Keywords: SPAIN/ DIPLOSCHISTES/ CHLOROPHYLL FLUORESCENCE/ SOIL CRUSTS/ LONG-TERM MEASUREMENT/ MICROCLIMATE
Abstract: [Study using chlorophyll fluorescence measurements. "Although living in one of Europe's most extreme and sunniest environments, the lichen, when active, behaved as if it was a temperate, shade species."]
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Keywords: ANTARCTIC/ LIVINGSTON ISLAND/ SOUTH SHETLAND ISLANDS/ BIOMONITORING/ CLIMATE CHANGE/ ECOPHYSIOLOGY/ TEMPERATURE/ MOISTURE
Abstract: [Two year study at Livingston Island, South Shetland Islands and at Botany Bay, Ross Sea region. "Temperature as a direct effect does not seem to explain the differences in biodiversity between the sites, but an indirect effect through active hours is much more probable. In addition there are negative effects of stresses such as high light and extreme winter cold at Botany Bay."]
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Keywords: HYDRATION/ PRODUCTIVITY/ SNOW FALL/ STRESS
Abstract: [Researchers measured the hydrated metabolic activity of Umbilicaria aprina, and found that the lichen was "active" 7% of the 28-month study period.]
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Keywords: ANTARCTICA/ DISTRIBUTION/ MAPPING/ METHODS/ THREE DIMENSIONAL MAPPING/ TOPOGRAPHY
Abstract: 5 fig.
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Keywords: STORAGE/ WATER RELATIONS/ PSEUDOCYPHELLARIA/ NEW ZEALAND/ DESICCATION/ RESPIRATION/ DAMAGE
Abstract: 1 figure. [Study on Pseudocyphellaria dissimilis from New Zealand showed no changes in "...the degree of desiccation damage in response to alternations in available respirable reserves ...." Authors conclude that "... the algae noramally transfer the bulk of their photosynthetic products to the fungus and the algae normally constitute less than 10 percent of the weight of the thallus, changes in the respiration rate of the whole lichen are presumed to reflect alternations in the fungal respirable reserves. Thus the algae appear to retain insufficient respirable reserves for the repair of desiccation damage and hence pretreatment designed to alter the reserves of the whole thallus do not change the desiccation sensitivity of the lichen."]
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Keywords: Biodiversity/ Biological soil crust/ Bryophytes/ Lichens/ Net primary productivity/ Soil microorganisms/ alga/ bacterium/ biodiversity/ bryophyte/ cyanobacterium/ ecosystem function/ lichen/ net primary production/ photosynthesis/ soil crust/ soil ecosystem/ soil microorganism/ Almeria [Andalucia]/ Andalucia/ Austria/ Germany/ Great Alvar/ Kalmar [Sweden]/ Oland/ Spain/ Sweden/ Tabernas/ algae/ Bacteria (microorganisms)/ Bryophyta/ bryophytes/ Cyanobacteria
Abstract: Here we report details of the European research initiative "Soil Crust International" (SCIN) focusing on the biodiversity of biological soil crusts (BSC, composed of bacteria, algae, lichens, and bryophytes) and on functional aspects in their specific environment. Known as the so-called "colored soil lichen community" (Bunte Erdflechtengesellschaft), these BSCs occur all over Europe, extending into subtropical and arid regions. Our goal is to study the uniqueness of these BSCs on the regional scale and investigate how this community can cope with large macroclimatic differences. One of the major aims of this project is to develop biodiversity conservation and sustainable management strategies for European BSCs. To achieve this, we established a latitudinal transect from the Great Alvar of Öland, Sweden in the north over Gössenheim, Central Germany and Hochtor in the Hohe Tauern National Park, Austria down to the badlands of Tabernas, Spain in the south. The transect stretches over 20° latitude and 2,300 m in altitude, including natural (Hochtor, Tabernas) and semi-natural sites that require maintenance such as by grazing activities (Öland, Gössenheim). At all four sites BSC coverage exceeded 30 % of the referring landscape, with the alpine site (Hochtor) reaching the highest cyanobacterial cover and the two semi-natural sites (Öland, Gössenheim) the highest bryophyte cover. Although BSCs of the four European sites share a common set of bacteria, algae (including cyanobacteria) lichens and bryophytes, first results indicate not only climate specific additions of species, but also genetic/phenotypic uniqueness of species between the four sites. While macroclimatic conditions are rather different, microclimatic conditions and partly soil properties seem fairly homogeneous between the four sites, with the exception of water availability. Continuous activity monitoring of photosystem II revealed the BSCs of the Spanish site as the least active in terms of photosynthetic active periods. © 2014 The Author(s).
URL: http://dx.doi.org/10.1007/s10531-014-0645-2
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Keywords: CORTEX/ MECHANICAL DAMAGE/ PSEUDOCYPHELLARIA/ RAINFALL/ WATER RELATIONS
Abstract: 2 fig. [Peeling of the upper cortex induced by heavy rainfall is reported.]
[Edit/Delete] [Upload PDF/URL] [ET: 2740]
Abstract: Biological soil crusts (BSCs) are small-scale communities of lichens, mosses, algae, and cyanobacteria that cover much of the surface area in regions where vascular plant growth is restricted due to harsh environmental conditions, such as perpetually ice-free areas in terrestrial Antarctic environments and alpine areas above the tree line. To our knowledge, none of the available studies provides a direct Antarctic-alpine comparison of BSC activity periods and the water use, both key traits to understand their physiological behavior and therefore related growth and fitness. Here, activity patterns and water relations were studied at two sites, one in continental Antarctica (Garwood Valley 78°S) and one in the High Alps of Austria (Hochtor, Großglockner 2350m). BSCs in continental Antarctica were only rarely active, and if so, then during melt after snowfalls and by fog. In the Austrian Alps, BSCs were continuously active and additionally activated by rainfall, fog, and dew. Consequently, high alpine BSCs can be expected to have much higher photosynthetic productivity supporting higher growth rates than the same functional vegetation unit has in continental Antarctica.
URL: http://www.bioone.org/doi/abs/10.1657/AAAR0015-047?journalCode=aare
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Keywords: Association/ CO / Ecophysiology/ Ecosystem functioning/ Plant interactions
Abstract: Facilitative effects and plant-plant interactions are well known for higher plants, but there is a lack of information about their relevance in cryptogams. Additional information about facilitative effects between bryophytes and lichens would be an important contribution to recent research on positive plant-plant interactions, as these can have striking influences not only on the organisation of early successional terrestrial communities but also on succession dynamics by kick-starting ecosystem development through the import of key nutrients. We investigated and quantified these mechanisms between Peltigera rufescens and its associated mosses. Moss-associated thalli had a different morphology that led to several benefits from the association. They had 66% higher net photosynthetic rate and, because the majority of the gas exchange of lichen thalli took place through the lower surface, there was a further increase as the CO
URL: http://dx.doi.org/10.1007/s00442-011-2224-5
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Keywords: METABOLISM/ RAMALINA/ PELTIGERA/ ANHYDROBIOSIS/ TRITIUM/ TECHNIQUE
Abstract: 8 tables. 7 figures. ["This method has proved effective in a study of a wide range of in vivo metabolic processes occurring at both high and low cellular water contents." Different metabolic systems vary in resistance to desiccation. "It is proposed that the synthesis of amino acids and sugar alcohols at low cellular saturation levles are important physiological processes. Amino acid synthesis results in the acumulation of an available store of stable intermediates, ready to feed into the T.C.A. cycle by transamination or deamination on rehydration of the lichen. Sugar alcohol metabolism assists in the maintenance of a high sugar alcohol concentration to act as a physiological buffer during extreme dehydration."]
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Keywords: METABOLISM/ RAMALINA/ PELTIGERA/ POLYOLS
Abstract: 3 tables. 4 figures. [Studies on Ramalina delastri and Peltigera polydactyla. "The dissimilarity between 3H and 14C labelling patterns has led to the conclusion that polyols synthesized in the absence of photosynthesis must be derived from other stored substrates within the thallus." The authors conclude that "...TCA cycle intermediate/amino acid interconversions are of major significance in lichen metabolism."]
