value. Most, but not all of them correspond to protected areas Monitoring programmes of the rarest taxa are proposed
Vascular plant richness along elevation gradient at Monte Velino (Central Apennines, Italy)
No full textSpecies richness was studied during two years in 100-m elevation bands along an elevation transect from 1100 m up to 2487 m asl on the southwestern slope of Monte Velino. The 1300- to the 2200-m elevation bands have a similar area in the range of 0.36 to 0.40 km2. A total of 636 taxa (species and subspecies) was recorded. Each species was attributed a life form, an elevation category and a chorotype. The richness per elevation band decreases monotonously along the transect with a plateau between 1300 and 1600 m asl. Because of the similarity of the area of the elevation bands between the 1300-m and the 2200-m elevation band, the richness pattern along the transect is not merely a function of the area. The rejection of the area hypothesis, at least between 1300 and 2300 m asl, is also demonstrated by the species traits. Most of them show a monotonous pattern with elevation, either decreasing or increasing. The cumulative increase of species richness along the transect follows the Arrhenius’ power function S = C x Az with a z value of 0.291. Endemics peak at an intermediate elevation in the 2000-m elevation band and follow the isolation-area hypothesis. In that the species-density matches the adiabatic decrease of air temperature, we consider the latter as the driving factor for the pattern of the species richness in relation to elevation. Colder temperatures (a) reduce the species pool in relation to elevation due to an increasingly colder and shorter vegetation period; (b) drive geomorphological processes that both reduce habitats number and spatial heterogeneity, and enhance their convergence and homogenization (temperature-physiography hypothesis). Therefore, area, temperature and isolation are the three main parameters to explain plant richness with elevation for Monte Velino
Pattern of floristic variation on a montane beech forest in the central Apennine (central Italy)
No full textClimate, history and human land use have a strong influence on the distribution and floristic composition of beech forest communities. In the last
50 years, the decrease in human activities has led to the resumption of reforestation dynamics, so a certain variability in floristic composition is
expected. We aim to identify the causes of local floristic variability in different stands of beech forests, integrating floristic, structural and ecological
analysis.
Cluster analysis and Indicator Species Analysis (ISA) were performed to highlight floristic differences; the clusters obtained were compared through
environmental and topographic variables, Ellenberg indicator values, life forms, Social Behaviour Types (SBT) and structural parameters. The
species heterogeneity derives from a climatic and edaphic gradient. Two main types of beech forests were recognized: a microthermal one, placed
at higher altitudes and cooler aspects (Cardamino kitaibelii - Fagetum sylvaticae), and the termophilous one, lying at lower altitudes and warmer
aspects (Lathyro veneti - Fagetum sylvaticae). SBT and structural parameters were useful for detecting the effects of dynamic processes of reforestation.
The integration of the floristic, structural and ecological analysis led to an accurate coenological overview of the beech forest communities
and to the detection of the natural reforestation processes currently ongoing
La vegetazione forestale dei substrati arenacei della Val d’Aso (Marche, Italia centrale).
Full text linkResults of a phytosociological study on the wood on the sandstone
bedrock are here presented. The studied area is located in the southern part of Marche Region, Ascoli Piceno Province, under the influence of temperate climate (lower/higher mesotemperate and lower supratemperate bioclimatic belts). The vegetation study has been performed throught 119 phytosociological relevés. All data were submitted to multivariate statistical analysis. The phytosociology analysis has permitted to characterize 6 associations, whereof 2 news: Erico arboreae-Quercetum pubescentis ericetosum arboreae and Hieracio murori-Ostryetum carpinifoliae hieracietosummurori. Chorological and synecological datas were described in the paper, compared to the corresponding associations of the limestones bedrock of the neighbouring area
Allium ducissae (A. subgen. Polyprason, Amaryllidaceae) a New Species from the Central Apennines (Italy)
Full text linkIn this paper, Allium ducissae (the LSID for the name Allium ducissae is: 77254606-1) is described as a new species based on morphological and molecular analyses, and its taxonomic relationships are discussed. It grows in crevices on calcareous rocks, rocky slopes and grassy ledges in the subalpine belt, within two regional protected areas in the Lazio and Abruzzo administrative regions (Central Apennines, Italy). Previously, these populations were attributed to A. strictum, a species described from Siberia, belonging to A. sect. Reticulatobulbosa. The new species is distinct from A. strictum in the morphology of vegetative and reproductive structures. Indeed, it is close to A. palentinum, an endemic species to Cantabrian Mountains (NW Spain). Both molecular and morphological data support the recognition of the Allium populations coming from the Central Apennines as a new species. Allium ducissae can be clearly distinguished from A. palentinum by longer and wider tepals, longer filaments, a tooth of inner filament, flower pedicels, spathe appendage, and smaller seeds. Moreover, seed testa micro-sculptures revealed slight differences between A. ducissae and A. palentinum. Chromosome counts showed that A. ducissae is diploid with 2n = 16 chromosomesas already known for A. palentinum. Molecular analyses support the affiliation of A. ducissae and Apalentinum to A. sect. Falcatifolia, contrary to what is known for the latter species, usually included in A. sect. Daghestanica. Finally, the IUCN assessment for the newly described species is proposed and briefly discussed
Typification and Correct Place of Publication of the Name Allium kermesinum (Amaryllidaceae)
No full textThe name Allium kermesinum Rchb. is typified, and the correct place of publication of the name is discussed. A specimen issued in 1842 of Reichenbach's "Flora Germanica Exsiccata, Centuria XXII: No. 2141," preserved at HAL, is designated here as the lectotype
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
- …
