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Yngvar Gauslaa - One of the best experts on this subject based on the ideXlab platform.
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Canopy settings shape elemental composition of the epiphytic lichen Lobaria Pulmonaria in unmanaged conifer forests
Ecological Indicators, 2020Co-Authors: Yngvar Gauslaa, Trevor Goward, Thomas G. PypkerAbstract:Abstract The importance of forest canopy settings for the elemental chemistry of epiphytic lichens in undisturbed forests is poorly understood despite its impact on epiphytes, understory vegetation and microbial soil communities. Here, we examine the elemental composition in standardized thalli of the cephalolichen Lobaria Pulmonaria transplanted to the lower branches of Picea glauca x engelmannii in inland British Columbia. Transplants were attached to nets (avoiding direct contact with tree bark) exposed to natural canopy throughfall in three categories of natural forest stands: 1) within dripzones of Populus species in mixed stands always supporting L. Pulmonaria; 2) outside Populus dripzones, yet with L. Pulmonaria and 3) outside Populus dripzones and without L. Pulmonaria, which is the most common canopy setting. After one year, and with the exception of Fe and Al, the elemental content in lichen transplants changed within and between forest categories. Lichen transplants within Populus dripzones had more base cations (Ca, Mg, K) and less Mn than in the two categories outside dripzones. In Picea canopies outside Populus dripzones, lichen transplants had higher Ca, Na, Mo and lower C, S and Cu in trees with L. Pulmonaria than without. The pH of Picea branches and soil within the rooting zone of trees with transplants were both approximately ten times more acidic outside Populus dripzones than within them. However, bark pH did not differ between the two categories of stands outside Populus dripzones. Based on our findings we conclude that canopy setting shapes the elemental composition of epiphytic lichen transplants, suggesting that such transplants might be used to monitor spatial variation in throughfall elements from forest canopies in unmanaged stands. We also conclude that elemental concentrations, Ca in particular, is a better predictor than bark pH for the occurrence of L. Pulmonaria on Picea.
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Short- and long-term freezing effects in a coastal (Lobaria virens) versus a widespread lichen (L. Pulmonaria).
Cryobiology, 2018Co-Authors: Knut Asbjørn Solhaug, Dipa Paul Chowdhury, Yngvar GauslaaAbstract:Abstract Lichens are considered freezing tolerant, although few species have been tested. Growth, a robust measure of fitness integrating processes in all partners of a lichen thallus, has not yet been used as a viability measure after freezing. We compared relative growth rates (RGR) after freezing with short-term viability measures of photo- and mycobiont functions in the coastal Lobaria virens and the widespread L. Pulmonaria to test the hypothesis that low temperature shapes the coastal distribution of L. virens. Hydrated thalli from sympatric populations were subjected to freezing at −10, −20 and −40 °C for 5 h. The rate of cooling and subsequent warming was 5 °C h−1. Short-term viability measures of photobiont (maximal photosystem II efficiency, effective PSII yield) and mycobiont viability (conductivity index), as well as subsequent RGR, were assessed. The exotherms showed that L. virens froze at −3 °C; L. Pulmonaria, at −4 °C. Freezing significantly impaired short-term viability measures of both photo- and mycobiont, particularly in the coastal species. Lobaria Pulmonaria grew 2.1 times faster than L. virens, but the short-term damage after one freezing event did not affect the long-term RGR in any species. Thereby, short-term responses were impaired by freezing, long-term responses were not. While the lacking RGR-responses to freezing suggest that freezing tolerance does not shape the coastal distribution of L. virens, the significant reported adverse short-term effects in L. virens may be aggravated by repeated freezing-thawing cycles in cold winters. In such a perspective, repeated freezing may eventually lead to reduced long-term fitness in L. virens.
