05 - Studia Geobotanica. An international journal - Vol. 5 (1985)

On the basis of an ecological model the relationships between the vegetation and geomorphology of the dolinas are described for the Karst region near Trieste. Observations about presence thresholds of primary coenoses and the classification of dolinas, according to vegetation are made.

This paper reports on the distribution of lichens in the urban environment of Trieste (NE Italy) and its surroundings. The study is based on 213 phytosociological releves, taken on trees with primarily acid bark, and on pollution data from a net of deposimetric stations located within the town center. Both data sets have been submitted to multivariate analysis (classification and ordination). The results of data analysis allowed to distinguish six main zones, three defined by a peculiar lichen vegetation, the remaining three delimited on the basis of pollution data. The ecology of the releve groups obtained by classification has been studied on the basis of the tolerance ranges associated to each species by Wirth (1980). From the perifery to the center of the town there is a decrease in species, and an increase in the relative frequency of xero- photo- nitro- and neutro-basiphytic species. The distribution of lichens within the survey area cannot be explained on the only basis of air pollution. Drought in the urban environment seems to be another important factor affecting the distribution of lichens in the town of Trieste.

A program in FORTRAN 77 for spatial pattern based on the methods of nearest-neighbor and autocorrelation is presented. It has been used with the option for autocorrelation to analyse the spatial pattern of 120 species and other variables as life-growth forms, chorological elements and classes of environmental variables, along transects from open grasslands to groups of trees (NR) in the Karst area near Trieste. The results proved that both the species and the other variables show significant pattern. Particularly a high degree of significance has been found for the variables of higher hierarchical meaning than species and especially for the classes of environmental variables. The number of entities with significant pattern increases in function of the length of the transect. The results prove that along the transect there is a composite ecologica] gradient which produces significant changes of vegetation pattern at different hierarchical levels, both structural and chorological.

The use of ellipses of equal concentration is suggested for the analysis of pattern in ordination scattergrams produced directly by environmental variables, or with axes obtained by numerical methods. The potentials of the method are illustrated by some examples using structural characteristics of mixed forest type of NE Italy and environmental variables estimated by ecological indicator values.

123 specie di licheni vengono riportate per l'Arcipelago delle Tremiti. Di queste, 68 sono epi-endolitiche su calcare, 40 sono epifite, 15 sono epigee. La relativa povertà della florula lichenica delle Tremiti è dovuta soprattutto al forte apporto di nitrati da parte di colonie di uccelli marini, ed alla scarsità di boschi naturali con un grado sufficiente di umidità atmosferica. Particolarmente interessanti sono i pochi frammenti di vegetazione lichenica epifita nell'isola di S. Domino, che ospitano una serie di specie ad affinità occidentali (subatlantiche).

The authors give preliminary observations on the main features of the flora and vegetation of Hormuzgan (Southern Iran).

Notes on the marginai karstic vegetation. The meadows with Arrhenatherum elatius and the therophytic coenosis with Cerastium pumilum are studied in the North Adriatic Karst (Trieste) with particular regard on its phytogeographical variability.

This paper describes in a more detailed way the Carpinus betulus wood - previously typified by its Author by means of a synthetic table - which grows on the North-oriented slopes of dolinas (sinkholes) and gives its subdivision in subassociations.

The flowering of Rubio longifoliae-Quercetum rotundifoliae fraxinetosum orni Costa. Peris & Figuerola. The flowering of Rubio longifoliae-Quercetum rotundifoliae fraxinetosum orni Costa, Peris & Figuerola 1982 is studied during the dry year 1983 in the "carrascal" maquis-wood of the Barranco Real (Valencia, Spain). The formation is characterised by high frequencies of multiple flowerings - more of one flowering along the year. The "optimum" flowering - highest frequency in a taxon - is pertaining to the spring, while the "suboptimum" flowering - low frequencies in a taxon - is autumnal and it is related with the season whose pluviometric values are highest.

Helleborus multifidus subsp. istriacus is an endemic Illyric Dalmatian species, that in the North-Adriatic area occurs at the border between Italy and Jugoslavia. The entity produces two bufadienolides (hellebrin and glucohellebrin) in the hypogeal organs. Three types of population are identified on the basis of their quantitative variations and their distributive ratio between roots and rhizomes. Their ranges have been estabilished on a 140 Km 2 area near Trieste (Friuli-Venezia Giulia). This distribution patterns seem to be related with a gradient in water availability. The correlation between phytochemical variability and variation of climatic factors, suggest that the investigated substances could have an adaptative value in respect with the ecology of the Helleborus entity.