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Abstract 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 pulmonaria onto tree trunks, seasonal growth rates were quantified. We added a phosphorus treatment, using site as a random factor. Growth was positive in winter, and negative in summer, particularly in L. amplissima. Reintroduction of L. amplissima was unsuccessful because gastropods caused significant loss, evidenced by grazing marks. Acer platanoides , a high-pH host, had more grazing than the more acidic Quercus petraea. Gastropods preferred the cephalodia, resulting in substantial loss of the cephalodiate L. amplissima. Phosphorus fertilization had no effects. The widespread L. pulmonaria grew faster than the rare L. amplissima that lost its local growth potential due to aggravated gastropod grazing. Highlights • Growth rates of reintroduced lichens were positive in winter, negative in summer. • Gastropod grazing was much higher in Lobaria amplissima than in Lobaria pulmonaria. • Gastropods grazed more on lichens transplanted to Acer than to Quercus in summer. • One P-fertilization dose did not influence growth rate or grazing. • Reintroduction of Lobaria amplissa to sites in SW Sweden was unsuccessful. [ABSTRACT FROM AUTHOR]

The old forest lichen Lobaria pulmonaria synthesizes melanic pigments when exposed to ultraviolet light and high solar radiation. Here, we tested the effect of melanisation on photosynthetic efficiency. Melanisation effectively reduces high-light stress in lichen photobionts, as the photobionts of melanised thalli are healthy, based on chlorophyll contents and maximum rates of photosynthesis. However, the quantum yields of both photosynthetic CO 2 uptake and O 2 evolution were more than 40 percent lower in melanised thalli compared with control thalli. While chlorophyll fluorescence measurements suggested that melanised and pale thalli had similar apparent electron transport rates, this result was probably an artefact caused by screening reducing the light reaching the photobionts. Melanic thalli also had a higher chlorophyll a/b ratio and more xanthophyll cycle pigments, suggesting that the photosynthetic apparatus had adapted to high light. In conclusion, while protecting photobionts from high light, melanisation clearly reduced photosynthetic efficiency. Melanised thalli will be significantly disadvantaged if light levels return to lower values, more typical for those habitats in which this shade adapted lichen is most abundant. [ABSTRACT FROM AUTHOR]

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 ( F V /F M ) during drying in darkness and effective PSII yield ( Ф PSII ) during drying in light (200 μmol m −2 s −1 ) was repeatedly monitored in lichens under controlled conditions, using chlorophyll fluorescence imaging with simultaneous recordings of wet mass. STM shaping the water holding capacity (WHC), water content in percent at start (WC), and water loss rate per thallus area (WLR) in combination determined the duration of active periods during desiccation between ( r 2 ad j = 0.86) and within species ( r 2 adj = 0.60–0.92). Lobaria pulmonaria with the lowest STM and the most upright growth form experienced the shortest active periods, Lobaria amplissima with the highest STM and the most prostrate growth form had the longest periods. Across the more compact species ( L. amplissima, L. virens ), WLR strongly declined with increasing thallus size, but weakly in the loosely attached L. pulmonaria . Ф PSII , a proxy of photosynthesis, exhibited suprasaturation depression at maximal hydration. Fluorescence imaging allowed a rapid, non-invasive evaluation of the contribution of various functional traits to active periods in entire thalli during desiccation. A thick, prostrate growth form prolongs active periods by maximizing water storage, whereas a thin, loosely attached growth form uses a more flexible hydration strategy with shorter active periods. [ABSTRACT FROM AUTHOR]

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 <325 nm. Exposing photobiont layers to direct radiation strongly aggravated photoinhibition ( P < 0.001), as did an increase in UV-exposure ( P < 0.001). The effect of CBSC-removal was weaker (yet significant at 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. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that structural variables related to old-growth features affect the distribution of Lobaria pulmonaria in a Mediterranean National Park of Italy. A total of 36 plots, with old-growth characteristics and representing overall three forest types (beech- oak- and mixed- forests) were studied. The lichen was absent in about half of the sites, suggesting that the selection of old-growth forests based solely on structural features is not sufficient to predict the presence of this species, which therefore proves to be rather sensitive and selective. Its abundance was related to high tree circumference and basal area, and to availability of deadwood, confirming the relevant effect of substrate and stand continuity in the conservation of this species and emphasizing its role of indicator species of undisturbed forest ecosystems with long ecological continuity. [ABSTRACT FROM AUTHOR]