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Fungal tissue per se is stronger as a UV-B screen than secondary fungal extrolites in Lobaria Pulmonaria
Fungal Ecology, 2017Co-Authors: Yngvar Gauslaa, Azharul Alam, Pierre-louis Lucas, Dipa Paul Chowdhury, Knut Asbjørn SolhaugAbstract:Abstract To test the hypotheses that (1) protective mycobiont tissues and/or (2) medullary UV-B-absorbing carbon-based secondary compounds (CBSCs) protect lichen photobionts against UV-B radiation, we quantified cortical UV-transmittance and ran a three-way factorial lab experiment with (1) three UV radiation regimes, (2) photobiont layers with/without a screening cortex, and (3) with natural/reduced CBSC-concentration. We used melanin-deficient Lobaria Pulmonaria from shaded forests. Maximum photochemical efficiency of photosystem II ( F v/ F m) in photobionts inside thalli with natural CBSC-concentrations was not affected by any UV-regime, consistent with close to 0% measured cortical transmittance of wavelengths P P P = 0.001), mainly affecting exposed photobiont layers given short-wavelength UV radiation. Based on these findings, we conclude that the primary role of extrolites in L. Pulmonaria is not to screen excess solar radiation.
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Growth and secondary compound investments in the epiphytic lichens Lobaria Pulmonaria and Hypogymnia occidentalis transplanted along an altitudinal gradient in British Columbia
Botany, 2013Co-Authors: Massimo Bidussi, Trevor Goward, Yngvar GauslaaAbstract:We investigated altitudinal variation (550–1650 m) in relative growth rates (RGR) and carbon-based secondary compounds (CBSC) in the cephalolichen Lobaria Pulmonaria (L.) Hoffm. and the chlorolichen Hypogymnia occidentalis L. H. Pike transplanted for 14 months in a U-shaped valley in inland southern British Columbia. Prior to transplantation, half of the thalli were treated with phosphorus (P) to examine effects of P on carbon allocation. Growth in L. Pulmonaria was substantially higher in the toe-slope position, corresponding to much higher bark pH. Sixty-four percent of the variation in RGR was accounted for by positive pH effects and adverse effects of direct light exposure in the best subset multiple regression model. For H. occidentalis, 57% of the variation in RGR was accounted for by positive and negative effects of indirect and direct light, respectively. Neither altitude nor P had a noticeable effect on RGR, the former possibly reflecting a trade-off between orographic precipitation and inversion...
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Contents of carbon based defence compounds in the old forest lichen Lobaria Pulmonaria vary along environmental gradients
Fungal Ecology, 2011Co-Authors: Steinar Vatne, Johan Asplund, Yngvar GauslaaAbstract:Abstract We quantified carbon based secondary compounds (CBSC) in 182 Lobaria Pulmonaria thalli sampled in a range of forest types along an elevation gradient in southern Norway to assess the importance of external and internal factors as a source of variation for the CBSC content. The best multiple regression model for CBSC content included altitude, soil pH, dry weight (DW) per area and thallus size. Total CBSC content decreased with altitude and increased with pH. L. Pulmonaria maximizes its CBSC content in sites with long gastropod grazing seasons (lowland forests) and high gastropod abundance (calcareous soils). Secondly, we assessed grazing damage in the L. Pulmonaria thalli to test the hypothesis that natural populations of gastropods respond to the CBSC level in situ . We found a significantly negative correlation between the stictic acid concentration and grazing damage from gastropods, which is consistent with an evolutionary arms race between lichens and gastropods. This relationship became stronger when using the tree trunk as a factor in the ANCOVA, consistent with spatial variation in gastropod occurrences.
Christoph Scheidegger - One of the best experts on this subject based on the ideXlab platform.
