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Climate change and atmospheric nitrogen (N) deposition on drylands are greatly threatening these especially vulnerable areas. Soil biocrust-forming lichens in drylands can provide early indicators of these disturbances and play a pivotal role, as they contribute to key ecosystem services. In this study, we explored the effects of different long-term water availability regimes simulating climate changes and their interaction with N addition on the physiological response of the soil lichen Cladonia rangiferina. Three sets of this lichen were subjected to control, reduced watering, and reduced watering and N addition (40 kg NH4NO3 ha−1 year−1) treatments for 16 months. Finally, all samples were subjected to daily hydration cycles with N-enriched water at two levels (40 and 80 kg NH4NO3 ha−1 year−1) for 23 days. We found that reduced watering significantly decreased the vitality of this lichen, whereas N addition unexpectedly helped lichens subjected to reduced watering to cope with stress produced by high temperatures. We also found that long-term exposure to N addition contributed to the acclimation to higher N availability. Overall, our data suggest that the interactions between reduced watering and increased N supply and temperature have an important potential to reduce the physiological performance of this soil lichen.

Forests host most terrestrial biodiversity and their sustainable management is crucial to halt biodiversity loss. Although scientific evidence indicates that sustainable forest management (SFM) should be assessed by monitoring multi-taxon biodiversity, most current SFM criteria and indicators account only for trees or consider indirect biodiversity proxies. Several projects performed multi-taxon sampling to investigate the effects of forest management on biodiversity, but the large variability of their sampling approaches hampers the identification of general trends, and limits broad-scale inference for designing SFM. Here we address the need of common sampling protocols for forest structure and multi-taxon biodiversity to be used at broad spatial scales. We established a network of researchers involved in 41 projects on forest multi-taxon biodiversity across 13 European countries. The network data structure comprised the assessment of at least three taxa, and the measurement of forest stand structure in the same plots or stands. We mapped the sampling approaches to multi-taxon biodiversity, standing trees and deadwood, and used this overview to provide operational answers to two simple, yet crucial, questions: what to sample? How to sample? The most commonly sampled taxonomic groups are vascular plants (83% of datasets), beetles (80%), lichens (66%), birds (66%), fungi (61%), bryophytes (49%). They cover different forest structures and habitats, with a limited focus on soil, litter and forest canopy. Notwithstanding the common goal of assessing forest management effects on biodiversity, sampling approaches differed widely within and among taxonomic groups. Differences derive from sampling units (plots size, use of stand vs. plot scale), and from the focus on different substrates or functional groups of organisms. Sampling methods for standing trees and lying deadwood were relatively homogeneous and focused on volume calculations, but with a great variability in sampling units and diameter thresholds. We developed a handbook of sampling methods (SI 3) aimed at the greatest possible comparability across taxonomic groups and studies as a basis for European-wide biodiversity monitoring programs, robust understanding of biodiversity response to forest structure and management, and the identification of direct indicators of SFM., This review was funded by the EU Framework Programme Horizon 2020 through the COST Association: COST Action CA18207: BOTTOMSUP- Biodiversity Of Temperate forest Taxa Orienting Management Sustainability by Unifying Perspectives.

The lichen Cladonia portentosa is generally considered to be sensitive to increased environmental nitrogen (N) deposition. However, the presence of this lichen in impacted environments suggests that it can cope with prolonged exposure to high N availability. To test the tolerance of this species to N, photosynthetic parameters, carbon and N concentrations and isotopic signature, chitin concentration, surface pH and extracellular enzymatic activity were measured in samples exposed for 11 years to different N doses and forms at the Whim bog N manipulation experimental site (United Kingdom). The results showed that C. portentosa is tolerant to long-term exposure to wet N deposition, maintaining its functionality with almost unaltered physiological parameters. The comparison of the proteome of short- and long-term exposed samples showed similar changes in protein expression suggesting that mechanisms to cope with N are not dependent on the exposure time even after more than a decade. Since empirical N Critical Loads are based on the response of sensitive components of the ecosystem, like C. portentosa, its capacity to cope with short- and long-term exposure to N needs to be recognized and taken into account when setting them, likewise, the significance of the form of N., Investigador - Fundação para Ciência e Tecnologia (FCT) contract and the FCT projects IF/00964/2013 and UID/BIA/00329/2013 (2015–2018).

