Multiple drivers of large-scale lichen decline in boreal forest canopies.

Thin, hair-like lichens (Alectoria, Bryoria, Usnea) form conspicuous epiphyte communities across the boreal biome. These poikilohydric organisms provide important ecosystem functions and are useful indicators of global change. We analyse how environmental drivers influence changes in occurrence and length of these lichens on Norway spruce (Picea abies) over 10 years in managed forests in Sweden using data from >6000 trees. Alectoria and Usnea showed strong declines in southern-central regions, whereas Bryoria declined in northern regions. Overall, relative loss rates across the country ranged from 1.7% per year in Alectoria to 0.5% in Bryoria. These losses contrasted with increased length of Bryoria and Usnea in some regions. Occurrence trajectories (extinction, colonization, presence, absence) on remeasured trees correlated best with temperature, rain, nitrogen deposition, and stand age in multinomial logistic regression models. Our analysis strongly suggests that industrial forestry, in combination with nitrogen, is the main driver of lichen declines. Logging of forests with long continuity of tree cover, short rotation cycles, substrate limitation and low light in dense forests are harmful for lichens. Nitrogen deposition has decreased but is apparently still sufficiently high to prevent recovery. Warming correlated with occurrence trajectories of Alectoria and Bryoria, likely by altering hydration regimes and increasing respiration during autumn/winter. The large-scale lichen decline on an important host has cascading effects on biodiversity and function of boreal forest canopies. Forest management must apply a broad spectrum of methods, including uneven-aged continuous cover forestry and retention of large patches, to secure the ecosystem functions of these important canopy components under future climates. Our findings highlight interactions among drivers of lichen decline (forestry, nitrogen, climate), functional traits (dispersal, lichen colour, sensitivity to nitrogen, water storage), and population processes (extinction/colonization).

Application of Index of Atmospheric Purity (IAP) along elevation gradients in Gunung Jerai, Kedah, Malaysia.

The utilisation of biological organisms, especially lichens in the environmental biomonitoring approach, has been proven to be an effective and low-cost technique suitable for developing countries like Malaysia. Index of Atmospheric Purity (IAP) tracked compositional changes in lichen communities which correlate with changes in levels of atmospheric pollution. Gunung Jerai was formed during the Cambrian Period; thus, it is a biodiversity hotspot ideal for a diverse range of lichens. In the present work, a total of 44 corticolous lichen species were sampled and identified to evaluate the pollution status of Gunung Jerai using IAP, starting from 80 to 1200 m with 300 m intervals. The samples were collected within 10 × 50 cm sampling grids attached to 60 trees, bringing a total of 120 000 cm2 of the sampling area. The air quality of the sampling area was determined by IAP score, a low score indicated by high levels of pollution. Results showed that the lowest IAP score was recorded at 300 m; meanwhile, the highest IAP score was recorded at 900 m elevation. Elevational gradient and pollution have a significant effect on the IAP score of Gunung Jerai. On average, Gunung Jerai is indicated as having a low pollution status. However, several elevations of the rainforest showed high and moderate pollution status. The IAP method is best to assess environmental pollution and provide quicker results than chemical monitoring methods. Further research could be done to evaluate the other sampling sites adjacent to other areas of Gunung Jerai.

Disentangling functional trait variation and covariation in epiphytic lichens along a continent-wide latitudinal gradient.

Characterizing functional trait variation and covariation, and its drivers, is critical to understand the response of species to changing environmental conditions. Evolutionary and environmental factors determine how traits vary among and within species at multiple scales. However, disentangling their relative contribution is challenging and a comprehensive trait-environment framework addressing such questions is missing in lichens. We investigated the variation in nine traits related to photosynthetic performance, water use and nutrient acquisition applying phylogenetic comparative analyses in lichen epiphytic communities on beech across Europe. These poikilohydric organisms offer a valuable model owing to their inherent limitations to buffer contrasting environmental conditions. Photobiont type and growth form captured differences in certain physiological traits whose variation was largely determined by evolutionary processes (i.e. phylogenetic history), although the intraspecific component was non-negligible. Seasonal temperature fluctuations also had an impact on trait variation, while nitrogen content depended on photobiont type rather than nitrogen deposition. The inconsistency of trait covariation among and within species prevented establishing major resource use strategies in lichens. However, we did identify a general pattern related to the water-use strategy. Thus, to robustly unveil lichen responses under different climatic scenarios, it is necessary to incorporate both among and within-species trait variation and covariation.

