We are fertilizing a thicket with 0, 10, 20 and 50kg nitrogen (N) ha⁻¹ yr⁻¹ in central Spain. Here we report changes in cover, pigments, pigment ratios and FvFm of the N-tolerant, terricolous, lichen Cladonia foliacea after 1–2 y adding N in order to study its potential as biomarker of atmospheric pollution. Cover tended to increase. Pigments increased with fertilization independently of the dose supplied but only significantly with soil nitrate as covariate. β-carotene/chlorophylls increased with 20–50kgNha⁻¹yr⁻¹ (over the background) and neoxanthin/chlorophylls also increased with N. (Neoxanthin+lutein)/carotene decreased with N when nitrate and pH seasonalities were used as covariates. FvFm showed a critical load above 40kgNha⁻¹yr⁻¹. Water-stress, iron and copper also explained variables of lichen physiology. We conclude that this tolerant lichen could be used as biomarker and that responses to N are complex in heterogeneous Mediterranean-type landscapes.

Lead concentrations and their isotopic compositions were measured in lichen genera Cladonia and Usnea and fungi genus Trametes from the Greater Sydney region (New South Wales, Australia) that had been collected and archived over the past 120 years. The median lead concentrations were elevated in lichens and fungi prior to the introduction of leaded petrol (Cladonia 12.5 mg/kg; Usnea 15.6 mg/kg; Trametes 1.85 mg/kg) corresponding to early industrial development. During the period of leaded petrol use in Australian automobiles from 1932 to 2002, total median lead concentrations rose: Cladonia 18.8 mg/kg; Usnea 21.5 mg/kg; Trametes 4.3 mg/kg. Following the cessation of leaded petrol use, median total lead concentrations decreased sharply in the 2000s: Cladonia 4.8 mg/kg; Usnea 1.7 mg/kg. The lichen and fungi isotopic compositions reveal a significant decrease in ²⁰⁶Pb/²⁰⁷Pb ratios from the end of 19th century to the 1970s. The following decades were characterised by lower allowable levels of lead additive in fuel and the introduction of unleaded petrol in 1985. The environmental response to these regulatory changes was that lichen and fungi ²⁰⁶Pb/²⁰⁷Pb ratios increased, particularly from 1995 onwards. Although the lead isotope ratios of lichens continued to increase in the 2000s they do not return to pre-leaded petrol values. This demonstrates that historic leaded petrol emissions, inter alia other sources, remain a persistent source of anthropogenic contamination in the Greater Sydney region.

Formaldehyde is one of the most toxic contaminants of indoor environments and very common in the anatomy laboratory. In this work, we investigated the level of formaldehyde exposure to staff and students who attended an anatomy lab and in nearby environments in the same university building. We also performed atmospheric biomonitoring of the sites with the lichen Cladonia verticillaris. Quantification samplings were performed over four weeks, on 7 days with and 7 days without practical classes, totaling 70 samples. The samples were collected in five different locations, three points inside the laboratory and two points outside the laboratory, representing nearby and susceptible environments to contamination. The results showed CHOH concentrations from 0.20–3.76 ppmv for days with practical courses and 0.17–3.06 ppmv for days without practical classes. Although the laboratory was more contaminated than the surrounding environments, the concentration of formaldehyde in these areas is not negligible, showing a dispersion of formaldehyde from the laboratory. Potential dose (PD) and cancer risk (CR) were calculated for an individual exposed to the same levels analyzed for 8 h daily and 30 years of work. The study on C. verticillaris lasted 90 days and evaluated the variation of chlorophyll and pheophytin (photosynthetic pigments). The results showed a significant difference in the production of chlorophylls a and b and total chlorophyll when compared to control, and there was also a progressive increase of the total pheophytin/total chlorophyll ratio. The results also showed the correlation between the increase in chlorophylls and the studied environments with less ventilation since these places provided greater accumulation of formaldehyde in the long run. Thus, measurable evidence was obtained of biological disorders in a living organism caused by exposure to formaldehyde.

This study was undertaken with the aim of investigating the effect of Cd2+ and Ni2+ containing solutions on selected physiological parameters (metal uptake, chlorophyll a fluorescence, assimilation pigment composition, thiobarbituric acid-reactive substance production, and ergosterol content) in the lichens Peltigera rufescens and Cladina arbuscula subsp. mitis growing on historic copper mine-spoil heaps at Ľubietová-Podlipa, Slovakia. Physiological measurements did not confirm significantly higher sensitivity to Cd and Ni of the cyanolichen P. rurescens compared to the green-algal lichen C. arbuscula subsp. mitis. Under natural conditions, C. arbuscula subsp. mitis is able to grow directly on copper mine heaps of Central Slovakia, while P. rufescens grows only on their margins. A crucial factor for this limited distribution of P. rufescens may be, at least in part, the higher intracellular accumulation of metals. Although lichen photobionts are generally regarded as key elements of lichen sensitivity, further research is necessary to elucidate this point since the higher levels of intracellular Cd and Ni do not allow to regard cyanobacterial photobionts of P. rufescens as more sensitive than the eukaryotic ones of C. arbuscula subsp. mitis.

