Abstract: Although the coastal fog zone of the Namib Desert has negligible rainfall, large parts may be covered by soil-crust lichens with chlorophyll contents and photosynthetic rates (under optimal conditions of hydration and light), on an area basis, almost equal to the leaves of typical higher plants. The photosynthetic and respiratory CO 2 exchange rates of three soil-crust lichens, Acarospora cf. schleicheri, Caloplaca volkii and Lecidella crystallina were measured in the field (September 1990). The three species responded in a similar fashion to changing environmental conditions. Nocturnal hydration, by fog and/or dew, activated dark respiration which was followed after sunrise by a short period of positive net photosynthesis that continued until metabolic inactivation occurred from desiccation (...)

Abstract: A review is presented on secondary products of lichens, including distribution according to developmental stage of the thallus and synthesis of these compounds in relation to the two symbiotic partners. Techniques for analyzing secondary substances are considered, as well as biosynthetic pathways and regulatory controls. The adaptiveness of secondary metabolites in a natural thallus and applications to human uses are also discussed.

Abstract: 1 Black spruce (Picea mariana) experienced increased radial growth and stem height over the last 100 years at treeline in subarctic Quebec, suggesting warmer and snowier conditions. We tested if recent climate change also induced a shift from forest to krummholz during the Little Ice Age and stand reversion from krummholz to forest during the 1900s. Whether the shifts caused measurable displacements of the forest limit were also examined. 2 Growth forms of living and dead spruces were compared in five lichen-spruce stands located 0, 2, 4, 6 and 8 km south of the krummholz limit. The age structure of supranival shoots (stems standing above the snow cover) at each site was also determined. 3 A reversion from lichen-spruce forest to krummholz probably occurred during the mid-1800s. Since the late 1800s, the forest limit moved 4 km northward most likely in response to milder winter conditions. Krummholz changed progressively to forest as spruce height and frequency of the tree growth form increased. Thus the northward advance of the forest limit resulted from structural changes of pre-established spruces, whereas there was no evidence for a recent spruce establishment in the tundra.

Abstract: A total of 32 calcicolous lichen species, one alga and one bryophyte were recorded on a limestone wall in the grassland Great Alvar on the Baltic island of Oland, Sweden. Fourteen (41%) of these 34 species and free-living cyanobacteria showed herbivore damage, most probably due to grazing by the land snails Chondrina clienta and Balea perversa which inhabited the limestone wall. Three laboratory experiments were conducted to examine the food preferences of individuals of C. clienta and B. perversa collected at this site and to evaluate any association between their preference and the net food quality of the lichens to the snails. Chondrina clienta and B. perversa exhibited food preferences, which differed significantly between species. Within species, variation in food choice was similar among individuals. This indicates that snail populations may be composed of polyphagous individuals with similar food preferences. Different lichen species were of different net food quality to the snails as indicated by growth rate differences. In both snail species the most preferred lichen species of the choice experiment caused the largest weight increase in juveniles, viz. Caloplaca flavovirescens for C. clienta and Aspicilia calcarea for B. perversa. This suggest that the snail species studied differ in their abilities to deal with secondary compounds and physical characteristics of certain lichens or that they can utilize the energy and nutrients of these lichens to a different extent. It is suggested that differential food preferences might reduce the intensity of interspecific competition for resources (lichens) between C. clienta and B. perversa.

Abstract: To estimate epiphyte biomass in tallforests, the only viable alternative to tree climbing methods is to sample litterfall. To evaluate the potentialfor using epiphyte litter to estimate epiphyte biomass, epiphyte litter and in situ epiphyte biomass were estimated independently in each of three Pseudotsuga-Tsuga heterophylla stands in the Cascade Range of Oregon and Washington, U.S.A. Litter was collected in late summers of two years in 20 2-m-radius plots. Groups of trees were felled and sampled for epiphytes. Samples were sorted into four groups: cyanolichens, alectorioid lichens, other lichens, and bryophytes. For lichens, biomass of litter (L) was strongly related to epiphyte biomass (B) (r2 = 0.87, n = 18), in about a 100:1 ratio (fit as VL = 0. 1 x v/B, yielding B = 100L). Year-to-year variation within stands was smaller than the differences among stands. Ten 2-m- radius plots are recommended for stands with simple structure, and 15 plots for older stands with more complex structure. The method is not recommended for bryophytes because bryophyte litterfall is highly aggregated. The method is recommended for large-scale surveys of lichens and other studies where large differences in epiphyte biomass are expected.

