229 research outputs found
Edaphic Characters of Brachypodium Communities on the Alps and the Apennines
No full textGrassland communities with Brachypodium cespitosum, B. genuense, or B. rupestre, distributed along Alps and Apennines were analysed, considering soil edaphic measures. Submitted to both principal components and cluster analysis six groups of relevés resulted, whose edaphic structure was compared to nominal characters. As a confirmation of results, stepwise discriminant analysis showed the edaphic characters responsible of the different species presence in the grasslands. As results, Brachypodium rupestre seems to be present on more basic soils, rich of clay, whereas B. genuense grows on more acid soils, rich in nourishment, and B. cespitosum seems to be in an intermediate position. The type of growth then, seems to depend strongly on the edaphic soil conditions.Des pâturages à Brachypodium cespitosum, B. rupestre ou B. genuense, répartis dans les Alpes et les Apennins, ont été étudiés du point de vue des caractères édaphiques. Une analyse en composantes principales suivie d’une classification a permis de déterminer six groupes de relevés dont la composition a été mise en rapport avec les mesures édaphiques. Une analyse discriminante pas à pas a montré les caractères édaphiques les plus corrélés avec la croissance des différentes espèces de Brachypodium de ces pâturages. En résumé, Brachypodium rupestre semble s’installer sur des sols plus basiques et plus riches en argile, tandis que B. genuense croît sur des sols plus acides et plus riches en éléments nutritifs, B. cespitosum se situant dans une position intermédiaire. Il semble donc que le type de croissance dépende fortement des conditions édaphiques.Camiz Sergio, Dowgiallo Giuseppina, Lucchese Fernando. Edaphic characters of Brachypodium communities on the Alps and the Apennines. In: Ecologia mediterranea, tome 17,1991. pp. 33-49
Microdistribution of macroinvertebrates in a temporary pond of Central Italy: Taxonomic and functional analyses
No full textAbstractSpatial distribution of physical and chemical variables and macroinvertebrate composition, structure and functional aspects were investigated in five microhabitats available (Ranunculus acquatilis+Ranunculus sardous, Spirogyra sp., Juncus effusus, and unvegetated littoral sediments and central sediments) in a temporary pond near Rome during spring 2004. The central sediments were found to differ greatly from the other substrates. They were characterized by higher nutrient contents (total P, total N), organic matter and organic C, and silt and clay in the sediments, and lower dissolved oxygen content and lower pH in the water. Species richness and densities of total macrofauna showed the lowest values in central sediments and the highest ones in submerged macrophytes (Ranunculus spp.) and emergent vegetation (Juncus effusus). Oligochaeta Tubificidae, some Nematoda (Dorylaimus spp.), and Chironomidae Tanypodinae (Procladius sp. and Psectrotanypus varius) and Chironominae (Chironomus plumosus group) characterized the central sediments, whereas Ephemeroptera and most of the Odonata and Coleoptera species were commonly found in submerged macrophyte beds. Some species of Coleoptera and Hemiptera (Hygrobia hermanni, Helochares lividus, Berosus signaticollis and Gerris maculatus) were mainly found in the algal substratum, and some Nematoda species (Tobrilus spp. and Aporcelaimellus obtusicaudatus), Oligochaeta Enchytraeidae, young larvae of Sympetrum and Diptera Ceratopogonidae in littoral sediments. Juncus effusus appeared to be mainly colonized by Chironomidae Orthocladiinae (Psectrocladius sordidellus group and Corynoneura scutellata) and Tanytarsini (Paratanytarsus sp.). Central sediments also favoured high abundances of collector-gatherers, burrowers and drought resistant forms with passive dispersal, whereas Ranunculus spp. hosted mainly scrapers, shredders, swimmers+divers and active dispersal forms without any resistant stages to desiccation. Juncus plants were mostly colonized by collector-filterers and by organisms capable of both active dispersal and surviving desiccation. Littoral sediments and algae showed similar functional organization and intermediate features between central sediments and submerged macrophyte beds. All these results demonstrate that microhabitat characteristics play a crucial role in selecting macroinvertebrate taxa according to their environmental requirement, feeding mechanism, movement and resistance to drought. Moreover, our study confirms the role of submerged and emergent vegetation in maintaining high biodiversity and suggests that all microhabitats should be considered to provide both an exhaustive collection of species for pond management and conservation and basic insights into the functioning of pond communities
