Vincenzo De Dominicis

EFFECTS OF AGRICULTURE ON EPIPHYTIC LICHEN VEGETATION IN CENTRAL ITALY

ABSTRACT The 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 ...

Vegetation of Tuscan ultramafic soils in relation to edaphic and physical factors

Vegetation and soil sampling were carried out in 80 plots located in five different ultramafic (serpentine) sites of Tuscany, central Italy. The physical and chemical features of each plot were determined and the species composition and cover recorded. The exchangeable fraction of soil metals was analysed because it gives a measure of their concentrations available to plants. The plots were classified by cluster analysis and ANOVA was used to compare the environmental variables of the groups of plots. Canonical correspondence analysis was used to detect the principal factors for gradients of species composition within the plant communities. A higher content of exchangeable metals was found under the more evolved and structured plant communities, suggesting that serpentine vegetation of Tuscany is not strongly limited by soil metals, such as chromium, cobalt, nickel and magnesium, typically associated with ultramafic soils. The low nutrient content of the soils and drought stress mainly due to topographical features, appear to have a more significant role in determining the typical scattered vegetation of the Tuscan ultramafics.

Evaluation and monitoring of the flora in a nature reserve by estimation methods

Abstract We tested the use of non-parametric estimators of species richness to evaluate the flora of a relatively large (431 ha) nature reserve, using a sampling area much lower than that used in previous studies. Different estimation methods were applied to floristic data obtained from 50 random plots: the number of observed species, the extrapolated accumulation curves based on the Michaelis–Menten model and the non-parametric estimators based on incidence data (Chao2, first-order Jackknife, second-order Jackknife and bootstrap). To test the performance of the estimators, five data sets were created on the basis of life-forms. The estimates were compared with reference values obtained by traditional floristic and vegetation sampling. The power of the different estimation methods could not definitively be determined, but the first- and second-order Jackknives seem to be the most precise. Although total species richness was underestimated, the sample-based approach provided accurate information for quantitative comparison of time series of data related to ecological changes, vegetation dynamics and environmental changes. This sample-based data included basic statistics on species richness and species frequency distributions as well as the life-form spectrum, at the plot and the whole site scales.

ANALYSIS OF THE DISTRIBUTION OF EPIPHYTIC LICHENS ON QUERCUS PUBESCENS ALONG AN ALTITUDINAL GRADIENT IN A MEDITERRANEAN AREA (TUSCANY, CENTRAL ITALY)

ABSTRACT The distribution of epiphytic lichens on Quercus pubescens in Tuscany, central Italy, was studied by means of multivariate techniques along an altitudinal gradient from 0 to 900 m. Great differences in community structure were found and the altitude of 500 m was identified as an ecotone. Epiphytic lichen vegetation on trees below the ecotone varied significantly in relation to bark pH. Climatic parameters (temperature and rainfall) were probably related to altitude. Dust was probably responsible for the rise in bark pH. The distribution of lichen species in the sampling belts fitted the core-satellite hypothesis. The use of core and satellite species as biomonitors of air pollution and bioindicators of environmental conditions is discussed.

Effects of temperature and rainfall on fruiting of macrofungi in oak forests of the Mediterranean area

The results of a study on the effects of weather (rainfall and minimum, mean, and maximum temperatures) on fruiting of macrofungi in a number of oak forests of Tuscany (central Italy) are reported. The fungal parameters (total number of species and total number of carpophores) were examined for statistical correlations with annual and seasonal temperature and rainfall and with temperature and rainfall in the 5-, 10-, 15-, and 30-day periods before the date of the sampling. It was found that abundant annual rainfall was necessary for the fungal mycelium to fruit. Spring rainfall in particular seemed to be related to the number of species found in autumn. Rainfall was the main influence on fruiting in the most important fruiting period (autumn). Highly significant correlations were found between the number of carpophores and rainfall in the 30 days preceding sampling.

Effects of pine plantations on ultramafic vegetation of central Italy.

ABSTRACT The influence of pine plantations on typical ultramafic plant communities of Tuscany was investigated by means of thirty 5 × 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 h...

A test of vegetation-environment relationship in serpentine soils of Tuscany, Italy

The present study evaluates the relative importance of environmental factors in affecting the species composition and abundance of the plant communities on ultramafic soils in Tuscany, Italy. We used rigorous sampling techniques to test hypotheses generated from exploratory studies performed previously. Vegetation–environmental relationships were analyzed using 50 plots, each 1 m2, randomly located throughout a 22-ha area in the Upper Tiber Valley. We confirm that the exchangeable fraction of nickel in the soil is almost never high enough to affect the vegetation. However, physical factors (e.g. substrate setting and elevation) are important in controlling the distribution of plant species. Tree cover (almost exclusively due to the introduced plantation pines) also had a significant affect on the vegetation composition and on soil features such as the C/N ratio. Other important factors significantly related to the gradients in vegetation composition (e.g. rockiness and total soil nitrogen) are interpreted as factors related to the vegetation composition through a positive feedback mechanism.

Germinable soil seed-bank of former grassland converted to coniferous plantation

The 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.

Relationship between environmental factors and the proportions of fungal trophic groups in forest ecosystems of the central Mediterranean area

Abstract Forest decline has recently been observed in many parts of Europe. Mycoflora, 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 influence the mycorrhizal ratio in these situations. The results show that the percentage, and especially the number of mycorrhizal fungi, was significantly 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 pollution.

Coenological research on macrofungi in evergreen oak woods in the hills near Siena (Italy)

For a mycocoenological study of macromycetes in Mediterranean evergreen forests in the Siencese province, five stands belonging to theQuercion ilicis have been observed during more than two years. The phytosociological analysis of these evergreen oak woods, situated at the limit of the geographical distribution of the alliance, reveals them as intermediate between the typical Mediterranean vegetation and the sub-Mediterranean deciduous broad-leaved forests. 181 fungal species were recognized and assigned to seven ecological groups on the basis of substratum, habitat, forest management and/or particular mycorrhizal relationship. Our results have been compared with those obtained in some European deciduous forests. Such a comparison shows the occurrence of 16 thermophilous fungal species in the Siena woods which are missing or very rare in the European deciduous forests. On the basis of our present knowledge, five of these species (Boletus lepidus, Hygrophorus dichrous, Hygrocybe nigrescens, Inocybe similis, Phellinus torulosus) may be considered as strictly tied to the evergreen oak woods. Five others, which have been reported for several European phytocoenoses, seem to be ‘preferential taxa’ of our evergreen oak woods, namely:cortinarius calochrous, C. sodagnitus, Hygrophorus arbustivus, H. russula, Lyophyllum immundum. On the whole the highest similarities have been found with the more xerothermophilous European forests (Querco-Lithospermetum andSorbo-Quercetum). The presence in theQuercus ilex woods of numerous more mesophilous fungi, some of which are widespread in beech forests, underlines the transitional nature of the phytocoenoses studied.