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Towards the adoption of an international standard for biomonitoring with lichens—Consistency of assessment performed by experts from six European countries
... The operator effect (non-sampling error) has been tackled in numerous studies that have tried to evaluate it on the basis of intercalibration tests between individual operators or groups of operators [29][30][31][32][33]. These tests represent basic activities for the assessment of quality assurance [34]. ...
... These tests represent basic activities for the assessment of quality assurance [34]. As lichen biomonitoring is based on the identification of all epiphytic lichen species within a sampling grid, it requires very high levels of taxonomic knowledge [6,[29][30][31][32]35,36]. In this regard, it has been shown that the effect of the operator can sometimes be relevant, even when expert lichenologists are involved in the sampling procedure. ...
... Although several tests [30][31][32] evaluated the accuracy of single operators, none have assessed the results obtained in cases of rotation or partial change of team composition in long-term biomonitoring programs. To fill this gap of knowledge, in this work we investigated temporal variations of epiphytic lichen diversity in relation to the composition of the teams involved in repeated biomonitoring surveys. ...
Lichen biomonitoring programs focus on temporal variations in epiphytic lichen communities in relation to the effects of atmospheric pollution. As repeated surveys are planned at medium to long term intervals, the alternation of different operators is often possible. This involves the need to consider the effect of non-sampling errors (e.g., observer errors). Here we relate the trends of lichen communities in repeated surveys with the contribution of different teams of specialists involved in sampling. For this reason, lichen diversity data collected in Italy within several ongoing biomonitoring programs have been considered. The variations of components of gamma diversity between the surveys have been related to the composition of the teams of operators. As a major result, the composition of the teams significantly affected data comparability: Similarity (S), Species Replacement (R), and Richness Difference (D) showed significant differences between “same” and “partially” versus “different” teams, with characteristics trends over time. The results suggest a more careful interpretation of temporal variations in biomonitoring studies.
... Epiphytic lichens are among the organisms most sensitive to climatic factors and air pollution and are increasingly used for biomonitoring purposes across Europe on the basis of standardized guidelines [5]. Recent studies have highlighted that the response of lichens to climate and pollution could depend on specific traits (e.g., photobiont type and thallus growth form), suggesting the usefulness of considering selected functional groups for evaluating environmental conditions [6]. ...
... Recent studies have highlighted that the response of lichens to climate and pollution could depend on specific traits (e.g., photobiont type and thallus growth form), suggesting the usefulness of considering selected functional groups for evaluating environmental conditions [6]. Contrary to lichen monitoring approaches based on community diversity data [5], the use of functional groups would allow comparisons across wide areas and would not require high lichenological expertise, making it less problematic in terms of applicability. ...
Climate change and the anthropic emission of pollutants are likely to have an accelerated impact in high-elevation mountain areas. This phenomenon could have negative consequences on alpine habitats and for species of conservation in relative proximity to dense human populations. This premise implies that the crucial task is in the early detection of warning signals of ecological changes. In alpine landscapes, high-elevation forests provide a unique environment for taking full advantage of epiphytic lichens as sensitive indicators of climate change and air pollution. This literature review is intended to provide a starting point for developing practical biomonitoring tools that elucidate the potential of hair-lichens, associated with high-elevation forests, as ecological indicators of global change in the European Alps. We found support for the practical use of hair-lichens to detect the impact of climate change and nitrogen pollution in high-elevation forest habitats. The use of these organisms as ecological indicators presents an opportunity to expand monitoring activities and develop predictive tools that support decisions on how to mitigate the effects of global change in the Alps.
... The process of standardization started in 2007 and took into account the previous European and national guidelines (Asta et al. 2002;VDI 2005;AFNOR 2008). In the meantime, some field tests have been performed to obtain information on the type and size of errors and the uncertainty of the methodologies under standardization (Brunialti et al. 2012a, Cristofolini et al. 2014. To fill this gap, the tests dealt with the entire process from survey design to field measurements. ...
... The recently developed European standards for lichen biomonitoring (Stofer et al. 2012;EN 16413 2014) have been developed as the result of a standardization process carried out in the last few years starting from the Index of Atmospheric Purity (IAP) approach (Hawksworth and Rose 1970;Nimis et al. 1990Nimis et al. , 1991 and upgrading it with previous guidelines (Asta et al. 2002;VDI 3957 2005). Furthermore, also field experience of several European researchers and the results of recent comparative tests (Brunialti et al. 2012a;Cristofolini et al. 2014) were useful to obtain the current sampling strategy for lichen survey. At the end of this process, to reduce the effect of several possible sources of error (e.g., different size of explored area on the trunk, subjectivity in the positioning of the sampling grid, etc.), several parameters have been standardized. ...