Abstract: An exclosure experiment performed in 1977-1985 in three tundra habitats was re-analyzed to examine species-specific plant responses for dominating species. In the lichen heath, four woody species showed the strongest increases as a response to the grazer exclosure. In the meadow, a tall grass showed the strongest increase in the exclosures, while a creeping woody plant increased in the snowbed exclosures. The species that increased in the exclosures were consistently those which were capable of elevating their foliage above the prevailing foliage height, while semiprostrate and prostrate plants (most notably bryophytes and lichens) suffered heavily from the exclusion of grazers.

Abstract: Abstract The view that lichen thalli should be regarded as analagous to insect and fungal galls produced on plants is critically analysed. Ten similarities and 13 differences are recognized and discussed. In view of the fundamental differences identified, the analogy cannot be upheld. Lichen thalli are regarded as a particular biological phenomenon with no exact analogue. An expanded definition of ‘lichen’ is provided. Coevolutionary and systematic aspects of the lichen mutualism are considered, stressing the need to emphasize non-coevolved structures in supraspecific taxonomies. Attention is also drawn to the galls produced on established lichen thalli by invasive fungi and other organisms, including nematodes and arthropods.

Abstract: The distribution and frequency of bryophyte and lichen vegetation on ice-free regions of the Windmill Islands are presented using data derived from aerial photography and ground surveying The qualitative and quantitative plant cover of sites are listed and related to the topography and major soil characteristics of each site The richest associations of macrolichens and bryophytes occurred on the metamorphic northern peninsulas Species richness and frequency was generally reduced on the charnockitic southern peninsula and the islands which have been deglaciated longer Salinity varied significantly throughout the region with the highest levels in the northern islands reflecting the presence of penguin colonies In such sites bryophytes and lichens were virtually absent Wind blown sea-spray contributed far less salts than direct excretion from penguins On the peninsulas snow cover and site exposure appeared to delimit plant distribution Higher salt levels from sea-spray on the northern aspects of the peninsulas seemed to have negligible impact on vegetation patterns with the possible exception ofBiatorella cerebriformis which was encountered only inland The total phosphorus and nitrogen levels of the skeletal soils were generally low except in eutrophic sites adjacent to penguin colonies The vegetation patterns are discussed in terms of the climate, topography and species autecology

Abstract: Levels of soluble carbohydrates, moisture, and pigments in the major bryophytes and lichens from the Windmill Islands, continental Antarctica, were monitored over a 14-month period. Gas-liquid chromatography revealed little seasonal change in soluble carbohydrate levels. Water content of vegetation varied throughout the season with maximum hydration occurring over the summer months. Pigment levels also varied seasonally with a decrease in total chlorophyll and chlorophyll a/b ratios during winter. Levels of total carotenoids increased over summer in response to high ambient irradiation. In contrast with the seasonality of soluble carbohydrates reported in some cryptogams from subpolar regions, the lack ofany significant seasonal changes in the Antarctic bryophytes and lichens may be due to the extreme climate and rapid temperature fluctuations in the continental Antarctic environment. Bryophytes and lichens form a dominant component of vegetation at high latitudes due to their ability to withstand extreme polar environments (Longton 1988; Tenhunen et al. 1992). An important factor in the resistance of these poikilohydric plants is considered to be the accumulation and maintenance of relatively high levels of cell solutes including lipids, amino acids, and soluble carbohydrates (Farrar 1976, 1978; Karunen & Salin 1982; Levitt 1980; Longton 1988). Although it has long been recognized that soluble carbohydrates confer frost resistance to higher plant cells by increasing their tolerance to osmotic and thermal stress (Carpenter & Crowe 1988; Levitt 1980), the significance of soluble carbohydrates in the frost resistance of polar bryophytes and lichens is unclear. Studies from subpolar regions have indicated seasonal trends in carbohydrate levels of mosses and lichens with the accumulation of photosynthates and inorganic nutrients during the periods preceding winter (Hicklenton & Oechel 1977; Smith 1978; Tearle 1987). These differences were high enough to suggest a role in frost resistance. In the latter study, maritimeantarctic lichens were found to have much higher soluble carbohydrate levels than those reported in lichens from temperate regions. Given the hostile nature of the antarctic environment, vegetation on continental Antarctica may similarly be expected to contain high levels of cell solutes in response to cold and desiccation stress. However, Rastorfer (1972) reported that many moss species are frost resistant despite low soluble sugar contents. Furthermore an initial survey offrigid-antarctic (sensu Longton 1988) cryptogams (Roser et al. 1992) showed soluble carbohydrate levels to be comparable to those found in temperate cryptogams and much lower than those reported by Tearle (1987) for maritime-antarctic cryptogams. However, as the former survey involved a single sampling over summer the possibility remained that seasonal increases in soluble carbohydrate levels may occur. In this paper the results of a long-term monitoring of the seasonal cycle of soluble carbohydrates in several of the dominant continental antarctic moss and lichen species are presented for the first time. To give some parallel measures of other growth paameters results are also given for seasonal variations in the moisture content and pigment levels of the plants. This information is important not only to clarify the adaptive physiology of plants in the extreme antarctic habitat but also in terms of the nutrients made available to the antarctic terrestrial ecosystem. The flush of soluble carbohydrates during the spring thaw is thought to contribute to the increase in soil microbial activity over this period in the maritime antarctic (Smith 1985; Tearle 1987; Wynn-Williams 1982). In continental Antarctica where the terrestrial biomass is much less, the nutrient input from cryptogamic vegetation is likely to be the major source of nutrients in areas away from bird colonies.

