1,721,084 research outputs found
Phytosociological study of the snow-bed vegetation in the Northern Apennines (Northern Italy).
No full textWarming effects and plant trait control on the early-decomposition in alpine snowbeds
No full textBackground and aims In cold biomes, litter decomposition, which controls the nutrient availability for plants and the ecosystem carbon budget, is strongly influenced by climatic conditions. In this study, focused on the early litter decay within snowbed habitats, the magnitude of the short- and long-term influences of climate warming, the direction of the effects of warmer temperature and advanced snowmelt, and the control of microclimatic features and plant traits were compared. Methods Combining experimental warming and spacefor- time substitution, mass loss and nutrient release of different plant functional types were estimated in different climatic treatments with the litter bag method. Results Plant functional types produced a larger variation in the early-decomposition compared to that produced by climatic treatments. Litter decay was not affected by warmer summer temperatures and reduced by advanced snowmelt. Structural-related plant traits exerted the major control over litter decomposition. Conclusions Long-term effects of climate warming, resulting from shifts in litter quality due to changes in the abundance of plant functional types, will likely have a stronger impact on plant litter decomposition than shortterm variations in microclimatic features. This weaker response of litter decay to short-term climate changes may be partially due to the opposite influences of higher summer temperatures and advanced snowmelt time
Effetti della durata dell’innevamento sulla biomassa delle vallette nivali a Polytrichastrum sexangulare (Brid.) G.L. Smith al Passo di Gavia (Alpi Retiche)
No full textFlora briologica e vegetazione delle vallette nivali nelle Vette di Feltre (Parco Nazionale Dolomiti Bellunesi, Italia settentrionale)
No full textFitosociologia ed ecologia delle fitocenosi arbustive ed arboree ripariali del torrente Baganza (Appennino settentrionale)
No full textInfluence of snowmelt time on species richness, density and production in a late snowbed community
No full textWithin the alpine life zone, snowbeds are regarded as especially vulnerable to the predicted decrease in
snowfall and may be considered as a suitable habitat for studies concerning the effects of global changes
on alpine vegetation. This paper investigated the influences of snow-free period on species richness,
density and primary production in a late snowbed dominated by the moss Polytrichastrum sexangulare.
An historical average difference of 2.4 weeks in the release from snow cover did not affect either density
or production of the dominant species. In contrast, vascular plant species richness was limited by the
length of growing season, and some vascular species showed differences in density and production
between late and early snow-free stands. Moreover, total vascular species production was found to be
markedly higher in the early snow-free stands. These results suggest that, in this extreme habitat,
vascular plant species richness, density and production are very responsive to variation in the snow cover
period. Accordingly, both structural properties and functional processes in this habitat may be noticeably
altered, within a climatic global change scenario
Effects of nutrient amendments on modular growth, flowering effort and reproduction of snowbed plants
No full textBackground: There have been few studies on the effects on alpine flora and vegetation of an increase in nutrient availability.
Two main potential sources of increased nutrient availability in alpine ecosystems are enhanced mineralisation caused by
climate warming and atmospheric nitrogen deposition. Little is known on how life history traits of different species are
related at individual and community levels to enhanced nutrient availability.
Aims: We investigated the effects of nitrogen and phosphorus addition on the modular growth, flowering and germination of
four species: two snowbed specialists and two alpine generalists.
Methods: We established in a late snowbed at the Gavia Pass, Italian Alps, a factorial experiment with four fertiliser
treatments (N, P, Low N+P, and High N+P) and an unfertilised control. Nutrients were applied in 2003–2006 and we recorded
the number of modules per individuals, total number of flowers, number of flowers per flowering module, and calculated the
percentage of flowering modules in 2005 and 2006, and counted the number of seedlings in 2006.
Results: The modular growth and flowering effort of the species appeared to be co-limited by N and P. The alpine generalists
showed greater responses to fertilization in vegetative growth and flowering compared with snowbed specialists. The number
of seedlings recorded indicated species-specific responses to nutrient addition.
Conclusions: Our results suggest that enhanced nutrient availability stimulates modular growth and flowering effort in
responsive alpine generalist species. This, in turn, could lead to an increase in their abundance, leading to changes in
community structure in snowbeds with enhanced nutrient availability
Crescita, produzione primaria e struttura di popolazione di Polytrichastrum sexangulare (Brid.) G.L. Smith al Passo di Gavia (Alpi Retiche)
No full textEcological profiles of wetland plant species in the northern Apennines (N. Italy)
Full text linkEighteen selected species occurring in the wetlands of the northern Apennines were studied by the ecological profile method. By this method, it is possible to identify the ecological factors mostly influencing species distribution within a particular vegetation. Moreover, it is possible to evaluate both ecological amplitude and ecological preferences of species. Ecological profiles were built for three factors (altitude, pH and electrical conductivity) from a data set of 265 phytosociological relevés, used for altitude, and from a set of 92 measures, carried out in selected sites, for idrochemical variables. By numerical classification, based on chord distance and minimum variance, the ecological species groups for each factor were individuated. Subsequently, they were ordered by correspondence analysis for detecting relationships between ecological groups and classes of factors. By applying a goodness-of-fit test to ecological profiles, the species significantly deviating from uniformity were detected. They can be regarded as indicators for the corresponding ecological factor. We found seven indicator species for altitude (Carex nigra, C. rostrata, Juncus filiformis, J. alpino-articulatus, Eriophorum latifolium, E. angustifolium and Warnstorfia exannulata), four indicator species for electrical conductivity (Campylium stellatum, Carex tumidicarpa, Eriophorum latifolium and Juncus alpino-articulatus) and one indicator species for pH (Sphagnum capillifolium). The ecological profiles of the wetland species in the northern Apennines were compared with those reported in literature for the same species from the Alps (namely Dolomites). In this way, a certain degree of ecological shift in several wetland species of the northern Apennines was documented. For altitude, it is possible to explain the shift considering the reduced elevational amplitude of northern Apennine wetlands with respect to those of the Alps. For pH, Sphagnum capillifolium occurs in less acidic habitats than in the Alps, probably due to the absence of ombrotrophic mires, and Viola palustris occurs mostly in neutro- basiphytic habitats. Some hypotheses to explain the ecological behaviour of this last species were proposed
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