Yngvar Gauslaa

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• PhD
• Professor Emeritus at Norwegian University of Life Sciences

The mat-forming fruticose lichens Cladonia stellaris and Cetraria islandica frequently co-occur on soils in sun-exposed boreal, subarctic, and alpine ecosystems. While the dominant reindeer lichen Cladonia lacks a cortex but produces the light-reflecting pale pigment usnic acid on its surface, the common but patchier Cetraria has a firm cortex seal...

Spatial variations in epiphytic macrolichen richness in the city of Oslo were assessed annually 1973–2019. These observations were contrasted with earlier published data from 1930 to examine how long-term changes in species richness of functional groups track different stages of air pollution regimes. From 1930 to the 1970’s, representing the early...

Canada's endangered Deep-Snow Mountain Caribou (DSC) are endemic to mountainous southern inland British Columbia, where they subsist in winter on an almost exclusive diet of epiphytic hair lichens, especially Bryoria fremontii and B. pseudofuscescens (the high-biomass Bryoria spp.) and Alectoria sarmentosa . Importantly, stand-level hair lichen loa...

This study aims to elucidate the connection between the phylogeny of epiphytic macrolichens and their chemical niches. We analyzed published floristic and environmental data from 90 canopies of Picea glauca x engelmannii across various forest settings in British Columbia. To explore the concordance between a principal coordinates analysis of the cl...

This study investigates extraction and quantification techniques for chlorophylls (Chl) in melanic lichens, with an emphasis on distinguishing between Chl and melanin absorbance during spectrophotometric assessments. We compared various extraction protocols, involving solvents such as dimethyl sulfoxide (DMSO) and acetone, and methods including int...

Epiphytic lichens are considered sensitive indicators of environmental change. Excess water is known to depress their photosynthesis, but the effect of long-lasting rain on species richness of epiphytic lichens is rarely reported. By annually repeated records of macrolichen species richness on tree trunks over a period of 33 years that included one...

There is a need for non-invasive monitoring of temporal and spatial variation in hydration and photosynthetic activity of red-listed poikilohydric autotrophs. Here, we simultaneously recorded kinetics in RGB-colors (photos), reflectance spectra, water content, maximal (F V /F M), and effective quantum yield of PSII (Φ PSII) during desiccation in fo...

Hair lichens are distinctive for their capillary growth and typically arboreal occurrence, especially in temperate and boreal forests. They consist of two morphogroups based on cortical pigments, i.e., a brown-black group with fungal melanin and a pale yellow-green group with usnic acid. Here we test the hypothesis that these morphogroups are ecolo...

Tree-dwelling hair lichens in the genus Bryoria provide crucial late-winter forage for Deep-Snow Mountain Caribou (DSC), an imperiled ungulate endemic to south-central British Columbia, Canada. Because DSC survival requires continuous access to heavy hair lichen loadings, conservation efforts can benefit from an improved understanding of the factor...

Lichen extinction occurs at rapid rates as a result of human activity, although species could potentially be rescued by conservation management based on ecophysiological knowledge. The boreal old forest cyanolichen Erioderma pedicellatum currently occurs in few sites worldwide. To protect it from extinction, it is essential to learn more about it....

Mat-forming lichens dominating high-latitudinal habitats vary in color and geometry. Widespread species are light greenish yellow (usnic acid) and reflect solar radiation, whereas melanic species absorbing most solar wavelengths are spatially more restricted. Color thereby influences lichens’ energy budget and thus their hydration and photosyntheti...

Conservation of epiphytic lichens in managed forest landscapes relies on understanding limitations to their dispersal and establishment after harvesting. A hot spot for cephalo- and cyanolichens, the Kispiox inland temperate rainforest of British Columbia, Canada, is an example of where forest managers seek silviculture options that allow for fores...

Lichens are frequently used as indicators of air-borne depositions, yet the differential effect of different mineral nutrients on lichen growth is still poorly understood. Here we quantify relative lichen growth rates (RGR) in representatives of three functional groups (chloro-, cephalo-, cyanolichens; Xanthoria parietina, Lobaria pulmonaria, Lobar...

To what extent does epiphytic community composition in boreal forests reflect soil nutrient status? To answer this question, we investigated potential links between terrestrial plants and lichen-dominated communities in Picea glauca x engelmannii canopies in south-central British Columbia. We combined original data on vegetational composition in th...

