1,720,999 research outputs found
A multi-taxon approach reveals the effect of management intensity on biodiversity in Alpine larch grasslands
No full textIn the Alps, larch grasslands form one of the most pleasing aspects of the landscape. However, their effectiveness in contributing to biodiversity conservation may depend on the intensity of their management. We used a multi-taxon approach to evaluate the effects of the intensification of management practices and those of abandonment on the biodiversity of the main autotrophic organisms hosted in this habitat, including vascular plants, bryophytes, and lichens. The study was carried out in the eastern part of South Tyrol, in the Italian Alps, where the diversity patterns of these three organismal groups were compared among intensively managed, extensively managed, and abandoned stands. The management intensity was found to strongly influence the biodiversity of the organisms, with a general pattern indicating the best conditions in extensively managed stands. Both abandonment and management intensification were detrimental to biodiversity through different mechanisms that led to species loss or to major shifts in species composition. However, the most negative effects were related to management intensification, mainly due to the high nitrogen supply, providing evidence for the increasing impact of eutrophication on Alpine environments. © 2014 Elsevier B.V
Springs like islands: implications on richness and species density
No full textMany hypotheses exist concerning specific factors that control plant species richness, but currently there is no consensus about the mechanisms underlying these relationships (GRIME 2001). As far as we know, works especially dedicated to investigate the diversity in spring habitats are completely lacking. Few works exist oil spring vegetation, and those are from a phytosociological point of view (e.g., ZECHMEISTER & MUCINA 1994). Spring habitats have several characteristics which make them worth to be studied and may provide interesting contributions to individuate the relative importance of different factors controlling diversity. Springs are generally distinguishable from the surrounding habitats because water is continuously present throughout the year, has minimal temperature fluctuations over the years (CANTONATI et al. 2006). and discharge usually shows only limited seasonal variations. These characteristics allow considering springs like "water islands," as proposed by WERUM (2001), both physically and theoretically. A large literature exists on island diversity (WHITTAKER et al. 2001 and references therein) showing that one of the most important factors in determining species richness is area extension. As demonstrated by LOMOLINO & WEISER (2001), confounding variation in area with variation in other environmental factors could lead to biased results. One way to control area, a fundamental step often ignored, is to use sample units of equal dimensions and calculate species density instead of species richness. We agree with the WHITTAKER et al. (200 1) distinction between diversity in richness (the number of species recorded in unstandardized way) and density (the number of plant species in standardized plots).
Springs and relative biota can be correctly considered as azonal (sensu Ellenberg) because of their relative independence of climate conditions. In other words, the spring communities appear in approximately the same form because they are determined more by the presence of water than overall climate as in the zonal units. Therefore, differences among spring assemblages are mainly determined by difference in water characteristics (e.g., chemistry, current flow). The "azonalness" of spring assemblages call depend on the degree of "aquaticness" of the species living in a spring. Considering an altitudinal gradient, for example, more species variation will occur in spring assemblages as the degree of species aquaticness decreases. CANTONATI et al. (2006) reported that diatoms did not show relevant patterns along altitudinal gradients with reference to samples collected always from submersed substrates. However, because bryophytes and vascular plants grow even outside the water in spring habitats, it would be interesting to explore plant richness and density in springs along altitudinal gradients.
