1,720,973 research outputs found
Effects of H2S on CO2 gas exchanges and growth rates of the epiphytic lichen Parmelia sulcata Taylor.
No full textSeasonal variation of Fo, Fm, and Fv/Fm in an epiphytic population of the lichen Punctelia subrudecta (Nyl.) Krog.
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Effects of Mediterranean summer conditions on chlorophyll a fluorescence emission in the epiphytic lichen Flavoparmelia soredians: a field study.
No full textRecent 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
Ambient NOx influences chlorophyll a fluorescence in transplanted Flavoparmelia caperata lichen.
No full textTransplants 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
Species delimitation in the Lepraria isidiata-L. santosii group: a population study in the Mediterranean-Macaronesian region
No full textIntrathalline variation of chlorophyll a fluorescence emission in the epiphytic lichen Flavoparmelia caperata
No full textEffetti del gradiente climatico altitudinale (Maremma, Monte Amiata) sulla composizione e l’accrescimento del lichene Parmelia sulcata Taylor
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