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Keywords: CO2 DIFFUSION/ CO2 EXCHANGE/ GAS EXCHANGE
Abstract: 8 fig. 6 tab. 9 equations [Laboratory study using one liverwort, Monoclea forsteri, and five lichens, Pseudocyphellaria faveolata, P. colensoi, Sticta fuliginosa, S. latifrons, and Ramalina maciformis.]
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[ET: 1745]
Keywords: Anatomy/ Cephalodia/ Gas exchange/ Nitrogen fixation/ Receding glaciers/ Soil crust/ Terricolous lichen
Abstract: The green algal lichen Placopsis pycnotheca was identified at Pia and Marinelli glaciers (Isla Grande of Tierra de Fuego, Chile) as a primary colonizer of bare soil in areas close to the front of the glacier or around small ponds created after glacier retreatment. Electron microscopy study showed that P. pycnotheca formed a thick hypothallus within which hyphae and their extracellular polymeric substances bind numerous soil particles. This structure augments water holding and soil stabilization capacities and constitutes an early stage in soil crust development. In addition, numerous cephalodia are formed within the hypothallus and subsequently develop upwards towards the thallus surface, sometimes before the formation of squamules with green algae. These anatomical and morphological strategies together with physiological properties such as the long photosynthetic activity period (measured in the laboratory) help explain its pioneering role as a colonizer and its apparently high growth rate. © 2011 Elsevier GmbH. All rights reserved.
URL: http://www.scopus.com/inward/record.url?eid=2-s2.0-79960655753&partnerID=40&md5=f87d72a7b3492c5ab9f86ac6f11dcfe6
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Keywords: ANTARCTICA/ ENDOLITHIC/ GRANITE
Abstract: 5 fig.
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Keywords: PHYCOSYMBIODEME/ LIGHT STRESS/ XANTHOPHYLLS/ CAROTENOIDS/ PSEUDOCYPHELLARIA
Abstract: 1 table. 4 figures. [Study on Pseudocyphellaria rufovirescens-P. murrayi phycosymbiodeme. "These findings represent further evidence that zeaxanthin is involved in the photoprotective dissipation of excessive excitation energy in photosynthetic membranes. The difference in the capacity for rapid zeaxanthin formation between the two partners of the Pseudocyphellaria phycosymbiodeme may be important in the habitat selection of the two species when living separate from one another."]
[Edit/Delete] [Upload PDF/URL] [ET: 1569]
Keywords: Antarctica/ Extreme environment/ Lichenometry/ Radial growth/ Ross Sea/ Snow
Abstract: Estimates of lichen growth rates based on the measurements of several thalli at any site do not exist for continental Antarctica. However, the very limited existing data suggest that lichen growth rate may be a good indicator of climate change in Antarctica. We present measurements made on thalli of the lichen Buellia frigida Darb. growing in the Dry Valleys, Southern Victoria Land, continental Antarctica, which appear to have some of the slowest radial growth rates yet measured. Photographs of thalli at three different sites were analysed for growth over a 25-year period using nano-GIS techniques. At one site, Mt. Falconer Summit, the lichens had a mean growth rate of 0.0052 mm year with one individual as low as 0.0036 mm year. Thalli at the other two sites had significantly higher mean growth rates, 0.0136 mm year at Mt. Falconer Ridge and 0.0118 mm year at Rhone Bench. Assuming a constant growth rate, thalli at Mt. Falconer Summit had a mean age of 5,367 years, whilst the thalli at the other two sites were much younger, 840-1,026 years. We suggest that the different ages represent the appearance of new substrate for colonisation following climate changes in the Dry Valleys that altered the amount and duration of snow. The results confirm that lichen growth rate differs by almost two orders of magnitude over a latitudinal range of 15 degrees from south to north across Antarctica. © 2011 Springer-Verlag.
URL: http://dx.doi.org/10.1007/s00300-011-1098-7
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Keywords: Beardmore Glacier/ Collembola/ Diversity/ Lichens/ Mosses/ Relict
Abstract: Investigations of lichens collected in 1959/1960, 1963/1964 and 2003 from near the Beardmore Glacier in the southern Ross Sea region (84°S) have more than doubled the number of known lichen species in the area to around 30. The ranges of 15 species have been extended to 84°S. A lichen diversity hotspot has also been found along Ebony Ridge and its associated peaks where 28 of the species occur, a number equivalent to more northerly sites in the Ross Sea (e.g. Botany Bay 77°S). Furthermore, 6 species had been previously recorded only from the Antarctic Peninsula region. In agreement with previous studies on mites and springtails from the same area, we suggest that these populations represent relicts that predate the present Ross Ice Shelf extension, with a possible age of 2,000,000 years or older. © 2011 Springer-Verlag.
URL: http://www.scopus.com/inward/record.url?eid=2-s2.0-79960472523&partnerID=40&md5=89dc0cee639cdd58e1e44d5976ffc344
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Keywords: EDUCATION/ LABORATORY EXERCISE/ USNIC ACID/ CHEMISTRY
Abstract: [Lab exercise in organic chemistry at the University of Alaska Fairbanks.
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Keywords: STICTA/ PSEUDOCYPHELLARIA/ CO2 EXCHANGE/ WATER RELATIONS/ PHOTOSYNTHESIS/ PHYSIOLOGY
Abstract: 3 figures. 1 table. [Studies on Sticta latifrons and Pseudocyphellaria amphisticta. "Both species exhibited an increase in transport resistance at high thallus water contents and an increase in both transport and carboxylation resistances at low water contents. However, at ambient CO2 concentrations carboxylation processes were the dominant factors limiting photosynthesis at all, except high, water contents."]
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Keywords: FOLIICOLOUS/ GARDENS/ GROWTH RATES/ HYPERPHYSCIA/ NEW ZEALAND/ SHRUBS
Abstract: 4 fig. 2 tab. 3 plates [The most common species on the leaves is Hyperphyscia adglutinata. Photographic techniques measured growth rates of up to 4.76 mm in 100 days.]
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Keywords: Lichens/ Mosses/ Stability/ Lichen growth rate/ Cryoturbation/ Disturbance/ Nitrogen/ Crater/ Cirque/ Football Saddle
Abstract: Cape Hallett (72°19′S; 170°13′E) lies at the northern end of the western coastline of the Ross Sea region, and, to date, there appears to be no full description of its terrestrial flora despite its probable importance in understanding links between biodiversity and latitude. Here we present information about lichens and mosses from published papers, herbarium collections and personal surveys for Cape Hallett and seven nearby sites. A total of 59 lichen and 11 moss species are reported for these eight sites. Cape Hallett is one of the richest sites for terrestrial biodiversity in the Ross Sea region with about 46 lichen species and nine species of bryophytes. Lichens have their greatest diversity on the upper scree and summit area (30 species, 330 m), the least within the large penguin colony at sea level (one species). The station at Cape Hallett was established in 1957, and some of the earliest ecological and ecophysiological studies in Antarctica were carried out there. Historical comparisons are possible and have revealed considerable changes in vegetation in the lower flush area, a high level of frost heave disturbance, new lichen growth rate estimates for northern Victoria Land and extreme stability of the snow banks on the scree slopes. Cape Hallett represents a very important site for studies on links between terrestrial flora and the environment as well as on possible effects of climate change.
Countries/Continents: Antarctica
Notes: 59 lichen species are reported.
URL: http://link.springer.com/article/10.1007/s00300-015-1744-6
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Keywords: ANTARCTICA/ COLD DESERTS/ CRYPTOGAMIC CRUSTS/ SOIL CRUSTS
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Keywords: CYANOBACTERIA/ GREEN ALGAE/ PHOTOSYMBIODEMES/ PHOTOSYNTHESIS/ PSEUDOCYPHELLARIA/ WATER BALANCE/ WATER RELATIONS
Abstract: 5 fig. ["The photosynthesis of the components of two Pseudocyphellaria photosymbiodemes were studied in the natural forest environment in New Zealand. It was found that the green algal component had a large photosynthetic advantage when thallus water contents were low and the thalli were in equilibrium with atmospheric humidity. The cyanobacterial components were at an advantage when thallus water contents were very high."]