Abstract: The photosynthetic properties of a range of lichens (eight species) containing green algal primary photobionts of either the genus Coccomyxa, Dictyochloropsis or Trebouxia were examined with the aim of obtaining a better understanding for the different CO2 acquisition strategies of lichenized green algae. Fast transients of light/dark-dependent CO2 uptake and release were measured in order to screen for the presence or absence of a photosynthetic CO2-concentrating mechanism (CCM) within the photobiont. It was found that lichens with Trebouxia photobionts (four species) were able to accumulate a small pool of inorganic carbon (DIC; 70–140 nmol per mg chlorophyll (Chl)), in the light, which theoretically may result in, at least, a two to threefold increase in the stromal CO2 concentration, as compared to that in equilibrium with ambient air. The other lichens (four species), which were tripartite associations between a fungus, a cyanobacterium (Nostoc) and a green alga (Coccomyxa or Dictyochloropsis) accumulated a much smaller pool of DIC (10–30 nmol·(mg Chl)−1). This pool is most probably associated with the previously documented CCM of Nostoc, inferred from the finding that free-living cells of Coccomyxa did not show any signs of DIC accumulation. In addition, the kinetics of fast CO2 exchange for free-living Nostoc were similar to those of intact tripartite lichens, especially in their responses to the CCM and the carbonic anhydrase (CA) inhibitor ethoxyzolamide. Trebouxia lichens had a higher photosynthetic capacity at low and limiting external CO2 concentrations, with an initial slope of the CO2-response curve of 2.6–3.9 μmol·(mg Chl)−1·h−1·Pa−1, compared to the tripartite lichens which had an initial slope of 0.5–1.1 μmol-(mg Chl)−1·h−1·-Pa−1, suggesting that the presence of a CCM in the photobiont affects the photosynthetic performance of the whole lichen. Regardless of these indications for the presence or absence of a CCM, ethoxyzolamide inhibited the steady-state rate of photosynthesis at low CO2 in all lichens, indicating a role of CA in the photosynthetic process within all of the photobionts. Measurements of CA activity in photobiont-enriched homogenates of the lichens showed that Coccomyxa had by far the highest activity, while the other photobionts displayed only traces or no activity at all. As the CCM is apparently absent in Coccomyxa, it is speculated that this alga compensates for this absence with high internal CA activity, which may function to reduce the CO2-diffusion resistance through the cell.