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The lichen Lobaria pulmonaria is a case-study species for research in forest ecology. Previous studies have emphasised both its niche specialism and slow growth with long generation times, explaining its occurrence on larger/older trees in forest stands with long temporal continuity. Contrastingly, L. pulmonaria is common among a broader range of habitats within an oceanic (‘temperate rainforest’) bioclimatic zone, and we investigate its population dynamics within this context to expand our understanding of the ecology of this model organism. The results indicated some of the highest growth rates and shortest generation times observed globally, with reproductive maturity achieved within c. 5–10 yr. This rapid growth to maturity and raised propagule density can explain the rapid colonisation of L. pulmonaria onto very young hazel stems. The work emphasises the viability of large populations of L. pulmonaria in western Scotland, underlining an International Responsibility for protection within a European context. [ABSTRACT FROM AUTHOR]

Abstract: We measured the water holding capacity per area (WHCA; mg H2O cm−2), 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 as WHCA drivers. Size increased WHCA by a factor of four. Cyanolichens had ≈1.5 times higher WHCA than cephalolichens. Finally, branch height significantly increased WHCA for the Lobaria species. Reported responses are consistent with higher optimal rainfall requirements for reproducing versus juvenile specimens, and for cyanolichens versus those with green algal photobionts. Increased WHCA with height in the canopy is consistent with acclimation to stronger evaporative demands. The results highlight the link between rainfall patterns and maximal sizes realized for a given lichen species and habitat, and extend our understanding of why the cyanolichen/green algal lichen-ratio increases in forests with increasing rainfall. [Copyright &y& Elsevier]

Highlights: [•] Carbon based secondary compounds in studied lichens varied across spatial and seasonal scales. [•] The cortical compound followed spatial variations in sun exposure. [•] The medullary compounds mainly varied seasonally with maxima in summer. [•] The seasonal variation is consistent with herbivore defense functions of medullary compounds. [•] There was no trade-off between relative growth rates and defense investments. [Copyright &y& Elsevier]

Abstract: Industrial forestry has caused large biodiversity changes in European boreal forests. One recently introduced conservation measure in production forestry is retention of trees at clearcutting to benefit flora and fauna. Aspen Populus tremula is often retained for conservation purposes since it is a key tree species for biodiversity with many associated species, a number of which are red-listed. Still, the importance to biodiversity of aspen trees retained at harvest is largely unknown. In 1994, a transplantation experiment with the old-growth forest indicator lichen Lobaria pulmonaria was set up on 280 aspens at 35 sites in east-central Sweden with a total of 1120 transplants, with the aim to assess the habitat suitability of retained aspens following harvest. After 14years 23% of L. pulmonaria transplants remained, with a significantly higher survival on retained aspens than on aspens in the surrounding forest, especially on the northern side of stems. Transplants were also more vital on northern than on southern sides of stems. There was no difference in survival or vitality of transplants between dispersed aspens and aspens in groups. Results largely agreed with a re-inventory made already after two years but the importance of the north side of retention trees became evident for species survival only after 14years, indicating that to gain deeper insights longer time-spans may be necessary. This study, which is the longest lichen transplantation time-series from a well replicated experiment so far published, shows that retention of trees at harvest may be an efficient conservation action. [Copyright &y& Elsevier]