[Edit/Delete] [Upload PDF/URL] [ET: 2930]
Keywords: CHLOROPHYLL/ FOREST/ LIGHT INTENSITY/ NEW ZEALAND/ NITROGEN/ PHOTOSYNTHESIS/ RAIN FORESTS/ SHADE
Abstract: 11 fig. 3 tab. ["The photosynthetic response to photosynthetically active photon flux density (PPFD) was measured in the field for nine New Zealand rain forest lichen species spanning environments from the deep shade within the forest through the forest margin to outside, open ground sites."]
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Keywords: NITROGEN FIXATION/ NEW ZEALAND/ STICTACEAE/ PSEUDOCYPHELLARIA/ STICTA
Abstract: 3 tables. 3 figures. ["Forty-four species of New Zealand lichens, including 22 species of Pseudocyphellaria and seven of Sticta, were analysed for nitrogenase activity by acetylene reduction. Nitrogen fixation was confirmed by 15N enrichment studies." All species with blue-green phycobionts showed positive activity, and nitrogen fixation rates were species specific.]
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Keywords: DESICCATION/ DROUGHT/ LIGHT/ PHOTOSYNTHESIS/ SHADE
Abstract: 8 fig. [This ecologiclly unusual cyanobacterial species is found to have very unusual water and light relations. It is extremely shade tolerant and also less tolerant to drying than even the very desiccation-sensitive aquatic lichens. The study was conducted in the laboratory.]
[Edit/Delete] [Upload PDF/URL] [ET: 1592]
Keywords: ADAPTATIONS/ DESICCATION/ LIGHT/ LIGHT SATURATION/ PHOTOSYMBIODEMES/ SHADE/ WATER RELATIONS/ WATER STORAGE
Abstract: 6 fig. 7 tab. ["These lichens exhibit a great diversity of both form and habitat range. Physiological and morphological adaptation has also been demonstrated. Pseudocyphellaria dissimilis shows changes in thallus water storage capacity with evaporative demand and is also highly shade-adapted. The species has the lowest light saturation and compensation values for photosynthesis yet known for lichens (20 and 1 µmol m-2s-1, PAR, respectively). Unexpectedly it is also highly desiccation-sensitive with some thalli being killed after only 20 h exposure to 15% relative humidity." The physiological differences between the green algal and cyanobacterial sectors of the P. rufovirescens-P. murrayi photosymbiodeme are also investigated.]
[Edit/Delete] [Upload PDF/URL] [ET: 1593]
Keywords: PHOTOSYNTHESIS/ PHOTOSYNTHESIS RATES/ POIKILOHYDRIC/ PRODUCTIVITY/ SHADE/ WATER CONTENT/ WATER STORAGE/ WATER TRANSPORT
Abstract: 3 fig. 5 tab. [Review paper.]
[Edit/Delete] [Upload PDF/URL] [ET: 2558]
Keywords: CO2 COMPENSATION/ CO2 CONCENTRATING MECHANISM/ CO2 DIFFUSION/ ECOPHYSIOLOGY/ PHOTOSYNTHESIS/ WATER BALANCE/ WATER CONTENT
Abstract: 12 fig. 2 tab. ["Lichens are poikilohydric plants and, as such, their thallus water content (WC) tends to equilibrate with the atmospheric humidity. An analysis is made of the typical response of lichen photosynthesis to thallus WC which is a three (subjectively delimitated) phase curve. At low WC the metabolism is thought to be limited by the low water potential and net photosynthesis (PN) is almost linearly related to WC. Green algal lichens show the special ability to achieve positive PN by equilibration only with atmospheric humidity. Factors that limit maximal PN at optimal WC have yet to be satisfactorily described. At high WC many lichens show a depression in PN and the evidence is summarised to show that this is a result of increased thallus CO2 diffusion resistances."]
[Edit/Delete] [Upload PDF/URL] [ET: 2561]
Keywords: CO2 EXCHANGE/ EXPOSURE/ GAS EXCHANGE/ LIGHT/ SHADE/ SUN FORMS/ WATER CONTENT
Abstract: 8 fig. 4 tab. ["The gas exchange of six temperate rain forest lichens was measured in the field in the Urewera National Park, New Zealand." Comparison of the effects of thallus water content and light on gas exchange in shade species, sun species, and marginal species.]
[Edit/Delete] [Upload PDF/URL] [ET: 2932]
Keywords: CHLOROPHYLL FLUORESCENCE/ NEW ZEALAND/ PHOTOSYMBIODEMES/ PHOTOSYNTHESIS/ WATER RELATIONS
Abstract: 7 fig.
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Keywords: ECOPHYSIOLOGY/ PHOTOBIONT/ PHOTOSYMBIODEMES/ WATER RELATIONS
Abstract: [Abstract from the International Association for Lichenology's fourth symposium, held in Barcelona, Spain, 3-8 September 2000.]
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Keywords: CHLOROPHYLL/ CHLOROPHYLL FLUORESCENCE/ CO2/ ELECTRON TRANSPORT RATE/ GAS EXCHANGE/ PHOTOSYNTHESIS/ RESPIRATION
Abstract: 7 fig. [Study of Umbilicaria aprina and Bryum argenteum.]
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Keywords: ANTARCTIC/ COLD RESISTANCE/ ENDOLITHIC/ FREEZING/ LIGHT/ MOISTURE/ PHOTOSYNTHESIS/ PRODUCTIVITY/ SNOW/ TEMPERATURE
Abstract: 18 fig. 4 tab. [Excellent review emphasizing lichens, the dominant group in the area.]
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Keywords: ANTARCTIC/ EPILITHIC
Abstract: 2 fig. [Reports Carbonea capsulata and a Sarcogyne sp. occurring on rock in the overflow zone where Canada Stream leaves Canada Lake, in an area of Antarctica generally regarded as too dry for epilithic lichens.]
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Keywords: LICHEN ALGAE / SYMBIOSIS / ISOLATION / PHYSIOLOGY / CULTURE / GROWTH
Abstract: ["... lichen algae begin to show substantial changes from their behavior in symbiosis as soon as they are separated from the fungus."]
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Keywords: GLASS/ NEW ZEALAND/ PARMELIA/ ECOLOGY/ HABITAT
Abstract: 1 plate.
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Keywords: PHOTOSYNTHESIS/ CO2 EXCHANGE/ NEW ZEALAND/ TECHNIQUE/ WATER RELATIONS/ PHYSIOLOGY
Abstract: 3 figures. [Studies done on 4 lichen species from New Zealand. "The results differ from previous studies which reported low CO2 saturation levels (200 microliters per liter) and no apparent effect of water content. It is suggested that some of these differences may result from the use of discrete sampling injection infrared gas analyzer system in the earlier studies and an assessment is made of the influence of nonsaturating CO2 levels, lack of cuvette ventilation, and data presentation for this technique."]
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Keywords: CO2 EXCHANGE/ NEW ZEALAND/ STICTACEAE/ ADAPTATION/ WATER RELATIONS
Abstract: 3 figures. [Study done on members of the Stictaceae from New Zealand showed that "... carbon dioxide and water vapour exchange occur by different pathways in these lichens. Consequently it is suggested that the lichens have structural adaptations which separate the functions of water uptake, water storage and carbon dioxide exchange."]
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Keywords: STICTA/ NEW ZEALAND/ CO2 EXCHANGE/ CYPHELLAE/ WATER RELATIONS/ PHYSIOLOGY
Abstract: 1 table. 2 figures. [New Zealand material was studied using an infrared gas analyzer. "The results provide strong circumstantial evidence for the suggestion that cyphellae act as air pores and the possible importance of such pores in the water relations of the species discussed."]