Environmental factors that drive the distribution and abundance of a threatened cyanolichen in Southern Europe: a multi-scale approach.

PREMISE OF THE STUDY: High-quality information about threatened species is required to prevent current global biodiversity losses. Lichens are important components of forest biodiversity and help to maintain ecosystem functioning. The epiphytic cyanolichen Lobarina scrobiculata is red-listed in Europe and North America, but knowledge of its ecology and distribution in Southern Europe is scarce. METHODS: We used a multispatial scale design to investigate the effects of macroclimate, forest structure, tree features, and microhabitat on the occurrence, abundance, spatial distribution, and performance of Lobarina scrobiculata in the Iberian Peninsula at plot and tree scales. Generalized linear models and mixed models were used for analysis. KEY RESULTS: We recorded ca 14000 individuals of the threatened species Lobarina scrobiculata from 22 populations in the Iberian Peninsula. Our results suggest that L. scrobiculata thrives mainly in oak forests with highly variable annual precipitation levels. At the plot scale, the L. scrobiculata abundance increased with annual precipitation and tree density (habitat quantity). At the tree scale, our models highlighted the importance of tree size and bark roughness (habitat quality) as the main drivers of species occurrence and abundance. We detected a marked spatial pattern on tree trunks, i.e., L. scrobiculata occurred preferentially on north-facing surfaces and close to the ground where humidity is higher. CONCLUSIONS: By integrating multiscale modeling, we analyzed a unique large dataset and these results are essential for understanding the ecology of this threatened cyanolichen. There is an urgent need to preserve the forests that this species currently inhabits as well as potential colonization sites.

Lichen Biodiversity and Near-Infrared Metabolomic Fingerprint as Diagnostic and Prognostic Complementary Tools for Biomonitoring: A Case Study in the Eastern Iberian Peninsula.

In the 1990s, a sampling network for the biomonitoring of forests using epiphytic lichen diversity was established in the eastern Iberian Peninsula. This area registered air pollution impacts by winds from the Andorra thermal power plant, as well as from photo-oxidants and nitrogen depositions from local and long-distance transport. In 1997, an assessment of the state of lichen communities was carried out by calculating the Index of Atmospheric Purity. In addition, visible symptoms of morphological injury were recorded in nine macrolichens pre-selected by the speed of symptom evolution and their wide distribution in the territory. The thermal power plant has been closed and inactive since 2020. During 2022, almost 25 years later, seven stations of this previously established biomonitoring were revaluated. To compare the results obtained in 1997 and 2022, the same methodology was used, and data from air quality stations were included. We tested if, by integrating innovative methodologies (NIRS) into biomonitoring tools, it is possible to render an integrated response. The results displayed a general decrease in biodiversity in several of the sampling plots and a generalised increase in damage symptoms in the target lichen species studied in 1997, which seem to be the consequence of a multifactorial response.

Microclimatic Alteration after Logging Affects the Growth of the Endangered Lichen Lobaria pulmonaria.