From April 2006 to April 2007, the geographical and seasonal variation in nitrogen content in terricolous lichen (Cladonia portentosa) and atmospheric ammonia concentrations were measured at five heathland sites. The seasonal variation in the nitrogen content of the lichen was small, even though there was a large seasonal variation in the air concentration of ammonia. A sizable local variation in the nitrogen content of the lichen was found even at the scale of a few kilometres. The nitrogen content in the lichen showed a high correlation to the yearly mean value of the measured ammonia concentration in air at the different locations. This investigation is part of a larger attempt to incorporate effects of nitrogen in the conservation status of terrestrial habitat types.

Lichens absorb water, gases, dissolved substances, and especially pollutants by the entire surface, and they are considered to be the indicators of air quality. In our experiment, a sensitivity of Cladonia arbuscula subsp. mitis and Cladonia furcata lichens with the same photobiont Trebouxia was tested to nitrogen excess through a sensitivity of both the photobiont and mycobiont. Lichen ecophysiological parameters like chlorophyll a fluorescence, chlorophyll a integrity, the content of photosynthetic pigments, ergosterol, soluble proteins, thiobarbituric acid reactive substances, and secondary compounds were measured during two experiments that differed in time of nitrogen exposure. In the short-term experiment, also higher nitrogen concentrations were used to evaluate the dependence of different nitrogen concentrations. In the short-term experiment, lichens were soaked at the different solutions of ammonium nitrate (NH₄NO₃) for describing an immediate effect of range of NH₄NO₃ concentrations. In the long-term experiment, lichens were sprayed with low NH₄NO₃ concentrations for 3 months for evaluating the effect of naturally occurring low nitrogen concentrations. Results showed that lichens responded differently in spite of having the same photobiont. The mycobiont of C. arbuscula subsp. mitis was more sensitive than mycobiont of C. furcata. In higher nitrogen concentrations, the photobiont of C. furcata was more sensitive than C. arbuscula subsp. mitis photobiont. Both lichens exhibited signs of damage; therefore, we conclude that they are sensitive to nitrogen excess, while C. arbuscula subsp. mitis is more sensitive species. The secondary compound content did not change in neither of lichen species. Cladonia sp. response to nitrogen excess depends on length and nitrogen dose exposure.

Phenotypic traits of lichens can be greatly modified by environmental factors. Granulose thalli on soil and podetia, densely covered with granules, referring to common and widespread lichen Cladonia cervicornis subsp. verticillata were found near zinc smelter. The granules are stratified, filled with fungal medulla and heavily encrusted with calcium oxalate weddellite crystals, not observed on regularly developed thalli of the species. Phylogenetic analysis revealed that deformed granulose forms belong to this taxon, showing that the phenotypic plasticity of the lichens of Cladonia can lead to the emergence of features that do not coincide with the taxonomic definition of the species. The heavy-metal accumulation capacity of both granulose and regular form of primary and secondary lichen thallus, in relation to the element content in corresponding substrate, was determined. Granulose-modified thalli accumulate greater amounts of heavy metals than regular ones, meaning that the bioaccumulation property of a given species may be greatly affected by morphological modifications. The granulose forms are also characterised by considerably higher ratios of Cd, Pb and As concentrations in lichen samples in relation to the corresponding substrates than regular ones. This means that collection of variously formed thalli should be avoided in biomonitoring sampling procedures. The results indicate that a substantial part of the element load, in particular zinc, in the examined lichen thalli collected near the smelter originates from atmospheric fallout.

The phenomenon of mass occurrence of the lichen Cladonia rei in extremely contaminated post-smelting slag dumps was studied in relation to metal accumulation capacity of this lichen. The research was aimed to evaluate the relationships between element contents in the thalli and in the corresponding substrate. The study was conducted in terms of a wide spectrum of Zn, Cd, Pb and As contents. The concentrations of these elements in the lichen thalli and substrate samples were measured. Various regression models were considered to find the best fitted one that greatly reflects the dependencies. Various Cladonia species and the hyperaccumulator Diploschistes muscorum were also included in the study for comparison purposes. Specific non-linear regression models described by a power function reflected relationships between Zn and Cd contents in C. rei thalli and in the host substrate in the most reliable way. The relationship for As was also noted, but none significant model was found. Contrarily, Pb concentrations in the thalli varied independently of the metal levels in the substrate. Nevertheless, the concentrations of all measured heavy metals in C. rei thalli are relatively low considering the frequently enormous substrate contamination. Different Cladonia species demonstrated a generally similar accumulation capacity and could be considered as weak accumulators. The restrained accumulation pattern may be one of the important attributes of C. rei which facilitates its colonisation of extremely contaminated dumps. This finding highlights ecological importance of this species as stable and resistant pioneer in such affected sites.