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Si descrive un'iniziativa finalizzata all'intercalibrazione di strumenti e messa a punto di protocolli operativi per l'effettuazione di misure ecofisiologiche su alberi in condizioni naturali. La cosa è particolarmente interessante tenendo conto che spesso, i dati ecofisiologici pubblicati in letteratura, provenienti da indagini di diversi gruppi di ricerca internazionali, vengono usati come supporto a decisioni di tipo politico e gestionale anche se non sempre sono realmente comparabili tra loro.

Transplants of Flavoparmelia caperata (L.) Hale were used to test possible relationships between chlorophyll a fluorescence (CaF) and ambient atmospheric conditions (temperature, precipitation, SO2 and NOx levels). Portions of the same thalli collected in a pristine site (A) of the Trieste Karst were exposed at that site, as the control, and in four other sites (B E) in NE Italy, near to pollution monitoring stations. These sites had been selected in order to provide similar two by two climatic conditions (sites B,C: more humid; D,E: drier) and air pollution load (sites B,D: low; C,E: high). Before exposure and after 43 and 90 days of exposure, CaF measurements were carried out in the laboratory under controlled conditions. A classification of meteorological and pollution parameters recorded during exposure substantially confirmed the differences between site couplets. After 90 days, samples from sites A (control) and B (with very low pollution load) showed only slightly reduced NPQ, qN, Fo, and Fm values. Samples from site D, with medium air pollution load, and sites C,E, with high air pollution loads, showed proportionally greater variation for most of the CaF parameters. A highly significant correlation was found between NPQ, qN, Fm, and NOx pollution but not with SO2 or O3. Effects of NOx on lichens and possible action mechanisms are discussed. The results strongly suggest that CaF measurements of lichen transplants can be a valid tool in biomonitoring studies.

2007/2008 L’obiettivo della ricerca è stato individuare i possibili effetti degli NOx, inquinanti aerodiffusi foto-ossidanti, sui licheni foliosi epifiti. Il lavoro è stato svolto con un particolare riguardo nell’individuare le modificazioni indotte a carico del processo fotosintetico del fotobionte lichenico attraverso metodi fluorimetrici. Le ricerche condotte hanno approfondito inizialmente alcuni aspetti metodologici, individuando, ad esempio, le variabili ambientali che influenzano maggiormente la capacità e l’efficienza fotosintetica di questi organismi. Successivamente, è stata disegnata una articolata sperimentazione, condotta mediante trapianti in siti urbani inquinati e non, che ha permesso di verificare gli effetti degli inquinanti aerodiffusi a concentrazioni ambientali in presenza di altri, naturali, fonti di disturbo. Questo lavoro dimostra, attraverso misure fisiologiche, che l’arido microclima urbano può essere un fattore limitante la fisiologia dei licheni e che la loro tolleranza agli NOx dipende strettamente dalla loro ecologia. XXI Ciclo 1980

Recent hypotheses suppose that dry lichens emit a faint chlorophyll a fluorescence because of a “long-wavelength quencher” embedded in the antenna complex that protects photosystem II (PSII) from photodamage. To verify in the field the PSII re-activation promptness induced by water availability, chlorophyll a fluorescence was measured on the epiphytic lichen Flavoparmelia soredians after two months without rainfall events in a Mediterranean cork oak wood (Bosco Santo Pietro, Sicily, Italy). Measurements were carried out at dawn and sunset on north- and south-exposed populations under different regimes of hydration and dark-adaptation. The results show that prolonged hydration increases the photochemical conveying of energy to PSII and decreases the non-photochemical energy dissipation that otherwise might occur in the antenna complex of the lichen photobionts. A slight decrease in PSII efficiency caused by photoinhibition was observed in thalli exposed to ambient light (up to 600 µmol photons m-2 s-1) only when kept fully hydrated. The results are discussed on the basis of our knowledge on the ecology of the species, that is a representative component of Mediterranean epiphytic lichen communities.