Main conclusion During desiccation, both apparent electron transport rate (ETRapp) and photosynthetic CO2 uptake peak when external water has evaporated. External water, causing suprasaturation, weakens the strong correlation between ETRapp and CO2 uptake. Abstract Lichens are poikilohydric organisms passively regulated by ambient conditions. In t...

The western temperate-tropical fruticose species lichen Usnea rubicunda Stirt. is reported as new to Scandinavia from a locality in Farsund municipality, Vest-Agder, south-west Norway. The fungal barcode marker, nrITS, shows a 99.8–100 % similarity with British specimens, and the known small Norwegian population is assumed to have recently immigrat...

Epiphytic lichens are important biodiversity components of forest canopies world‐wide, significantly contributing to ecosystem function. The RGR, a measure of fitness, drives population dynamics and shapes lichens’ large‐scale distributions. In a climate change scenario, we need to know how external (macro‐ and microclimate, and nitrogen deposition...

How do elemental composition (published data) and melanin (new data) shape the relative growth rate (RGR; new data) of the cephalolichen Lobaria pulmonaria, a member of the Lobarion community? We transplanted L.pulmonaria onto Picea glauca x engelmannii branches in three unmanaged canopy settings in inland British Columbia: within Populus dripzones...

Although water is essential for photosynthetic activation in lichens, rates of vapor uptake and activation in humid air, which likely influence their niche preferences and distribution ranges, are insufficiently known. This study simultaneously quantifies rehydration kinetics and PSII reactivation in sympatric, yet morphologically and functionally...

Erioderma pedicellatum, an enigmatic boreal cyanolichen epiphyte is sympatric with the widespread pantropical cyanolichen Coccocarpia palmicola in cool and damp forests in Atlantic parts of Canada. After sampling co-occurring specimens of these lichens in Newfoundland, we quantified important hydration traits. We hypothesized that 1: these lichens...

We quantified annual growth rate and loss of Bryoria capillaris and Usnea dasopoga transplants on Picea abies on parts of lower branches in the inner versus outer canopy in small, medium and tall trees in hemiboreal forests. Light at branches in the inner canopy was 2.7 x (for Bryoria capillaris) and 2.0 x (for Usnea dasopoga) higher than the liche...

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 low...

Some lichenized ascomycetes synthesize melanic pigments in their upper cortices when exposed to ultraviolet light and high solar radiation. Our previous work showed that melanized chloro- and cyanolichens from both high light and more shaded habitats were less photoinhibited than pale ones during controlled exposure to high light. However, protecti...

Main conclusion Photobiont type influences the relative humidity threshold at which photosystem II activates in green algal lichens. Abstract Water vapor uptake alone can activate photosynthesis in lichens with green algal photobionts. However, the minimum relative humidity needed for activation is insufficiently known. The objective of this study...

Hydration traits determine much of a lichen’s distribution pattern along a climatic gradient but the mechanisms involved are still incompletely known. A higher abundance of large external cephalodia in wet oceanic than in drier climates has previously been reported in Lobaria amplissima . This study aims to quantify how much more rain L. amplissima...

Main conclusion Chlorophyll fluorescence, infrared gas exchange and photoinhibition data consistently show that vulpinic acid in L. vulpina functions as a strong blue light screening compound. The cortical lichen compounds, parietin, atranorin, usnic acid and melanins are known to screen photosynthetically active radiation (PAR), thereby protecting...

Retention of trees after logging is a method of preserving epiphytic lichens; however, epiphytes’ responses to logging disturbance are insufficiently known. We aimed to characterize four viability measures — effective PSII yield (ΦPSII; a proxy for photosynthesis), maximal photosystem II efficiency (FV/FM; a proxy for photoinhibition), chlorophyll...

Links between lichen morphology, internal/external water storage and distribution patterns are poorly known. We compared mass- (WC, % H2O) and area-based (WHC, mg H2O cm-2) hydration traits in seven pendent or shrubby Usnea species from oceanic to continental climates. All species held more external than internal water. Internal WHC and WC increase...

We studied the potential to use reintroduction of two declining N-fixing flagship lichens to identify factors affecting failure or success in SW Swedish sites that had experienced substantially reduced acidification. After transplanting the critically endangered Lobaria amplissima ± external cephalodia and its near-threatened associate Lobaria pulm...

Lichen photobionts in situ have an extremely UV-B tolerant photosystem II efficiency (Fv/Fm). We have quantified the UV-B-screening offered by the mycobiont and the photobiont separately. The foliose lichens Nephroma arcticum and Umbilicaria spodochroa with 1: intact or 2: removed cortices were exposed to 0.7 Wm⁻² UV-BBE for 4 h. Intact thalli expe...

