Lichen and moss bags as monitoring device: active or passive uptake of trace metals?

Adamo, P. (1), Agnorelli, C. (2), Bargagli, R. (2), Baruffo, L. (3), Giordano, S. (4), Modenesi, P. (5), Orlando, S. (1), Pittao, E. (3) & Tretiach, M. (3)
(1) Dipartimento del Suolo, della Pianta e dell&Mac226; Ambiente, Università Federico II di Napoli, Italy; (2) Dipartimento di Scienze Ambientali, Università di Siena, Italy; (3) Dipartimento di Biologia, Università di Trieste, Italy; (4) Dipartimento di Biologia Vegetale, Università Federico II di Napoli, Italy; (5) DIP.TE.RIS., Università di Genova, Italy

Although small bags containing living or dead moss or lichens are widely used to monitor persistent atmospheric pollutants in urban and industrial environments, uptake mechanisms and the reliability of this approach have been scarcely investigated.
Shoots of the moss Hypnum cupressiforme Hedw. and lobes of the lichen Pseudevernia furfuracea (L.) Zopf from unpolluted areas were pre-treated by: 1) water washing (WL, WM); 2), oven drying at 120 °C for 24 h (OL, OM); 3) HNO3 washing (AL, AM); 4) NH4-oxalate extraction at 85 °C for 15 h (OLoxa, OMoxa, ALoxa, AMoxa). Four bags with 500 mg of each material were exposed for six weeks in Trieste and Naples (Italy) on the roof of automatic devices for continuous recording of NOx, SO2, CO, PM10, and climatic data. Two synthetic materials (A: quartz fibre filter Whatman QMA 1851047; B: cation-exchange filter Pall ICE 450) were exposed in the same conditions to compare uptake processes and accumulation capacity with bio-materials. 15 elements were analysed before and after exposure. CO2 gaseous exchange, chlorophyll fluorescence, chlorophyll content, and K, Ca and Mg intra- and extra-cellular distribution assessed in WL and WM.
WM was more sensitive than WL according to exposure at both sites, whereas WL increased the C and N content in relation to CO and NOx pollution. Average concentrations (µg g-1 dry wt) of trace metals increased significantly in all materials and were scarcely influenced by vitality or pre-treatment type, although concentrations were always higher in moss shoots than in lichen lobes. The specific surface area was estimated and concentrations expressed as ng cm-2 to compare accumulation by synthetic and biological materials. Similar concentrations were found in moss shoots and lichen lobes, but significantly lower concentrations in synthetic materials. Passive capture of airborne particulate matter accounted for most metal uptake.


Mapping and monitoring biological soil crusts in SE Spain

Alexander, R. (1) Bevan, J. (1) Lazaro-Suau, R. (2)
(1) University College Chester, Chester, UK; (2) EEZA, Almería, Spain

Biological soil crusts, comprising lichens, bryophytes, algae, fungi and bacteria living in close association within the top few millimetres of the soil, occur widely in arid and semi arid regions, occupying spaces between sparse vascular plants or constituting the sole vegetation cover. They influence soil stabilisation and surface hydrology, fix nitrogen and carbon and provide establishment sites for seedlings.
Despite wide occurrence these crusts remain relatively poorly researched in Mediterranean Europe. The lichen-dominated soil crusts of SE Spain seem to occupy a narrow climatic window between higher rainfall, where vascular plants dominate, and lower, but more intense rainfall, where erosion dominates. The most favourable regime has frequent, low intensity, low volume rainfall events and frequent dew. A Spanish Government-funded project, PECOS, will assess the potential of biological soil crusts as sensors of climatic change, examining their status, distribution and ecophysiology and exploring their relationship to topography and geomorphological processes.
Work on the extensive crusts in the El Cautivo badlands in Almería, has distinguished broad community types with internal variability sensitive to microclimatic and topographic differences. Spectral signatures of the dominant lichen crust species, sediments, and vascular plants have been used to inform classification of airborne imagery in an attempt to map crust distribution. Results of this work are presented together with a preview of the more extensive scope of PECOS.