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Keywords: STICTACEAE/ WATER RELATIONS/ PHOTOSYNTHESIS/ ANATOMY/ PSEUDOCYPHELLARIA/ STICTA/ CO2 EXCHANGE
Abstract: 7 figures. 4 tables. ["The thallus of these lichens appears to show an unexpected degree of structural complexity as a result of adaptations to allow both CO2 diffusion and water storage. The low radiation, wet, evergreen forests allow this option to be developed to its full in the form of cyphellate and pseudocyphellate thalli of the Stictaceae, which allow the majority of the thallus surface to be available for storage. The major limitation of the system is the possibility of pore blockage by excess surface water."]
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Keywords: carbon dioxide/ article/ Ascomycetes/ cyanobacterium/ green alga/ lichen (organism)/ metabolism/ microbiology/ nitrogen fixation/ photosynthesis/ physiology/ symbiosis/ Ascomycota/ Carbon Dioxide/ Chlorophyta/ Cyanobacteria/ Lichens/ Nitrogen Fixation/ Photosynthesis/ Symbiosis
Abstract: Cyanolichens are usually stated to be bipartite (mycobiont plus cyanobacterial photobiont). Analyses revealed green algal carbohydrates in supposedly cyanobacterial lichens (in the genera Pseudocyphellaria, Sticta and Peltigera). Investigations were carried out to determine if both cyanobacteria and green algae were present in these lichens and, if so, what were their roles. The types of photobiont present were determined by light and fluorescence microscopy. Small carbohydrates were analysed to detect the presence of green algal metabolites. Thalli were treated with selected strengths of Zn(2+) solutions that stop cyanobacterial but not green algal photosynthesis. CO(2) exchange was measured before and after treatment to determine the contribution of each photobiont to total thallus photosynthesis. Heterocyst frequencies were determined to clarify whether the cyanobacteria were modified for increased nitrogen fixation (high heterocyst frequencies) or were normal, vegetative cells. Several cyanobacterial lichens had green algae present in the photosynthetic layer of the thallus. The presence of the green algal transfer carbohydrate (ribitol) and the incomplete inhibition of thallus photosynthesis upon treatment with Zn(2+) solutions showed that both photobionts contributed to the photosynthesis of the lichen thallus. Low heterocyst frequencies showed that, despite the presence of adjacent green algae, the cyanobacteria were not altered to increase nitrogen fixation. These cyanobacterial lichens are a tripartite lichen symbiont combination in which the mycobiont has two primarily photosynthetic photobionts, 'co-primary photobionts', a cyanobacterium (dominant) and a green alga. This demonstrates high flexibility in photobiont choice by the mycobiont in the Peltigerales. Overall thallus appearance does not change whether one or two photobionts are present in the cyanobacterial thallus. This suggests that, if there is a photobiont effect on thallus structure, it is not specific to one or the other photobiont.
URL: http://dx.doi.org/10.1093/aob/mcs108
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Keywords: Algae/ Lichens/ Mycobiont/ Photobiont/ Ross Dependency/ Selectivity/ Symbiosis
Abstract: Lichens are a symbiosis consisting of heterotrophic, fungal (mycobiont) and photosynthetic algal or cyanobacterial (photobiont) components. We examined photobiont sequences from lichens in the Ross Sea Region of Antarctica using the internal transcribed spacer region of ribosomal DNA and tested the hypothesis that lichens from this extreme environment would demonstrate low selectivity in their choice of photobionts. Sequence data from three targeted lichen species (Buellia frigida, Umbilicaria aprina and Umbilicaria decussata) showed that all three were associated with a common algal haplotype (an unnamed Trebouxia species) which was present in all taxa and at all sites, suggesting lower selectivity. However, there was also association with unique, local photobionts as well as evidence for species-specific selection. For example, the cosmopolitan U. decussata was associated with two photobiont species, Trebouxia jamesii and an unnamed species. The most commonly collected lichen (B. frigida) had its highest photobiont haplotype diversity in the Dry Valley region, which may have served as a refugium during glacial periods. We conclude that even in these extreme environments, photobiont selectivity still has an influence on the successful colonisation of lichens. However, the level of selectivity is variable among species and may be related to the ability of some (e.g. B. frigida) to colonise a wider range of habitats. © 2013 Springer-Verlag Berlin Heidelberg.
URL: http://dx.doi.org/10.1007/s00300-013-1295-7
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Keywords: Antarctica/ Buellia frigida/ Microsatellites/ Physciaceae/ Population structure
Abstract: Premise of the study: Microsatellite markers were characterized for an Antarctic endemic, Buellia frigida, to investigate population structure and origin of Antarctic lichens. Methods and Results: Five primer sets were characterized. All loci were polymorphic with eight to 16 alleles per locus in a sample of 59 lichens. Conclusions: The microsatellite markers potentially provide insight into population structure and gene flow of B. frigida. © 2012 Botanical Society of America.
URL: http://dx.doi.org/10.3732/ajb.1100440
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Keywords: Buellia frigida/ Dispersal/ Refugia/ Antarctica/ Microsatellites
Abstract: In order to assess the origins of Antarctic lichens (local or long distance), we examined the population genetic structure of the endemic Antarctic lichen Buellia frigida across a latitudinal gradient of roughly 10° along the Transantarctic Mountains, Western Antarctica, using four microsatellite loci. All loci were highly polymorphic. Data were analysed as both biallelic (dikaryotic) and as haploid in order to determine whether different life-cycle phases could influence our interpretation of population structure. For biallelic data, allelic richness (A) ranged from 5.25 to 7.99 and measures of diversity suggested low levels of gene flow among most sites (e.g. F
Genera/Families: Buellia
Countries/Continents: Antarctica
Notes: "We conclude that a combination of prevailing wind patterns and physical barriers restrict spore settlement and therefore dispersal and recruitment among regions."
URL: http://link.springer.com/article/10.1007%2Fs00300-015-1652-9
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Keywords: CHLOROPHYLL/ CO2 EXCHANGE/ FLUORESCENCE/ LIGHT/ TEMPERATURE/ UMBILICARIA
Abstract: 5 fig. [Simultaneous field measurements of CO2 exchange and chlorophyll a fluorescence indicate no photoinhibition when the lichen was exposed to strong sun irradiance for nearly 11 hours a day.]
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Keywords: ANTARCTIC/ BUELLIA/ LIGHT/ MELTWATER/ MICROCLIMATE/ PATTERNING
Abstract: 4 fig. 1 tab.
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Keywords: Maritime Antarctica/ Lichens/ Usnea/ Ecophysiology/ Microclimate
Abstract: The factors that control lichen distribution in Antarctica are still not well understood, and in this investigation we focused on the distribution, local and continental, and gas exchange of a species pair, closely related lichens with differing reproductive strategies, Usnea aurantiaco-atra (fertile) and Usnea antarctica (sterile, sorediate). The local distributions of these species were recorded along an altitudinal gradient of nearly 300 m at South Bay, Livingston Island, and microclimate was also recorded over 1 year. The photosynthetic responses to temperature, light and thallus water content were determined under controlled conditions in the laboratory. The species were almost identical in their photosynthetic profiles. Locally, on Livingston Island, U. antarctica was confined to low altitude sites which were warmer and drier, whilst U. aurantiaco-atra was present at all altitudes. This contrasts with its distribution across Antarctica where U. antarctica grows 9° latitude further south than U. aurantiaco-atra. Temperature appears not to be the main controller of distribution in these species, but dryness of habitat, which will influence length of activity periods, may be important.
