Die flechten Helgolands ...

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Thesaurus litteraturae mycologicae et lichenologicae ratione habita praecipue omnium quae adhuc scripta sunt de mycologia applicata quem congesserunt

Accompanied by "Supplementum 1911-1940 [di] R. Ciferri." (4 v. 25 cm.) Published: Papia, Cortina, 1957-60.

Lichenes extra-Europaei a pluribus collectoribus ad Museum Parisiense missi et ab A.-M. Hue elaborati.

Extracted from Archives du Muséum national d'histoire naturelle, 3e sér., t. X, 4e sór., t. I-III.

Lichenes morphologice et anatomice disposuit A.M. Hue.

Extracted from Archives du Muséum national d'histoire naturelle de Paris, 4e-5e série.

Lichenes.

Extracted from United States exploring expedition, 1838-1842. United States exploring expedition. v. XVII.

Climate change manipulations show Antarctic flora is more strongly affected by elevated nutrients than water

Climate change is expected to affect the high latitudes first and most severely, rendering Antarctica one of the most significant baseline environments for the study of global climate change. The indirect effects of climate warming, including changes to the availability of key environmental resources, such as water and nutrients, are likely to have a greater impact upon continental Antarctic terrestrial ecosystems than the effects of fluctuations in temperature alone. To investigate the likely impacts of a wetter climate on Antarctic terrestrial communities a multiseason, manipulative field experiment was conducted in the floristically important Windmill Islands region of East Antarctica. Four cryptogamic communities (pure bryophyte, moribund bryophyte, crustose and fructicose lichen-dominated) received increased water and/or nutrient additions over two consecutive summer seasons. The increased water approximated an 18% increase in snow melt days (0.2 degrees C increase in temperature), while the nutrient addition of 3.5g Nm(-2) yr(-1) was within the range of soil N in the vicinity. A range of physiological and biochemical measurements were conducted in order to quantify the community response. While an overall increase in productivity in response to water and nutrient additions was observed, productivity appeared to respond more strongly to nutrient additions than to water additions. Pure bryophyte communities, and lichen communities dominated by the genus Usnea, showed stronger positive responses to nutrient additions, identifying some communities that may be better able to adapt and prosper under the ameliorating conditions associated with a warmer, wetter future climate. Under such a climate, productivity is overall likely to increase but some cryptogamic communities are likely to thrive more than others. Regeneration of moribund bryophytes appears likely only if a future moisture regime creates consistently moist conditions.

Competitive interactions between four foliose lichen species with and without nutrient enrichment

Competition between four foliose lichen species, common on slate rock surfaces in South Gwynedd, Wales, UK, was studied in experimental plots with and without nutrient enrichment by bird droppings. Fragments of the four lichens were glued to pieces of slate on horizontal boards in monoculture and in two-, three- and four-species mixtures in a factorial experimental design. In monoculture, nutrient enrichment increased thallus area of Parmelia conspersa (Ehrh. ex. Ach.) Ach., decreased thallus areas of Parmelia saxatilis (L.) Ach. and Parmelia glabratula ssp. fuliginosa (Fr. ex. Duby) Laundon, and did not affect thallus area of Phaeophyscia orbicularis (Necker) Moberg compared with untreated thalli. In the mixtures, P. conspersa and Ph. orbicularis were equally effective competitors in plots with and without nutrient enrichment. Addition of bird droppings, however, altered the ability of P. saxatilis and P. glabratula ssp. fuliginosa, to compete with the other species, the competitive ability of both species being reduced in some mixtures but increased in others. The results suggest that nutrient enrichment may alter the competitive balance between the four lichen species and this may be a factor determining their relative abundance on rock surfaces in South Gwynedd.