Lichens and global warming: further evidence and the role of Trentepohlia

Aptroot, A.
Centraalbureau voor Schimmelcultures, P.O. Box. 85167, NL-3508 AD Utrecht, Netherlands

Two types of evidence are being reported to confirm the hypothesis that lichens in Western Europe are responding to climate change: statistical and observational. Examples of both are given from several countries in Western Europe. Many more species seem to be increasing rather than declining as a result of global warming. Changes are markedly more rapid in formerly heavily polluted or generally built-up or open rural areas, as compared to large forested regions in, for example, Central Europe.
The increase of epiphytic lichens in forested areas over the last decade seems also attributable to global warming. The most rapidly increasing species, although taxonomically unrelated and preferring different tree species, surprisingly share one character, in addition to their southern distribution. They all contain Trentepohlia as phycobiont. In fact, all lichens with Trentepohlia occurring in this area have increased, some by over 4 times within 10 years; thus the whole increase in lichen diversity can be explained in terms of the relatively few and diverse species with Trentepohlia. Global warming may well have affected the Trentepohlia phycobiont rather than the lichen in toto.


Concentration of secondary substances in arctic-alpine lichens in relation to UV-B radiation and other factors

Bjerke, J. W.
Department of Biology, Faculty of Science, University of Tromsø, N-9037 Tromsø, Norway

Depletion of the stratospheric ozone layer over the poles has led to increased UV-B radiation fluxes at high latitudes. In spite of this, the effects of enhanced UV-B radiation on lichens have until recently been given little attention. Several experimental and observational studies were conducted to assess the effects of UV-B radiation on lichens in arctic-alpine habitats, in particular on the content of certain UV-absorbing substances. Responses to other factors such as temperature, seasonality, thallus size, grazing pressure and precipitation rates were also measured. Current studies provide new data on lichen responses to UV-B and other factors. Although usnic acid concentrations are affected by UV-B radiation, other factors, such as hydration, low temperature and PAR, are just as, or even more important, in usnic acid synthesis. Usnic acid concentrations, therefore, have limited potential as a biomonitor of recent UV-B fluxes; depsides do not play a significant role as sun-screens in lichens. The studied lichens appear to be well-adapted to enhanced UV-B radiation fluxes. UV-B radiation may enhance lichen viability by reducing the activity of microfungi, bacteria and grazing insects. However, cumulative effects through longer exposure times than used in the current studies, may be more adverse than the observed, modest, shorter-term effects. Significant interactive effects of enhanced UV-B radiation and warming strongly indicate that chemical responses to various abiotic factors can have opposite effects. Longer-term, combined effect and iterative studies along temporal and spatial gradients, with close monitoring of physical conditions, will no doubt increase our knowledge as to how lichens respond to rapid climate change at high latitudes.


Epiphytic lichens as biomonitors of atmospheric pollution in Slovenian forests

Jeran, Z. (1), Jacimovic, R. (1), Mrak, T. (1), Batic, F. (2), Kastelec, D. (2), Mavsar, R. (3) & Kalan, P. (3)
(1) Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia; (2) University of Ljubljana, Biotechnical Faculty, Department of Agronomy, Jamnikarjeva 101 1000 Ljubljana, Slovenia; (3) Slovenian Forestry Institute, Vecna pot 2, 1001 Ljubljana, Slovenia

Two different national surveys using epiphytic lichens were carried out during 2000 in Slovenia and the results of both combined in this study. In the first survey, performed within the framework of forest decline inventories, lichen diversity was studied on more than 500 plots of a 4x4 km national grid. In the second survey, Hypogymnia physodes (L.) Nyl. was collected on a wider, 16x16 km bioindication grid and analysed for sulphur, nitrogen, As, Br, Ce, Cd, Cr, K, La, Mo, Rb, Sb, Th, U and Zn. Only sampling points lying inside the forest were included in this study. The aim of the work was to establish if there is a relationship between the richness of foliose epiphytic lichens and quantitative levels of certain trace elements, N and S in H. physodes. The epiphytic lichen flora was found to be quite poor, with about 70 % of the territory in the second or third classes, which represent highly and moderately polluted air. However, by application of multivariate statistics, no negative effect of trace elements or of N and S, on the richness of foliose epiphytic lichens was found.