Abstract: . The vegetation of anthropogenically disturbed sites on the Chukotka Peninsula was investigated in 1986 and 1990. 102 sites had been bulldozed free of vegetation and soil between 2 and 20 yr ago and revegetated. Anthropogenic vegetation differs considerably from natural tundra. The total plant cover decreases, lichens are absent, moss composition changes, and graminoids predominate. A floristic classification was developed in order to describe the diversity of anthropogenic communities formed on these sites. Four associations were distinguished, all belonging to the alliance Poion glaucomalacanthae. An additional alliance characterized by Alopecurus alpinus is suggested for colder sites, but it has not yet been described. There is a correspondence of associations to substrate types. The association Phippsietum algidae was found only on loam substrate. The Artemisietum glomeratae and Saxifragetum punctatae are connected with rubble or gravel. The graminoid association Arctagrostietum arundinaceae is generally widespread in disturbed habitats and occurs on a variety of substrate types.

Abstract: A 3 year research project in Thailand on lichens as indicators of environmental change in tropical forests was undertaken in protected areas where monitoring for long-term changes is now set up. Sites were selected in Huay Kha Khaeng, Doi Suthep and Doi Inthanon in deciduous dry dipterocarp and evergreen forests where phanerogamic diversity and fire history is known. Through collection and analysis of lichen and environmental data, the association of lichens with tree species and forest type, and the use of lichens as indicators of recent changes in forest history, is demonstrated. Factors affecting the lowering of lichen biodiversity are discussed, in particular the effects of fire on the constituent phanerogamic and cryptogamic communities.

Abstract: The occurrence and distribution of the South Georgia fungal flora, particularly Ascomycotina and Basidiomycotina, is assessed in terms of habitat and substrate preference. The 113 taxa reported comprise 37 basidiomycetes, 49 ascomycetes, six myxomycetes and at least 21 lower fungi. Peat and litter substrata associated with tall tussock grassland have a rich macro-fungal flora, and numerous species occur in bog and mire communities, some in abundance from mid to late summer. Many micro-fungi and ascomycetes colonize dying leaves and inflorescences of specific vascular plants, and a few colonize bryophytes and lichens. At least a dozen species, probably non-indigenous, are associated with rotting timber and other imported materials at former whaling stations. An intensive survey of the South Georgia mycoflora is necessary to gain better understanding of their role in decomposition and nutrient cycling processes in the principal plant communities.