URL: http://link.springer.com/article/10.1007/s00300-015-1832-7
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Keywords: RESPIRATION/ CARBON BALANCE/ PHOTOSYNTHESIS/ LECANORA MURALIS/ CLADONIA/ COLLEMA/ SOIL CRUSTS/ DARK RESPIRATION
Abstract: [Studies using Lecanora muralis, Cladonia convoluta, and Collema cristatum. "Overall it is concluded that no substrate-driven dependency of DR [dark respiration] on preceding NP [net photosynthesis] under natural conditions could be recognised. The periods of desiccation that often occur between the NP and following DR as well as the wide range of combinations of conditions would certainly contribute to this lack of relationship."
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Keywords: TELOSCHISTES/ WATER RELATIONS/ NAMIB DESERT/ FOG DESERT/ AFRICA/ PHYSIOLOGY/ DEW/ PHOTOSYNTHESIS
Abstract: [This species is well-adapted to its high fog/dew environment " ... so that even the smallest levels of hydration could be used for carbon gain before desiccation took place again."
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Keywords: CLADONIA/ HUMAN IMPACT/ PRIMARY THALLI/ SQUAMULES/ TRAMPLING
Abstract: 6 fig.
[Edit/Delete] [Upload PDF/URL] [ET: 3054]
Keywords: CO2 EXCHANGE/ DIFFUSION/ DIFFUSIVE RESISTANCE/ PHOTOSYNTHESIS/ RAIN FORESTS/ WATER CONTENT/ WATER RELATIONS
Abstract: 8 fig. 1 tab. ["CO2 exchange rate in relation to thallus water content (WC, % of dry weight) was determined for 22 species of lichens, mainly members of the genera Pseudocyphellaria and Sticta, from a temperate rainforest, Urewera National Park, New Zealand. All data were obtained in the field, either using a standard technique in which the lichens were initially wetted (soaked or sprayed, then shaken) and allowed to slowly dry, or from periodic measurements on samples that were continuously exposed in their natural habitat. A wide range of WC was found, with species varying from 357 to 3360% for maximal WC in the field, and from 86 to 1300% for optimal WC for photosynthesis."]
[Edit/Delete] [Upload PDF/URL] [ET: 2412]
Keywords: CO2 EXCHANGE/ DIFFUSIVE RESISTANCE/ PHOTOSYNTHESIS/ POIKILOHYDRIC/ WATER CONTENT/ WATER RELATIONS
Abstract: 6 fig. 1 tab. [Comparison of laboratory and field studies on Xanthoria calcicola and Lecanora muralis. "It is concluded that blockage of diffusive pathways for CO2 in the thallus through high water contents is an important ecological factor for productivity of these central European epilithic lichens.]
[Edit/Delete] [Upload PDF/URL] [ET: 3050]
Keywords: CO2 EXCHANGE/ PHOTOSYNTHESIS/ PRODUCTIVITY/ WATER CONTENT/ WATER RELATIONS
Abstract: 11 fig. ["Laboratory studies under controlled conditions showed clearly depressed net photosynthesis (NP) of water saturated thalli of Fulgensia fulgens, Lecanora muralis, Psora cerebriformis and Xanthoria calcicola. The depression was severe and present at all light levels and temperatures tested. In contrast, Diploschistes muscorum and D. diacapsis had no depression of photosynthesis at high WC."]
[Edit/Delete] [Upload PDF/URL] [ET: 3049]
Keywords: CLADONIA/ HYDRATION/ MOISTURE/ PHOTOSYNTHESIS/ PHOTOSYNTHESIS RATES/ SUPRASATURATION/ WATER RELATIONS
Abstract: 12 fig. 4 tab.
[Edit/Delete] [Upload PDF/URL] [ET: 3822]
Keywords: CO2 EXCHANGE/ PHOTOSYNTHESIS/ SOIL CRUSTS/ SQUAMARINA/ WATER RELATIONS
Abstract: 15 fig. 4 tab.
[Edit/Delete] [Upload PDF/URL] [ET: 3823]
Keywords: ACCLIMATION/ ADAPTATIONS/ CLIMATE CHANGE/ PHOTOSYNTHESIS/ RESPIRATION/ SOIL CRUSTS/ TEMPERATURE
Abstract: 5 fig. ["Five species of lichens, the majority members of a soil-crust community (Cladonia convoluta, Diploschistes muscorum, Fulgensia fulgens, Lecanora muralis, Squamarina lentigera) showed seasonal changes of temperature sensitivity of their dark respiration (DR) to such an extent that several substantially met the definition of full acclimation, i.e. near identical DR under different nocturnal temperature conditions during the course of the year." Published online August 2004.]
[Edit/Delete] [Upload PDF/URL] [ET: 3820]
Keywords: CHLOROPHYLL FLUORESCENCE/ HUMIDITY/ HYDRATION/ PHOTOSYNTHESIS/ SUPRASATURATION/ TEMPERATE FORESTS/ WATER RELATIONS/ WATER VAPOR UPTAKE
Abstract: 9 fig. ["In general, laboratory studies seem to be able to predict extremely well the behaviour of lichens in their natural habitat."]
[Edit/Delete] [Upload PDF/URL] [ET: 3589]
Keywords: CO2 CONCENTRATING MECHANISM/ DIFFUSION RESISTANCE/ PHOTOSYNTHESIS/ WATER CONTENT/ WATER RELATIONS
Abstract: 4 fig. 1 tab. [Three species exhibiting different responses in net photosynthesis (NP) to high water content (WC) were compared: Diploschistes muscorum, with no depression in NP, D. scruposus, with a slight depression in NP, and Fulgensia fulgens, with a severe depression in NP. "The major differences in NP at high WC and ambient CO2 concentration were due not just to how high these additional resistances were. There was a major contrast between the three species in how they managed the interaction between CO2 diffusion pathways and water storage at high WC. Since underlying carboxylation processes were nearly identical our studies confirmed that the difference in NP performances at high WC must have a morphological basis and be a product of the symbiosis rather than just of the photobiont."]
[Edit/Delete] [Upload PDF/URL] [ET: 3051]
Keywords: CHEMISTRY ROLE/ CO2 DIFFUSION/ LICHEN SUBSTANCES/ PHOTOSYNTHESIS/ WATER CONTENT/ WATER RELATIONS
Abstract: 1 fig. [Extraction experiments with Diploschistes muscorum indicate that secondary substances do not promote CO2 diffusion.]
[Edit/Delete] [Upload PDF/URL] [ET: 3052]
Keywords: CO2 EXCHANGE/ PHOTOSYNTHESIS/ WATER CONTENT/ WATER RELATIONS
Abstract: 7 fig. [Study of net photosynthesis (NP) and water content (WC) in Peltigera leucophlebia and P. neckeri. "Our results show that, for these lichens, the depression in NP at high WC is a real fall in photosynthetic rate of the photobionts and is not due to recycling of CO2."]
[Edit/Delete] [Upload PDF/URL] [ET: 3053]
Keywords: PSEUDOCYPHELLARIA/ WATER RELATIONS/ PHOTOSYNTHESIS/ ISOTOPES/ PHOTOBIONTS/ PHOTOSYMBIODEMES
Abstract: 4 tables. 2 figures. ["Green lichens have been shown to attain positive net photosynthesis in the presence of water vapour while blue-green lichens require liquid water.... The behaviour is confirmed not only for species with differing photobionts in the genus Pseudocyphellaria but for green and blue-green photobionts in a single joined thallus (photosymbiodeme), with a single mycobiont, and also when adjacent as co-primary photobionts. The different response is therefore a property of the photobiont. It is proposed that the presence of sugar alcohols in green algae allow them to retain a liquid pool (concentrated solution) in their chloroplasts at low water potentials and even to reform it by water vapour uptake after being dried."]
[Edit/Delete] [Upload PDF/URL] [ET: 1645]
Keywords: CHLOROPHYLL FLUORESCENCE/ ECOPHYSIOLOGY/ FIELD MEASUREMENTS/ GAS EXCHANGE/ PHOTOBIONT/ PHOTOINHIBITION/ PHOTOSYNTHESIS/ TECHNIQUES
Abstract: 5 fig. [Field investigations of Lecanora muralis using an automatically operating C02 gas exchange measuring cuvette with integrated MINI-PAM chlorophyll fluorometer were carried out, and compared to laboratory experiments.].
