1,721,021 research outputs found
Grado di naturalità e fattori antropici in una zona di particolare rilevanza ambientale: il caso della bassa Val Bregaglia.
No full textLa vegetazione forestale dell’ordine Piceetalia excelsae Pawl. in Pawl. et al. 1928 nelle Alpi Lombarde.
No full textIn Lombardy, boreal-like conifer forests are widespread on the whole alpine chain, particularly in the central Raethian Alps with continental climate and, on a lesser extent, in the Lepontine Alps with oceanic climate and in the peripheral chains with intermediate climatic traits (Orobian Alps, Camonica Valley, Pre-Alps). The average yearly rainfall can exceed 2000 mm in the Lepontine Alps, while it falls below 1000 mm in the inner Rhaetian Alps. The bedrock consists mainly in siliceous rocks.
In the present work, the main forest communities have been outlined on the basis of 253 relevés, analysed by multivariate analyses and by the comparison with the main syntaxonomic schemes found in literature. The described communities can be related to the main biogeographical and ecological domains of Lombardy. Communities belonging to Piceetalia excelsae Pawl. in Pawl. et al. 1928 can be observed on acidic, oligotrophic soils. The alliance Piceion excelsae Pawl. in Pawl. et al. 1928 is divided into two suballiances: the first (Vaccinio-Piceenion Oberd. 1957) includes the subalpine forests of the continental inner Alps; the second (Vaccinio-Abietenion Oberd. 1962) the upper montane and subalpine forests belonging to the oceanic domains (e.g. Lepontine and Orobian Alps)
Le fitocenosi a Fagus sylvatica L. dell'alto Lario occidentale: caratterizzazione e significato fitogeografico (nota preliminare).
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Landform–vegetation units for investigating the dynamics and geomorphologic evolution of alpine composite debris cones (Valle dell'Avio, Adamello Group, Italy)
No full textCluster analysis of 245 vegetation plots, along 17 transects on alpine composite debris cones in the Italian Alps, allowed us to classify complex mosaics of landforms and plant communities. A variety of active and past geomorphic processes (mass wasting, avalanche activity, and running water) were responsible for the construction of the debris cones. By assessing plant community distribution in the context of the different landform units and geomorphic processes, represented in detailed geomorphological maps, a sequence of landform–vegetation units was identified. This approach contributes to the assessment of environmental hazards on the cones, and may also be applied in other environmental contexts. Plant community distribution and development inValle dell'Avio reflects the frequency and intensity of the processes that built composite alpine debris cones, creating environmental gradients and/or generating new habitats. Therefore this patchy landscape allows the preservation of local biodiversity, with typical plant communities adapted to particular niches
Vegetation dynamics on composite debris cones.
No full textInteractions between landforms and vegetation cover
are particularly evident in mountain areas where ecological factors change along altitudinal gradients within a limited geographical area. In particular, landform heterogeneity in extreme plant habitats gives rise to environmental diversity and biodiversity gradients. Plant community distribution on the cones is very heterogeneouswith discontinuous
and scattered vegetation cover that correlate with the direction, intensity and overlapping of the geomorphic processes. In particular, geomorphic processes create
habitats where specific plant communities can develop. These processes act as disturbance factors that induce partial or total vegetation destruction and limit plant biomass production. The disturbance is measured as a function of intensity and frequency of the events. Thus, on geomorphic active landforms, plant communities consist of species with similar ecological requirements. Therefore, geomorphic processes are a decisive selective factor
Geomorphological disturbance affects ecological driving forces and plant turnover along an altitudinal stress gradient on alpine slopes
No full textThe altitudinal gradient is considered as a stress gradient for plant species because the development and fitness of plant communities tend to decrease as a result of the extreme environmental conditions present at high elevations. Abiotic factors are predicted to be the primary filter for species assemblage in high alpine areas, influencing biotic interactions through both competition for resources and positive interactions among species. We hypothesised that the relative importance of the ecological driving forces that affect the biotic interactions within plant communities changes along an elevation gradient on alpine debris slopes. We used multiple gradient analyses of 180 vegetation plots along an altitudinal range from 1,600 to 2,600 m and single 100 m-bands in the Adamello-Presanella Group (Central Alps) to investigate our hypothesis; we measured multiple environmental variables related to different ecological driving forces. Our results illustrate that resource limitations at higher elevations affect not only the shift from competition to facilitation among species. A geomorphological disturbance regime along alpine slopes favours the resilience of the high-altitude species within topographic/geomorphological traps. An understanding of the ecological driving forces and positive interactions as a function of altitude may clarify the mechanisms underlying plant responses to present and future environmental changes
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