Abstract: The new genus Ramboldia (Lecanoraceae) is described and its affinities to other genera in the family are discussed. Ramboldia is most closely related to Pyrrhospora, the most obvious difference being the absence ofanthraquinone pigments in the apothecia ofRamboldia. Five species are included in the new genus: the chiefly lignicolous R. stuartii (Hampe) comb. nov. and R. subnexa (Stirton) comb. nov., the corticolous R. brunneocarpa sp. nov., and the saxicolous R. petraeoides (Nyl. ex Church. Bab. & Mitten) comb. nov and R. plicatula (Mill. Arg.) comb. nov. Lecidea lampra Stirton is synonymous with R. stuartii, Biatora byssacea Hampe is not referable to any lichen, and the new combination, Micarea intersociella (Stirton) Coppins, is proposed. Lecidea lampra and L. subnexa are lectotypified. A study of some Australian lignicolous lichens, referred to collectively by past authors (e.g., Miiller 1893; Weber & Wetmore 1972) as Lecidea elabens Fr. [= Pyrrhospora elabens (Fr.) Hafellner], has revealed that two distinctly Australasian taxa are involved: L. stuartii Hampe and L. subnexa Stirton. These lichens, discerned mainly by their abundant black apothecia, are particularly common in cool temperate eucalypt woodlands in southern Australia and typically predominate on dead, decorticated trunks and branches. Neither species belongs to the genus Lecidea s.s. and both are clearly members of the Lecanoraceae as defined by Hafellner (1984) and generally accepted by subsequent workers. Although showing some affinities with the genus Pyrrhospora in the sense of Hafellner (1993), these species cannot be readily accommodated in any of the known genera of the Lecanoraceae, and accordingly we describe the new genus Ramboldia. Three further Australian lichens, one hitherto undescribed, are also included in this new genus. MATERIALS AND METHODS The study is based on material in ANUC, CBG, HO, M, MEL, and relevant types from other herbaria. Anatomical observations and measurements were carried out on apothecial sections mounted in 10% KOH, or in Lugols iodine, lactophenol cotton blue, or trypan blue, after pretreatment with 10% KOH. Chemical constituents were identified by thin layer chromatography using methods standardized for lichen products (Culberson & Ammann 1979; Culberson & Johnson 1982; Elix & Ernst-Russell 1993) and by comparison with authentic materials (Elix & Norfolk 1975). Nomenclature of lichens mentioned follows Kantvilas (1989). RAMBOLDIA Kantvilas & Elix gen. nov. Genus cum thallo, ascis et ascosporis ut in Pyrrhospora sed ab hoc genere apotheciis nigris vel rufo-brunneis et pigmento K+ kermesino vel violaceo noncontinente differt. Asci clavati, ad formam Lecanorae pertinentes: tholus parte laterali valde amyloideo; corpus axialis non amyloideus, late divergens, zona summa crassa, non amyloidea et strato extimo dilute amyloideo. Paraphyses parce ramosae anastomosantesque, apicibus typice non inflatis hyalinisque. TYPE: Ramboldia stuartii (Hampe) Kantvilas & Elix Thallus crustose, areolate, effuse or endophloeodal; photobiont green, trebouxioid; apothecia lecideine, sessile or broadly adnate, black or reddish brown, with margin persistent except in the oldest apothecia; excipulum unpigmented internally, composed of conglutinate, radiating, branched and anastomosing hyphae; hypothecium unpigmented; asci clavate, of the Lecanora-type: tholus with a strongly amyloid lateral part, a nonamyloid, broadly-diverging masse axiale with a thick nonamyloid "cap" above, and a weakly amyloid outer layer; paraphyses sparsely branched and anastomosing, generally with apices unexpanded and unpigmented; ascospores eight per ascus, simple, hyaline, narrowly ellipsoid, nonhalonate; pycnidia immersed (noted only in R. petraeoides and R. plicatula); conidia filiform. The new genus is characterized by the anatomy of its apothecia. It is most closely related to Pyrrhospora (Hafellner 1993; Rambold 1989), the ascus structure and ascospore shape and size of which are virtually identical (e.g., see Hafellner 1984) but which differs in containing K+ crimson or purple apothe0007-2745/94/296-304$1.05/0 This content downloaded from 157.55.39.11 on Sun, 17 Apr 2016 07:38:14 UTC All use subject to http://about.jstor.org/terms 1994] KANTVILAS & ELIX: RAMBOLDIA GEN. NOV. 297 cial pigments. Pyrrhospora has several representatives in the Australasian lichen flora, including P. laeta (Stirton) Hafellner, P. sanguinolenta (Krempelh.) Rambold & Hafellner, and an undescribed species from eastern Australia (Australian Capital Territory and Queensland). Ramboldia is also related to Protoparmelia which, in its current circumscription, is considered heterogeneous (Poelt & Grube 1992; Rambold 1989). The type species, P. badia, has lecanorine apothecia and its asci have a considerably narrower, more or less cylindrical masse axiale. Species of Ramboldia also show some similarities to those of the genus Miriquidica but that genus differs clearly from Ramboldia (and the other genera discussed) by its weakly amyloid tholus (see Rambold & Schwab 1990). Conidia have been shown to aid in the delimitation of at least some of the closely related lecideoid genera (e.g., Rambold 1989) but unfortunately these have only been detected in two species, R. petraeoides and R. plicatula, where they are of the same type as in Pyrrhospora. Given its current circumscription, the genus Ramboldia is chemically homogeneous, with all species containing highly oxidized 0-orcinol derivatives. Thus R. stuartii and R. subnexa produce the 0-orcinol meta-depsides, hypothamnolic acid and thamnolic acid, respectively, R. plicatula produces the 0-orcinol para-depsides baeomycesic, barbatic, and squamatic acids, while R. brunneocarpa and R. petraeoides produce the 0-orcinol depsidones, norstictic and connorstictic acids. These secondary metabolites are all derived from the same (f-orsellinic acid) or similarly substituted biosynthetic precur-

Abstract: Atmospheric CO2 levels were determined (at 2 m height) in the rainforest and in a clearing outside the forest, during spring (November) 1991, Urewera National Park, New Zealand. CO2 levels within the forest were 30 ppm higher and showed a more variable diel pattern (range up to 70 ppm) than outside the forest. CO2 levels were generally higher at night than during the day. Detailed measurements were made at several sites at a depth of 25 mm in the phylloplane of three moss species and under, or between, the thalli of four lichen species. Mean levels were 50% (moss phylloplane) and 10% (lichen thalli) higher than the levels in the clearing and, in 80% of sites, also higher than air within the rainforest. The diel pattern of the CO2 concentration at each of the sites was not predictable from measurements of CO2 in the bulk air of the forest. High levels of CO2 may be important in elevating photosynthetic rates of mosses and, to a lesser extent, lichens in the field.