Competition in lichen communities

Lichens are symbiotic organisms that often dominate stressful environments such as the surfaces of rock and tree bark. Whether or not competition occurs between lichens in these environments, however, is controversial. This review considers various aspects of the competitive interactions between lichens including the observational studies that suggest competitive effects may be important, the methods that have been used to study lichen competition in the field, the result of marginal contacts between lichen thalli, the attributes that may give a species a competitive advantage, and the role of competition in structuring lichen communities. These studies suggest that competition for space and light does occur in lichen communities and that individual lichen species can be excluded from a substratum as a result of competition. Moreover, competitive interactions in multi-species communities can also lead to stable assemblages of species. Future research should consider those aspects of the lichen symbiosis that may confer a competitive advantage and the factors that may promote stability in multi-species communities. Studies of competition in lichen communities may have implications for other stressful environments in which symbiotic organisms play a significant role. ©2007 Balaban.

Lobe growth variation and the maintenance of symmetry in foliose lichen thalli

The aim of this study was to determine how thallus symmetry could be maintained in foliose lichens when variation in the growth of individual lobes may be high. Hence, the radial growth of a sample of lobes was studied monthly, over 22 months, in 7 thalli of Parmelia conspersa (Ehrh. Ex Ach.) Ach. And 5 thalli of P. glabratula ssp fuliginosa (fr. ex Duby) Laund. The degree of variation in the total radial growth of different lobes within a thallus over 22 months varied between thalli. Individual lobes showed a fluctuating pattern of radial growth from month to month with alternating periods of fast and slow growth. Monthly variations in radial growth of different lobes were synchronized in some but not in all thalli. Few significant correlations were found between the radial growth of individual lobes and total monthly rainfall or shortwave radiation. The levels of ribitol, arabitol and mannitol were measured in individual lobes. All three polyols varied significantly between lobes within a thallus suggesting that variations in algal phostosynthesis and in the partitioning of fungal polyols may contribute to lobe growth variation. The effect on thallus symmetry of lobes which grew radially either consistently faster or slower than average was studied. Slow growing lobes were overgrown, and gaps in the perimeter were eliminated by the growth of neighbouring lobes, in approximately 7 to 9 months. However, a rapidly growing lobe, with its neighbours removed on either side, continued to grow radially at the same rate as rapidly growing control lobes. The results suggested that lobe growth variation results from a combination of factors which may include the origin of the lobes, lobe morphology and the patterns of algal cell division and hyphal elongation in different lobes. No convincing evidence was found to suggest that exchange of carbohydrate occurred between lobes which would tend to equalize their radial growth. Hence, the fluctuating pattern of lobe growth observed may be sufficient to maintain a degree of symmetry in most thalli. In addition, slow growing lobes would tend to be overgrown by faster growing neighbours thus preventing the formation of indentations in the thallus perimeter.

Competition between three lichen species using a factorial experimental design

Competition between three foliose lichens common on slate rock in south Gwynedd, Wales was studied in the field using a factorial experimental design. The lichens were grown as fragments glued to pieces of slate in two- and three-species mixtures. In the two-species mixtures, Parmelia conspersa (Ehrh. Ex Ach.) Ach. outcompeted Parmelia glabratula ssp. fuliginosa (Fr. ex Duby) Laund. strongly and Physcia orbicularis (Neck.) Poetsch less strongly, while P. orbicularis outcompeted P. glabratula weakly. Significant two-factor interactions indicated that the results from the three-species mixture could not be predicted from the two-species mixtures. Parmelia glabratula and P. orbicularis grew better in the presence of two competitors than one. This result suggests that the three species may co-occur on well-lit rock surfaces at the site.

Growth and regeneration of lichen thalli with the central portions artificially removed

The 12-month radial growth of Parmelia conspersa thalli with isidia or with apothecia and isidia was not influenced by removal of the thalli centres. When large thalli had their centres removed and the thallus perimeter was divided into fragments of about 1.0cm in diameter, growth of the fragments was less than the controls, but recovered to near control values after four or five months growth. These results suggest first, that fixed carbon for radial growth may be made in a narrow annulus at the perimeter and second, that there may be little transfer of fixed carbon between the annulus and the centre of the thallus ar around the annulus. Fragments of the centre and the perimeter regenerated growing points, suggesting that fragmentation may be an important method of vegetative reproduction in some lichens.

The levels of ribitol, arabitol and mannitol in individual lobes of the lichen Parmelia conspersa (Ehrh. ex Ach.) ACH.