Abstract: Persistence and abundance of species is determined by habitat availability and the ability to disperse and colonize habitats at contrasting spatial scales. Favourable habitat fragments are also heterogeneous in quality, providing differing opportunities for establishment and affecting the population dynamics of a species. Based on these principles, we suggest that the presence and abundance of epiphytes may reflect their dispersal ability, which is primarily determined by the spatial structure of host trees, but also by host quality. To our knowledge there has been no explicit test of the importance of host tree spatial pattern for epiphytes in Mediterranean forests. We hypothesized that performance and host occupancy in a favourable habitat depend on the spatial pattern of host trees, because this pattern affects the dispersal ability of each epiphyte and it also determines the availability of suitable sites for establishment. We tested this hypothesis using new point pattern analysis tools and generalized linear mixed models to investigate the spatial distribution and performance of the epiphytic lichen Lobaria pulmonaria, which inhabits two types of host trees (beeches and Iberian oaks). We tested the effects on L. pulmonaria distribution of tree size, spatial configuration, and host tree identity. We built a model including tree size, stand structure, and several neighbourhood predictors to understand the effect of host tree on L. pulmonaria. We also investigated the relative importance of spatial patterning on the presence and abundance of the species, independently of the host tree configuration. L. pulmonaria distribution was highly dependent on habitat quality for successful establishment, i.e., tree species identity, tree diameter, and several forest stand structure surrogates. For beech trees, tree diameter was the main factor influencing presence and cover of the lichen, although larger lichen-colonized trees were located close to focal trees, i.e., young trees. However, oak diameter was not an important factor, suggesting that bark roughness at all diameters favoured lichen establishment. Our results indicate that L. pulmonaria dispersal is not spatially restricted, but it is dependent on habitat quality. Furthermore, new spatial analysis tools suggested that L. pulmonaria cover exhibits a distinct pattern, although the spatial pattern of tree position and size was random. [Copyright &y& Elsevier]

Abstract: Understanding species climatic sensitivity is a central theme in biodiversity conservation. However, climate, and the response to climate change, is one component in a multiplicity of drivers which interact to control the occurrence of lichens. This paper investigates patterns of lichen species occurrence and abundance (for Degelia spp., Lobaria pulmonaria and Sphaerophorus globosus) in response to the simultaneous and interacting nested effect of macroclimate and local habitat quality. We show that for a very steep climatic gradient in Scotland occurrence is delimited by a climatic threshold, but also that abundance within a suitable locale is controlled by an interaction with local habitat quality. This interaction between cross-scale drivers – climate and local habitat – provides a powerful conservation tool, enabling predictive management to optimise habitat conditions, in order to offset the possible negative impacts of larger-scale environmental stress (e.g. climate change). [Copyright &y& Elsevier]

Abstract: 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 forest lichen Lobaria pulmonaria were cultivated for 15 days in the laboratory in a factorial experiments with temperature (12 and 21°C) and UV-B (0, 0.1, 0.3 and 1.0Wm−2) as treatments. Prior to the experiment, the cortical pigment parietin was non-destructively extracted from X. aureola, whereas the sampled shade-adapted thalli of L. pulmonaria lacked cortical melanic compounds. Therefore both lichens were deficient in cortical sun-screening compounds when the UV-B exposure started. At 12°C, the relative growth rate was 7.2±0.6 and 3.0±0.8mgg−1 day−1 in L. pulmonaria and X. aureola, respectively, reduced to 1.8±0.5 and −2.6±0.9mgg−1 day−1, at 21°C. These figures showed that lichen growth is a useful response variable in short-term laboratory experiments. Growth was not influenced by UV-B alone in these pigment-deficient transplants, suggesting that UV-B had little adverse effects on either of the lichen bionts. The cortical sun screens (parietin and melanic compounds) were synthesized in the presence of UV-B, and increased statistically significantly with increasing UV-B at both cultivation temperatures. However, in X. aureola the synthesis was highest at the lowest temperature (12°C). At 12°C, changes in chlorophylls, F v/F m and NPQ during cultivation were consistent with a substantial level of acclimation to the growth chamber conditions for both species, whereas strong reductions in photosynthetic pigments, F v/F m and Ф II at 21°C indicated serious damage and chlorophyll degradation at high temperature. In conclusion, lichen growth and the synthesis of protective compounds are highly responsive lichen processes in short-term experiments. [Copyright &y& Elsevier]