Although lichen diversity values are broadly used as bioindicators, mainly for air pollution
, lichen communities can be substantially influenced by other ecological factors, such as tree species and forest structure, and microclimatic conditions. In particular, species composition may be a suitable indicator for climate
and land-use effects as well. For effective utilization of lichen diversity data in biomonitoring
studies including air pollution, ecosystem
functioning
, and forestry studies, standardized sampling procedure and avoiding sampling and non-sampling errors are the important aspects to be considered. Further interpretation of lichen diversity data requires careful data analysis for providing affirmative results related to ambient air quality. In any lichen biomonitoring program, expected deliverables are based on a hypothesis, which may be achieved by standardization of the sampling procedures
based on the functional requirement of the dependent environmental variables. The chapter discusses the procedures and methodology for sampling and interpreting lichen diversity data for biomonitoring
purposes.
... However, lichen species richness and LDV that are frequently used in the literature (Brunialti et al., 2012(Brunialti et al., , 2002Cristofolini et al., 2014;Giordani et al., 2009) do not best reflect the relevé quality. Indeed, these indicators do not consider the correct identification. ...
The Lichens GO program is a French citizen science initiative based on the European guidelines that aims to evaluate the lichen diversity for urban air quality monitoring. In this study, we assessed the performance and applicability of the current Lichens GO protocol to then propose adaptations to make it more reliable and feasible for citizen science. To achieve this goal, we considered four aspects of the citizen science program: potential protocol simplifications, sampling site availability, observer bias, and volunteer feedbacks. Simulated simplification scenarios from a reference data set highlighted the large influence of reducing the number of sampled trees on taxonomic and functional structure metrics compared to reducing the number of sampled tree exposure sides and considered lichen species list. When considering the Lichens GO protocol (i.e., three trees, four exposure sides, Lichens GO species list) compared to the reference data set (i.e., five trees, four exposure sides, exhaustive species list), we evaluated an underestimation of lichen species richness (−25%), acidophilous species proportion (−94%), and functional diversity (−21%). In parallel, the maximum distance between sampled trees did not influence the taxonomic and functional structure metrics when considering a homogeneous sampling area (i.e., similar light or shade conditions). Finally, we compared Lichens GO relevés from 25 volunteers in the same site to highlight the major identification difficulties that could compromise the ecological interpretation. To improve the quality of data collected by citizens without increasing the sampling effort, we suggest to: (1) increase the maximum distance between trees from 10 to 50 m to extend the sampling site availability; (2) adapt the Lichens GO identification key to limit species confusion; and (3) assign an ecological trait to some lichen species groupings to improve the ecological interpretation. The proposed adaptations were tested and showed an improvement in the acidophilous species proportion (from −94 to −13%) and functional diversity (from −21 to −4%).
... Epiphytic lichen diversity was sampled following the European standard method (Asta et al., 2002;Cristofolini et al., 2014) (Fig. S2). The four trees closest to the centroid were sampled while following the method selection criteria (see Supplementary Material for more details). ...
To create more resilient cities, it is important that we understand the effects of the global change drivers in cities. Biodiversity-based ecological indicators (EIs) can be used for this, as biodiversity is the basis of ecosystem structure, composition, and function. In previous studies, lichens have been used as EIs to monitor the effects of global change drivers in an urban context, but only in single-city studies. Thus, we currently do not understand how lichens are affected by drivers that work on a broader scale. Therefore, our aim was to quantify the variance in lichen biodiversity-based metrics (taxonomic and trait-based) that can be explained by environmental drivers working on a broad spatial scale, in an urban context where local drivers are superimposed. To this end, we performed an unprecedented effort to sample epiphytic lichens in 219 green spaces across a continental gradient from Portugal to Estonia. Twenty-six broad-scale drivers were retrieved, including air pollution and bio-climatic variables, and their dimensionality reduced by means of a principal component analysis (PCA). Thirty-eight lichen metrics were then modelled against the scores of the first two axes of each PCA, and their variance partitioned into pollution and climate components. For the first time, we determined that 15% of the metric variance was explained by broad-scale drivers, with broad-scale air pollution showing more importance than climate across the majority of metrics. Taxonomic metrics were better explained by air pollution, as expected, while climate did not surpass air pollution in any of the trait-based metric groups. Consequently, 85% of the metric variance was shown to occur at the local scale. This suggests that further work is necessary to decipher the effects of climate change. Furthermore, although drivers working within cities are prevailing, both spatial scales must be considered simultaneously if we are to use lichens as EIs in cities at continental to global scales.