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Genetic structure of Lobaria Pulmonaria in the Alps as a result of post-glacial recolonization history
Herzogia, 2018Co-Authors: Michèle Lerch, Olga Nadyeina, Christoph ScheideggerAbstract:Lerch M., Nadyeina O. & Scheidegger C. 2018: Genetic structure of Lobaria Pulmonaria in the Alps as a result of post-glacial recolonization history. – Herzogia 31: 650 – 665.The present-day genetic structure of a species is highly influenced by its history. Quaternary range expansions and contractions had a major impact on the genetic diversity and structure of species, which has implications for presentday conservation strategies of rare and threatened species. The aim of this study was to investigate the genetic structure of Lobaria Pulmonaria and its green-algal photobiont Symbiochloris reticulata from the Alps. Here we present the genetic structure of 75 Lobaria Pulmonaria populations and we investigated which of three fungal and two algal genetic lineages that were recognized in a broader study on the European phylogeography of this species are present in the Alps and from where postglacial recolonization might have occurred. Our study showed that only the fungal genepool A and the algal genepool R contributed to the recolonization of the Alps. The fungal genepools B1 and B2 were restricted to the eastern and western borders of the Alps but play an important role in the current populations in the Jura Mountains, the Vosges and the Black Forest. The algal genepool S was only found at the southwestern borders of the Alps and we hypothesize that this genepool is adapted to Mediterranean climates. For both symbionts we found a significant positive correlation between longitude and allelic richness, indicating a recolonization of the Alps from a peripheral refugium for genepool A at the eastern border of the Alps or from the Carpathian Mountains.
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Multiple mating events and spermatia-mediated gene flow in the lichen-forming fungus Lobaria Pulmonaria
Herzogia, 2016Co-Authors: Christine Keller, Christoph ScheideggerAbstract:Abstract: Keller, C. & Scheidegger, C. 2016. Multiple mating events and spermatia-mediated gene flow in the lichen-forming fungus Lobaria Pulmonaria. — Herzogia 29: 435–450. Lichen-forming fungi have developed combined reproductive strategies that involve both sexual and asexual propagules, which are produced in varying frequencies over space and time. Lobaria Pulmonaria reveals the characteristic traits of genetically diverse, fully recombinant populations, despite the generally rare occurrence of sexual reproductive structures. This study aimed at investigating the genetic diversity of the progenies of single apothecia of L. Pulmonaria from different populations. Because the percentage of germinating ascospores is often very small and single spore cultures are thus difficult to obtain, we tested a protocol of DNA isolation from a multispore fraction and identified the alleles of three fungus-specific microsatellite markers. Multispore samples analysed from single apothecia revealed two to three differen...
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Distribution and dispersal ecology of Lobaria Pulmonaria in the largest primeval beech forest of Europe
Biodiversity and Conservation, 2014Co-Authors: Olga Nadyeina, Lyudmyla Dymytrova, Anna Naumovych, Sergyi Postoyalkin, Christoph ScheideggerAbstract:Occupancy and density of the epiphytic lichen L. Pulmonaria were studied in the mountains of Uholka–Shyrokyi Luh (Ukraine), which include the largest primeval beech forest in Europe. The lichen occupancy was assessed on 314 plots laid out on a systematic grid. Additional data on population density were collected from 483 trees growing both, on and between these plots. The trees harbouring L. Pulmonaria were distributed very sparsely within Uholka–Shyrokyi Luh, and occupy nearly 10 % of the studied perimeter. The generalized linear models showed that area of occupancy of L. Pulmonaria was significantly influenced by altitude and canopy cover, whereas the species’ density was explained by habitat types and slope exposition. Population density is higher at the timberline than in the interior forest or on lowland meadows. We found a bimodal altitudinal distribution of L. Pulmonaria , with maxima below and above 900 m a.s.l., where it prefers forest stands with loose or scattered canopy. The preferred position of L. Pulmonaria on host tree trunks depends on stand density and allows the species to get the necessary level of insolation also in shaded sites where it grows higher up on the trunk than in open stands. While L. Pulmonaria occupied trees with various diameters, juvenile individuals are more frequent on small trees, but mature lichen individuals are predominantly found on trees of average or large sizes. Fertile individuals require specific environmental conditions, which are available at intermediate altitudes, related with sheltered light, and horizontal terraces on slopes with eastern exposition. In general, the primeval beech forest of Uholka–Shyrokyi Luh harbours a high percentage of juvenile thalli of L. Pulmonaria , which lack vegetative propagules. Mature individuals have a low frequency of fruit bodies and reproduce mainly with vegetative diaspores. We interpret this as an indication of a currently growing population of L. Pulmonaria within the area. We hypothesize that transboundary air pollution has decreased the lichens’ population frequency and density and has altered the ratio of developmental stages in L. Pulmonaria during earlier decades.
