1,721,029 research outputs found
Lichens as long–term biomonitors of air quality in central Italy
No full textThe results of a long-term study (data of 1978 and 1993) performed in central Italy using epiphytic lichens both as indicators and monitors (accumulators) are presented. Floristic data showed that air quality in the study area did not change markedly in this 15-year period and is currently fairly good. Similarly, the concentrations of trace elements in Parmelia caperata thalli showed no substantial change, with values similar to those in lichens of unpolluted areas. The concentration of Cs-137 in P. caperata and Lobaria pulmonaria thalli doubled after the Chernobyl accident, but was low compared to other European areas
Effects of agriculture on epiphytic lichen vegetation in central Italy
No full textThe influence of agriculture, i.e., of fertilizers and ammonia emissions from crops and sheep grazing, on epiphytic lichen vegetation, and the use of nitrophytic lichen species in bioindication of air pollution were investigated in a geothermal area in central Italy. Floristic analysis showed that the lichen vegetation is only slightly influenced by agriculture. Analysis of the lichen data and chemico-physical parameters of tree bark supporting lichen growth failed to demonstrate marked differences between agricultural and non-agricultural sites, the higher total frequency of nitrophytic species in agricultural sites being the only parameter discriminating between the two site types. Bark nitrogen and pH were not discriminant. Factors determining the higher total frequency of nitrophytic species in agricultural sites may include dust impregnation of bark and the drier microclimate of trees in these sites. It is concluded that nitrophytic lichens can be included in the calculation of the Index of Atmospheric Purity in the study area
Effects of pine plantations on ultramafic vegetation of central Italy
No full textThe influence of pine plantations on typical ultramafic plant communities of Tuscany was investigated by means of thirty 5 x 5 m plots in three environmental situations with different pine canopy cover. The main changes in natural vegetation were an increase in species richness and ground cover, resulting from the spread of alien grassland and woody species, and the almost complete disappearance of therophytes and some of the serpentine plants. The typical Armerio-Alyssetum bertolonii, an endemic garigue-steppe association characterized by large areas of bare soil, was modified into a grassland community with almost complete ground cover. The main soil changes associated with the presence of a pine canopy were found to be increases in depth and organic matter. Exchangeable cation concentrations increased with pedological evolution and were positively correlated with organic matter content. The positive relationships between soil metal ion content, species richness, and ground cover suggest that hydrological and nutritional soil characteristics were more determinant for typical ultramafic vegetation than soil metal toxicity. Artificial pinewoods may be a serious threat to biodiversity conservation, because the alpha-diversity increase found at the spatial scale of the present study would correspond to a beta- and gamma-diversity decrease should pine plantations spread to all ultramafic areas
Germinable soil seed-bank of former grassland converted to coniferous plantation
No full textThe influence of afforestation with cedars on field layer vegetation and on the germinable soil seed-bank were investigated along a 60-m transect merging from open grassland to sparse and dense canopy cover. A total of 132 species were found, 76 in the seed-bank and 109 in the vegetation, with 53 species in common. Conifer cover was not found to be associated with a decrease in total number of species in the vegetation or seed-bank, but the mean number of species in the vegetation, total cover in field layer vegetation and mean number of individuals in the seed-bank decreased significantly from grassland to forest stands. The grassland seed-bank was dominated by Saxifraga tridactylites and Veronica agrestis; the seed-bank of plots of scattered cedars was dominated by Trifolium incarnatum ssp. molinerii; and that of dense cedar plantations was dominated by Campanula rapunculus. The number and cover of grassland species of field layer vegetation decreased in the forest, with respect to open grassland, and the same trend was found for density of individuals in the seed-bank. It is concluded that grassland restoration by cutting cedars cannot rely on the presence of grassland species in the soil seed-bank
Structure and species diversity of Bromus erectus grassland of biancana badlands
No full textSpecies richness, diversity and structure were studied in Bromus erectus grasslands on the top of biancana landforms of the Orcia Valley, Tuscany (central Italy). Three community types were recognized : uneven B. erectus grasslands on less stable morphologies, and compact B. erectus grasslands and B. erectus grasslands colonized by Spartium junceum scrub, both on more stable morphologies. The main difference between them was a dramatic decline in species richness and diversity from the former to the latter. The number and cover of annual herbs, many of which are low-growing species (e.g. legumes and graminoids), also decreased significantly in the same order. The frequency of B. erectus was constant (100%) in all three types of community, whereas percentage cover increased sharply (54.2 vs. 85.5%) between uneven and compact grasslands, remaining high in the scrub communities (83.8%). Cover of phanerophytes showed low values in the uneven and compact grasslands, but reached 80% in the scrub communities. The increase in cover of B. erectus caused the disappearance of species typical of the pioneer vegetation of Pliocene clay soils with Artemisia cretacea. Colonization of the compact grasslands by S. junceum induced a reduction in grassland species of the class Festuco-Brometea. The implications of these findings for the conservation of B. erectus grasslands and biancana badlands are discussed
