Galactomannans were isolated from Cladonia signata, C. furcata, C. imperialis, and C. clathrata via successive alkaline extraction and precipitation with Fehling solution and Cetavlon. They were investigated using ⊃13C-NMR spectroscopy, methylation analysis, and Smith degradation, and their specific rotations and monosaccharide compositions determined. As with galactomannans of other Cladonia species, they contained (l →6)-linked main chains of α-mannopyranose, which were non-substituted (structure 4 in Fig. 2), monosubstituted at O-2 with α-mannopyranose (structure 6) or α-galactopyranose (structure 1), O-4 with β-galactopyranose (structure 2), and disubstituted at O-2 and O-4 with α-mannopyranosyl and β-galactopyranosyl units, respectively (structure 5). Disubstitution was present to a greater extent in the galactomannans of C. clathrata and C. imperialis than in those of C. signata and C. furcata. In the case of the galactomannans of C. furcata, C. clathrata, and C. imperialis, substitution also occurred at O-2 with O-β-galactofuranosyl-(l→6)-O-α-mannopyranosyl units (structure 7). As observed in previous investigations, the C-l portion of the ⊃13C-NMR of mannose-containing polysaccharides is typical of the lichen species. However, those of galactomannans of C. imperialis and C. clathrata are almost identical and, although other chemical data showed many structures in common, some differences were evident.

The response of corticolous lichens to artificially induced chemical damage was compared to symptoms found on damaged lichens in the field. Experimental thalli were damaged and observed (1) in situ in a relatively pristine area, and (2) in a growth chamber either hydrated continuously or periodically. Lichenicolous fungi encountered included Cornutispora lichenicola, Lichenoconium erodens, Phoma cytospora, Vouauxiomyces truncatus, Hobsonia christiansenii, Pronectria oligospora, Nectria rubefaciens and its anamorph, Acremonium rhabdosporum, and a variety of hyphomycetes. The results support the idea that both thallus necrosis and moist conditions are necessary to produce the full suite of symptoms observed on ailing lichens in the field.

A method is described for the selective amplification of single mycobiont rDNA sequences from vegetative, non-ascomatal material of the lichenized thalli of Parmelia sulcata and P. saxatilis. The method includes a simple DNA extraction procedure employing rhizines, which avoids the use of liquid nitrogen disruption methods and phenol based extractions. The resulting amplified DNA is suitable for restriction enzyme analysis, and can be used to provide material for investigating population distribution and species concepts.

Net photosynthesis (NP) and dark respiration (DR) of thalli of the lichen species Umbilicaria grisea and U. freyi growing together in the same habitat the Sierra de Guadarrama, central Spain, were measured under controlled conditions in the laboratory and under natural conditions in the field over a range of photosynthetic photon flux densities (PPFD), thallus temperatures and thallus water contents. Laboratory experiments revealed that the photosynthetic response to PPFD at optimum thallus water content is very similar in both species. The light compensation points of NP increased from PPFD of c. 20 µmol m−2 s−1 at 0°C up to c. 100 µmol m−2 s−1 PPFD at 25°C. In both species light saturation was not reached up to 700 µmol m−2 s−1 PPFD except at 0°C. By contrast, the temperature dependence of CO2 gas exchange differed substantially between U. grisea and U. freyi. Both species gave significant rates at 0°C. Optimal temperatures of NP were always higher in U. grisea at various PPFD levels if the samples were kept at optimal thallus water content. NP showed maximal rates at 95% dw in U. grisea and 110% dw in U. freyi respectively. In U. grisea a much stronger depression of NP was observed with only 5% of maximal NP reached at 180% dw. At all PPFD and temperature combinations U. freyi showed higher rates of NP and more negative rates of DR if calculated on a dry weight basis. This was also true under natural conditions at the same site, when U. freyi was always more productive than U. grisea. The differences in the photosynthetic response to temperature between both species correlated well with the different distribution patterns of both species. The possibility of genetic control of the physiological performance of these species and its influence on their distribution patterns and autecology is discussed.

The FT-Raman spectra of encrustations of Dirina massiliensis f. sorediata on a variety of substrata collected from several locations have been recorded and analysed. This is the first time that such a comprehensive spectroscopic study has been made of lichen encrustations of the same species on different substrata. This lichen is able to bring about deterioration in all six different lichen substrata studied. Calcium oxalate dihydrate is produced in significant amounts by the reaction of lichen-generated oxalic acid with various calcareous rock substrata, as well as particles of the particular substratum itself. However, for specimens growing on a non-calcareous substratum in an exposed maritime location only traces of calcium oxalate are produced and more noticeable quartz particles are incorporated into the thalli. The results indicate that this lichen can degrade its substratum highly effectively and there is evidence of different strategies being exhibited by lichens in different habitats and geographical locations.

Peltigera canina thalli have been successfully transplanted onto soil in a garden and in flowerpots. Garden samples showed marked seasonality and achieved growth rates of 6·4 cm per year. Pot-grown samples showed variation in the growth of individual thallus lobes and established that, under different soil hydration regimes, permanently hydrated thalli could sustain considerable linear growth rates for at least 140 days.