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Microclimatic differentiation of gene pools in the Lobaria Pulmonaria symbiosis in a primeval forest landscape
Molecular Ecology, 2014Co-Authors: Olga Nadyeina, Lyudmyla Dymytrova, Anna Naumovych, Sergyi Postoyalkin, Silke Werth, Saran Cheenacharoen, Christoph ScheideggerAbstract:Abstract Population genetics of the tree-colonizing lichen Lobaria Pulmonaria were studied inthe largest primeval beech forest of Europe, covering 10 000 ha. During an intensivesurvey of the area, we collected 1522 thallus fragments originating from 483 trees,which were genotyped with eight mycobiont- and 14 photobiont-specific microsatellitemarkers. The mycobiont and photobiont of L. Pulmonaria were found to consist of twodistinct gene pools, which are co-existing within small areas of 3–180 ha in a homoge-neous beech forest. The small-scale distribution pattern of the symbiotic gene poolsshow habitat partitioning of lineages associated with either floodplains or mountainforests. Using approximate Bayesian computation (ABC), we dated the divergence ofthe two fungal gene pools of L. Pulmonaria as the Early Pleistocene. Both fungal genepools survived the Pleistocene glacial cycles in the Carpathians, although possibly inclimatically different refugia. Fungal diversification prior to these cycles and the selec-tion of photobionts with different altitudinal distributions explain the current sympat-ric, but ecologically differentiated habitat partitioning of L. Pulmonaria. In addition,the habitat preferences of the mycobiont are determined by other factors and are ratherindependent of those of the photobiont at the landscape level. The distinct gene poolsshould be considered evolutionarily significant units and deserve specific conservationpriorities in the future, for example gene pool A, which is a Pliocene relict.Keywords: altitude, approximate Bayesian computation, Dictyochloropsis reticulata, epiphyticlichen, mycobiont, population geneticsReceived 18 September 2013; revision received 30 August 2014; accepted 15 September 2014
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Characterization of microsatellite loci in the lichen fungus Lobaria Pulmonaria (Lobariaceae)
Applications in Plant Sciences, 2013Co-Authors: Silke Werth, Carolina Cornejo, Christoph ScheideggerAbstract:Premise of the study: Microsatellite loci were developed for the threatened haploid lichen fungus Lobaria Pulmonaria to increase the resolution to identify clonal individuals, and to study its population subdivision. Methods and Results: We developed 14 microsatellite markers from 454 DNA sequencing data of L. Pulmonaria and tested for cross-amplification with L. immixta and L. macaronesica. The number of alleles per locus ranged from two to 23. Nei's unbiased gene diversity, averaged over loci, ranged from 0.434 to 0.517 in the three studied populations. Conclusions: The new markers will increase the genetic resolution in studies that aim at disentangling clones in L. Pulmonaria and may be useful for closely related species within Lobaria sect. Lobaria.
Knut Asbjørn Solhaug - One of the best experts on this subject based on the ideXlab platform.
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Short- and long-term freezing effects in a coastal (Lobaria virens) versus a widespread lichen (L. Pulmonaria).