We formulated the following hypotheses: (a) richness (intended as the summation of the bryophytes and vascular plants species per spring) depends on spring area because of the well known species-area relationship; (b) density (intended as number of sp/m(2)) is independent from spring area; (c) because the majority of plants growing in springs are not strictly aquatic, we expected both density and richness to change along altitude, analogously to other habitats
Palustriella falcata (Brid.) Hedenas (Amblystegiaceae, Bryopsida) with pluristratose lamina: morphological variability of specimens in springs of the Italian Alps
No full textPluristratose leaf lamina in pleurocarpous aquatic mosses is a mysterious morphological character state because of its recurrence among unrelated lineages. It has been found sporadically around the world in phylogenetically distant taxa, and is thought to be a mutation and/or adaptation to aquatic habitats. During an extensive survey of bryophytes in spring habitats in the Italian Alps (Province of Trento), we found different numbers of leaf lamina cell layers among specimens of Palustriella falcata. We carried out a thorough study, measuring a set of morphological characters that identify variability among specimens within the same spring and among multiple springs. The main goals were to assess the amount of morphological variability, to quantify the concordance among morphological traits, and to test to what extent environmental variables account for morphological variability. Our results showed that, in many cases, morphological characters differed even among shoots within a spring. We found positive and significant partial correlation between pluristratose lamina and width of costa, but negative correlation between pluristratose lamina and length of cells. Constrained multivariate analysis showed that 40.3% of this morphological variation was explained by a set of environmental variables, but most importantly, we observed extensive pluristratose laminae in constantly submerged habitats. We interpreted the different numbers of cell layers in the leaf lamina as a phenotypic continuum from P. falcata, with a single layer of cells, to Palustriella pluristratosa Stech & Frahm, with a multilayered lamina. In addition we offer a point of view concerning the evolutionary significance of this trait, its possible origin, and its evolution in aquatic mosses
Patterns of beta-diversity along elevational gradients inform epiphyte conservation in alpine forests under a climate change scenario
No full textWe explored the patterns of beta-diversity of forest epiphytic bryophytes and lichens along elevational gradients to elucidate the potential impact of climate change on these functionally relevant components of the forest biota of the Alps. Eight elevational gradients were selected from a regional forest database matching the requirement of hosting spruce-dominated forests within the whole elevational range of this forest type (900â1900 m). We calculated the decay of species compositional similarity along the gradients, considering the beta diversity components, turnover and richness difference. We then assessed the importance of temperature in explaining variation in these components of beta diversity along the elevational gradients by using a distance-based redundancy analysis. Our results warn against the impact of climate change on epiphytic bryophyte and lichen communities in alpine spruce forests. This impact could be more rapid (higher rate of similarity decay) and severe for lichens, triggering species loss with temperature warming. In contrast, temperature warming is expected to cause relevant shifts in species composition to bryophyte communities, despite allowing to maintain species richness through species replacement. The contrasting mechanisms (species loss vs species replacement) by which climate influences bryophyte and lichen communities, suggest that conservation strategies should be tailored to each organism group. In particular, for bryophytes conservation efforts should be assigned to forests at each band of the elevation gradient which hosts peculiar assemblages. In contrast, for lichens priority for conservation should be assigned to forests at higher elevation that currently host the largest species pool. In this context, forest management is the primary tool available to mitigate the effect of climate change and to give a chance to delay the local extinction of several species
Impact of cattle grazing on peat properties and diatoms
No full textPeatlands are a major carbon (C) sink and represent important habitats for nature conservation because of the occurrence of specifically adapted organisms. Peatlands are typically nutrient-poor environments, and thus extremely sensitive to nitrogen (N) depositions. In fact, increasing N inputs can cause a shift from a Sphagnum moss- to a vascular plant-dominated vegetation as well as an alteration of the mire geochemistry which, in turn, affects the litter composition and decomposition rate. Peatland is an extremely fragile ecosystem: at the European level, >60% of this habitat type has been lost just in the last decades. In Alpine peatlands, in particular, overgrazing has been identified as a main problem for habitat integrity and biodiversity. In the present study, six Belarus (50-cm deep) cores were collected from several peatlands located in the Adamello-Brenta Nature Park (Trentino, Italy) mirroring a grazing-induced disturbance gradient. All cores were cut frozen into 3-cm sections, and analysed for dry density, water content, pH, EC, and elemental (CHNS) composition. Diatom taphocoenoses were also determined. In particular, diatom frustules were prepared using hot hydrogen peroxide and finally mounted in the Naphrax© resin to produce permanent mounts for identifications and counts. 