Ammonia and ammonium have received less attention than other forms of air pollution, with limited progress in controlling emissions at UK, European and global scales. By contrast, these compounds have been of significant past interest to science and society, the recollection of which can inform future strategies. Sal ammoniac ( nūshādir , nao sha ) is found to have been extremely valuable in long-distance trade ( ca AD 600–1150) from Egypt and China, where 6–8 kg N could purchase a human life, while air pollution associated with nūshādir collection was attributed to this nitrogen form. Ammonia was one of the keys to alchemy—seen as an early experimental mesocosm to understand the world—and later became of interest as ‘alkaline air’ within the eighteenth century development of pneumatic chemistry. The same economic, chemical and environmental properties are found to make ammonia and ammonium of huge relevance today. Successful control of acidifying SO 2 and NO x emissions leaves atmospheric NH 3 in excess in many areas, contributing to particulate matter (PM 2.5 ) formation, while leading to a new significance of alkaline air, with adverse impacts on natural ecosystems. Investigations of epiphytic lichens and bog ecosystems show how the alkalinity effect of NH 3 may explain its having three to five times the adverse effect of ammonium and nitrate, respectively. It is concluded that future air pollution policy should no longer neglect ammonia. Progress is likely to be mobilized by emphasizing the lost economic value of global N emissions ($200 billion yr −1 ), as part of developing the circular economy for sustainable nitrogen management. This article is part of a discussion meeting issue ‘Air quality, past present and future’.

Review of the book "Sailing School Navigating Science and Skill, 1550-1800", from Margaret E. Schotte. With a style enjoyable to scholars and enthusiasts, Margaret Schotte analyzes archival records from six different countries to trace the evolution of a new paradigm of knowledge transfer, education and practice of navigation.

Although it is generally accepted that δ15N in lichen reflects predominating N isotope sources in the environment, confirmation of the direct correlation between lichen δ15N and atmospheric δ15N is still missing, especially under field conditions with most confounding factors controlled. To fill this gap and investigate the response of lichens with different tolerance to atmospheric N deposition, thalli of the sensitive Evernia prunastri and the tolerant Xanthoria parietina were exposed for ten weeks to different forms and doses of N in a field manipulation experiment where confounding factors were minimized. During this period, several parameters, namely total N, δ15N and chlorophyll a fluorescence, were measured. Under the experimental conditions, δ15N in lichens quantitatively responded to the δ15N of released gaseous ammonia (NH3). Although a high correlation between the isotopic signatures in lichen tissue and supplied N was found both in tolerant and sensitive species, chlorophyll a fluorescence indicated that the sensitive species very soon lost its photosynthetic functionality with increasing N availability. The most damaging response to the different N chemical forms was observed with dry deposition of NH3, although wet deposition of ammonium ions had a significant observable physiological impact. Conversely, there was no significant effect of nitrate ions on chlorophyll a fluorescence, implying differential sensitivity to dry deposition versus wet deposition and to ammonium versus nitrate in wet deposition. Evernia prunastri was most sensitive to NH3, then NH4+, with lowest sensitivity to NO3−. Moreover, these results confirm that lichen δ15N can be used to indicate the δ15N of atmospheric ammonia, providing a suitable tool for the interpretation of the spatial distribution of NH3 sources in relation to their δ15N signal.