Tree species differ in longevity, canopy structure, and bark texture, chemistry and water storage. Tree species-specific traits play a role in shaping epiphytic vegetation and likely influence the community assembly of organisms feeding on epiphytes. Lichenivorous gastropods, species with calcium-rich shells in particular, need calcium and likely o...

Lichen photobionts in situ have an extremely UV-B tolerant photosystem II efficiency (Fv/Fm). We have quantified the UV-B-screening offered by the mycobiont and the photobiont separately. The foliose lichens Nephroma arcticum and Umbilicaria spodochroa with 1: intact or 2: removed cortices were exposed to 0.7 Wm-2 UV-BBE for 4 h. Intact thalli expe...

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...

Identifying lichen traits that influence hydration and photosynthetic reactivation kinetics in humid air provides insight into niche preferences. Water vapor uptake and concurring reactivation of PSII efficiency (Fv/Fm) were monitored at high temporal resolution by means of programmed balance measurements and chlorophyll fluorescence imaging during...

Woodlice are not widely recognized as lichen-feeding invertebrates. We sought to discover whether the woodlouse, Porcellio scaber, could feed on the lichen Hypogymnia physodes and if the lichen carbon-based secondary compounds CBSCs would reduce grazing. We cut lichen thalli in two pieces, one was non-destructively rinsed in acetone to remove CBSCs...

Usnea longissima is a threatened hair lichen requiring long ecological continuity in forests. Assumingly it needs a combination of high light and high humidity which is rarely realized under modern forestry regimes. In this study, we tested the hypothesis that the longest individuals of U. longissima, one measure of lichen fitness, occurs in forest...

Lichens hold water inside (internal pool) and outside their body (external pool). Yet, external pool size is not known in hair lichens dominating boreal forest canopies. Here we quantify morphological traits and internal/external water in two widespread Bryoria species along Picea abies canopy-height gradients: Bryoria fuscescens at 5–20 m and Bryo...

Background and aims: Understanding to what extent parasites affect host fitness is a focus of research on ecological interactions. Fungal parasites usually affect the functions of vascular plants. However, parasitic interactions comprising effects of fungal parasites on the fitness of lichen hosts are less well known. This study assesses the effec...

We quantified relative growth rates (RGR) in shade-adapted and melanin-deficient thalli of Cetraria islandica and Lobaria pulmonaria cultivated in short-term growth chamber experiments with and without UV-B radiation. In the first experiment done under optimal PAR (125 μmol m⁻² s⁻¹), but high UV-B radiation (1 W m⁻²), UV-B radiation significantly r...

This study aims to quantify the size-dependency of important hydration traits in Lobaria amplissima, L. pulmonaria and L. virens sampled in sympatric populations on deciduous tree trunks in southern Norway, and to discuss possible implications of species-specific traits for the ecological niches of these old forest cephalolichens. Traits measured w...

By fluorescence imaging, we quantified how hydration traits and thallus size determine the duration of photosynthetic activity during drying in light and darkness for sympatric populations of three epiphytic old forest cephalolichens differing in specific thallus mass (STM) and growth form. Maximal PS II efficiency (FV/FM) during drying in darkness...

Lichens as sessile and slow-growing symbiotic associations have evolved various carbon-based secondary compounds (CBSCs) to mitigate the effects of some stressors in the extreme environments in which they often grow. The mat-forming lichen Cladonia stellaris , an important fodder for reindeer, produces usnic acid in the outermost layer and perlatol...

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 sc...

In order to improve growth chamber protocols for lichens, we tested the effect of 1) wet filter paper versus self-drained nets as a substratum for lichens, and 2) gradual versus abrupt transitions between dark and light periods. For Lobaria pulmonaria (L.) Hoffm. cultivated on nets, RGR increased by 60% compared to those on wet papers, whereas abru...

Relative growth rates (RGR) and carbon-based secondary compounds (CBSCs) were quantified in four dominant terricolous arctic-alpine mat-forming lichens with different preferences for snow cover. The aim was to evaluate the effects of snow depth, and thus snow cover duration, on lichen growth and performance. The species, Alectoria ochroleuca , Flav...

Lichens are hosts for a variety of lichenicolous fungi. By investigating two lichens with specialized parasites, we will test the hypothesis that these parasites reduce lichen fitness by increasing the palatability of their respective hosts. The palatability of Lobarina scrobiculata and Lobaria pulmonaria with or without galls of the lichenicolous...