... Overall, the approaches of previous studies are in line with the current processes of standardization of protocols for monitoring lichens (see Giordani & Brunialti, 2015) that account for two main sources of uncertainty: i) the sampling error related to the high variability of lichen response to macro-and microenvironmental factors (Cristofolini et al., 2014;Matos et al., 2017), and ii) the non-sampling error depending on the taxonomic knowledge of the sampling expert(s), as well as on lichen species detectability Giordani et al., 2009). ...
... While numerous studies have investigated vascular plants in these severe environments, there are few that have resolution at species level or community responses that include bryophyte and lichen diversity (Bjerke et al., 2011;Klanderud, 2008;Lang et al., 2012;Olsen and Klanderud, 2014;Potter et al., 1995). Bryophytes and lichens are frequently used as ecological indicator species (Cristofolini et al., 2014;Mölder et al., 2015), but in experimental environmental change studies bryophytes and lichens are not usually identified at species level Hill and Henry, 2011). This is probably because ecologists commonly have problems identifying bryophytes and lichens to species level (Brunialti et al., 2012;Turetsky et al., 2012). ...
Global change is predicted to have large and rapid impact on polar and alpine regions. Bryophytes and lichens increase their importance in terms of biomass, carbon/nutrient cycling, cover and ecosystem functioning at higher latitudes/altitudes. Here we report from a seven year factorial experiment with nutrient addition and warming on the abundance of bryophytes and lichens in an alpine meadow and heath community. Treatments had significant negative effect on relative change of total abundance bryophytes and lichens, the largest decline to the nutrient addition and the combined nutrient addition and warming treatments, bryophytes decreasing most in the meadow, lichens most in the heath. Nutrient addition, and the combined nutrient addition and warming brought rapid decrease in both bryophytes and lichens, while warming had a delayed negative impact. Of sixteen species that were included the statistical analyses, we found significant negative effects on seven species. We show that impact of simulated global change on bryophytes and lichens differ in in time and magnitude among treatments and plant communities. Our results underscore the importance of longer-term studies to improve the quality of climate change models, as short-term studies are poor predictors of longer-term responses of bryophytes and lichens, similar to what have been shown for vascular plants. Species-specific responses may differ in time, and this will likely cause changes in the dominance structures of bryophytes and lichens over time.
... Recently, the Comité Européen de Normalization (CEN) has adopted a standard procedure for sampling design and assessment of lichen diversity (Ambient air -Biomonitoring with lichens -Assessing epiphytic lichen diversity; European Standard EN 16413:2014). The sampling strategy included in that document was developed mainly for air pollution monitoring activities and focused only on tree trunks (1-1·5 m above ground) (Cristofolini et al. 2014), thus overlooking several additional microhabitats relevant for lichens in forest ecosystems. A reduction of sampling effort on tree trunks has been suggested by previous studies (Nascimbene et al. 2010) as a potential strategy to redirect the sampling effort to currently overlooked microhabitats, such as the canopy and coarse woody debris (CWD), and to design sampling schemes that would result in a more comprehensive species capture in forest ecosystems. ...
Epiphytic lichens are increasingly included in forest biodiversity monitoring schemes, but most of the standardized guidelines consider only lichens colonizing a small part of tree trunks (1·0–1·5 m) and overlook other important microhabitats, such as fallen branches and stumps. In this paper, we present results of a small-scale pilot study to evaluate the possible advantage of including four distinct microhabitats in standardized procedures for assessing epiphytic lichen diversity. Trunk bases, trunks between 100 and 150 cm above the ground, stumps, and fallen branches were each sampled with a different standardized sampling method along a forest age gradient in temperate deciduous forests of the Caucasian region. Plot-level species richness was contrasted between the standardized sampling procedures of different substrata and a non-probabilistic floristic sampling. The interactions between sampling procedure and stand age were analysed using linear mixed models, and non-metric multidimensional scaling (NMDS) and multi-response permutation procedures (MRPP) were used for comparing species composition. Overall, 97 species were recorded, their richness increasing with increasing stand age. Results were consistent across the gradient of stand age and demonstrated that the adoption of standardized sampling procedures which include stumps and fallen branches in addition to tree trunks would increase the capability of maximizing species capture. This approach would allow researchers to evaluate lichen patterns by simultaneously considering the response of different communities sensitive to different stand-related factors. Despite the likelihood that a non-probabilistic floristic survey would give a more exhaustive picture of the plot-level lichen diversity, standardized sampling procedures that include tree trunks, fallen branches and stumps are likely to represent a reasonable trade-off between exhaustiveness and cost-effectiveness.
