1,721,055 research outputs found
Vegetation surveys in the circumboreal coniferous forests: A review
No full textAs an introduction to the special issue "Vegetation of Circumboreal Coniferous Forests", a brief history is provided of the development and present state of floristic vegetation surveys of the boreal and mountain coniferous forests of Europe, northern Asia and North America. The focus is on forests assigned to the phytosociological class Vaccinio-Piceetea and closely related vegetation types
Regional metacommunities in two coastal systems: spatial structure and drivers of plant assemblages
No full textAim Biogeographical patterns in metacommunities are still poorly understood, and different processes are expected to occur in different habitats. We analysed the regional plant metacommunities of coastal habitats to test whether (1) the influence of space and climate differs between two habitats differentiated along the seashore–inland gradient, and (2) regional variation in species composition of these habitats can be ascribed to different metacommunity paradigms.
Location The entire coast of the Iberian Peninsula, south-western Europe.
Methods We collected data on the plant species composition of coastal sites on sand dunes across 3000 km of coastline. The sites were classified into two habitats corresponding to shifting and stable sand dunes, and divided into three distinct geographical regions: Cantabrian, Atlantic and Mediterranean. We assessed the geographical structure of the species composition using ordination, estimates of species turnover and spatial autocorrelation. We then used multivariate models and variation partitioning to test the influence of climatic and spatial effects. Analyses were conducted for the whole data set and the geographical subsets.
Results Metacommunities from shifting and stable dunes showed similar spa- tial patterns, with the highest species turnover occurring in the Mediterranean region. Similarities between communities that were nearer each other (typically < 100 km) were weaker in shifting than in stable dunes, although the distance decay for sites that were further apart was similar in both habitats. Variation in species composition in shifting dunes was mainly explained by distance and climate, while in stable dunes the effect of climate was clearly dominant. The observed differences were relatively consistent across geographical regions.
Main conclusions Distinct processes structure the metacommunities in two dune habitats differentiated along the seashore–inland gradient. Communities of shifting dunes seem to be structured by an interplay of neutral or patch-dynamic processes and to a lesser degree by species sorting. In contrast, communities of stable dunes are mainly governed by species sorting in response to climatic gradi- ents. These results highlight the importance of differentiating habitats according to local ecological factors when analysing regional patterns in metacommunities
From the data stored in the anArchive database to a formalized phytosociological classification of Italian aquatic vegetation
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Alien plant invasions in Mediterranean habitats. An assessment for Sicily
Full text linkLevels of plant invasions in different habitat types were assessed in several regional studies, but few of them were from the Mediterranean. Here we compare the levels of vascular plant invasion across habitats and plant communities of Sicily. We used a large dataset of plant species presences/absences in vegetation plots to analyze the invasion patterns across habitats considering biogeography, life form and phenology of alien plants. Vegetation plots were classified based on the EUNIS classification of European habitats. The invasiveness of each species was expressed in terms of its absolute and percentage frequency. Representation of different life forms and phenological patterns was compared between alien and native species. The fidelity of alien species to individual habitats was calculated using the phi coefficient. Our analysis shows that annual and woody species are the most represented life forms in the alien flora of Sicily and that alien species tend to have a longer flowering period than the native species. The investigated habitats differed strongly in their level of invasion by alien species, ranging from 0 to 15.6% of aliens of all species recorded. Most of the habitats were colonized by very few alien species or completely lacked them, except for sandy coasts, naturally-disturbed riverbeds, and synanthropic habitats. It must be noted, however, that the number of alien species occurring in a given habitat does not relate to the severity of the impact of invasion in that habitat. Some habitats are invaded by few (or single) species, which attain a high cover, transforming the whole ecosystem. The habitat-based approach proved to be suitable for evaluating the habitat specificity and frequency of alien species at a regional scale, improving the capacity for risk assessment in different ecological contexts
Formalized phytosociological classification of the Lake Trasimeno vegetation: an application of the Cocktail method.
No full textLake Trasimeno is a large (about 124 km2) shallow lake with significant fluctuations of water table, and a site of high conservation value (Site of Community Importance, Special Protection Area and Regional Park) in central Italy. Data about macrophytic, wetland, wet meadow, scrub, forest and ruderal vegetation of this area were collected during the last three decades by the present authors and other researchers and recently stored in the Anarchive database system. Vegetation classification was performed on a data set of 966 relevés using the Cocktail method. This method, designed to simulate the Braun-Blanquet approach, is largely based on expert knowledge, reflecting the field experience of the authors and the classifications published in the literature. In some cases, cluster analysis was also used to reveal the differences between communities with several generalist species, in particular within the class Molinio-Arrhenatheretea. All analyses were performed in the program Juice 7.0. The formal definitions were created using logical operators (AND, OR and AND NOT), combining species cover values and species groups. Sociological species groups and diagnostic species of the associations were determined using the phi coefficient of association. This method allowed to produce formal definitions for 79 communities included in 30 different alliances and 15 classes. The present work represents the first application of the Cocktail method in the Mediterranean area and Southern Europe. The number and distribution of the relevés are not sufficient for creating formalized definitions valid for a wide geographical area, but the Cocktail classification is largely in accordance with the expert-based classifications reported in the literature. It allowed to characterize different associations also in disturbed and floristically impoverished vegetation
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