The levels of the soluble carbohydrates ribitol, arabitol and mannitol were measured in individual lobes of the lichen Parmelia conspersa (Ehrh. ex Ach.) Ach. Lobes were collected from a north and a south facing slate rock surface in South Gwynedd, Wales, U.K. on 4 days during 1990-1991. On each day sampled, the most significant variation in soluble carbohydrate levels was between the individual lobes of a thallus. In addition, carbohydrate levels were significantly greater on the south facing rock surface on 2 of the 4 days sampled. Factorial analyses of variance suggested that the levels of individual carbohydrates varied significantly between days but not between north and south facing rock surfaces. Mannitol levels varied less between days than arabitol levels. Levels of ribitol, arabitol and mannitol were positively correlated in individual lobes. A stepwise multiple regression suggested that on the north facing rock surface, arabitol and mannitol levels could be explained by variations in the level of ribitol. By contrast, on the south facing rock surface, the levels of fungal carbohydrates were less dependent on the level of ribitol and there was evidence of a relationship between arabitol and mannitol. Variations in carbohydrate production, allocation and metabolism could help to explain lobe growth variation in foliose lichens and the radial growth of lobes over a longer period of time. Greater carbohydrate production rather than differences in allocation and metabolism may explain the increased growth and frequency of P. conspersa on south facing rock surfaces in South Gwynedd. © 1994.

A comparison of the growth curves of the foliose lichen Parmelia conspersa determined by a cross-sectional study and by direct measurement

Changes in the radial growth rate (RGR mm/yr) through life were studied in thalli of the foliose lichen Parmelia conspersa by two methods: (1) a cross-sectional study (Study A) in which the RGR was measured in 60 thalli from 0.2 to 13 cm in diameter, and (2) by radial growth measurements over 4.5 years of fragments, consisting of a single major lobe, which were removed from large thalli and glued to pieces of slate (Study B). Both studies suggested there was a phase of increasing RGR in small thalli followed by a more constant phase, the latter beginning at approximately a thallus radius of 6-8 mm. However, in Study B significantly increased RGR was observed during the second 6-month growth period. This phase of growth was more likely to be due to an increase in lobe width than to an effect of climate. In addition, a lobe in a large thallus with both adjacent lobes removed significantly increased in width over 1 year compared with control lobes. These results suggest that (1) mean lobe width in a thallus may be determined by the intensity of marginal competition between adjacent lobes, and (2) changes in lobe width during the life of a lichen thallus may be a factor determining the establishment of the linear phase of growth in foliose lichens. © 1992.

The response of lichen growth to additions of distilled water, rainwater and water from a rock surface

Three lichen species were wetted in the field with distilled water, rainwater or water which had run off a rock surafce, during July 1974 to February 1975. The radial growth rate of Parmelia glabratula ssp. fuliginosa was not influenced by the wetting treatments. The radial growth rate of P. conspersa with the distilled water was greater than the control, rainwater and runoff treatments. The radial growth rate of Physcia orbicularis was lower with rainwater and runoff treatmentss than the control and distilled water treatment. These results may be explained by the effect of wetting on the carbon balance of the lichens and by the influence of water chemistry.

The reponse of lichen growth to transplantation to rock surfaces of different aspect

Thalli of four saxicolous lichens on slate rock fragments were transplanted from rock surafces to horizontal boards and then to south-east-facing and north-west-facing rock surfaces. The radial growth rate of Physcia orbicularis and Parmelia conspersa thalli declined after transplatation to north-west-facing rock surfaces and was unchanged after transplantation to south-east-facing rock surfaces cmpared with growth rates on the boards. The radial growth rate of P. glabratula ssp. fuliginosa thalli declined after transplantation to south-east-facing rock surfaces and was unchanged after transplantation to north-west-facing rock surfaces compared with grwoth rate on the boards. The radial growth rate of P. saxatilis thalli was similar on the horizontal boards, south-east-facing and north-west-facing rock surfaces. These results are dsicussed in relation to the aspect distribution of the four lichens in South Gwynedd, Wales.