... Lichens have been widely used for monitoring air pollution because they directly respond to the atmospheric conditions . The mapping of epiphytic lichen diversity to assess changes at community level is an increasingly common approach (Larsen et al. 2007;Cristofolini et al. 2014). One of the first responses of lichen assemblages to increased nitrogen depositions is the reduction in oligotrophic lichens in favour of an increase Table 1. in nitrophilous species (Pinho et al. 2009), bringing about a general homogenization of the lichen vegetation (Liška & Herben 2008). ...
We analysed a dataset composed by the frequency of 79 epiphytic lichens recorded on 243 oaks distributed in 29 oak dominated stands of the Western Carpathians, representing areas with high environmental quality up to disturbed environments. Lichen diversity indices (based on total frequencies and on functional and morphological groups) were used as indicators of the response to air quality and forest management. The level of air quality in these categories was a function of NOx, SO2 and particulate matter. From management viewpoint the units were classified as managed (areas subjected to periodic logging) and semi-natural (which currently have the status of National Nature Reserve and where eventual management practices date back to the history). The results showed that higher environmental levels of pollution were associated to the decrease of fruticose and in general pollution sensitive species, while low environmental levels of pollution were associated to the diffusion of common nitrophilous lichens as well as to a higher share of fruticose and in general pollution sensitive species. As far as forest management is concerned, a higher share of fruticose and sensitive species was associated to semi-natural and natural stands, whereas a higher share of foliose (pioneer and tolerant) species was associated to the managed stands.
... Lichen diversity was used as a surrogate of both air purification and habitat quality, by using different metrics. Epiphytic lichen diversity was measured in September 2015 in 29 trees of Quercus spp., using the European standard methodology (Asta et al., 2002;Cristofolini et al., 2014). Tree selection was done by stratifying for vegetation unit, ensuring that all units were sampled, and sampling five locations per unit. ...
Urban areas' population has grown during the last century and it is expected that over 60% of the world population will live in cities by 2050. Urban parks provide several ecosystem services that are valuable to the well-being of city-dwellers and they are also considered a nature-based solution to tackle multiple environmental problems in cities. However, the type and amount of ecosystem services provided will vary with each park vegetation type, even within same the park. Our main goal was to quantify the trade-offs in ecosystem services associated to different vegetation types, using a spatially detailed approach. Rather than relying solely on general vegetation typologies, we took a more ecologically oriented approach, by explicitly considering different units of vegetation structure and composition. This was demonstrated in a large park (44ha) located in the city of Almada (Lisbon metropolitan area, Portugal), where six vegetation units were mapped in detail and six ecosystem services were evaluated: carbon sequestration, seed dispersal, erosion prevention, water purification, air purification and habitat quality. The results showed that, when looking at the park in detail, some ecosystem services varied greatly with vegetation type. Carbon sequestration was positively influenced by tree density, independently of species composition. Seed dispersal potential was higher in lawns, and mixed forest provided the highest amount of habitat quality. Air purification service was slightly higher in mixed forest, but was high in all vegetation types, probably due to low background pollution, and both water purification and erosion prevention were high in all vegetation types. Knowing the type, location, and amount of ecosystem services provided by each vegetation type can help to improve management options based on ecosystem services trade-offs and looking for win-win situations. The trade-offs are, for example, very clear for carbon: tree planting will boost carbon sequestration regardless of species, but may not be enough to increase habitat quality. Moreover, it may also negatively influence seed dispersal service. Informed practitioners can use this ecological knowledge to promote the role of urban parks as a nature-based solution to provide multiple ecosystem services, and ultimately improve the design and management of the green infrastructure. This will also improve the science of Ecosystem Services, acknowledging that the type of vegetation matters for the provision of ecosystem services and trade-offs analysis.
