Two species of Verrucariaceae, Endocarpon globosum Harada & L.-S. Wangsp. nov., and Staurothele yunnana Harada & L.-S. Wang sp. nov., are described. Both grow on stones submerged in a stream on Meili Snow Mountain in NW Yunnan, China.

Spirographa vinosa Holien & Triebel is described from boreal spruce forest of Norway. It is lichenicolous on different species of Ochrolechia and Pertusaria. Within the genus S. vinosa is characterized by its 8-spored asci, up to 5-septate ascospores with obtuse ends and its apothecial pigments causing aeruginose and purplish reactions with KOH.

The distribution of crustose Caliciales has been surveyed in 100 spruce forest patches in Sør-Trøndelag, central Norway. Relationships between occurrence of the species and a number of site and stand variables were analysed by detrended correspondence analysis (DCA) and direct gradient analysis. Species diversity7 was significantly higher in old forests and in forests at higher altitudes compared to young forests and forests at lower altitudes. Old trees and snags are considered to be the most important structural components in old forests promoting species diversity of the Caliciales. Threatened or vulnerable species, such as Chaenotheca gracilliina, Cybebe gracilenta, Sclerophora coniophaea and S. peronella were confined to forest on rich soils showing no correlation with forest stand age. Chaenotheca brachypoda and C. trichialis were found to be the most typical old forest species among the Caliciales. Humidiphilous species are considered to be less affected by forestry in a humid climate. A change in forestry practice towards methods imitating the natural dynamic processes is considered necessary to maintain species diversity of the Caliciales in boreal forests.

A significant negative correlation was found between the quantity of acetone-extractable phenolic compounds and the degree of enzyme polymorphism in eight eastern North American populations of Umbilicaria americana. In sites higher elevations, where UV irradiance was more intense, phenolic levels were significantly lower and within-stand enzyme variability significantly greater than in low elevation sites. Similarly, the phenolic content of thalli collected in Ontario, Canada, over a 16-month sampling period was negatively correlated with mean monthly UV-B irradiance.

For experiments run at 350 ppm CO2, the subtropical lichen Coenogonium does not exhibit net photosynthetic depression at water contents above those at which initial maximal values are reached. This is in contrast to most lichens for which such a depression occurs. We infer that the results reflect the unusual morphology of Coenogomum, in which the alga is the dominant symbiont, occurring as filaments at the lichen surface. This arrangement should minimize CO2 diffusion resistance to the algal surface. With light saturation occurring by 70 μmol photons m−2 s−1, Coenogoniium has one of the lowest light saturation values reported among lichens.

Snow meltwater containing 36 ng ml−1 NO3−−N (raised here to between 95–101 ng ml−1 NO3−−N) and 112 ng ml−1 NH4+ −N was sprayed onto illuminated Usnea sphacelata at 2°C in a 2−1 capacity transparent perspex chamber force-ventilated with either air or O2− (and CO2−) free N2. The NO3-concentration in meltwater recirculated through a layer of U. sphacelata fell to c. 8 ng ml−1 after 1.25 h. Although the pattern of decline was broadly comparable in both air and N2, the initial rate of decline was lower in N2. When undepleted meltwater was continuously sprayed onto the lichen and the effluent collected for analysis, the lichen was found to retain 55% of the wet deposited NO3− in air but only 27% under N2. Up to 90%) of NH4+ supplied in a continuous spray of meltwater was retained by the lichen but this was affected little by O2 and CO2 deprivation.

Xanthona parietina thalli were collected from a ‘clean-air’ location and from a polluted area. Ramalina duriaei thalli were collected from the same ‘clean-air’ location and some thalli were transplanted to air polluted locations, where R. duriaei no longer occurs. The effects of air contaminants on these two lichens were compared under controlled laboratory conditions and in field experiments. Air contaminants and exposure to bisulphite ions had little or no damaging effect on X. parietina, whereas severe damage was caused to R. duriaei, as judged by chlorophyll degradation, autofluorescence of photobionts, photosynthetic activity, membrane integrity and ATP content. The different responses presented confirm the sensitivity of R. duriaei and resistance of X. parietina to air pollution.

Surveys of the distribution of the lichens Xanthoria panetina and Ramalina duriaei in Israel showed that environments with air pollution had no damaging effectson X. panetina, whereas R. duriaei had disappeared from polluted environments: physiological studies supported this relative sensitivity. Investigations of possible defence mechanisms protecting X. parietina from the damaging effects of air pollution showed a multitude of possible protective systems. These included constitutive avoidance such as: efficient buffering capacity; a relatively high potassium content; and antioxidation by parietin, and induced tolerance such as: SO2 oxidation to non-toxic sulphate; increased glutathione content; induced praline and arginine synthesis; and increased detoxification of active oxygen forms.

Early stages of lichen colonization on glass are reported for the first time from Antarctica. In the initial establishment of the lichen thallus rhizomorphs play an importantrole for the attachment to the substratum and the exploitation of nutrient and photobiont resources. The micrographs presented indicate that in Antarctica colonization of bare substrata bylichens is not necessarily an extremely slow process. Furthermore, our findings demonstrate that the use of artificial substrata such as glass could provide a simple method for studies in lichencolonization and development in extreme environments.