400 valves were counted and identified to the species level in each slide using a light microscope at x1000 magnification. The whole procedure was kept quantitative to allow the calculation of absolute abundances (n-valves/g-peat-dw). Physical, chemical and biological parameters generally underlined how the grazing influence was clear mainly in the top 20 cm, and resulted in an increasing of density (up to 2×) and N concentration (up to 3×) as well as in a lower gravimetric water content (up to 50%). No significant differences were observed below 30 cm of depth. More than 100 diatom species were identified throughout the 6 cores investigated, and several of them are included in threat categories of the Red List for central Europe (e.g., Cymbopleura valaiseana, Eunotia hexaglyphis, E. triodon). Since diatoms can reflect major regional environmental gradients, they can be used as indicators of ecological conditions in peatlands. In fact, some species that are trivial (= frequent and often abundant) in mire environments in spite of being relatively rare at the overall level of European inland waters (e.g., Aulacoseira alpigena, Encyonema perpusillum, Kobayasiella micropunctata) were found in the cores from highly-grazed areas whilst several rare and sensitive species were detected only (or were clearly more frequent) in cores from mildly-grazed areas. This research can provide useful indications on the harmful effects of grazing in terms of both biogeochemical cycles and nature/habitats conservation
Rise of subgen. Rhoicosphenula Lange-Bert. to the genus level, and description of a new Gomphosphenia s.s. species from Puerto Rico
No full textSaber, Abdullah A., Angeli, Nicola, Lange-Bertalot, Horst, Kociolek, John P., Spitale, Daniel, Charles, Donald F., Cantonati, Marco (2021): Rise of subgen. Rhoicosphenula Lange-Bert. to the genus level, and description of a new Gomphosphenia s.s. species from Puerto Rico. Cryptogamie, Algologie 20 (13): 217-229, DOI: 10.5252/cryptogamie-algologie2021v42a13, URL: http://dx.doi.org/10.5252/cryptogamie-algologie2021v42a1
Vertical migration of a dinoflagellate in a column-shaped enclosure in Lake Tovel (Adamello-Brenta Natural Park, Italian Alps)
No full textGlenodinium sanguineum Marchesoni is a dinoflagellate that caused a spectacular red summer bloom in the southwestern portion (Red Bay) of Lake Tovel (Trentino, Italy); this phenomenon ceased suddenly in 1964. According to BALDI (1941) the reddening mechanism required also the massive surface movement of the algae after sunrise. The aim o f the present research was to provide clear evidence of vertical movements using high densities of G. sanguineum in artificial systems positioned in the Red Bay
FIG. 1 in Rise of subgen. Rhoicosphenula Lange-Bert. to the genus level, and description of a new Gomphosphenia s.s. species from Puerto Rico
No full textFIG. 1. — Box-and-whisker plots for selected physical and chemical variables for the two study streams.Published as part of Saber, Abdullah A., Angeli, Nicola, Lange-Bertalot, Horst, Kociolek, John P., Spitale, Daniel, Charles, Donald F. & Cantonati, Marco, 2021, Rise of subgen. Rhoicosphenula Lange-Bert. to the genus level, and description of a new Gomphosphenia s.s. species from Puerto Rico, pp. 217-229 in Cryptogamie, Algologie 20 (13) on page 220, DOI: 10.5252/cryptogamie-algologie2021v42a13, http://zenodo.org/record/781926
FIG. 4. — A-U in Rise of subgen. Rhoicosphenula Lange-Bert. to the genus level, and description of a new Gomphosphenia s.s. species from Puerto Rico
No full textFIG. 4. — A-U, Light micrographs of Gomphosphenia patrickiana Cantonati, Lange-Bert., Kociolek & A.A.Saber, sp. nov., depicting the valve size-diminution series and girdle view of the holotype specimens. Scale bar: 10 μm.Published as part of Saber, Abdullah A., Angeli, Nicola, Lange-Bertalot, Horst, Kociolek, John P., Spitale, Daniel, Charles, Donald F. & Cantonati, Marco, 2021, Rise of subgen. Rhoicosphenula Lange-Bert. to the genus level, and description of a new Gomphosphenia s.s. species from Puerto Rico, pp. 217-229 in Cryptogamie, Algologie 20 (13) on page 223, DOI: 10.5252/cryptogamie-algologie2021v42a13, http://zenodo.org/record/781926
Long-term ecological research in springs of the Italian Alps: six years of standardised sampling
No full textAt the beginning ofthe 1990s a comprehensive study of 30 springs within the Adamello-Brenta Nature Park (ltalian Alps) was carried out. This study considered ecomorphology, hydrochemistry, algae, mosses, higher plants and zoobenthos. In 1998 five ofthese springs were chosen for a long-term ecological research programme. The aim of this study was to highlight potentialities and problems of this long-term spring monitoring project by considering a selection of results gained during the first six years of standardized monitoring. This first organization and analysis of the biological materials sampled and of the morphological, physical and chemical data is expected to conclude a first phase leading to the final structure o f this spring monitoring programme through the optimization of sampling sites and procedures
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