Cryobiology, 2018Co-Authors: Knut Asbjørn Solhaug, Dipa Paul Chowdhury, Yngvar GauslaaAbstract:Abstract Lichens are considered freezing tolerant, although few species have been tested. Growth, a robust measure of fitness integrating processes in all partners of a lichen thallus, has not yet been used as a viability measure after freezing. We compared relative growth rates (RGR) after freezing with short-term viability measures of photo- and mycobiont functions in the coastal Lobaria virens and the widespread L. Pulmonaria to test the hypothesis that low temperature shapes the coastal distribution of L. virens. Hydrated thalli from sympatric populations were subjected to freezing at −10, −20 and −40 °C for 5 h. The rate of cooling and subsequent warming was 5 °C h−1. Short-term viability measures of photobiont (maximal photosystem II efficiency, effective PSII yield) and mycobiont viability (conductivity index), as well as subsequent RGR, were assessed. The exotherms showed that L. virens froze at −3 °C; L. Pulmonaria, at −4 °C. Freezing significantly impaired short-term viability measures of both photo- and mycobiont, particularly in the coastal species. Lobaria Pulmonaria grew 2.1 times faster than L. virens, but the short-term damage after one freezing event did not affect the long-term RGR in any species. Thereby, short-term responses were impaired by freezing, long-term responses were not. While the lacking RGR-responses to freezing suggest that freezing tolerance does not shape the coastal distribution of L. virens, the significant reported adverse short-term effects in L. virens may be aggravated by repeated freezing-thawing cycles in cold winters. In such a perspective, repeated freezing may eventually lead to reduced long-term fitness in L. virens.
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Fungal tissue per se is stronger as a UV-B screen than secondary fungal extrolites in Lobaria Pulmonaria
Fungal Ecology, 2017Co-Authors: Yngvar Gauslaa, Azharul Alam, Pierre-louis Lucas, Dipa Paul Chowdhury, Knut Asbjørn SolhaugAbstract:Abstract To test the hypotheses that (1) protective mycobiont tissues and/or (2) medullary UV-B-absorbing carbon-based secondary compounds (CBSCs) protect lichen photobionts against UV-B radiation, we quantified cortical UV-transmittance and ran a three-way factorial lab experiment with (1) three UV radiation regimes, (2) photobiont layers with/without a screening cortex, and (3) with natural/reduced CBSC-concentration. We used melanin-deficient Lobaria Pulmonaria from shaded forests. Maximum photochemical efficiency of photosystem II ( F v/ F m) in photobionts inside thalli with natural CBSC-concentrations was not affected by any UV-regime, consistent with close to 0% measured cortical transmittance of wavelengths P P P = 0.001), mainly affecting exposed photobiont layers given short-wavelength UV radiation. Based on these findings, we conclude that the primary role of extrolites in L. Pulmonaria is not to screen excess solar radiation.
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fungal depsidones an inducible or constitutive defence against herbivores in the lichen lobaria Pulmonaria
Basic and Applied Ecology, 2009Co-Authors: Johan Asplund, Knut Asbjørn Solhaug, Yngvar GauslaaAbstract:Herbivore-deterrent depsidones in the epiphytic lichen Lobaria Pulmonaria were quantified after a 104-day exposure to indigenous lichen-feeding mollusc communities in broadleaved deciduous forests in southeastern Norway. Controls and acetone-rinsed living thalli were transplanted under open and shaded tree canopies. Rinsed thalli had their depsidone concentration reduced to 36% of the pre-rinsing level, which is below the level needed to deter grazing molluscs. Grazing did not raise the concentration of depsidones beyond the level occurring in control to which molluscs had no access. Inducible responses were not detected in controls nor in acetone-rinsed thalli. Depsidone resynthesis was negligible in acetone-rinsed thalli regardless of grazing and/or light regimes. Our results suggest that C-based depsidones represent a constitutive type of herbivore defence in L. Pulmonaria. A constitutive defence is probably an advantage for stress-tolerant slow-growing lichens inhabiting habitats with a constant presence of generalist invertebrate herbivores.
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Fungal depsidones – an inducible or constitutive defence against herbivores in the lichen Lobaria Pulmonaria?