Abstract: The influence of forest management on species richness and composition of epiphytic macrolichens was studied on beech stems in two differently managed stands in northern Italy: (1) mixed-multilayered stand with silver fir, spruce and beech, managed by selective-cutting and (2) pure beech stand, intensively managed by shelterwood-cutting. Macrolichens and easily identifiable crustose lichens were surveyed on 150 randomly selected beech trees in 10 management units. Trees of the two stands significantly differed in lichen composition, but not in species richness. However, most of the rare species were exclusive of the sites managed by selective-cutting. The lichen flora of mixed stands mainly included suboceanic species-sensitive to forest management and habitat modification; that of pure stands was dominated by generalist species common in disturbed habitats. Lobaria pulmonaria is suggested as a signal species for rapidly assessing the conservation importance of forests. Some practical suggestions are given to enhance lichen conservation in intensively managed stands. [Copyright &y& Elsevier]

Abstract: Mn uptake from MnCl2 solution and chlorophyll fluorescence (as a selected vitality parameter) were studied in the epiphytic lichens Lobaria pulmonaria (tripartite, heteromerous lichen with the green alga Dictyochloropsis as primary photobiont and Nostoc in cephalodia), Nephroma helveticum (bipartite, heteromerous lichen with Nostoc photobiont) and Leptogium saturninum (bipartite, homoiomerous lichen with Nostoc photobiont). Extracellular adsorption and intracellular uptake of Mn increased in the order L. pulmonaria < N. helveticum < L. saturninum. Mn increasingly reduced the effective quantum yield of photosystem 2 (Φ 2) in the same order. CaCl2 and MgCl2 alleviated the Mn-induced reduction of Φ 2. Moist thalli of all species transferred significant amounts of extracellular Mn into the cells during a recovery day subsequent to incubation with metal solution. This suggests that even short exposures to Mn in the field, e.g. via stemflow, can affect the physiology of the lichen species studied. The experimental results support the hypothesis that cyanolichens are sensitive to excess Mn. Data also suggest that the tripartite L. pulmonaria is less Mn-sensitive than the bipartite cyanolichens. This agrees with published field observations from Montana, where bipartite cyanolichens (including L. saturninum and N. helveticum) occurred on conifer bark with the lowest Mn concentration, while L. pulmonaria was also found on bark with higher Mn concentrations. [Copyright &y& Elsevier]

• Air pollution influences the success of lichen translocation for conservation purposes. • The translocation of Lobaria pulmonaria is effective only in unpolluted environments. • Higher contents of heavy metals in translocated thalli reflect their lower survival. • Current air quality in Central Europe limits recolonization by sensitive lichens. Species translocation can be considered as a primary conservation strategy with reference to in situ conservation. In the case of lichens, translocations often risk to fail due stress factors associated with unsuitable receptor sites. Considering the bioecological characteristics of lichens, air pollution is among the most limiting stress factors. In this study, the forest macrolichen Lobaria pulmonaria was used as a model to test the hypothesis that the translocation of sensitive lichens is effective only in unpolluted environments. At purpose, 500 fragments or whole thalli were translocated in selected beech forests of Central Europe (the Western Carpathians, Slovakia) where the species disappeared in the past and in oak forests of Southern Europe (Tuscany, Central Italy) where native populations are present. Prior to the translocation (May 2016) and after one year, morphological and ultrastructural features, trace elements as well as chlorophyll a fluorescence emission were analysed. Four years later, the effectiveness of lichen translocation was further evaluated as presence of the transplants and of newly formed individuals. After one year, the translocation ensured an effective survival of the thalli in remote oak and beech forests characterized by a negligible or low contamination by heavy metals. The transplants were considered successful and developed new lobules and rhizines, attaching by themselves to the bark of the host trees, looking overall healthy, without evident signs of alteration also at ultrastructural level. Moreover, in a few cases newly formed individuals were observed after four years. On the other hand, the results highlighted the link between the unsuccess of the translocation and air pollution in other areas of the Western Carpathians and suggested that current air quality still limits the possibility of recolonization in areas where the model species disappeared. [ABSTRACT FROM AUTHOR]