Impact of current atmospheric conditions on epiphytic lichens and bryophytes in London

Larsen, R.S. (1), Bell, J.N.B. (2), Chimonides, P.J. (1), James, P.W. (1), Purvis, O.W. (1), Rumsey, F. (1) & Tremper, A. (3)
(1) The Natural History Museum, Cromwell Road, London, SW7 5BD, UK; (2) Department of Environmental Science and Technology, Imperial College London, London SW7 2AZ, UK; (3) Environment Research Group, Kings College London. 150 Stamford Street, London SE1 9NN

Lichens are currently re-invading London remarkably quickly, including some unexpected species. 74 lichens and 6 mosses were found on 147 young oak trees in parks throughout London. Lichen distribution today is associated with road transport emissions, the major pollution source in London. The number of lichen species found increase with distance from the city centre, despite new lichens entering Central London. One third of recorded species were only found more than 23 km from Central London. Lichens known to prefer acidic conditions prefer London’s periphery and large parks far from roads where pollution levels are lower. Lichens tolerant of high nitrogen and dust levels occur throughout London, most showing no clear relationship with air quality, but some, like Phaeophyscia orbicularis, being most abundant in Central London.
Many trees support both ‘nitrophyte’ and ‘acidophyte’ flora suggesting either a transition in lichen flora due to changing atmospheric conditions, or the need to revise the ‘nitrophyte’ and ‘acidophyte’ concept to suit urban situations.
The numerous pollutants, their transformation into secondary phases and their interactions, make it difficult to interpret correlations of the epiphyte’s distribution in London. By comparing distribution with NO, NO2, CO, O3, SO2 and PM10 using appropriate statistical techniques, potential factors governing the present day lichen distribution in London are determined.


Rainforest lichens as models of community formation and indicators of microclimatic zonation and ecological continuity

Lücking, R.
The Field Museum, Chicago, USA

Recent studies demonstrate rainforest lichens, in particular foliicolous taxa, are suitable models to investigate community formation and as indicators of microclimatic zonation and ecological continuity. Artificial leaves have been used to monitor the succession of foliicolous lichen communities beyond the average lifespan of natural leaves, to elucidate the mechanisms that underly the maintenance of communities within ecologically equivalent species. Based on a study using microclimatic sensors, the suitability of foliicolous lichens were assessed as indicators of small-scale microclimatic variation, and their use for zonation of rainforest strata, microsites, and tree canopies. Comparison of lichen communities between habitats showing different disturbance levels, demonstrates the use of selected taxa, such as Thelotremataceae, as indicators of ecological community of rainforests habitats. These findings can be applied to evaluate rainforest sites potentially suitable for conservation, such as in the Rapid Biological Inventories Program of The Field Museum.


Lichens as monitors of urban pollution in northern Thailand

Saipunkaew, W. (1), Wolseley, P. (1), Chimonides, J. (2) & Boonpragob, K. (3)
(1) Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; (2) The Natural History Museum, Cromwell Road, London, UK; (3) Department of Biology, Faculty of Science, Ramkhamhaeng University, Bangkok 10240, Thailand

Lichens have long been used as indicators of pollution in temperate regions, but their use as bioindicators in tropical regions has only recently been investigated. Lichen mapping in and around Chiang Mai city in 1994 and 2002, using the VDI method developed in Germany, has shown that epiphytic lichens can be used as biomonitors of pollution in Thailand. This technique is being applied to urban and rural areas in 8 provinces of Northern Thailand. Preliminary results show that lichen diversity is lowest in the city and highest in less disturbed rural areas. Foliose species are less frequent than crustose species in almost all sites. Due to inadequate pollution data, population density is used here as a surrogate measure for pollution levels. Cluster analysis of lichen genera and frequency from all sites shows that city sites in Chiang Mai and Lampang provinces, with higher population density, are most similar, whereas rural sites with low population counts, are separated in another group. Foliose species with the greatest frequency in the cities are Pyxine cocoes and Hyperphyscia adglutinata. Distribution of these species suggests that they are most tolerant of polluted sites, whereas Physcia krogiae is only found at low frequency in areas of low population. Crustose species are frequent and often dominant, particularly in urban sites, but their relationship to pollution is as yet poorly understood and requires further evaluation. Arthonia species (including undescribed taxa) are present in all sites, whereas an undescribed species related to cf. Graphidastra was found in less polluted sites. Further analysis of crustose components and their relationship to pollutants and other environmental factors is required to identify taxa that can be used as indicators of atmospheric pollution in the monsoon tropics.