Basic and Applied Ecology, 2009Co-Authors: Johan Asplund, Knut Asbjørn Solhaug, Yngvar GauslaaAbstract:Herbivore-deterrent depsidones in the epiphytic lichen Lobaria Pulmonaria were quantified after a 104-day exposure to indigenous lichen-feeding mollusc communities in broadleaved deciduous forests in southeastern Norway. Controls and acetone-rinsed living thalli were transplanted under open and shaded tree canopies. Rinsed thalli had their depsidone concentration reduced to 36% of the pre-rinsing level, which is below the level needed to deter grazing molluscs. Grazing did not raise the concentration of depsidones beyond the level occurring in control to which molluscs had no access. Inducible responses were not detected in controls nor in acetone-rinsed thalli. Depsidone resynthesis was negligible in acetone-rinsed thalli regardless of grazing and/or light regimes. Our results suggest that C-based depsidones represent a constitutive type of herbivore defence in L. Pulmonaria. A constitutive defence is probably an advantage for stress-tolerant slow-growing lichens inhabiting habitats with a constant presence of generalist invertebrate herbivores.
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Curling during desiccation protects the foliose lichen Lobaria Pulmonaria against photoinhibition
Oecologia, 2006Co-Authors: Miloš Barták, Knut Asbjørn Solhaug, Hana Vráblíková, Yngvar GauslaaAbstract:This study aims to assess the photoprotective potential of desiccation-induced curling in the light-susceptible old forest lichen Lobaria Pulmonaria by using chlorophyll fluorescence imaging. Naturally curled thalli showed less photoinhibition-induced limitations in primary processes of photosynthesis than artificially flattened specimens during exposures to 450 μmol m^−2 s^−1 in the laboratory after both 12- (medium dose treatment) and 62-h duration (high dose treatment). Thallus areas shaded by curled lobes during light exposure showed unchanged values of measured chlorophyll fluorescence parameters ( F _V/ F _M, Φ_PS II), whereas non-shaded parts of curled thalli, as well as the mean for the entire flattened thalli, showed photoinhibitory limitation after light treatments. Furthermore, the chlorophyll fluorescence imaging showed that the typical small-scale reticulated ridges on the upper side of L. Pulmonaria caused a spatial, small-scale reduction in damage due to minor shading. Severe dry-state photoinhibition readily occurred in flattened and light-treated L. Pulmonaria , although the mechanisms for such damage in a desiccated and inactive stage are not well known. Natural curling is one strategy to reduce the chance for serious photoinhibition in desiccated L. Pulmonaria thalli during high light exposures.
Branko Zupan - One of the best experts on this subject based on the ideXlab platform.
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New locality and sites of Pulmonaria australis in the Triglav Mountains (the Julian Alps, NW Slovenia) / Novo nahajališče in rastišča vrste Pulmonaria australis v Triglavskem pogorju (Julijske Alpe, Slovenija)
2013Co-Authors: Igor Dakskobler, Branko ZupanAbstract:The paper describes a new locality and sites of Pulmunaria australis in the Triglav Mountains under the peak Spodnja Brda on the northern edge of the Pokljuka plateau. Pulmonaria australis is a new species in the flora of both the Triglav National Park and the eastern Julian Alps. This locality is very different from its other known localities in Slovenia in terms of its elevation belt (almost 1800 m a.s.l.) and its sites (stony grassland on an overgrown scree slope with dominating species of the class Elyno-Seslerietea); it is, however, similar to some Pulmonaria australis sites in other Alpine regions, such as South Tyrol in N Italy. Key words: phytogeography, phytosociology, Pulmonaria australis, Julian Alps, Triglav National Park, northwestern Slovenia Opisujemo novo nahajalisce in rastisca vrste Pulmunaria australis v Triglavskem pogorju, pod vzpetino Spodnja Brda na severnem robu Pokljuke. To je novost za floro Triglavskega narodnega parka in vzhodnih Julijskih Alp. Po visinskem pasu uspevanja (skoraj 1800 m nm. v.) in rastiscih (kamnito travisce na poraslem meliscu s prevladujocimi vrstami razreda Elyno-Seslerietea) se to nahajalisce precej razlikuje od njenih drugih znanih nahajalisc v Sloveniji, podobno pa je nekaterim njenim nahajaliscem v drugih alpskih pokrajinah, na primer na Južnem Tirolskem v severni Italiji. Kljucne besede: fitogeografija, fitocenologija, Pulmonaria australis, Julijske Alpe, Triglavski narodni park, severozahodna Slovenija