Abstract: Lichens, especially saxicolous (rock-in-habiting) lichens, are encountered almost daily by the field geologist. Despite the difficulties in readily identifying lichens, there is increasing evidence that many species have a preference for some rock types, and that certain species can chemically modify their substrate. There is also increasing evidence that certain lichens, some of which change colour based on absorbed metal content, may make effective indicator plants in mineral exploration, particularly in areas such as the Northwest Territories. Resume A tous les jours ou presque, le geologue de terrain peut observer des lichens et particulierement les lichens saxicoles. Bien qu'il ne soit pas facile d'identifier rapidement les lichens, un nombre croissant d'indices montrent que plusieurs especes ont un penchant pour certains types de roche, et que certaines especes peuvent alterer chimiquement leur substrat. Il est egalement de plus en plus evident que certains lichens changent de couleur en fonction des metaux absorbes, et qu'il pourrait en cela etre de bons vegetaux indicateurs pour l'exploration minerale, particulierement dans des regions comme celles des Territoires du Nord-ouest.

Abstract: Volume 55 contains an account of the largest family of lichens in Australia, the Parmeliaceae. This family, familiar to most people as the common grey or brown to yellowish green foliose lichens of rocks, soil and bark, has about 60 genera and 1000 species worldwide. Thirty-one genera and 395 species are recorded from Australia. The book has keys for identification of genera and species. Each species is fully described, with bibliographic information, a full Australian synonymy, notes on habitat and distribution, and a summary of its chemistry. A distribution map is provided for each taxon and many species are illustrated in colour. An innovation in this volume is the inclusion of a synoptic key to the genera. This volume provides an excellent modern account of a difficult family.

Abstract: The species ofthe genus Caloplaca occurring on seashore rocks in eastern North America have been studied with regard to taxonomy, geographical distribution, and ecology. Five species were found to inhabit the coastal rocks. The species also occur in Europe, and three of them in Asia. Three of the species, C. microthallina (Wedd.) Zahlbr., C. scopularis (Nyl.) Lettau, and C. verru- culifera (Vainio) Zahlbr. occur exclusively on seashore rocks, while C. lithophila H. Magn. and C. fraudans (Th. Fr.) H. Olivier occur also in inland localities. One-way analysis of variance of both morphological and anatomical characters was carried out on the American and the European populations of the species, except C. fraudans. No significant differences were found in C. lithophila, but in the other three species significant differences were recorded in two or three characters. However, the differences were mostly very small, the overlaps large, and no discontinuities could be detected. Therefore no infraspecific taxa were recognized. The lichen flora occurring on seashore rocks in eastern North America has previously been studied on several occasions. In the late 19th and the early 20th century contributions to the knowledge of lit- toral lichens were made mainly with scattered col- lections by botanists such as E. Tuckerman, H. Wil- ley, W. G. Farlow, and G. K. Merrill. Degelius (1940) was one of the first lichenologists to investigate the lichens on seashore rocks in North America more thoroughly. He studied the flora of Maine and com- pared it with the European flora, and found great similarities. The work of Degelius inspired I. M. Lamb (1954) to carry out similar studies in Nova Scotia, Canada. The most extensive collections of littoral lichens in eastern North America were made by R. M. Tay- lor. His work mainly concerned the vertical distri- bution patterns, interspecific associations, and the general geographical distribution of the species col- lected, but also comprised taxonomical studies of the genus Verrucaria and a key to the 21 species included in the study (Taylor 1974). One of the latest studies in eastern North America, including littoral lichens, is that of the flora of Fundy National Park, New Brunswick, Canada, by Gowan and Bro- do (1988). They pointed out that the maritime prov- inces are still not very well known and that the need for further studies is high. This study was carried out to investigate the spe- cies of Caloplaca occurring on seashore rocks in eastern North America, and to compare the Euro- pean and the American populations of the species. No extensive studies have previously been done on this group in this region. Three of the species, oc- curring also in northern Europe, have been treated by Nordin (1972), but only for the European range of the species.