Lichens in outer space: the BIOPAN experiment

Sancho, L. G. (1), de la Torre, R. (2), Horneck, G. (3), Ascaso, C. (4), Wierzchos, J. (5), de los Rios, A. (4), Pintado, A. (1)
(1) Departamento de Biología Vegetal II, Universidad Complutense, Madrid, Spain; (2) Instituto Nacional de Técnica Aeroespacial, Madrid, Spain; (3) Institute of Aerospace Medicine, German Aerospace Center DLR, Köln, Germany; (4) Centro de Ciencias Medioambientales, CSIC, Madrid, Spain; (5) Servei de Microscopia Electrónica, Universitat de LLeida, Spain

Several lichens are well known for their high resistance to harsh environmental conditions. These include extreme temperatures, long desiccation periods and high PAR and UV radiation. Lichens can survive unfavorable periods in a dry and inactive state and withstand long drought periods. They can quickly rehydrate and gain metabolic activity if water is available. Thus lichens in the anabiotic state may well be able to persist in the most extreme environments. Lichens have therefore been previously proposed, together with unicellular algae and bacteria, as the living system most likely to resist the extreme conditions of outer space. This enables speculation about the possibility of life transfer between Earth and other planets.
The European Space Agency approved our proposal for a lichen experiment and included it in the BIOPAN-4 Mission, scheduled for October 2002. For this experiment we selected lichen thalli from high mountains and endolithic lichens from the Antarctic Dry Valleys. Before launching we tested the lichen sensitivity to simulated space conditions, using the space simulation facilities of the Institute of Aerospace Medicine at the German Aerospace Center DLR. Studied species showed a high resistance against the conditions tested (UV radiation, high temperatures and vacuum) confirming them as excellent test objects for the BIOPAN Mission. Analysis included chlorophyll fluorescence for the measurement of photosynthetic parameters. Scanning electron microscope in back- scattered mode was applied to study the organization and composition of the lithobiontic communities and Confocal Laser Scanning Microscope, in combination with the use of specific fluorescent probes, to analyse the physiological state of cells. Unfortunately, the satellite exploded during launch when the rocket failed. However, a new BIOPAN Mission, including the same experiments as BIOPAN-4, has been scheduled for April 2005.


Formation and accumulation of pharmaceutically relevant lichen metabolites in mycobiont cultures: are they induced by environmental stress factors?

Stocker-Wörgötter, E.
Institute of Plant Physiology, University of Salzburg, Hellbrunner Str.34, A-5020 Salzburg, Austria

Lichen metabolites (end products of different biogenetic and biochemical pathways) exert a broad variety of biological activities, e.g. antibiotic, antimycobacterial, antiviral, anti-inflammatory, analgesic, antipyretic, antiproliferative and cytotoxic effects. From a culture collection (about 250 apoymbiotically grown mycobionts) several examples that produce small-molecule constituents, probably useful for pharmaceutical applications, were selected and chemically tested by TLC and HPLC analyses. Particularly, the induction and biosynthesis of aliphatic acids, pulvinic acid derivatives, diverse polyketides as well as epidithiopiperazinedones (scabrosinesters) were investigated.
Surprisingly, most biologically active lichen metabolites in cultures are formed under environmental and physiological stress conditions that were simulated in electronically adjustable culture chambers. Various combinations of environmental factors, interestingly associated with the morphogenetic capacity of lichen fungi, were studied and their influence on the biosynthesis of pharmaceutically relevant lichen compounds and lichen substances, in general is discussed.

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