[Edit/Delete] [Upload PDF/URL] [ET: 3063]
Keywords: BIOMASS/ CANOPY/ EPIPHYTES/ LIGHT/ LIGHT PENETRATION/ OLD GROWTH FORESTS/ VERTICAL ZONATION
Abstract: 2 fig. 1 tab.
[Edit/Delete] [Upload PDF/URL] [ET: 3098]
Keywords: NEPHROMA/ CHEMISTRY/ DEPSIDONE/ HYPOSTICTIC/ HYPOSALAZINIC
Abstract: 1 table. Several unnumbered figures. [A new lichen depsidone, hypoconsitict acid-triacetate, was isolated from Nephroma antarcticum. Hypostictic and hyposalazinic acids were found in N. australe.]
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Keywords: LECANORA MURALIS/ SAXICOLOUS/ PHOTOSYNTHESIS/ CO2 ASSIMILATION/ MICROCLIMATE/ DEW/ GLOBAL CLIMATE CHANGE/ WATER CONTENT/ GERMANY/ BAVARIA
Abstract: [Study in suburban Würzburg, Germany, attempting to model CO2 assimilation in relation to various environmental factors, especially light and water content from nocturnal dew or frost. "Conditions, especially interrelationships between lichen hydration, light and CO2 are so complex that we are not yet able to extend our estimates to other environmental situations of photosynthetic activity of L. muralis." Authors also note: "As is true for many other lichen carbon fixation problems, the accurate modelling and prediction of thallus water content remains the Holy Grail of lichen ecophysiology."]
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Keywords: WATER RELATIONS/ CO2 EXCHANGE/ NAMIB DESERT/ FOG DESERT/ PHOTOSYNTHESIS/ HETERODERMIA/ RAMALINA/ XANTHORIA/ DEW/ SOUTHERN AFRICA/ ECOPHYSIOLOGY
Abstract: [Study on Heterodermia namaquana, Ramalina lacera and Xanthoria turbinata showed " ... response patterns very similar to the epilithic and epigaeic species at the same site. All three species, despite their different morphologies, performed optimally at the highest nocturnal moistening achieved by natural fog and were not able to make use of higher hydration."]
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Keywords: WATER RELATIONS/ NAMIBIA/ FOG DESERT/ PRODUCTIVITY/ PHOTOSYNTHESIS/ DEW/ NAMIB DESERT
Abstract: [Study of daily response patterns for net photosynthesis using Santessonia hereroensis, Xanthoparmelia walteri, X. incomposita, and Caloplaca elegantisssima. "Higher fog and dew intensity in spring increased maximal nocturnal water contents, maximal attainted NP [net photosynthesis] and integrated daily carbon income ... compared to the autumn measurements." Autumn results are about 40% less than in the spring.]
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Keywords: XANTHORIA/ ROSS SEA REGION/ ANTARCTICA/ PHOTOSYNTHESIS/ OPTIMUM TEMPERATURE/ WATER CONTENT/ CHLOROPHYLL/ α-FLUROESCENCE
Abstract: [Photosynthetic activity in X. mawsonii was exceptionally high for Antarctic lichens and highly adapted to strong irradiance, and has a short reactivation phase. "Recovery of activity by absorbing water vapour from air, though practically possible, seems to be of ecological importance only under snow at subzero temperatures."
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Keywords: Ascomycota/ Lichen-forming fungi/ Photobionts/ Selectivity/ Spatial structure/ Symbiosis/ bryophyte/ environmental conditions/ extreme event/ fungus/ lichen/ population distribution/ spatial analysis/ species diversity/ symbiosis/ vascular plant/ Antarctica/ East Antarctica/ McMurdo Dry Valleys/ Ascomycota/ Bryophyta/ bryophytes/ Fungi/ Tracheophyta
Abstract: Lichen-forming fungi are among the most diverse group of organisms in Antarctica. Being poikilohydric, lichens are able to cope with harsh environmental conditions that exclude other organisms like vascular plants. The McMurdo Dry Valleys (Victoria Land, Continental Antarctica) are a hyperarid cold desert where macroscopic life is reduced to a few lichens and bryophyte species. We investigated the diversity of lichen-forming fungi and their associated photobionts in three valleys (Garwood, Marshall, and Miers). Correct identification of lichen-forming fungi from extreme ecosystems is complicated by the presence of numerous sterile and extremely modified thalli. To overcome this problem, we used a combined approach for the identification of the species present in the area, the first involving identification by means of standard characters and the second, two DNA-based (ITS region) species delimitation methods (General Mixed Yule-Coalescent model and genetic distances). In addition, we also used ITS sequences for the identification of the photobionts associated with the mycobionts. We studied the relationships between both bionts and assessed the degree of selectivity and specificity found in those associations. We also looked for landscape level spatial patterns in these associations. The two DNA-based methods performed quite differently, but 27 species of lichen-forming fungi and five putative species of photobionts were found in the studied area. Although there was a general trend for low selectivity in the relationships, high specificity was found in some associations and differential selectivity was observed in some lichen-forming fungi. No spatial structure was detected in the distribution of photobionts in the studied area. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd.
URL: http://dx.doi.org/10.1111/j.1574-6941.2012.01422.x
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Keywords: DIPLOSCHISTES/ ECOPHYSIOLOGY/ SEMIARID LAND/ SOIL CRUSTS/ SPAIN
Abstract: 3 fig. 3 tab.
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Keywords: BIODIVERSITY/ CLIMATE CHANGE/ CRYPTOGAMS/ VEGETATION ASSOCIATIONS/ VICTORIA LAND
Abstract: [29 lichen taxa were identified, with notes on the nutrient availabilities of this habitat.]
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Keywords: PHOTOSYNTHESIS/ WATER RELATIONS/ CO2 EXCHANGE/ PPFD/ LIGHT COMPENSATION/ DRY WEIGHT/ DIURNAL COURSES/ MICROCLIMATE/ ALPINE ZONE/ ANTARCTICA/ PHOTOSYNTHETIC PHOTON FLUX DENSITY/ RELATIVE HUMIDITY/ VAPOR PRESSURE DEFICIT
Abstract: [Study using Umbilicaria cylindrica, Brodoa atrofusca and Xanthoria elegans. "In the field the lichens were metabolically active at air temperatures between –0.7 and 12.8°C. On sunny days the lichens in the field were metabolically active only for 3h during the early morning. In this time they reached the maximal values or values close to the maximal CO2 uptake in situ." Comparisons are made with data from Antarctica.]
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Keywords: UMBILICARIA/ PHOTOSYNTHESIS/ ALPINE/ NIVAL BELT/ PHYSIOLOGY/ GAS EXCHANGE
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Keywords: Adaptation strategies/ Antarctica/ Chlorophyll fluorescence/ Lichens/ Microclimate/ Monitoring/ Caloplaca/ Umbilicaria
Abstract: Lichens are the dominant organisms in terrestrial Antarctic ecosystems and show a decline in species number, coverage, and growth rate from the maritime Antarctic (62°S) to the McMurdo Dry Valleys (78°S). While Livingston Island (maritime Antarctica) is a hot spot for lichen biodiversity, the McMurdo Dry Valleys (continental Antarctica) are known as one of the most extreme environments for life. Previous studies suggest the biodiversity gradient to be linked to water availability acting through length of active period, but no activity data are available for the Dry Valleys. The work presented here compares metabolic activity of lichens at Livingston Island and the Dry Valleys for 4˝ months from continuous monitoring that involves concurrent measurements of chlorophyll fluorescence and microclimate. The latitudinal comparison involves two contrasting habitats for plant physiological activity and microclimate. Two species of the foliose genus Umbilicaria were monitored in both regions plus one sample of the crustose Caloplaca in the Dry Valleys. The results showed a very large difference in the duration of activity over the monitoring period, and this supports the different coverage, species abundance, and growth rates already reported for lichens between both regions. Despite this large difference in activity, and in habitat conditions, analysis of the activity behaviour of the two Umbilicaria species shows interesting common features, while the crustose Caloplaca had additional strategies to improve hydration. This offers one explanation for the abundance of crustose lichens inside the Valleys, indicating better adaptation strategies to a polar desert.