Microclimatic conditions are important in determining lichen distribution at small scale, and may determine whether the species persist when the surrounding environmental conditions have drastically changed. This is the case with forest management, since a sudden variation of microclimatic conditions (increase of solar radiation, temperature, wind and a reduction of humidity) may occur after logging. In this study, the combined effect of forest logging and microclimatic conditions on the growth probabilities and growth rates of the model species Lobaria pulmonaria was assessed in mixed oak stands. To this purpose, 800 fragments of L. pulmonaria (<1 cm) were transplanted in logged and unlogged stands for two years. Young and adult fragments were positioned on Turkey oak boles according to distance from the ground (100 and 50 cm) and aspect (north and south). The results, evaluated by generalized linear mixed models on a yearly basis, highlighted differences in growth-particularly on isolated trees in the logged stand. South-exposed samples in the logged stand showed a low probability of growth, while samples transplanted north in the unlogged stand showed higher growth probabilities. However, the highest annual growth coefficients corresponded to south-exposed samples 50 cm from the ground in the unlogged stand. In general, higher growth rates were observed in young thallus fragments when compared with adult ones. Beyond confirming the importance of microclimate for lichen ecology, these results could be implemented in conservation actions to preserve L. pulmonaria populations in logged forests.

Habitat Fragmentation and Lichen Diversity in Peri-Urban Woodlands: A Case Study in the Municipality of Potenza (Southern Italy).

The fragmentation of the natural habitat is a process that is exponentially increasing worldwide and represents one of the biggest threats to biological diversity. Habitat destruction and fragmentation have a major impact on landscapes and may also affect ecosystems, populations, and species. The ongoing anthropogenic process can result in habitat loss for some species, habitat creation for others, reduced patch size, and increased distance between patches, which may lead to local extinction. We analyzed the effects of patch size and isolation on lichens in Quercus pubescens woods surrounding the city of Potenza (south Italy). We randomly sampled 11 forest patches with homogeneous environmental variables using circular plots with a 10 m radius; the patches ranged from 0.3 to 30 ha. For each plot, we collected data about presence and abundance of epiphytic lichens. We performed the analyses at the patch level using linear regression and multivariate analysis, searching for effects on species richness, life forms, and community compositions. Multivariate analyses were used to study the effect of fragmentation on the structure of lichen vegetation. We investigated the main predictor of lichen species richness in habitat fragmentations and concluded that patch area per se is an important (positive) driver of lichen species richness in Mediterranean peri-urban forests.

Range shifts of native and invasive trees exacerbate the impact of climate change on epiphyte distribution: The case of lung lichen and black locust in Italy.

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.

Citizen science identifies the effects of nitrogen deposition, climate and tree species on epiphytic lichens across the UK.

A national citizen survey quantified the abundance of epiphytic lichens that are known to be either sensitive or tolerant to nitrogen (N) deposition. Records were collected across the UK from over 10,000 individual trees of 22 deciduous species. Mean abundance of tolerant and sensitive lichens was related to mean N deposition rates and climatic variables at a 5 km scale, and the response of lichens was compared on the three most common trees (Quercus, Fraxinus and Acer) and by assigning all 22 tree species to three bark pH groups. The abundance of N-sensitive lichens on trunks decreased with increasing total N deposition, while that of N-tolerant lichens increased. The abundance of N-sensitive lichens on trunks was reduced close to a busy road, while the abundance of N-tolerant lichens increased. The abundance of N-tolerant lichen species on trunks was lower on Quercus and other low bark pH species, but the abundance of N-sensitive lichens was similar on different tree species. Lichen abundance relationships with total N deposition did not differ between tree species or bark pH groups. The response of N-sensitive lichens to reduced nitrogen was greater than to oxidised N, and the response of N-tolerant lichens was greater to oxidised N than to reduced N. There were differences in the response of N-sensitive and N-tolerant lichens to rainfall, humidity and temperature. Relationships with N deposition and climatic variables were similar for lichen presence on twigs as for lichen abundance on trunks, but N-sensitive lichens increased, rather than decreased, on twigs of Quercus/low bark pH species. The results demonstrate the unique power of citizen science to detect and quantify the air pollution impacts over a wide geographical range, and specifically to contribute to understanding of lichen responses to different chemical forms of N deposition, local pollution sources and bark chemistry.

Thalli Growth, Propagule Survival, and Integrated Physiological Response to Nitrogen Stress of Ramalina calicaris var. japonica in Shennongjia Mountain (China).