While changing climatic conditions may directly impact species distribution ranges, indirect effects related to altered biotic interactions may exacerbate range shifts. This situation fully applies to epiphytic lichens that are sensitive to climatic factors and strongly depend on substrate occurrence and features for their dispersal and establishment. In this work, we modelled the climatic suitability across Italy under current and future climate of the forest species Lobaria pulmonaria , the lung lichen. Comparatively, we modelled the suitability of its main tree species in Italy, as well as that of the alien tree Robinia pseudoacacia , black locust, whose spread may cause the decline of many forest lichen species. Our results support the view that climate change may cause range shifts of epiphytes by altering the spatial pattern of their climatic suitability (direct effect) and simultaneously causing range shifts of their host-tree species (indirect effect). This phenomenon seems to be emphasized by the invasion of alien trees, as in the case of black locust, that may replace native host tree species. Results indicate that a reduction of the habitat suitability of the lung lichen across Italy should be expected in the face of climate change and that this is coupled with a loss of suitable substrate. This situation seems to be determined by two main processes that act simultaneously: 1) a partial reduction of the spatial overlap between the climatic niche of the lung lichen and that of its host tree species, and 2) the invasion of native woods by black locust. The case of lung lichen and black locust in Italy highlights that epiphytes are prone to both direct and indirect effects of climate change. The invasion of alien trees may have consequences that are still poorly evaluated for epiphytes. Unlabelled Image • Climate change may directly and indirectly impact species distribution ranges. • We tested direct and indirect effects of climate change on the epiphytic lung lichen. • We used species distribution modelling for the lung lichen and host tree species. • Range reduction of the lung lichen is coupled with a co-reduction of its host trees. • Lung lichen range reduction is exacerbated by the spread of the alien black locust. [ABSTRACT FROM AUTHOR]

• Traditional old-growth chestnut orchards are a habitat worthy of conservation. • Veteran trees host some valuable epiphytic lichens. • High failure risk more than diseases could seriously affect veteran trees. • Undergrowth plant diversity is higher in managed than in abandoned sites. • Preserving trees and biodiversity needs the maintenance of low-intensity management. In mountain regions of southern Europe, old-growth chestnut orchards maintained by traditional management were a key component of the economic, cultural, and ecological heritage. Currently, many stands are abandoned due to decreased economic sustainability even though, according to European policies, the loss of traditionally managed old-growth chestnut orchards should be contrasted to prevent biodiversity loss. In this study, we preliminarily mapped the remnants of old-growth chestnut orchards across a region of the northern Apennines (Italy) with a strong tradition of chestnut orchard cultivation. Then, we assessed the effects of management/abandonment in terms of tree features (e.g. size, crown structure, health conditions), occurrence and abundance of target epiphytic lichens, and richness and composition of understory vegetation. Our results revealed contrasting patterns of tree features, lichen, and plant diversity in managed and abandoned old-growth chestnut orchards of the northern Apennines, supporting the view that traditional management is fundamental for the long-term maintenance of healthy veteran trees, the enhancement of epiphytic lichens related to old-growth conditions, and plant diversity. This indicates that 1000 years of chestnut civilization represent a cultural heritage that benefits nature conservation, promoting a virtuous interplay between human activities and biodiversity. For this reason, policies aimed at sustaining traditional management in old-growth chestnut orchards are indispensable to avoid the degradation and loss of this habitat and its centuries-old cultural and ecological legacy. [ABSTRACT FROM AUTHOR]

• Ecologically significant canopy leachates should be explored in undisturbed forests. • We used lichens to assess leachates from cottonwood/aspen and hybrid spruce canopy. • Standardized lichen transplants accumulated elements for 1 year in tree dripzones. • Base cations, soil pH and conifer bark pH was highest in cottonwood/aspen dripzones. • Lichen transplants are ecologically relevant indicators of throughfall chemistry. 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. [ABSTRACT FROM AUTHOR]

The growth inhibition of stictic acid, a secondary metabolite isolated from the lichen Lobaria pulmonaria (L.) Hoffm. (Lobariaceae), was evaluated in vitro on three human cell lines for the first time. The cell lines HT-29 and MCF-7 were utilized for measuring the activity of stictic acid against cancer cells, while the cell line MRC-5 was selected for estimation of its effect on normal cells. The results suggest a moderate anticancer activity (IC 50 value for the cell line HT-29 was 29.29 μg/ml) and a low growth inhibition on nonmalignant cells (IC 50 value for the cell line MRC-5 was 2478.40 μg/ml) of stictic acid. This natural product can be considered as a promising lead compound for the design of novel human colon adenocarcinoma drugs. [ABSTRACT FROM AUTHOR]