... If monitoring protocols are not consistent, then signals may be lost in statistical noise, or results may not be comparable across time and/or space. A recent paper comparing epiphytic lichen data gathered from specialists from six different European countries found discrepancies in methods, and in identification of taxa, which made it difficult to compare findings across space (Cristofolini et al., 2014). A similar assessment of the same region by five teams of investigators found that, despite being given identical standard operating procedures (SOPs), each of the teams interpreted procedures differently, with the result that sampling strategies and resultant data were not consistent (Brunialti et al., 2012). ...
Arboreal lichens have a wide range of tolerance to habitat disturbance. As a result, they have been used globally as bioindicators of environmental change, particularly for monitoring atmospheric pollution. Here, we use lichens to monitor air quality and ecological integrity (EI) at Kejimkujik National Park and National Historic Site in Nova Scotia, Canada. We provide descriptions of two protocols and compare the results using data gathered in 2006, 2011, and 2016. To monitor air quality, we established 12 monitoring sites throughout the park and used a suite of lichens that are intolerant to air pollution to develop an index of air purity (IAP) that we compared every 5 years. Our protocol for monitoring EI of forest ecosystems was set up at these same 12 sites. We selected 50 regionally common field-identifiable lichen species and genera ranging in sensitivity from disturbance-tolerant to intolerant, and compare their presence in spatially constrained zones on a variety of tree species every 5 years. Our results suggest that air quality in Kejimkujik has increased slightly in the 10 years since monitoring was implemented, which is consistent with improvements in local air quality. Species richness also increased slightly, suggesting that EI has not declined. The maintenance of EI, through protection and restoration of natural resources, is a key priority in the management of national parks in Canada. Our protocols will provide early detection of changes to EI, enabling park managers to take responsive action. We are confident that our protocols can be replicated in other parts of the world with different suites of regionally common lichens.
... While numerous studies have investigated vascular plants in these severe environments, there are few that have resolution at species level or community responses that include bryophyte and lichen diversity (Bjerke et al., 2011;Klanderud, 2008;Lang et al., 2012;Olsen and Klanderud, 2014;Potter et al., 1995). Bryophytes and lichens are frequently used as ecological indicator species (Cristofolini et al., 2014;Mölder et al., 2015), but in experimental environmental change studies bryophytes and lichens are not usually identified at species level Hill and Henry, 2011). This is probably because ecologists commonly have problems identifying bryophytes and lichens to species level (Brunialti et al., 2012;Turetsky et al., 2012). ...
Environmental changes are predicted to have severe and rapid impacts on polar and alpine regions. At high latitudes/altitudes, cryptogams such as bryophytes and lichens are of great importance in terms of biomass, carbon/nutrient cycling, cover and ecosystem functioning. This seven-year factorial experiment examined the effects of fertilizing and experimental warming on bryophyte and lichen abundance in an alpine meadow and a heath community in subarctic Sweden. The aim was to determine whether short-term responses (five years) are good predictors of longer-term responses (seven years). Fertilizing and warming had significant negative effects on total and relative abundance of bryophytes and lichens, with the largest and most rapid decline caused by fertilizing and combined fertilizing and warming. Bryophytes decreased most in the alpine meadow community, which was bryophyte-dominated, and lichens decreased most in the heath community, which was lichen-dominated. This was surprising, as the most diverse group in each community was expected to be most resistant to perturbation. Warming alone had a delayed negative impact. Of the 16 species included in statistical analyses, seven were significantly negatively affected. Overall, the impacts of simulated warming on bryophytes and lichens as a whole and on individual species differed in time and magnitude between treatments and plant communities (meadow and heath). This will likely cause changes in the dominance structures over time. These results underscore the importance of longer-term studies to improve the quality of data used in climate change models, as models based on short-term data are poor predictors of long-term responses of bryophytes and lichens.
... Effects were especially devastating to lichen biota because of their sensitivity to air pollution (Henderson 2000; Landis et al. 2012) and substrate acidity (Bates 1992; Mežka et al. 2008). This sensitivity is a result of their biology (e.g., permeable thallus surface; Nash 2008) and has made them a wellrecognized bioindicator of air pollution (Nimis et al. 2002; Larsen et al. 2007; Cristofolini et al. 2014). Few studies have examined the long-term recovery of lichen communities in this landscape (Beckett 1995 and Leblanc et al. 1972). ...