The interpretation of lichen bioaccumulation data is of paramount importance in environmental forensics and decision-making processes. By implementing basic ideas underlying previous interpretative scales, new dimensionless, species-independent &ldquo, bioaccumulation scales&rdquo, for native and transplanted lichens are proposed. Methodologically consistent element concentration datasets were populated with data from biomonitoring studies relying on native and transplanted lichens. The scale for native lichens was built up by analyzing the distribution of ratios between element concentration data and species-specific background concentration references (B ratios), herein provided for Flavoparmelia caperata and Xanthoria parietina (foliose lichens). The scale for transplants was built up by analyzing the distribution of ratios between element concentration in exposed and unexposed samples (EU ratio) of Evernia prunastri and Pseudevernia furfuracea (fruticose lichens). Both scales consist of five percentile-based classes, namely, &ldquo, Absence of&rdquo, &ldquo, Low&rdquo, Moderate&rdquo, High&rdquo, and &ldquo, Severe&rdquo, bioaccumulation. A comparative analysis of extant interpretative tools showed that previous ones for native lichens suffered from the obsolescence of source data, whereas the previous expert-assessed scale for transplants failed in describing noticeable element concentration variations. The new scales, based on the concept that pollution can be quantified by dimensionless ratios between experimental and benchmark values, overcome most critical points affecting the previous scales.

Lichens and mosses represent the macroscopic components of biological soil crusts (biocrusts). Their ability to exploit short periods of water availability and reversibly deactivate metabolism is crucial for their growth and survival. In this work we investigated photosynthesis reactivation, respectively after long (65–66 days) and short (15 days) dry periods, in lichen and moss species widespread in two Mediterranean environments (Portugal and Italy). Chlorophyll a fluorescence emission of the samples was investigated and the parameter Fv/Fm, an indicator of vitality of photosynthetic organisms, was used as a proxy for photosynthesis reactivation. The fruticose lichens Cladonia convoluta and C. rangiformis, and the moss Pleurochaete squarrosa, typical of Mediterranean environments, showed a significantly slower reactivation of photosynthetic activity when subjected to a longer period of drought. Conversely, the alien invasive moss Campylopus introflexus was not affected by prolonged dry conditions. The study showed that drought duration influences the reactivation of photosynthetic activity in terricolous lichens and mosses forming biocrusts in re-hydration cycles. These results indicate the likelihood of a reduction in biocrust productivity as a consequence of climate change in Mediterranean drylands.

Ajuts: This manuscript resulted from the 1st "Committee on Air Pollution Effects Research on Mediterranean Ecosystems" (CAPERmed) Conference celebrated in Lisbon, 2014 (http://capermed.weebly.com/). All attendants to this conference are, therefore, greatly acknowledged. Fundação para a Ciência e Tecnologia (FCT) is acknowledged through the Post Doc grant SFRH/BPD/85419/2012 to Teresa Dias and the Investigador grant to Silvana Munzi. ADM, EP and PS thank the LIFE10 ENV/FR/208 project MOTTLES. EP thanks also the Fondazione Cassa di Risparmio di Firenze (2013/7956). ROH is supported by a Juan de la Cierva Fellowship (IJCI-2014-21252) of the Spanish Ministry of Economy and Competitiveness. The authors declare no conflicts of interest. Mediterranean Basin ecosystems, their unique biodiversity, and the key services they provide are currently at risk due to air pollution and climate change, yet only a limited number of isolated and geographically-restricted studies have addressed this topic, often with contrasting results. Particularities of air pollution in this region include high O3 levels due to high air temperatures and solar radiation, the stability of air masses, and dominance of dry over wet nitrogen deposition. Moreover, the unique abiotic and biotic factors (e.g., climate, vegetation type, relevance of Saharan dust inputs) modulating the response of Mediterranean ecosystems at various spatiotemporal scales make it difficult to understand, and thus predict, the consequences of human activities that cause air pollution in the Mediterranean Basin. Therefore, there is an urgent need to implement coordinated research and experimental platforms along with wider environmental monitoring networks in the region. In particular, a robust deposition monitoring network in conjunction with modelling estimates is crucial, possibly including a set of common biomonitors (ideally cryptogams, an important component of the Mediterranean vegetation), to help refine pollutant deposition maps. Additionally, increased attention must be paid to functional diversity measures in future air pollution and climate change studies to establish the necessary link between biodiversity and the provision of ecosystem services in Mediterranean ecosystems. Through a coordinated effort, the Mediterranean scientific community can fill the above-mentioned gaps and reach a greater understanding of the mechanisms underlying the combined effects of air pollution and climate change in the Mediterranean Basin.

