09 - Studia Geobotanica. An international journal - Vol. 9 (1989)

LICHENS AS BIOMONITORS OF AIR POILUTION. A CASE STUDY AT MACERATA (ITALY). This study presents the results of a research carried out around an incinerator at Macerata (Central Italy), aiming at monitoring air pollution with the use of epiphytic lichens as bioindicators and bioaccumulators. Two main approaches have been adopted: 1) lndirect approach, based on the relative frequencies of epiphytic species; 2) Direct approach, based on measurements of metal concentrations in the lichen thalli. The two approaches are complementary: the former mainly gives information on pollutants with a long-range deposition, such as S02 and NOx, the latter indicates the pollution by metals. The frequency of species within a 10-mesh grid of 30 x 50 cm has been recorded in 34 sampling stations (average 3 trees per station). The metal concentrations in the thalli of Xanthoria parietina have been recorded in 19 stations. Pollution maps have been constructed by programs of authomatic mapping. Tue results indicate that the incinerator should be considered as the main emitting source for the following metals: Cr, Cu, Fe, Hg, Mn, Ni. The main source for Pb is the vehicular traffic. Al is mostly of terrigenous origin. Most of the gaseous pollutants are probably produced by domestic heating.

The relationships between the present distribution of native Fuegian vascular plants and their ecological behaviour have been studied on the basis of information and multivariate analysis. 216 species (54 % of the total flora) were collected during two surveys within a transect across the main vegetation zones of Isla Grande de Tierra del Fuego; the ecological and phytogeographic informations are derived from field and literature data. The results show that: 1) the species list obtained by the survey along the transect have the same informational content of the total flora of lsla Grande; 2) seven out of twelve species groups obtained by numerical classification of phytogeographic data are well correlateci to the main habitat-types of Fuegia, i.e. steppe, forest and bog communities; 3) the Andean Cordilleras played the main role in plant migration to Fuegia after the ice retreat.

This paper is a study of the ombrophobous saxicolous lichen vegetation along the coasts of southwestern Europe and northern Africa, with some comments on the bioclimatic features of this area. All taxa mentioned in the text are included in a commented list. The species considered as characteristic or transgressive of ombrophilous communities are provided with a comment on their distribution, ecology and syntaxonomy. Distribution maps are provided for some little known species. On the basis of the phytosociological approach 6 associations and 2 communities are recognized, according to the following syntaxonomic scheme: Roccelletea phycopsis Class. proy. Saxicolous, ombrophobous, thermophytic, aerohygrophytic, halotolerant, photophytic to skiophytic, scarcely to not nitrophytic. Littoral or sublittoral areas, in Europe and northern Africa. Dirinetalia massiliensis Ord. prov. On carbonatic rocks. Mediterranean and Eurosiberian regions. Roccellion phycopsis Egea et Llimona em. On carbonatic rocks. Optimum in the Mediterranean region. Dirinetum repandae Clauzade et Roux 1975. Littoral or sublittoral areas, in the infrathermo-mesomediterranean and thermocolline stage. ? Community of Opegrapha durieui On porous more or less soft rocks near the sea. Thermomediterranean. Roccelletalia fuciformis Ord. prov. Siliceous and volcanic rocks. Macaronesian, Mediterranean and Eurosiberian regions. Roccellion tinctoriae Klement 1965. On vertical and overhanging cliffs, very aerohygrophytic, photophytic. Optimum in the Macaronesian region. Present also in high air moisture areas of the Mediterranean and Eurosiberian regions. Roccelletum tinctoriae Klement 1965. Shaded volcanic rocks. Infra- thermo-Mediterranean-Canarian. From arid to humid ombroclimate. Lecanactidion monstrosae Ali. prov. Acidophitic, anombrophytic, from photophytic to very skiophytic, less aerohigrophytic than the former alliance. Littoral of the Mediterranean, Macaronesian and southern half of the Eurosiberian region. Dirinetum africanae Egea et Llimona 1984 corr. Siliceous and volcanic rocks. On cavities, small caves, overhanging and vertical cliffs thermo (meso ?)- Mediterranean and infrathermocanarian. From arid to dry ombroclimates. Lecanactino plocinae-Dirinetum sorediatae Egea et Rowe 1987 Sandstone and schists. Coast and sublittoral hills of Cadiz and Tanger. Thermomediterranean subhumid (humid ?). Sclerophytetum circumscriptae James, Hawksworth et Rose 1977 Southern part of the Eurosiberian region. Siliceous rocks. Lecanactino monstrosae-Dirinetum insulanae Ass. nova. Volcanic rocks. Infrathermomediterranean-canarian, (thermocolline?). Ombroclimate arid to subhumid. The ecology, distribution and floristic composition of all syntaxonomic units are discussed.