Phytosociology and ecology of the Festuca puccinellii-grasslands in the Northern Apennines (N-Italy)
No full textBiological flora of Central Europe: Leucojum aestivum L
No full textLeucojum aestivum L. (Amaryllidaceae) is a polycarpic C-S-European/W-Asiatic geophyte. It is a threatened wetland species and is protected in several European countries, as a consequence of the destruction or alteration of its habitats across Europe and the harvesting of its bulbs for medical purposes (alkaloids). This paper deals with the taxonomic status, morphology, distribution, ecology and population biology of this species, with special emphasis on habitat requirements, reproductive biology, and seed germination. A detailed study in N-Italy found that L. aestivum grows on alluvial soils with high nitrogen levels. The mean size of the plants increased with the water content of the soil. Similarly, within the habitats, the water and nitrogen contents of the soil were higher in plots with L. aestivum than in those without the species. Seed set of the plants was not influenced by the size of a population, but strongly increased with the density of flowering plants. This was due to a decrease in the proportion of unfertilised eggs, indicating pollen limitation of reproduction in low-density populations. Germination tests revealed that the optimal germination temperature is between 20 °C and 25 °C. © 2011 Perspectives in Plant Ecology, Evolution and Systematics
Macrophyte diversity and physico-chemical characteristics of Tyrrhenian coast ponds in central Italy: Implications for conservation
No full textAwareness of pond conservation value is growing all over Europe. Ponds are recognized as important ecosystems supporting large numbers of species and several rare and threatened aquatic plants, macroinvertebrates and amphibians. Notwithstanding ponds, particularly temporary ones, are still neglected in Italy. There are some gaps in our understanding of the macrophyte ecology and the conservation value of Mediterranean small still waters. Therefore, this study investigated the macrophyte communities and physico-chemical characteristics of 8 permanent and 13 temporary ponds along the Tyrrhenian coast near Rome, with the aim to relate the distribution of aquatic plants to environmental variables, and to define the botanical conservation value of ponds. Throughout the study period (Spring 2002), Principal Component Analysis performed on abiotic variables clearly discriminated temporary ponds, smaller and more eutrophic, from permanent ponds, larger and with higher pH and oxygen concentration. A total of 73 macrophyte taxa were collected in the study ponds. Temporary waters hosted a smaller number of plant species than permanent ones. Besides hydroperiod length, the environmental factors related to plant richness were maximum depth, surface area, dissolved oxygen and nitrogen concentration in the water. Moreover, the Non-metric Multidimensional Scaling showed a high dissimilarity in the taxonomic composition of aquatic plants between temporary and permanent ponds. The former contained more annual fast-growing species (Callitriche sp. pl. and Ranunculus sp. pl.), while in the latter species with long life-cycles (i.e. Potamogeton sp. pl.) were more abundant. Our results highlighted that temporary and permanent ponds in central Italy have different macrophyte assemblages, with aquatic species (including some of conservation interest at regional scale) exclusively found in each pond type. This suggested that both type of ponds could give an irreplaceable contribution to the conservation of aquatic plant diversity of these freshwater ecosystems. © 2007 Springer Science+Business Media B.V
Multiscale heterogeneity of topsoil properties in southern European old-growth forests
No full textAssessing the contribution of forest soils to carbon (C) and nutrient dynamics is extremely complex due to the high spatial variability of soil properties, at fine to very broad scales. Improving our understanding of soil variability is necessary to scale up sample-based inventory data for the estimation of regional contribution of forest soils to C dynamics.
We analyzed the patterns of variation of soil properties in 11 southern European old-growth beech stands. We analyzed the topsoil spatial variability of organic carbon and matter, nitrogen (N), C/N ratio, texture and pH with the aim of assessing their within- and among-stand variability, and determining the drivers underlying this variation.
For each stand we sampled the topsoil in 25 quadrats in a 1-ha regular grid, where we recorded overstorey structural and compositional attributes, deadwood quantity and quality, microtopography and site conditions.