Lichens are useful monitoring organisms for heavy metal pollution. They are high in carbon based secondary compounds (CBSCs) among which some may chelate heavy metals and thus increase metal accumulation. This study quantifies CBSCs in four epiphytic lichens transplanted for 6months on stands along transects from a highway in southern Norway to sea...

Hair lichens (Alectoria, Bryoria, Usnea) with high surface-area-to-mass ratios rapidly trap moisture. By photography and scanning we examined how internal water storage depended on morphological traits in five species. Specific thallus mass (STM, mg DM cm-2) and water holding capacity (WHC, mg H2O cm-2) after shaking and blotting a fully hydrated t...

In the lab, we exposed three foliose lichen species, Lobaria pulmonaria, Parmelia sulcata and Xanthoria aureola, to 0, 0.01, 0.2, and 0.6 M NaCl in combinations with copper and zinc (0, 10, 100, 500 μM). High salt concentrations adversely affected the lichen membrane integrity as measured by conductivity methods, whereas the potential photosystem I...

The lichen Hypogymnia physodes was sampled from spruce trunks and we used to assess natural elements in the throughfall from pairs of neighbouring beech (Fagus sylvatica) and spruce (Picea abies) canopies in an unmanaged forest reserve. The beech bark (pH = 4.36 ± 0.13) was less acidic than spruce bark (3.71 ± 0.06). After a 1 yr transplantation on...

This growth chamber experiment evaluates how temperature and humidity regimes shape soluble carbohydrate pools and growth rates in lichens with different photobionts. We assessed soluble carbohydrates, relative growth rates ( RGRs ) and relative thallus area growth rates ( RT A GRs ) in Parmelia sulcata (chlorolichen), Peltigera canina (cyanolichen...

Reasonable lichen growth rates are required to maintain the important ecosystem functions provided by epiphytic lichen populations. Previously, lichen growth has mainly been quantified in boreal forests. Thus, there is a need for comparable studies from Mediterranean forests. We used reciprocal transplantation to compare relative biomass (RGR) and...

We explore relative growth rates (RGRs) and carbon-based secondary compounds (CBSCs) in epiphytic lichens along height-above-the-ground gradients. The chlorolichen (Letharia vulpina (L.) Hue), the cephalolichen (Lobaria pulmonaria (L.) Hoffm.), and the cyanolichens (Lobaria hallii (Tuck.) Zahlbr., Nephroma helveticum Ach.) were attached to branches...

Chemical interactions between highly host-specific lichenicolous fungi and their lichen hosts have been little studied. In an allometric study, we quantified carbon-based secondary compounds (CBSCs) in a mixed natural Lobarina scrobiculata population (N = 147) of the normal and the stictic acid-deficient chemotypes, both with and without galls of P...

Epiphytic lichens, comprising an important biodiversity component with significant functions in old boreal forests, are susceptible to logging. Leaving retention trees may partly compensate for the adverse effects of logging, but the impact of logging season on retained lichens is unknown. To identify the least harmful logging season seen from an e...

This study aims to quantify dispersal of airborne traffic-related elemental pollutants and concurring responses – relative growth rate (RGR), maximal quantum yield of PSII (Fv/Fm), and chlorophylls (Chl ab) – in four epiphytic lichens (Lobaria pulmonaria, Parmelia sulcata, Ramalina farinacea, Usnea dasopoga). Lichens were transplanted from 25 Septe...

Pendulous lichens dominate canopies of boreal forests, with dark Bryoria species in the upper canopy vs. light Alectoria and Usnea species in lower canopy. These genera offer important ecosystem services such as winter forage for reindeer and caribou. The mechanism behind this niche separation is poorly understood. We tested the hypothesis that spe...

Photosynthesis was compared in two cyanobacterial lichens (Lobaria hallii and Peltigera praetextata) and two green algal lichens (Lobaria pulmonaria and Peltigera leucophlebia) exposed to red, green or blue light. Cyanolichens had substantially lower photosynthetic CO2 uptake and O2 evolution than the green algal lichens in blue light, but slightly...

We measured the water holding capacity per area (WHCA;mgH2O/cm2), and thus the saturating rainfall (mm), for sympatric cyano- (Lobaria scrobiculata and Pseudocyphellaria crocata) and cephalolichens (Lobaria pulmonaria) along canopy height gradients in boreal rainforests, to quantify the importance of specimen size, photobiont type and branch height...