Analisi fitosociologica dei fiumi della Toscana meridionale: il tratto medio-basso del Merse (Italia centrale)
No full textAfter a brief introduction on the geological, hydrological and
climatic characteristics, the authors describe the results of a phytosociological study
concerning riparian and aquatic vegetation of the lower-middle Merse river (southern
Tuscany, central Italy). Purpose of the contribution is to further knowledge on the
syntaxonomy, ecology and dynamics of river vegetational communities in southern
Tuscany. The paper outlines a rather complex syntaxonomy scheme pointing out the
vegetation abundance of the section of the river studied. In fact, coenosis belonging
to 12 different phytosociological classes were identified: Querco-Fagetea, Salicetea
purpureae, Rhamno-Prunetea, Rosmarinetea officinalis, Molinio-Arrhenatheretea,
Artemisietea vulgaris, Isoeto-Nanojuncetea, Bidentetea tripartitae, Agrostietea
stoloniferae, Phragmito-Magnocaricetea, Potamogetonetea pectinati, Charetea
fragilis. High environmental quality was evidenced by floristic and synecological
analysis of the community. Due to the low presence of human activity, hydrophytic
community indicating oligotrophic aquatic environment, high phytocoenotic
diversity, floristically, structurally and ecologically well characterized tree/shrub
population were found
Grasslands of the order Brometalia erecti Br.-Bl. 1936 on Antiapennine calcareous massifs in central-southern Tuscany (central Italy)
No full textFloristic characteristics, syntaxonomy and synecology of grasslands of the order Brometalia erecti on calcareous massifs of central-southern Tuscany are reported. Multivariate analysis was used to compare 64 phytosociological relevés made in the years 1997, 2000 and 2001. These pastures occur in areas of the temperate oceanic region, with upper hill to montane thermotype and lower humid to lower hyperhumid ombrotype, in serial contact with woods of Ostrya carpinifolia Scop. and with beech woods on summits. The plant communities surveyed were classified in the following associations: i) Cerastio etrusci-Brometum erecti ass. nova (Phleo-Bromion Biondi and Blasi ex Biondi and al. 1995), identified for xeric grasslands on moderate to steep slopes with basic lithosols in the hill and lower montane belts; it has two variants related to soil chemical and physical characters; comparison with similar vegetation of other Apennine areas confirms the western connotation and autonomous nature of these communities; ii) Trifolio incarnati-Brometum erecti Oberdorfer and Hofmann 1967 (Bromion W. Koch 1926), known from the Ligurian Apennine downwards; in the area studied it shows a new «Antiapenninic» subassociation named phleetosum ambigui that includes: a mesophilous variant with Arrhenatherum elatius, related to flat or north-exposed stations in the mountain belt linked to mature soils with high moisture all year, rich in transgressive species of the class Molinio-Arrhenatheretea Tüxen 1937; a subnitrophilous variant with Carlina corymbosa, related to grazing and exclusive to soils with high clay component; a transition variant towards xerophilous grasslands. The study confirms the presence of the alliance Phleo-Bromion in Tuscany as an isolated appendage with northern outposts of xerocalcicolous communities widespread in the central-southern Apennine; a similarity with vegetation of northern Tyrrhenian sectors was also observed
Relationship between environmental factors and the proportions of fungal trophic groups in forest ecosystems of the central Mediterranean area
No full textForest decline has recently been observed in many parts of Europe. Myco ̄ora, especially symbionts, has been reported to
decrease 5±10 years before the forest community begins to decline. Mycological research can therefore be useful for
forecasting the evolution of forests subject to man-made stress. Researchers in central Europe have found that the mycorrhizal
ratio (percentage of mycorrhizal fungi with respect to all macromycetes) is a useful index of the level of forest pollution, being
much lower in contaminated areas. Here, data on macromycetes of different forest ecosystems from central Italy were
examined to determine whether this index is applicable to the Mediterranean area, and to determine whether factors other than
atmospheric pollution could in ̄uence the mycorrhizal ratio in these situations. The results show that the percentage, and
especially the number of mycorrhizal fungi, was signi®cantly correlated with environmental parameters such as altitude,
number of tree species and tree cover. It is concluded that in the Mediterranean area a low mycorrhizal ratio does not always
indicate that a forest is subject to air pollutio
Epiphytic lichens and bryophytes of forest ecosystems in Tuscany (C. Italy)
No full textThe distribution of epiphytic bryophytes and lichens on three species of trees (Quercus ilex, Quercus cerris and Fagus sylvatica, representing the forest ecosystems of central Italy at low, medium and high elevations, respectively) was examined with respect to host specificity and habitat differences. Although most species were host-specific, the results suggested that habitat characteristics are more important than phorophyte properties in determining the distribution of lichens and bryophytes. Factors affecting the diversity of the epiphytic flora were different for lichens and bryophytes. In the case of lichens, climatic parameters and forest monospecificity were important factors, whereas tree cover (i.e. shade) and to a certain extent the number of available trees seemed more important for bryophytes
Ricerche geobotaniche in Val di Merse (Toscana meridionale).IV. Contributo alla conoscenza della flora della Val di Farma
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