In this study, effects of nitrogen (N) availability on growth, survival of Ramalina calicaris var. japonica, and whether it respond nitrogen stress in an integrated physiological way was evaluated. Thalli growth and propagule survival, thalli N and phosphorus (P) content, and activity of phosphomonoesterase (PME) of R. calicaris var. japonica were determined in a field experiment. Its differentiate adsorption in ammonia and nitrate, the activity of glutamine synthetase (GSA) and nitrate reductase (NRA) also were investigated in a series of indoor experiments. The results showed that N deposition significantly decreased the growth and survival of this lichen, and the N sensitivity threshold was suggested at 6.0 kg N⋅ha-1⋅y-1. When the N deposition increased from 8.59 kg N⋅ha-1⋅y-1 to 14.24, 20.49, 32.99 and 57.99 kg N⋅ha-1⋅y-1, the growth rates of lichen thalli decreased by 26.47, 39.01, 52.18 and 60.3%, respectively; Whereas the survival rate of the lichen propagules decreased from 92.8% of control (0.0 kg N⋅ha-1⋅y-1) to 10.7% of 50.0 kg N⋅ha-1⋅y-1, when they were treated with 0.00, 6.25, 12.5, 25.0, and 50.0 kg N⋅ha-1⋅y-1 deposition. Compared with an adequate adsorption of ammonium N, no nitrate adsorption occurred when thalli was submerged in solution lower than 0.4 mM. Our results also suggested that thalli total nitrogen, N:P ratio increased with N availability, and the activity of PME was significantly correlated with thalli total nitrogen. These all indicated that phosphorus limitation occurred when R. calicaris var. japonica treated with higher nitrogen deposition. Compared with slightly effects of NRA, GSA of R. calicaris var. japonica responded nitrogen availability significantly; In addition, GSA and NRA negatively correlated with thalli growth rate and propagule survival significantly. These results indicated that nitrogen stress do decrease growth and survival of R. calicaris var. japonica, and lichen would be impacted by excess nitrogen in a integrated, not a fragmentary way, including nitrogen uptake, assimilation, even nutrient balance of nitrogen and phosphorous.

Carbon based secondary compounds do not provide protection against heavy metal road pollutants in epiphytic macrolichens.

Lichens are useful monitoring organisms for heavy metal pollution. They are high in carbon based secondary compounds (CBSCs) among which some may chelate heavy metals and thus increase metal accumulation. This study quantifies CBSCs in four epiphytic lichens transplanted for 6months on stands along transects from a highway in southern Norway to search for relationships between concentrations of heavy metals and CBSCs along a gradient in heavy metal pollutants. Viability parameters and concentrations of 21 elements including nutrients and heavy metals in these lichen samples were reported in a separate paper. Medullary CBSCs in fruticose lichens (Ramalina farinacea, Usnea dasypoga) were reduced in the most polluted sites, but not in foliose ones (Parmelia sulcata, Lobaria pulmonaria), whereas cortical CBSC did not change with distance from the road in any species. Strong positive correlations only occurred between the major medullary compound stictic acid present in L. pulmonaria and most heavy metals, consistent with a chelating role of stictic acid, but not of other studied CBSCs or in other species. However, heavy metal chelating did not protect L. pulmonaria against damage because this species experienced the strongest reduction in viability in the polluted sites. CBSCs with an accumulation potential for heavy metals should be quantified in lichen biomonitoring studies of heavy metals because they, like stictic acid, could overshadow pollutant inputs in some species rendering biomonitoring data less useful. In the two fruticose lichen species, CBSCs decreased with increasing heavy metal concentration, probably because heavy metal exposure impaired secondary metabolism. Thus, we found no support for a heavy metal protection role of any CBSCs in studied epiphytic lichens. No intraspecific relationships occurred between CBSCs versus N or C/N-ratio. Interspecifically, medullary CBSCs decreased and cortical CBSCs increased with increasing C/N-ratio.