This review is a first attempt to combine and compare spatial distribution of the three main water sources, rain, dew and humid air, with water-related traits of mainly epiphytic macrolichens in a conceptual and functional model. By comparing climatic and lichenological knowledge, various effects of dewfall, rainfall and humid air on epiphytic lich...

All specimens of three foliose lichens (Lobaria pulmonaria (L.) Hoffm., n = 725; Lobaria scrobiculata (Scop.) DC., n = 6613; Pseudocyphellaria crocata (L.) Vain., n = 1237) and two pendulous lichens (Alectoria sarmentosa (Ach.) Ach., n = 441; Ramalina thrausta (Ach.) Nyl., n = 990) were collected from 160 random Picea abies (L.) H. Karst. branches...

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...

This study investigates how hydration during light and dark periods influences growth in two epiphytic old forest lichens, the green algal Lobaria pulmonaria and the cyanobacterial L. scrobiculata. The lichens were cultivated in growth chambers for 14 days (200 μmol m−1 s−2; 12 h photoperiod) at four temperature regimes (25/20 °C, 21/16 °C, 13/8 °C...

Overstory Populus has been shown to facilitate establishment by cyano- and cephalolichens on conifer branches within its dripzone; though the mechanisms behind this “dripzone effect” have yet to be elucidated. Here we test the following hypotheses that throughfall from Populus: (i) elevates bark pH; (ii) increases relative growth rate in cephalolic...

The functional roles of secondary lichen compounds are reviewed with focus on sun-screening and herbivore-deterring functions. Hypotheses on ecological functions can be tested because lichen compounds can nondestructively be extracted from air-dry lichens with 100% acetone. Substantial evidence supports a sun-screening function of cortical compound...

Desiccation tolerance was quantified in four cyanolichens (Lobaria hallii, Lobaria retigera, Lobaria scrobiculata, Pseudocyphellaria anomala), one cephalolichen (Lobaria pulmonaria) and one chlorolichen (Platismatia glauca) from xeric and mesic, open and closed North American boreal forests. These sympatric epiphytes were exposed to 0%, 33%, 55% a...

We explored patterns of plant species richness and composition along an elevational gradient (4,985–5,685 m a.s.l.) on Buddha Mountain, 100 km northwest of Lhasa, Tibet. We recorded the presence of plants and lichens in 1-m2 quadrats separated by 25-m elevational intervals (174 quadrats in 29 elevational bands) along a vertical transect with a SE a...

Growth in two old forest lichens was studied to evaluate how temporal (seasonal) and spatial (aspect-wise) partitioning of biomass and area growth respond to seasonal changes in light and climate. We monitored relative growth rates during annual courses in the cephalolichen Lobaria pulmonaria and the cyanolichen Lobaria scrobiculata transplanted in...

Punctelia jeckeri, a foliose lichen considered to be critically endangered in Norway, was recently found in abundance on a number of trees located by a stone wall between two small and old meadows near the southernmost tip of Norway. One large oak Quercus sp. (70 cm girth), abundant with P. jeckeri from the base up to thin canopy twigs supported a...

Cyanolichens (Lobaria hallii, Lobaria retigera, Lobaria scrobiculata, Pseudocyphellaria anomala) and cephalodial (Lobaria pulmonaria) and noncephalodial (Platismatia glauca) chlorolichens were sampled in dry open, mesic open, and mesic closed forests in central British Columbia. Specific thallus mass (STM), water-holding capacity (WHC), percent wat...

textlessptextgreatertextlessbr/textgreaterWe 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...

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...

This study compares the success of vegetative diaspore establishment of the old forest lichens Lobaria pulmonaria and L. scrobiculata sown on Picea abies branches in boreal rainforests. The larger diaspores of L. pulmonaria (green algal photobiont) established more successfully, and showed a greater flexibility in ecological amplitude, than the sma...

Generation time and juvenile growth rates are important but poorly known parameters in lichen population biology. By using a noninvasive method, we aimed to quantify these variables in juvenile thalli of Lobaria pulmonaria (L.) Hoffm., L.scrobiculata (Scop.) D.C.,and Pseudocyphellaria crocata (L.) Vain., in situ, on twigs of Picea abies (L.) H.Kars...

The optimal defense theory (ODT) deals with defensive compounds improving fitness of a particular organism. It predicts that these compounds are allocated in proportion to the risk for a specific plant tissue being attacked and this tissue's value for plant fitness. As the benefit of defense cannot easily be measured in plants, the empirical eviden...