Pollution control initiatives in Greater Sudbury, Ontario, Canada, resulted in the decommissioning of the Coniston Smelter in 1972. The last assessment of the effects from the smelter on the surrounding lichen biota was in 1990, which showed an overall improvement in richness following these initiatives, but still few species were present close to the smelter. We examined five sites along this gradient to determine if this pattern is still present on the landscape. Sixty-four macrolichen species in 15 genera were found. Lichen richness and Shannon diversity increased at all sites, but the increase was no longer linear with distance from the smelter. There was no significant difference between lichen richness and diversity at sites at increasing distances from the smelter. We show that past air pollution from the Coniston Smelter is no longer restricting lichen growth and development in the Greater Sudbury area as it was historically. Lichen populations are, therefore, now shaped by other environmental variables.
‘Signposting the Anthropocene: Air care, poleotolerance and the queering of ecosystem services’ by Alexandra R. Toland, Harriet Rabe von Froreich, and Beate Körner aims at (1) problematizing the exploitative and anthropocentric framing of Ecosystem Services (ESS) associated with the atmosphere, and (2) exploring the communicative potential of signposting atmospheric change through developing artistic practices that ask what it means to care for air.
From a human perspective, it may be difficult to perceive air as the complex body it is, composed of different gasses and aerosols, pressures and particles, movements and atmospheres. It roams freely and interacts with other bodies such as soil, water, humans and other life forms. Some of these interactions fall under what is considered to be pollution. Air quality equals the possibility for life – and it takes work. There is multispecies labour involved in the manifold interactions with air, such as filtering and cooling, which then make up for livable habitats. The term Ecosystem Services (ESS) is one possible framing to imagine and describe the non-human labor in keeping air ‘beneficial’. However, as we argue, it is a problematic framing, for instance, because of the patriarchal and colonial roots of ‘service’ as a word and concept, which potentially hinder alternative modes of relating to and valuing nature.
This article uses a multispecies approach to explore the agencies of those soliciting and providing ‘air-care services’. To challenge the anthropocentric perspective, we propose to turn to non-human narrators, so-called bioindicators, and pick one specialized in the communicative services of signposting and storytelling: lichen.
What can we learn from these humble, omnipresent and symbiotic organisms which can literally live on air? What practices can we as artist-researchers and ecosystem inhabitants develop, to shift our perspective on what it means to clear the air?
In the search for cost-effective methods for measuring and monitoring lichen diversity, we tested the performance of two possible indicators: lichen genus diversity and macrolichen diversity. We studied the lichen vegetation of eight European countries situated in six different biogeographic regions. In each country, six land-use units (each 1 km(2)) representing a land-use gradient ranging from old-growth forest to farmland were sampled (n=48) for terricolous, saxicolous, and epiphytic lichens at 16 plots each. We found 768 different lichen species belonging to 157 genera. Relationships between richness and density of genera and species, species and macrolichens, and crustose lichens and macrolichens were highly significant (p<0.001) for all substrates combined and for epiphytic and saxicolous lichens. Richness and density of genera and macrolichens explained a large amount. of variation of the species richness and density (R(2): 71.9%-98.0%). The relationship between crustose lichens and macrolichens explained less of the variation (R(2): 37.7%-70.1%). Effects of land-use intensity on the richness and density of genera, species, and crustose lichens were similar, except for a strong difference between the forested and the more open land-use units for epiphytic crustose lichens. For epiphytic macrolichens there were fewer significant effects. Detrended correspondence analysis indicated similar ordering of sites along the major gradients and similar length of these gradients for genera, species, macrolichens, and crustose lichens. Both genera and macrolichens are useful indicators of total lichen species richness and density. Macrolichens, however, are more suitable indicators than genera owing to (1) their more stable taxonomy of species than of genera, (2) the potential that nonspecialists could do the sampling, (3) the limited use of genera data for species conservation, and (4) the fact that species extinctions will not be indicated by nonmonotypic genera.
In the last decades, several methods were proposed for assessing environmental quality — mainly air pollution — on the basis of lichen data (see chapter 4, this volume). At the end of the 80s the predictivity of 20 different methods with respect to instrumental pollution data was tested in Switzerland using multiple regression [1, 5]. The highest correlation was found with the sum of frequencies of lichen species within a sampling grid of 10 units positioned on the trunks of free-standing trees. This method was immediately and widely adopted in several other countries, esp. Italy and Germany, with some modifications, chiefly concerning the size of the sampling grid. Since 1987, hundreds of studies were carried out with this approach, which led to its standardization in the form of guidelines both in Germany [13], and in Italy [7].