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NOVO NAHAJALIŠČE IN RASTIŠČA VRSTE Pulmonaria AUSTRALIS V TRIGLAVSKEM POGORJU (JULIJSKE ALPE, SLOVENIJA)
2013Co-Authors: Igor Dakskobler, Branko ZupanAbstract:UDC 581.9(234.323.6:497.4):582.901 New locality and sites of Pulmonaria australis in the Triglav Mountains (the Julian Alps, NW Slovenia) The paper describes a new locality and sites of Pulmunaria australis in the Triglav Mountains under the peak Spodnja Brda on the northern edge of the Pokljuka plateau. Pulmonaria australis is a new species in the flora of both the Triglav National Park and the eastern Julian Alps. This locality is very different from its other known localities in Slovenia in terms of its elevation belt (almost 1800 m a.s.l.) and its sites (stony grassland on an overgrown scree slope with dominating species of the class Elyno-Seslerietea); it
Johan Asplund - One of the best experts on this subject based on the ideXlab platform.
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Contrasting changes in palatability following senescence of the lichenized fungi Lobaria Pulmonaria and L. scrobiculata
Fungal Ecology, 2012Co-Authors: Johan Asplund, David A. WardleAbstract:Epiphytic lichens can contribute significantly to ecosystem nutrient input because they efficiently accumulate atmospheric mineral nutrients and, in the case of cyanolichens, also fix nitrogen. The rate at which carbon and other nutrients gained by lichens enters the ecosystem is determined by lichen litter decomposability and by invertebrate consumption of lichen litter. In turn, these processes are driven by the secondary compounds present in senesced lichens. Therefore, we explored how lichen palatability and concentrations of secondary compounds change with tissue senescence for Lobaria Pulmonaria, a green-algal lichen with cyanobacterial cephalodia, and Lobaria scrobiculata, a cyanobacterial lichen. During senescence both lichens lost 38–48 % of their stictic acid chemosyndrome, while m-scrobiculin and usnic acid in L. scrobiculata remained unchanged. Snails preferred senesced rather than fresh L. Pulmonaria, while senesced L. scrobiculata were avoided. This provides evidence that species with labile secondary compounds will have higher turnover rates, through consumption and decomposition, than those producing more stable secondary compounds.
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Contents of carbon based defence compounds in the old forest lichen Lobaria Pulmonaria vary along environmental gradients
Fungal Ecology, 2011Co-Authors: Steinar Vatne, Johan Asplund, Yngvar GauslaaAbstract:Abstract We quantified carbon based secondary compounds (CBSC) in 182 Lobaria Pulmonaria thalli sampled in a range of forest types along an elevation gradient in southern Norway to assess the importance of external and internal factors as a source of variation for the CBSC content. The best multiple regression model for CBSC content included altitude, soil pH, dry weight (DW) per area and thallus size. Total CBSC content decreased with altitude and increased with pH. L. Pulmonaria maximizes its CBSC content in sites with long gastropod grazing seasons (lowland forests) and high gastropod abundance (calcareous soils). Secondly, we assessed grazing damage in the L. Pulmonaria thalli to test the hypothesis that natural populations of gastropods respond to the CBSC level in situ . We found a significantly negative correlation between the stictic acid concentration and grazing damage from gastropods, which is consistent with an evolutionary arms race between lichens and gastropods. This relationship became stronger when using the tree trunk as a factor in the ANCOVA, consistent with spatial variation in gastropod occurrences.