In this paper, we investigated whether growth form and substrate in lichens influence their physiological responses along an aridity gradient. Thalli of the foliose lichen Parmotrema perlatum and the fruticose lichen Ramalina canariensis were transplanted in selected rural/forested sites of Southern Portugal characterized by a different aridity index. Physiological parameters including photosynthetic performances, assimilation pigments, ergosterol content and sample viability were measured prior to exposure (winter) and after 6-month exposure (summer). Photosynthetic performances were also investigated in common native foliose and fruticose epiphytic lichens and in fruticose terricolous species. Both transplanted and native lichens showed a decrease in photosynthetic performances in summer and lower performances in sites classified as drier and higher performances in humid forested sites. No relevant differences occurred between epiphytic foliose and fruticose growth forms. However, terricolous fruticose samples showed a significant difference in humid and drier sites and between winter and summer, probably due to microclimatic conditions similarly to other biological crusts.

The results of antiproliferative activity against murine myeloma cells (line P3X63-Ag8.653) of water, ethanol, and methanol crude extracts of three lichen species belonging to the genus Peltigera (P. canina, P. elisabethae, and P. praetextata) are reported. Cell proliferation was evaluated by means of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test, which is commonly used to assess the activity of living cells through mitochondrial dehydrogenases. The results showed that water extracts were the most effective in reducing cell proliferation; however, 40 μl of all Peltigera extracts, irrespective of water, ethanol, or methanol, induced a consistent reduction in cell proliferation. It is suggested that this important biological activity is due to antioxidant properties, possibly linked with phenolic compounds. A possible role of quaternary ammonium compounds is also discussed.

This study investigated the influence of angular exposure and distance from vehicular traffic on the diversity of epiphytic lichens and the bioaccumulation of traffic-related elements in a town of central Italy. An Index of Lichen Diversity (ILD) was calculated on the street-facing and the opposite side of road-lining trees and in a urban park 250 m away, and the content of selected trace elements (Al, Ba, Ce, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, V, and Zn) was determined in samples of the lichen Punctelia borreri (Sm.) Krog growing on tree bark, both on the exposed and opposite sides. ILD increases with distance from traffic emissions. However, at the site with vehicle traffic, non-nitrophilous lichens decreased while nitrophilous ones increased. The concentration of the traffic-related elements Ba, Cr, Cu, Mn, Sb, and Zn accumulated in thalli of P. borreri was higher on roadside trees than in trees from the urban park. ILD was not affected by the angular exposure to the road and the bioaccumulation of traffic-related elements was similar in lichens from the side of the bole exposed to traffic emissions and particulate resuspension and from the opposite side. The angular exposure in respect to the traffic source does not influence trace element accumulation. These results are important when using lichens for biomonitoring purposes, both for planning future studies and for the reliability of the interpretation of past surveys that do not report information about the angular exposure of the collected lichen material.

In this paper we tested if treating the lichen Xanthoria parietina with Sb-containing solutions causes Sb bioaccumulation as well as physiological and ultrastructural changes. Total and intracellular antimony content in Sb-treated samples increased progressively with increasing concentration in the treatment solutions. Incubation of X. parietina thalli with Sb at concentrations as low as 0.1 mM caused a decrease in sample viability, measured as intensity of respiratory activity, and damage to cell membranes, expressed in terms of membrane lipid peroxidation, as well as ultrastructural changes such as plasmolysis, impairment of the thylakoid system of the alga and cytoplasmic lipid droplets. The photosynthetic system hardly responded, at least under the tested experimental conditions.