Gastropod abundance was quantified in forest litter around 33 trees harbouring Lobaria pulmonaria in southern Norway. In total, 1709 snails representing 28 species were found, and the number of snail species strongly increased with the total number of specimens found. Number of snail species, as well as snail abundance, was highest around trees on...

Les lichens sont souvent importants comme organismes photosynthétiques dans les environnements oligotrophiques où les plantes fourragères de haute qualité sont rares. Une forte défense contre les herbivores et/ou une faible qualité nutritionnelle permet une grande accumulation de biomasse de lichens dans de tels secteurs. Cependant, on ne sait pas...

The optimal defense theory (ODT) deals with defensive compounds improving fitness of a particular organism. It predicts that these compounds are allocated in proportion to the risk for a specific plant tissue being attacked and this tissue's value for plant fitness. As the benefit of defense cannot easily be measured in plants, the empirical eviden...

Lichens, representing mutualistic symbioses between photobionts and mycobionts, often accumulate high concentrations of secondary compounds synthesized by the fungal partner. Light screening is one function for cortical compounds being deposited as crystals outside fungal hyphae. These compounds can non-destructively be extracted by 100% acetone fr...

Some lichen compounds are known to deter feeding by invertebrate herbivores. We attempted to quantify the deterring efficiency of lichen compounds against a generalist vertebrate, the bank vole (Myodes glareolus). In two separate experiments, caged bank voles had the choice to feed on lichens with natural or reduced concentrations of secondary comp...

This study of elevation gradients of lichen species richness in Nepal aimed to compare distribution patterns of different life-forms, substratum affinities, photobiont types, and Nepalese endemism. Distribution patterns of lichens were compared with elevational patterns shown by a wide range of taxonomic groups of plants along the Nepalese Himalaya...

Although the tripartite terricolous lichen Nephroma arcticum is easily accessible to lichen-feeding gastropods, grazing marks are mainly restricted to localized cephalodia with N-fixing Nostoc. We tested if this gastropod preference for cephalodia can be explained by differences in carbon based secondary compounds (CBSCs) in cyanobacterial versus g...

Secondary compounds were quantified in 75 thalli of the foliose lichen Hypogymnia physodes collected in habitats along a natural shade-sun gradient from dark spruce forests to sun-exposed sea cliffs. The irradiance in all the 75 lichen sites was estimated from hemispherical photographs. The content of lichen compounds per thallus area correlated po...

This study aimed to assess biomass growth as a response variable in lichens during short-term laboratory experiments. To do this, we studied the influence of UV-B and temperature on lichen performance including the synthesis of solar radiation screening cortical compounds. The pioneer lichen Xanthoria aureola from exposed sea cliffs and the old for...

1. Species composition and biomass of epiphytic lichens varies along a complex environmental gradient from the ground to the top of the forest canopy. It is not known if this gradient, considered to be shaped by succession (age of bark surface) and climatic factors, is also influenced by invertebrate grazing. 2. To investigate the grazing hypothesi...

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 depsidon...

Relationships between thallus size and growth variables were analysed for the foliose Lobaria pulmonaria and the pendulous Usnea longissima with the aim of elucidating their morphogenesis and the factors determining thallus area (A) versus biomass (dry weight (DW) gain. Size and growth data originated from a factorial transplantation experiment tha...

This study reports on mollusc grazing of two epiphytic cyanobacterial lichens (Pseudocyphellaria crocata and Lobaria pulmonaria) transplanted within three Picea abies-dominated boreal rain forest stands (clear-cut, young and old forests) in west central Norway. Grazing was particularly high in transplants located in the old forest and was almost ab...

Hydrated thalli of the lichen Lobaria pulmonaria were either preconditioned to dim irradiance (DI, 5 µmol m−2 s−1) or medium irradiance (MI, 200 µmol m−2 s−1) for 6 h. After this 6 h period, the thalli were allowed to desiccate under the two respective irradiances. Thereafter, these dry lichens were exposed to high irradiance (HI, 1 000 µmol m−2 s−...

Alectorioid and foliose lichens were weighed from full-size branches of Picea abies cut at two canopy heights in 100 trees in an old subalpine forested area in eastern Norway. The mean lichen biomass per branch decreased from 46 to 37 g moving upwards from 2–3 to 5–6 m canopy height. The lichen biomass correlated strongly with branch size variables...