URL: http://link.springer.com/article/10.1007%2Fs00300-015-1676-1
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Keywords: Arid/ semiarid environments/ BSC/ Chlorophyll a fluorescence/ Microclimate/ Productivity/ arid region/ badlands/ biological production/ carbon dioxide/ carbon flux/ chlorophyll a/ fluorescence/ gas exchange/ lichen/ microclimate/ moss/ soil crust/ soil ecosystem/ Almeria [Andalucia]/ Andalucia/ Spain/ Tabernas/ Bryophyta/ Didymodon rigidulus/ Diploschistes diacapsis/ Psora decipiens/ Squamarina cartilaginea/ Toninia
Abstract: The Soil Crust International project aims to better understand the functioning of biological soil crust environments (BSC) in Europe in order to understand the importance of these ecosystems. The final objective of this project is to inform and strengthen protection strategies for these types of habitats in the frame of the European Union. To achieve this, four different soil crust regions have been chosen in Europe following latitudinal and altitudinal gradients. The work presented here is based on the simultaneous monitoring of gas exchange, chlorophyll fluorescence and microclimate of the most abundant BSC in one of these four locations, the Tabernas badlands, Almeria, SE Spain, one of the driest regions in Europe. The five BSC types monitored are dominated by the lichen species Squamarina cartilaginea, Diploschistes diacapsis, Toninia albilabra and Psora decipiens and by the moss Didymodon rigidulus. We aim to understand the conditions in which the BSC are metabolically active in order to get a better knowledge about the contribution of the BSC to the carbon budget of the ecosystem. Our first results after nearly 1 year of chlorophyll fluorescence and microclimatic monitoring linked to gas exchange data during typical activity days obtained in the field suggest similar physiological performance between the different BSC types studied. BSC were active under suboptimal conditions, and activity duration was not different whether measured by chlorophyll a fluorescence or CO2 gas exchange, a relationship that will be the basis of a productivity model. © 2014 Springer Science+Business Media Dordrecht.
URL: http://dx.doi.org/10.1007/s10531-014-0692-8
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Abstract: Lichen species belonging to the genus Placopsis are early colonisers on snow free moraines of exposed land surfaces in the subantarctic region of Tierra de Fuego, South Chile. The physiological performance of three co-occurring species, P. pycnotheca, (terricolous), and P. perrugosa, and P. stenophylla (both saxicolous) was studied. All, possess green algal photobionts but have cyanobacteria in cephalodia. It was found that there was (i) a strong positive correlation between the acetylene reduction rate (AR) and the maximum photosynthetic rate (Amax), between the N content and the AR rate, and between the N and P contents, and (ii) the relationship between the CO2-exchange rates and the responses obtained in the laboratory reflected the ecology of these three lichens in the field. The results provide new information about the dynamics of some of the fastest growing crustose lichens. We hypothesize that the performance of these three species may have developed as a response to growing in an unstable environment that resulted from frequent glacial fluctuations.
URL: http://dx.doi.org/10.1007/s13199-012-0159-1
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Keywords: FOSSILS/ SUBFOSSIL/ EVOLUTION
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Keywords: Cryptic diversity/ ITS/ Lecanoroid lichens/ Polar regions
Abstract: Taxonomic evaluation of lecideoid lichens in the family Lecanoraceae (Carbonea, Lecanora, Lecidella, Rhizoplaca) from continental Antarctica showed a higher diversity and different distributions compared to previous reports. Morphological, chemical and molecular (nuclear ITS) investigations were made to classify and restudy the different species. Sampling was carried out in the Ross Sea region (continental Antarctica) along a north
URL: http://dx.doi.org/10.1127/0029-5035/2012/0017
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Abstract: The goals of this study were to accurately determine the annual growth rate of two key lichen species for lichenometric studies in Tierra del Fuego and to provide more information on recent glacial evolution in the southernmost mountain range of South America. The study site was located on recent moraines deposited in front of a terminus of Pia Glacier in the East Arm of Pia Bay, a fjord of the Beagle Channel. Lichenometric measurements were made of the maximum and minimum axes on the five largest thalli of Rhizocarpon geographicum and Placopsis perrugosa at selected localities in the recently deglaciated area. Average growth rates were estimated from dated surfaces to be 0.63 mm year-1 for R. geographicum and of 9.0 mm year-1 for P. perrugosa. However, maximum growth rate of individual thalli of P. perrugosa could be as high as about 20 mm year-1 increase in diameter directly measured from comparison between pictures taken over a 2-year interval. Both species had an almost linear increase in diameter size with the age of the rock surfaces and the distance from the glacier. The rapid colonization and growth of the lichens is mirrored by the higher plants with ecesis for Nothofagus trees being estimated at 4 years and height growth elongation at 30 cm year-1.
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Keywords: ANTARCTIC/ LIGHT/ PHOTOSYNTHESIS/ PHOTOSYNTHESIS RATES/ SIZE/ UMBILICARIA
Abstract: 6 fig. 2 tab.
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Keywords: ANTARCTIC/ METABOLISM/ PHOTOSYNTHESIS/ RESPIRATION
Abstract: 7 fig.
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Keywords: CYANOBACTERIA/ MOISTURE CONTENT/ NEW ZEALAND/ PHOTOSYMBIODEMES/ PHOTOSYNTHESIS/ PSEUDOCYPHELLARIA/ WATER RELATIONS
Abstract: 9 fig. ["Water relations of two photosymbiodemes plus a green algal and a cyanobacterial species of the genus Pseudocyphellaria were investigated by measurements of chlorophyll a fluorescence under controlled conditions."]
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Keywords: Antarctica/ Chlorophyll fluorescence/ Climate change/ Lichens/ Monitoring/ Mosses/ Water regime/ climate change/ environmental factor/ hydration/ lichen/ light effect/ metabolism/ monitoring/ moss/ photosynthetically active radiation/ precipitation (climatology)/ pristine environment/ vegetation structure/ Antarctic Peninsula/ Antarctica/ West Antarctica/ Bryophyta/ bryophytes
Abstract: Antarctica, with its almost pristine conditions and relatively simple vegetation, offers excellent opportunities to investigate the influence of environmental factors on species performance, such information being crucial if the effects of possible climate change are to be understood. Antarctic vegetation is mainly cryptogamic. Cryptogams are poikilohydric and are only metabolically and photosynthetically active when hydrated. Activity patterns of the main life forms present, bryophytes (10 species, ecto- and endohydric), lichens (5 species) and phanerogams (2 species), were monitored for 21 days using chlorophyll a fluorescence as an indicator of metabolic activity and, therefore, of water regime at a mesic (hydration by meltwater) and a xeric (hydration by precipitation) site on Léonie Island/West Antarctic Peninsula (67°36?S). Length of activity depended mainly on site and form of hydration. Plants at the mesic site that were hydrated by meltwater were active for long periods, up to 100 % of the measurement period, whilst activity was much shorter at the xeric site where hydration was entirely by precipitation. There were also differences due to life form, with phanerogams and mesic bryophytes being most active and lichens generally much less so. The length of the active period for lichens was longer than in continental Antarctica but shorter than in the more northern Antarctic Peninsula. Light intensity when hydrated was positively related to the length of the active period. High activity species were strongly coupled to the incident light whilst low activity species were active under lower light levels and essentially uncoupled from incident light. Temperatures were little different between sites and also almost identical to temperatures, when active, for lichens in continental and peninsular Antarctica. Gradients in vegetation cover and growth rates across Antarctica are, therefore, not likely to be due to differences in temperature but more likely to the length of the hydrated (active) period. The strong effect on activity of the mode of hydration and the life form, plus the uncoupling from incident light for less active species, all make modelling of vegetation change with climate a more difficult exercise. © 2013 Springer-Verlag Berlin Heidelberg.