This study investigated the physiological response of the epiphytic lichen Evernia prunastri to ecologically relevant concentrations of nitrogen compounds. Lichen samples were sprayed for 4 weeks either with water or 50, 150 and 500 μM NH 4 Cl. The integrity of cell membranes and chlorophyll a fluorescence emission ( F V / F M and PI ABS ) were analyzed. No membrane damage occurred after the exposure period. F V / F M , a classical fluorescence indicator, decreased during the second week of treatment with 500 μM NH 4 Cl and the third week with 50 and 150 μM NH 4 Cl. PI ABS , an overall index of the photosynthetic performance, was more sensitive and decreased already during the first week with 500 μM NH 4 Cl and the second week with 150 μM NH 4 Cl. Since E. prunastri has been exposed to ammonium loads corresponding to real environmental conditions, these findings open the way to an effective use of this species as early indicators of environmental nitrogen excess.

Epiphytic lichens have long been used as ecological indicators. Lichen biomonitoring surveys were carried out by five experienced teams and the results compared across the entire process, from sampling design planning to species counting. The five teams received the same background information and worked in parallel but independently in the same area. European standard operating procedures (SOPs), which are still in preparation, were followed in order to identify possible critical issues and improve consistency. Five exercises with progressive reduction in the degree of operational freedom were carried out by the teams. The results revealed differences between teams on each exercise and showed that investigations run by different teams in the same area and at the same time may not be entirely comparable. This was partly due to inherent differences between crews (skills, familiarity with local flora, and accuracy in applying SOPs), partly to ambiguities in the SOPs, and partly to insufficient training with the SOPs. The results may be valuable in improving biomonitoring procedures and in achieving high-quality, consistent lichen diversity data. © 2012 Elsevier Ltd.

The aim of this study was to test in a short term laboratory experiment the accumulation and physiological effects of As in the epiphytic lichen Xanthoria parietina. Arsenic content in treated samples increased progressively with increasing concentration in treatment solutions. Treatment of X. parietina thalli with 0.1, 1, 10 ppm As solutions caused significant decrease of viability, measured as intensity of respiratory activity, and damages to cell membranes, assessed by increase of electric conductivity of rinsing water and lipid peroxidation products. Soluble proteins content decreased and H₂O₂ content increased already at the lowest As concentration tested (0.01 ppm). Photosynthetic efficiency, measured in terms of F(V)/F(M) ratio, decreased significantly only at the highest As concentration (10 ppm). It was concluded that As exposure causes physiological stress both on the mycobiont and the photobiont and that cell membrane damage, expressed in terms of electric conductivity of rinsing water, is the parameter most affected by As treatment.

The results of a study aimed at investigating the effects of boron excess on a set of ecophysiological parameters in the lichen Xanthoria parietina , to set up a monitoring system to trace early biological effects of boron pollution in geothermal areas, are reported. To this purpose, lichen thalli have been incubated for 24 h in solutions at boron concentrations of 0.1, 1, 10 and 100 ppm, which were within the range in bulk deposition and geothermal fluids. The results showed a general trend of decreasing sample viability and increasing cell membrane damage and membrane lipid peroxidation under increasing boron concentrations, while photosynthetic efficiency, chlorophyll degradation and the contents of H 2 O 2 and water-soluble proteins were not affected. It was argued that the fungal partner, that represents the large majority of the lichen biomass, is more sensitive to boron excess than the algal partner.

The sensitivity of lichens measuring photosynthetic efficiency and polyamines as modulator of nitrogen stress tolerance was investigated. Two lichen species with a markedly different tolerance to nitrogen compounds, namely Evernia prunastri (L.) Ach. and Xanthoria parietina (L.) Th.Fr., were incubated with deionized water (control) and solutions of KNO 3 , NH 4 NO 3 and (NH 4 ) 2 SO 4 and then exposed to different light conditions. The F v / F m parameter (maximum quantum efficiency of photosystem II) was used as stress indicator. The results showed that F v / F m values, in the produced experimental conditions, were independent from the light gradient. Photosynthetic efficiency of E. prunastri was impaired by high ammonium concentrations, while nitrate had no effect; X. parietina was hardly influenced by nitrogen compounds. External supply of polyamines reduced the sensitivity of E. prunastri , while polyamine inhibitors reduced the tolerance of X. parietina to NH 4 + , suggesting that polyamines play an important role in modulating the sensitivity/tolerance to nitrogen stress.