Carlo Andreis

Alpine debris-covered glaciers as a habitat for plant life:

Debris-covered glaciers represent a significant, increasing fraction of glaciers and can host plant life on their surface. The goal of this work was to evaluate the suitability of supraglacial debris as a habitat for plant life and to discuss its ecological and biogeographic role. The research was carried out on the Miage Glacier (Mont Blanc massif, Western Alps, Italy). Vegetation cover was sampled using a regular sampling grid, recording plant species and number of individuals in 71 plots. Detailed glaciological parameters (surface temperature, debris thickness, glacier surface velocity) were recorded or derived from published data. Relationships between vegetation and environmental variables were assessed through Generalized Linear Models, Principal Components Analysis and Canonical Correspondence Analysis. The glacier surface hosted a high biodiversity, with 40 vascular plant species, including trees and shrubs. Plant cover was arranged along an altitude/glacier velocity gradient, whilst debris thickness as low as 10 cm could sustain plant growth on moving ice. Glacier velocity was the main physical factor affecting vegetation cover, probably through its influence on debris stability. The observed species assemblage is comparable with those of subalpine glacier forelands, but with the addition of high-altitude species. Debris-covered glaciers can provide a relatively favourable habitat for plant life wherever the glacier surface is sufficiently stable, acting as a refugium of high-altitude taxa below their altitudinal limits. Glaciers may behave as a dispersal vector for alpine plant species, which could have been important both during glacial periods and during warm stages of the Holocene.

Vegetation and environmental factors during primary succession on glacier forelands: Some outlines from the Italian Alps

ABSTRACT Relationships between plant communities and the physical environment during primary succession on recently deglaciated glacier forelands were studied in 3 areas of the Italian Alps. The aim of the research was to relate traditional phytosociological data with environmental variables. Twenty-eight phytosociological relevés were performed, each associated with twenty-six environmental variables; quantitative parameters of richness and diversity were also calculated. Species/relevés, environmental variables/relevés and species/environmental variables matrices were analyzed by cluster analysis, PCA and Spearman correlation coefficient. Three main stages of succession were identified by floristic composition and confirmed by environmental parameter evaluation. A complex of environmental variables seems to be closely correlated with terrain age and richness/diversity parameters, even though diversity decreases in late successional stages. The phytosociological significance of species is in accordance with their position in the context of succession.

Climate continentality and treeline species distribution in the Alps

Abstract The distribution of tree species and the elevation of the alpine treeline are strongly affected by climate continentality. In the present work we performed a detailed survey of the upper limits of tree vegetation in two areas with contrasting climate located in the central Italian Alps, in order to evaluate the structure of the treeline under different degrees of continentality. Tree and krummholz (stunted) individual position, their dimension and life form were recorded from the upper limit of the closed forest to the species limit. The results were compared with an estimation of tree species distribution at the treeline in the whole Lombardy Alps, performed by a survey of tree species occurrence in areas of known climatic traits. The structure of the treeline (upper limits, life form altitudinal arrangement) and its ongoing dynamics were different in the two areas: climate continentality assessed by hygric and thermal continentality indices influenced the distribution of some treeline species. Although the influence of human and geomorphologic disturbance could not be excluded, the importance of the degree of continentality must be stressed when evaluating the response of the treeline to past and present climatic change.

Secondary metabolites and antioxidant capacities of Waldheimia glabra (Decne.) Regel from Nepal.

BACKGROUND The phenolic content, volatile compound fingerprint and antioxidant capacity of Waldheimia glabra (Decne.) Regel (Asteraceae), a wild plant from the Himalayan mountains used in Sherpa religious rituals and in traditional medicine, were determined for the first time to investigate its suitability as a source of natural antioxidants. RESULTS The total phenolic content and antioxidant capacity of dried and powdered plants from two different altitudes (5000 and 5200 m above sea level) in Khumbu Valley, Nepal were estimated by the Folin-Ciocalteu and 2,2-diphenyl-1-picrylhydrazyl radical methods respectively. The volatile organic compound (VOC) fingerprints from leafing plants (in vivo and in situ VOC sampling) and from dried plant samples were evaluated by headspace solid phase microextraction. The results indicated that W. glabra was a good source of phenolics with antioxidant properties. A correlation between total phenolic content and antioxidant capacity was found (r² = 0.9111). Seychellene, a volatile compound that characterises patchouli oil, was detected for the first time in a species of the Asteraceae family. CONCLUSION Waldheimia glabra was proved to be a good source of antioxidants, partially supporting its traditional uses. Further studies aimed at deepening knowledge on W. glabra bioactivity and its possible uses will be of interest, considering the lack of proper scientific awareness regarding these aspects.