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Grazing damage in the old forest lichen Lobaria Pulmonaria increases with gastropod abundance in deciduous forests.
The Lichenologist, 2010Co-Authors: Steinar Vatne, Johan Asplund, Torstein Solhøy, Yngvar GauslaaAbstract:Abstract: Gastropod abundance was quantified in forest litter around 33 trees harbouring LobariaPulmonaria in southern Norway. In total, 1709 snails representing 28 species were found, and thenumberofsnailspeciesstronglyincreasedwiththetotalnumberofspecimensfound.Numberofsnailspecies, as well as snail abundance, was highest around trees on high pH soils. There was a positiverelationship between number of snail specimens and cover of grazing traces on L. Pulmonaria ,presumablybecausecalcareoussoilsfacilitatebothlitterdwellingandclimbinggastropods.Theresultssuggest that gastropods may limit the distribution of L. Pulmonaria in calcareous broad-leaved forests. Key words: epiphytes, herbivory, leaf litter, pH, snails Introduction Some gastropods eat lichens, but the grazingimpact depends, among other factors, on thecontent of lichen compounds that have adeterringeffect(e.g.Zukal1895;Stahl1904;Lawrey 1980). As lichen compounds canbe non-destructively extracted from livinglichens (Solhaug & Gauslaa 2001), their de-terring effect can be quantified in experi-ments (Gauslaa 2005). Gastropod grazingdecreases with increasing concentration ofcertain lichen compounds such as the sticticacid complex in
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fungal depsidones an inducible or constitutive defence against herbivores in the lichen lobaria Pulmonaria
Basic and Applied Ecology, 2009Co-Authors: Johan Asplund, Knut Asbjørn Solhaug, Yngvar GauslaaAbstract:Herbivore-deterrent depsidones in the epiphytic lichen Lobaria Pulmonaria were quantified after a 104-day exposure to indigenous lichen-feeding mollusc communities in broadleaved deciduous forests in southeastern Norway. Controls and acetone-rinsed living thalli were transplanted under open and shaded tree canopies. Rinsed thalli had their depsidone concentration reduced to 36% of the pre-rinsing level, which is below the level needed to deter grazing molluscs. Grazing did not raise the concentration of depsidones beyond the level occurring in control to which molluscs had no access. Inducible responses were not detected in controls nor in acetone-rinsed thalli. Depsidone resynthesis was negligible in acetone-rinsed thalli regardless of grazing and/or light regimes. Our results suggest that C-based depsidones represent a constitutive type of herbivore defence in L. Pulmonaria. A constitutive defence is probably an advantage for stress-tolerant slow-growing lichens inhabiting habitats with a constant presence of generalist invertebrate herbivores.
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Fungal depsidones – an inducible or constitutive defence against herbivores in the lichen Lobaria Pulmonaria?
Basic and Applied Ecology, 2009Co-Authors: Johan Asplund, Knut Asbjørn Solhaug, Yngvar GauslaaAbstract:Herbivore-deterrent depsidones in the epiphytic lichen Lobaria Pulmonaria were quantified after a 104-day exposure to indigenous lichen-feeding mollusc communities in broadleaved deciduous forests in southeastern Norway. Controls and acetone-rinsed living thalli were transplanted under open and shaded tree canopies. Rinsed thalli had their depsidone concentration reduced to 36% of the pre-rinsing level, which is below the level needed to deter grazing molluscs. Grazing did not raise the concentration of depsidones beyond the level occurring in control to which molluscs had no access. Inducible responses were not detected in controls nor in acetone-rinsed thalli. Depsidone resynthesis was negligible in acetone-rinsed thalli regardless of grazing and/or light regimes. Our results suggest that C-based depsidones represent a constitutive type of herbivore defence in L. Pulmonaria. A constitutive defence is probably an advantage for stress-tolerant slow-growing lichens inhabiting habitats with a constant presence of generalist invertebrate herbivores.