URL: http://dx.doi.org/10.1007/s00442-013-2608-9
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Keywords: ANTARCTICA/ DARK RESPIRATION/ PHOTOSYNTHESIS/ SNOW/ TEMPERATURE/ UMBILICARIA
Abstract: 5 fig.
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Keywords: ANTARCTIC/ CHLOROPHYLL FLUORESCENCE/ CO2 EXCHANGE/ ELECTRON TRANSPORT RATE/ PHOTOSYNTHESIS/ PHOTOSYSTEM II
Abstract: 4 fig. [Study of Umbilicaria aprina and Bryum argenteum.]
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Keywords: ANTARCTICA/ HISTORY
Abstract: 5 fig. [This description of a historic site in Antarctica includes a brief summary of the local biota, and indicates 31 species of lichens are present.]
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Keywords: ANTARCTIC/ CO2 EXCHANGE/ CRUSTOSE/ FLUORESCENCE YIELD/ INSTRUMENT/ PHOTOSYNTHESIS/ WATER CONTENT
Abstract: 5 fig. 2 tab. ["CO2 exchange and fluorescence yield of the crustose lichen Buellia frigida were measured in situ by means of a CO2 porometer and a PAM-2000, a newly developed portable fluorescence system....It proved possible, using the PAM-2000, to differentiate the physiological performance of the thallus centre and the marginal lobes. The distribution of water in the thallus during a drying cycle was shown to be inhomogeneous. The photosynthetic rates of B. frigida calculated on an area basis are comparatively high and indicate that this lichen is well adapted to its habitat conditions in this part of continental Antarctica."]
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Keywords: ANTARCTICA/ PHOTOSYNTHESIS/ SNOW/ TEMPERATURE/ UMBILICARIA/ WATER RELATIONS
Abstract: 8 fig. [From the Proceedings of an International Workshop on Polar Desert Ecosystems, held in Christchurch, New Zealand, 1-4 July 1996. "In this paper we demonstrate to what extent lichens are able to profit from snow as a water source for rehydration under the extreme environmental conditions in Continental Antarctica. Net photosynthesis of the foliose macrolichen Umbilicaria aprina occurred at subzero temperatures in the field even when snow was the only water source."]
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Keywords: RADIONUCLIDES/ POLAND/ CESIUM/ UMBILICARIA/ CHERNOBYL/ USSR
Abstract: 2 tables. 2 figures. [Recent significant increases in 134Cs and 137Cs have been found in Umbilicaria species when compared to studies in 1978-79. "The composition and ratio of the various radionuclides, particularly in respect of 134Cs and 137Cs, exhibit a characteristic signature consistent with contamination derived from the accident at Chernobyl nuclear reactor in April 1986."]
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Keywords: ANTARCTICA/ VICTORIA LAND
Abstract: 1 fig. 1 tab. [Notes and descriptions are given for 22 species. New: Rhizoplaca priestleyi (Dodge) Seppelt comb. nov. (comb. invalid., Art. 33.2)]
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Keywords: ANTARCTICA/ VICTORIA LAND
Abstract: [New: Rhizoplaca priestleyi (Dodge) Seppelt comb. nov.]
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Keywords: PHOTORESPIRATION/ CO2 EXCHANGE/ STICTACEAE
Abstract: 2 tables. ["In this study we are able to show that some lichens do nota behave as typical C3 plants but appear to have no, or very low, apparent photorespiratory activity. The results come from studies of carbon dioxide compensation levels and carbon dioxide exchange in the presence and absence of oxygen." Ten of the 13 species tested were members of the Stictaceae.]
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Keywords: CO2 EXCHANGE/ STICTACEAE/ PHOTORESPIRATION/ PHYSIOLOGY
Abstract: 3 figures. 1 table. [From the study of 5 species of Stictaceae, authors conclude that lichens "...join the group of plants with low CO2 compensation values and photorespiration."]
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Keywords: PSEUDOCYPHELLARIA/ MORPHOLOGY/ NEW ZEALAND/ NITROGEN FIXATION/ ECOLOGY/ WATER RELATIONS
Abstract: 8 tables. 3 figures. [New Zealand populations "... were shown to possess different morphologies which correlated with the evaporative demand of their environment."]
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Keywords: CO2 EXCHANGE/ STICTA/ PSEUDOCYPHELLARIA/ REFIXATION/ PHOTOSYNTHESIS/ PHYCOBIONT/ PHYSIOLOGY
Abstract: 1 table. 2 figures. [Studies on Sticta latifrons and Pseudocyphellaria amphistica suggest that the "...arrangement of resistances may simultaneously encourage refixation of respired CO2 and maintain a non-desiccating environment for the lichen algae."]
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Keywords: CO2 EXCHANGE/ WATER RELATIONS/ PSEUDOCYPHELLARIA/ STICTA/ PELTIGERA/ NEW ZEALAND
Abstract: 1 table. 3 figures. [Study on species of Pseudocyphellaria (4), Sticta (1), and Peltigera (1) from New Zealand. "In all cases the curves are triphasic with a high resistance at low and high water contents and a low resistance at intermediate water contents."]
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Keywords: NEW ZEALAND/ STICTA/ PSEUDOCYPHELLARIA/ STICTACEAE/ GROWTH RATES
Abstract: 1 table. 2 figures. [Photographic growth rate study of Pseudocyphellaria homoeophylla and Sticta caperata over a two year period showed that "... the mean annual radial increases of both species were linearly related to thallus diameter and ranged from 2.0 to 27.0 mm and 3.0 and 16.7 mm, respectively."]
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Keywords: Calluna vulgaris/ Carbon budget/ Climate change/ Drought injury/ Ecosystem functioning/ Eutrophication/ Vegetation recovery
Abstract: Increases in the emissions and associated atmospheric deposition of nitrogen (N) have the potential to cause significant changes to the structure and function of N-limited ecosystems. Here, we present the results of a long-term (13 year) experiment assessing the impacts of N addition (30 kg ha-1 yr-1) on a UK lowland heathland under a wide range of environmental conditions, including the occurrence of prolonged natural drought episodes and a severe summer fire. Our findings indicate that elevated N deposition results in large, persistent effects on Calluna growth, phenology and chemistry, severe suppression of understorey lichen flora and changes in soil biogeochemistry. Growing season rainfall was found to be a strong driver of inter-annual variation in Calluna growth and, although interactions between N and rainfall for shoot growth were not significant until the later phase of the experiment, N addition exacerbated the extent of drought injury to Calluna shoots following naturally occurring droughts in 2003 and 2009. Following a severe wildfire at the experimental site in 2006, heathland regeneration dynamics were significantly affected by N, with a greater abundance of pioneering moss species and suppression of the lichen flora in plots receiving N additions. Significant interactions between climate and N were also apparent post fire, with the characteristic stimulation in Calluna growth in +N plots suppressed during dry years. Carbon (C) and N budgets demonstrate large increases in both above- and below-ground stocks of these elements in N-treated plots prior to the fire, despite higher levels of soil microbial activity and organic matter turnover. Although much of the organic material was removed during the fire, pre-existing treatment differences were still evident following the burn. Post fire accumulation of below-ground C and N stocks was increased rapidly in N-treated plots, highlighting the role of N deposition in ecosystem C sequestration. © 2012 Blackwell Publishing Ltd.
URL: http://dx.doi.org/10.1111/j.1365-2486.2012.02732.x
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Keywords: ARCTIC/ ALPINE/ ANTARCTIC/ REVIEW/ ECOPHYSIOLOGY
Abstract: [Review of the ecophysiology of lichens in these ecosystems. "Environmental temperature is rising due to global warming in some of these areas, and it is likely that this will have a negative effect on lichen biodiversity at the margins of these zones because of the improved competitiveness of the vascular plants." In English with a German summary.]
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