The identification of lichens is important in several applied fields, such as the biological monitoring of air pollution and the restoration of open-air stone monuments. This often creates relevant problems for non-specialists and technicians which are in charge of routinely applying lichen monitoring techniques. The coupling of a complex information system (ITALIC), together with a new software which can automatically produce identification keys for any subset of species included in a database (FRIDA), is an innovative approach in the field of identifying biodiversity. ITALIC is able to produce a list of species which potentially occur under a set of ecological and distributional conditions specified by the user. The list is automatically transferred to FRIDA, which generates a user-oriented interactive identification key limited to the species present in the "virtual habitat" created by the user. The new system has relevant applications, since it effectively supports the technical personnel of Environmental Agencies, Nature Parks, Cultural Heritage Conservation Agencies involved in lichen monitoring throughout the Country.
This chapter presents analytic methods for matched studies with multiple risk factors of interest. We consider matched sample designs of two types, prospective (cohort or randomized) and retrospective (case-control) studies. We discuss direct and indirect parametric modeling of matched sample data and then focus on conditional logistic regression in matched case-control studies. Next, we describe the general case for matched samples including polytomous outcomes. An illustration of matched sample case-control analysis is presented. A problem solving section appears at the end of the chapter.
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.
The variability of biological data is a main constraint affecting the quality and reliability of lichen biomonitoring surveys for estimation of the effects of atmospheric pollution. Although most epiphytic lichen bioindication surveys focus on between-site differences at the landscape level, associated with the large scale effects of atmospheric pollution, current protocols are based on multilevel sampling, thus adding further sources of variation and affecting the error budget. We test the hypothesis that assemblages of lichen communities vary at each spatial scale examined, in order to determine what scales should be included in future monitoring studies. We compared four sites in Italy, along gradients of atmospheric pollution and climate, to test the partitioning of the variance components of lichen diversity across spatial scales (from trunks to landscapes). Despite environmental heterogeneity, we observed comparable spatial variance. However, residuals often overcame between-plot variability, leading to biased estimation of atmospheric pollution effects.
Rapid Biodiversity Assessments (RBAs) of lichen communities, obtained by means of simplified sampling lists based on morphospecies, showed good correlations with Lichen Diversity Values (LDVs), based on the complete identification of lichen species only when performed by operators with high levels of taxonomic knowledge. Furthermore, the use of highly simplified sampling lists did not lead to significant advantages in terms of time needed for field operations. This approach proved to be especially unreliable in high diversity ecological contexts where variation of morpho-structural composition within lichen communities is frequent (i.e. co-occurring crustose- and foliose-dominated communities); it may also lead to weak results if applied for conservation purposes. Hence, the use of simplified RBA sampling lists in lichen monitoring has to be carefully evaluated and, in any case, should be based on sound taxonomic knowledge on the part of those in charge of data collection. The proper assessment of descriptors of lichen abundance and/or frequency, however, strictly depends on the skill, taxonomic knowledge, and willingness to learn of the lichenologist-in-training.
Epiphytic lichen and bryophyte distribution and frequency were investigated on the trunks of 145 young oak trees throughout London and surrounding counties, and compared with pollution levels and bark pH. Sixty-four lichen and four bryophyte species were recorded. Three major zones were identified: (i) two central regions with a few lichens, bryophytes absent; (ii) a surrounding region with a more diverse flora including a high cover of nitrophyte lichens; and (iii) an outer region, characterised by species absent from central London, including acidophytes. Nineteen species were correlated with nitrogen oxides and 16 with bark pH, suggesting that transport-related pollution and bark acidity influence lichen and bryophyte distribution in London today. Lichens and bryophytes are responding to factors that influence human and environmental health in London. Biomonitoring therefore has a practical role to assess the effects of measures to improve London's air quality.
Monitoring with Lichens -Monitoring Lichens. Kluwer Academic Published in Association with the NATO Scientific Affairs Division
- P L Nimis
- C Scheidegger
- P A Wolseley
Nimis, P.L., Scheidegger, C., Wolseley, P.A., 2002. Monitoring with Lichens -Monitoring Lichens. Kluwer Academic Published in Association with the NATO Scientific
Affairs Division, Dordrecht, The Netherlands.
Performance of macrolichens and lichen genera as indicators of lichen species richness and composition
- Bergamini