Impacts of nitrogen deposition on herbaceous ground flora and epiphytic foliose lichen species in southern Ontario hardwood forests.

In this study 70 sugar maple (Acer saccharum Marsh.) dominated plots in Ontario, Canada were sampled in the spring of 2009 and 2010 and herbaceous plant and epiphytic foliose lichen species data were compared against modeled N and S deposition data, climate parameters and measured soil and plant/lichen S and N concentration. Herbaceous plant species richness was positively correlated with temperature and indices of diversity (Shannon Weiner and Simpson's Index) were positively correlated with soil pH but not N or S deposition or standardized foliar N scores. Herbaceous community composition was strongly controlled by traditional factors, but there was a small and significant influence of atmospheric S and N deposition. Epiphytic lichen species richness exhibited a strong negative relationship with standardized foliar N score and only one lichen species (Phaeophyscia rubropulchra) was observed at sites with a standardized foliar N score of 0.76.

Severe photobiont injuries of lichens are strongly associated with air pollution.

The photobiont ultrastructure of the epiphytic lichens Bryoria fuscescens and Bryoria fremontii was studied along the pollution gradient from two Cu-Ni smelters in Nikel and Monchegorsk in northern Finland and north-western Russia. The relationship between ultrastructural characteristics of B. fuscescens and environmental factors (i.e. climate, atmospheric SO2 and bark element concentrations) was studied by using a principal component analysis (PCA) aiming to assess the air quality in a northern environment. Based on PCA, increased plasmolysis and mitochondrial changes in the Trebouxia photobiont were significantly correlated with elevated pollutant concentrations. Degenerated cells, showing altered chloroplasts and electron-translucent pyrenoglobuli, occurred in lichens growing 35-50 km from the Monchegorsk smelter. Cell wall and cytoplasmic lipid volumes, and size of pyrenoglobuli, positively correlated with the distance from the Monchegorsk smelter. Vacuoles and electron-opaque vacuolar deposits were significantly increased at the Finnish site in the vicinity of a pulp mill. Swelling of mitochondrial cristae and thylakoids showed little correlation with environmental factors, but indicated of initial stage of injuries and were observed at several slightly polluted sites in northern Finland and north-western Russia. The results suggest that the severe photobiont injuries of lichens are strongly associated with poor air quality.

The significance of thallus size for the water economy of the cyanobacterial old-forest lichen Degelia plumbea.

Rosette-formed, circular thalli of Degelia plumbea were studied in the laboratory. Regardless of thallus size, the optimal quantum yield of photosystem II (F V/F M) remained at a high, constant level during a drying cycle starting with fully hydrated thalli until the thallus water content reached about 200%. Net photosynthesis reached a maximum level at this hydration level. Thereafter, both F V/F M and net photosynthesis fell rapidly to zero at a water content of somewhat less than 100%. There was a highly significant, positive relationship between thallus size and the water-holding capacity, as well as a strong, negative correlation between size and water loss per thallus area. Consequently, an increase in thallus size from 1 to 36 cm2 lead to a tenfold prolongation of the photosynthetically active period during a drying cycle at a low radiation regime. The improved water-holding capacity in larger thalli is mainly a result of a thicker hypothallus. The fast desiccation of small thalli suggests that the regeneration of D. plumbea could be severely hampered by nearby logging that raises the evaporative demand by increasing radiation loads and wind exposure at remaining lichen sites.

Patterns of traffic polycyclic aromatic hydrocarbon pollution in mountain areas can be revealed by lichen biomonitoring: a case study in the Dolomites (Eastern Italian Alps).

In mountain areas of touristic interest the evaluation of the impact of human activities is crucial for ensuring long-term conservation of ecosystem biodiversity, functions and services. This study aimed at verifying the biological impact of polycyclic aromatic hydrocarbon (PAH) emissions due to traffic along the roads leading to seven passes of the Dolomites (SE Alps), which were recently declared a UNESCO World Heritage Site. Thalli of the epiphytic lichen Pseudevernia furfuracea, collected at increasing distances from the roads, were used as biomonitors. Our study revealed a gradient of decreasing PAH pollution within 300 m from the roads. Differences among passes were evident mainly for samples collected nearest to the roads, but PAH concentrations at 300 m were almost always higher than those of undisturbed reference sites, indicating that traffic PAH pollution may impact natural ecosystems and lichen diversity at relatively long distances from the emission source.