Abstract: Devonshire, in South-West England, is considered to be a clean-air county. However, an increase in the common subaerial green alga, Desmococcus sp., is affecting the corticolous lichen flora in the parish of Plymtree. First noticed in 1984, it soon became clear that no part of the parish was unaffected. Monitoring over several years has shed some light on this phenomenon. This field study is complementary to recent laboratory-based investigations of the tolerance of lichens to ammonia (Brown 1992), and with chemical analysis and statistical procedures that have been applied to microhabitats of epiphytic lichen vegetation in The Netherlands (van Dobben & Wamelink 1992). The parish of Plymtree is composed of gently undulating farmland. The average annual rainfall is 1000 mm. The pH of the rain, recorded with an electronic pH meter during the first 4 months of each of the last 5 years has fluctuated between 4-5 and 72. Data from the Grassland Research Station at North Wyke in Devon, indicates that rain pH occasionally rose to 7-3 between 1985 and 1987 (Tyson, pers. comm.). The lower pH levels generally coincide with winds from the north or east, and snow from the south-east in 1986 dramatically increased the concentration of sulphate at North Wyke. After the demise of the local cider industry by 1975, dairy farming became almost exclusive. Some fields were occasionally planted with fodder crops or wheat but the use of herbicides, pesticides and fungicides was and is minimal and liming rare. Herds increased in size and in winter large numbers of cattle were housed on deep straw pallets. During the 1980s, methods of overwintering changed to a cubicle system whereby dung was directed into a central channel that was regularly hosed down and collected for spreading on the fields. The composition of manure, therefore, changed from a heavy solid strawmixed product to a liquid of pH 80-8-5. This is distributed from slurry tankers with an approximate spread of 15 m or a side discharge of up to 60 m. Since the removal of hedges, clouds of fine slurry-laden spray drift across farmland, especially in winter when spreading is at its maximum. Until the late 1980s general fertilisers were extensively used but these were in pellet or granule form and, with the recent increase in price and rising popularity of organic manures, the quantity used has decreased considerably. Powdered fertilisers have not been used in Plymtree for 20-30 years. Since the introduction of milk quotas in 1984, the number of sheep and poultry has increased but cattle still predominate. The village population has increased from 250 to 450 since 1970. Exeter is 13 miles to the south-west and the prevailing winds are from that direction.

Abstract: Isolates of four hypocrealean fungi were used in laboratory experiments designed to determine their ability to degrade lichen tissues and the extent to which lichen secondary metabolites inhibit this deg? radation. Two fungi {Nectria parmeliae and Pronectria oligospora) were originally isolated from lichens and two (Nectriopsis squamulosa and Nectria zonata) were isolated from nonlichen substrates. A series of growth experiments was done on five test lichens: Flavopar- melia baltimorensis, Xanthoparmelia conspersa, Punctelia rudecta, Myelochroa aurulenta, and Lasallia papulosa. These lichen species were chosen based on previous experiments with the lichenicolous hyphomycete Hob-

Abstract: Species in lichenized ascomycetes can, according to their biology, be arranged roughly into three different categories. Many belong to a group of very stable sexual species, which are homogeneous over large areas. A second group, mostly silicicolous lichens, conists of genetically very variable taxa, where thalli with varied combinations of small, but distinct differences grow side by side; examples can be found within Bellemerea, Fuscidea, Graphis, Lecidea and Sporastatia; taxonomy in this group is difficult. The third group consists of taxa with solely or predominantly asexual reproduction. Such taxa are apomicts, genetically isolated from their sexual relatives. Contrary to a modern trend, but in agreement with taxonomic practice in other groups of plants and fungi, those taxa should be retained as species. Synonymizing would result in the loss of most important information about their evolution and history.

Abstract: The vertical distributions of Parmelia olivacea and a few other epiphytic lichens on trunks of deciduous trees were studied in relation to maximum snow depth along an oceanic-continental climate gr...