The Thecal Surface of Some Dinophyceae: A Comparative SEM Approach

The micromorphological characters of the theca of some Dinophyceae have been examined by SEM. Different ornamentation types (depressions, pores, ridges and other reliefs) can be detected on the plates. One or more ornamentation patterns may occur on a single plate. Based upon ornamentation types, it has been possible to classify the plates by structurai models (from simple to complex). While these structurai characters of the plates have been proved to be a useful parameter for distinguishing taxa of lower rank, they are of little significance for the distinction of superior taxa. In fact, plates with different ornamentation patterns may be observed in the same subject and subjects of different genera may have plates exhibiting the same ornamentation. By arranging the various ornamentation types according to their morphological structures (ranging from simple to complex) a certain morphological trend can be determined even though without an evolutive value.

Microbes in deep-sea anoxic basins

Abstract Biological studies on the anoxic basins of the Eastern Mediterranean started after the discovery of gelatinous matter of organic origin. The laminar gelatinous matter was observed within the cores containing anoxic sediments obtained during oceanographic expeditions for geological study of the Mediterranean Ridge. Microbiological and ultrastructural investigations were carried out on core sediment samples and on the overlying water. The organic nature of the mucilaginous pellicles found in the cores and their relation with numerous microbic forms present in all the samples were demonstrated. Viable microorganisms, prevalently Gram negative and aerobic as well as facultative anaerobes, were found in the water samples. Different microbic forms were isolated in pure culture : a vibrio ( Nitrosovibrio spp.), a coccus ( Staphylococcus spp.) and some rods of the family Pseudomonadaceae . In addition, laminar formations were observed in growth medium of mixed cultures that could be interpreted as the first stages of the mucilaginous pellicles seen in the cores.

The genus Drosera L. in northern Italy: Pollen morphology as a taxonomic tool

The pollen morphology of Drosera L. belonging to the Italian flora was studied by investigating alpine populations of D. intermedia, D. rotundifolia, D. anglica, and a natural hybrid, D. x obovata. Studies were carried out on fresh material by light microscopy and scanning electron microscopy. Features of the distal face seem to represent an important diagnostic element. A pollen key, based on micro-morphological data, is presented.

SEM survey on mediterranean species of Podolampas

Abstract In this work we have considered the features of thecal plates of some mediterranean species of Podolampas. The thecal plates have pores different in size and distribution according to their position and to the species considered. We have found some constant structures: kind of perforations of the apical, preequatorial and postequatorial thecal plates. The antiapical thecal plates have both constant and distinctive specific features.

The Quercus petraea -dominated communities in Italy: Floristic, coenological and chorological diversity in an European perspective

Abstract In Italy, woods dominated by Quercus petraea are well documented within local and regional phytosociological studies but a critical revision of their principal ecological-floristic components based on a comprehensive Italian data set was missing. We gathered 209 published and unpublished Italian phytosociological relevés, where Q. petraea was dominant, that were investigated by means of multivariate analysis. The ecological requirements of the resulting groups were indirectly calculated by means of Ellenberg indicator value, and a chorological analysis was performed. The fidelity coefficient (phi) for the diagnostic species of each group was calculated. According to our analysis, five different types of Q. petraea woods were found to be present in Italy. Each group was characterized by means of its floristic, ecological and chorological components. These resulting five groups were further compared with similar Q. petraea-dominated woods recorded in other European locations, as to the floristic and chorological components. We collected 57 synoptic tables of Q. petraea communities coming from all over Europe. This data set, together with the Italian relevés, was submitted to exploratory multivariate analysis using also the chorological information. According to these analyses, the Italian woods dominated by Q. petraea can be subdivided in two main clusters: the communities belonging to It-1 group (Alps) fell within the central European communities, distinguished by the predominance of large distribution and European chorotypes. All the other Italian groups of relevés resulted to be positioned in the cluster which includes central southern, central eastern and eastern European Q. petraea communities. From the syntaxonomical point of view, the results of this analysis allow to attribute the Italian Q. petraea woods to seven alliances of three different orders. The ecological similarities between Erythronio-Quercion petraeae and Erythronio-Carpinion betuli are highlighted and the distribution of Erythronio-Quercion petraeae is limited to northern Apennines, in particular, to slopes facing the Po Valley.

A survey of different types of vacuoles in the Cyanophyceae

Abstract Different types of vacuoles have been observed in a fresh-water alga: Oscillatoria sp. Among these, the ones showing a limiting membrane have been considered in more detail and their mechanism of formation studied. These membrane-bound vacuoles appear to be related to enlargements of the thylakoids. Thylakoid enlargement can occur in different ways: 1) The thylakoid itself becomes uniformly and regularly enlarged to form the true vacuoles. 2) Enlargements appear only in precisely localized areas of the thylakoid. These areas appear to be terminal points which increase in size to form vacuoles star-shaped in section. 3) The thylakoids enlarge irregularly to form the keritoms.