Soil parameters varied highly at both scales: when considering all the topsoil properties together through multivariate analysis, most of the variability occurred at the within-stand scale (mostly due to shifts in organic matter content, C/N and litter depth); the opposite was true when considering soil properties singularly, with pH, soil texture and N concentration varying greatly among stands. Most of the among-stand variability depended on climate and on the direct and indirect effects of parent material. Fine-scale variation, instead depended mainly on overstorey composition and microtopographical variation. Surprisingly, we found no direct influence of overstorey structure on topsoil parameters, likely because soil parameters respond to changes in stand structural features only after a substantial time lag
Assessing hypolimnetic stress in a monomictic, eutrophic lake using profundal sediment and macrobenthic characteristics
No full textSummer-winter variations of the physico-chemical features of profundal sediments and of the characteristics of the profundal benthic community in a small, monomictic and eutrophic fake were analyzed in order to define their relations to environmental stress in the hypolimnion. The sediments were rich in P and N compounds. The benthic fauna exhibited a very poor taxa richness and diversity in summer, probably due to reduced oxygen in the hypolimnion, and there was only slight improvement of these community parameters in winter when reoxygenation occurred. The macrofauna was influenced by both sediments and overlying waters
Preliminary researches on fungal population dinamic of natural and cultivate soils in tropical rainforest
No full textSignificant differences in the species composition of the mycoflora in tropical rainforest soils were compared between natural and cultivated areas. The last one's were prepared by cutting, burning and sowing natural areas. Community composition and structure were based upon statistical analyses of 6957 colonies from seven samplings collected from December 1978 to January 1980. Moreover pedological and vagetational analyses in every areas were carried out
Tolerance to vanadium as a response of agricultural soil fungi in the Valle Latina (Italy): which are the potentialities for mycoremediation?
No full textThe aim of this work was to investigate a soil fungal community of contaminated agricultural soils and to test the growth response of selected species to the toxic metal vanadium. Physico-chemical analysis was performed on contaminated soils that lay under maize and wheat crops in the Valle Latina (southern Lazio, Italy). The Valle Latina is one of the 57 sites of national interest (S.I.N.). It’s a high environmental risk area due to its industrial sites, waste landfills and agricultural activities and the environmental contamination of hexachlorocyclohexane, an anthropogenic pollutant. Moreover, natural background high level of potentially toxic elements due to volcanic rocks (pyroclastic deposits) occurs in this area in which several elements, including vanadium, thallium and beryllium exceed the threshold values established by Italian legislation, as well. The soil community of saprotrophic fungi of contaminated agricultural soils near the Sacco River have been studied. Contrary to expectations, the community was found to be rich in fungal species (150 species in total), although the typical Penicillium and Aspergillus species components were poorly represented. Species, reported to be tolerant/resistant to heavy metals in the literature and potentially useful in bioremediation, were found. The occurrence of these may be taken as a potential bioindicator of environmental pollution. Vanadium, one of the elements which exceed threshold values, was chosen as metal to test fungi tolerance. In the last decades, evidence in increasing of the environmental levels of vanadium, has raised concern over its release into the atmosphere from anthropogenic sources of which hydrocarbon fuel combustion is the most important. Burning of fossil fuels caused about 110000 t V/a to enter the atmosphere globally (Manfred, 2004). Vanadium is essential for several species of green algae, fungi and nitrogen-fixing microorganisms, as well. We selected six species : Aspergillus terreus Tiegh., Cladosporium cladosporioides (Fresen.) G.A. de Vries, Clonostachys rosea (Preuss) Mussat, Paecilomyces lilacinus (Thom) Samson, Penicillum citrinum Sopp and Rhizopus arrhizus Fischer, among isolated species, reported to be tolerant/resistant to heavy metals in the literature, and examined the growth response by inoculating them with malt extract agar amended with ammonium vanadate at concentrations of 1, 2, 3 and 6 mM to simulate potential environmental concentrations. Metal tolerance was assessed in all samples by means of growth measurements, tolerance index, scanning electron microscopy, electron dispersion spectroscopy and biomass metal concentrations. Results revealed that all the fungi tested tolerated 6 mM concentrations, Clonostachys rosea and Rhizopus arrhizus being the most tolerant. Soil fungi tolerance to natural metal occurrence may explain their tolerance to anthropogenic contamination. Therefore results of this research can contribute to enhance knowledge on the potential use of these fungal species for mycoremediation purposes in polluted sites
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