The importance of old deciduous trees and wooden fences for lichen diversity - an example from the Teichalm area (Eastern Alps).

BILOVITZ, P. O. 2014. The importance of old deciduous trees and wooden fences for lichen diversity - an example from the Teichalm area (Eastern Alps). - Herzogia 27: 199 -204. The investigation of the epiphytic lichen diversity on four neighbouring old, isolated deciduous trees and a wooden fence in the Teichalm area yielded 74 lichen taxa and 4 lichenicolous fungi. Anaptychia ciliaris, Cyphelium notarisii, Ramalina fastigiata and R. fraxinea are remarkable records. The usually sterile lichen Thelomma ocellatum was rich in fertile thalli. The known lichen diversity of the Teichalm-Sommeralm region increases from 87 to 122 taxa.

ESTRUCTURA DE UNA COMUNIDAD DE LÍQUENES Y MORFOLOGIA DEL GÉNERO Sticta(STICTACEAE) EN UN GRADIENTE ALTITUDINAL / Lichen Community Structure And Morphological Changes In The Genus Sticta (STICTACEAE) Associated To An Altitude Gradient

La distribución y el crecimiento de los líquenes están condicionados por diferentes factores ambientales, entre estos la variación en gradientes altitudinales. En la cordillera Oriental de los Andes de Colombia, no se han realizado estudios sobre zonación altitudinal de líquenes. En este trabajo se estudiaron las variaciones en la estructura de la comunidad de líquenes epifitos en un gradiente altitudinal (2.000- 2.600 m) en el PNN Tatamá. Se encontró que con el aumento en altura hay una disminución en riqueza y diversidad, siendo esto una desviación del patrón encontrado generalmente en otros trabajos sobre líquenes y gradientes altitudinales. La comunidad a bajas alturas se compone principalmente de líquenes fruticosos (cobertura de 30% a 2.070 m y 0% a 2.560 m) y a mayores alturas de líquenes foliosos (cobertura de 15% a 2.070 m y 43% a 2.560 m). La altura, además de influenciar la estructura de la comunidad de los líquenes, puede afectar el desarrollo y la morfología de estos. En el género folioso Sticta se presentaron variaciones intraespecificas en la densidad de cifelas (órganos de intercambio gaseoso) asociadas a la altura, encontrándose un efecto significativo de la altura sobre la densidad de cifelas en las especies S. andensis y S. gyalocarpa (ANOVA, valor p= 0.008 y 0.05 respectivamente). Esto muestra un mecanismo de adaptación a los cambios ambientales que se dan con la altura.

Lichen’s growth and distribution are conditioned by various environemental factors, altitude being an important one. In the Cordillera Oriental of Colombian Andes, there haven’t been studies on lichen’s altitudinal zonation. We studied the variation on lichen community structure along an altitudinal gradient (2000- 2600 m) in PNN Tatamá, we found diversity diminishes as altitude increases, this being a variation from what’s generally found in lichen community behavior. At low altitudes, the community was conformed by fruticose lichens (30% cover at 2070 m and 0% at 2560 m), and by foliose lichens at high altitudes (15% cover at 2070 m and 43% at 2560 m). Altitude, besides influencing lichen’s community structure, may affect their development and morphology. In the foliose genus Sticta we found intraspecific variation on cyphellae (gaseous exchange organs) density associated with altitude, a significant effect of altitude on cyphellae density was found for the species S. andensis and S. gyalocarpa (ANOVA p value= 0.008 and 0.05 respectively). This shows an adaptation mechanism of these organisms to the environmental changes given with altitude.