Lichen Species Richness Research Articles

Disturbance and diversity: Lichen species richness decreases with increasing anthropogenic disturbance

Anthropogenic disturbance is rapidly increasing through habitat degradation, development, and deforestation. Gaps remain in understanding the effects of this disturbance on diverse and ecologically important organisms such as lichens. In North America, studies have focused on epiphytic macrolichens and catastrophic disturbance, largely ignoring microlichens and less severe disturbances. The Intermediate Disturbance Hypothesis predicts these moderate disturbances will lead to higher species richness. Here we examine the effects of anthropogenic disturbance in the form of land management on overall lichen richness, including microlichens, and on the species richness of eight lichen functional groups. The study draws on a comprehensive data set of 872 species, in 208 one-hectare plots throughout the Southern Appalachian Mountains, a global biodiversity hotspot in eastern North America. A habitat quality index based on an established forestry metric was used as a proxy for anthropogenic disturbance and was quantified using a 10-part score including categories such as percent native tree canopy cover and degree of fragmentation. Linear models were used to compare habitat quality scores to overall species richness and to species richness of functional groups. Rather than following the Intermediate Disturbance Hypothesis, all groups uniformly follow a negative linear relationship: as disturbance increases, species richness decreases. This pattern held even for widely variable functional groups such as morphotype. Effective conservation of lichen richness should prioritize the maintenance of existing older, less-disturbed stands within large, contiguously forested areas.

Hot-spots of epiphytic and epixylic lichens in fragmented temperate forests are underpinned by microhabitat heterogeneity and spatiotemporal habitat continuity

Habitat loss, fragmentation and degradation are major causes of the ongoing decline of epiphytic and epixylic lichen species in temperate forests throughout Europe. We investigated how extant species richness and composition of epiphytic and epixylic lichen communities in ten hot-spots of lichen diversity in the Czech Republic reflected the occurrence and properties of potentially suitable microhabitats and habitats. At each hot-spot, we surveyed a pair of 1-ha square plots, one in (over-)mature managed and the second in unmanaged forest. In total, we recorded 513 epiphytic and epixylic lichen species which represent a substantial part of lichen biota in Central Europe. Species richness and composition of lichen communities were explained by microhabitat heterogeneity, and also by the area of near-natural forest habitats (habitat extent) at the landscape scale. In addition, lichen species richness and number of red-listed species were explained by a categorial variable distinguishing mature managed and unmanaged plots, used as a proxy of temporal continuity of natural succession. This finding illustrates that temporal continuity of natural succession in unmanaged forests likely had an extra stimulus for lichen communities that may not be reflected by observed aspects of forest habitats. Hence, we confirmed indispensable positive effects of (micro)habitat heterogeneity, and spatial and temporal continuity for preserved hot-spots of lichen diversity in Central Europe. Due to generally slow colonization-extinction dynamics of epiphytic and epixylic lichens we call for strengthening microhabitat heterogeneity, and the spatial and temporal continuity of European temperate forests at the landscape scale.

Mixed trends in heavy metal-enriched fugitive dust on National Park Service lands along the Red Dog Mine haul road, Alaska, 2006-2017.

This study presents the status and trends of long-term monitoring of the elemental concentrations of zinc (Zn), lead (Pb), and cadmium (Cd) in Hylocomium splendens moss tissue in Cape Krusenstern National Monument (CAKR), Alaska, adjacent to the Red Dog Mine haul road. Spatial patterns of the deposition of these metals were re-assessed for the period from 2006-2017 following an identical study that assessed trends between 2001-2006. In contrast to the widespread and steep declines in Zn and Pb levels throughout most of the study area between 2001-2006, this study showed more mixed results for 2006-2017. At distances within 100 m of the haul road, only Pb decreased between 2006-2017. At distances between 100-5,000 m, however, both Zn and Cd decreased between 2006-2017, with high probabilities of decrease and percent decreases of 11-20% and 46-52% respectively. Lead did not decrease in any of the more distant areas. Following earlier work on lichen species richness in the study area, it appears that 2017 Zn levels are approaching those associated with "background" lichen species richness throughout a relatively large proportion of the study area at least 2,000 m from the haul road and several km from the port site. The findings in this study may be used to plan additional mitigation measures to reduce Zn deposition related to impacts on lichen communities.

Effects of the Abandonment of Traditional Cultural Practices on Epiphytic Bryolichenic Communities in Chestnut Orchards in North-West Spain

This study delves into the impact of contrasting management practices on epiphytic bryolichenic communities, shedding light on their divergent responses to management regimes on Castanea sativa Mill. orchards. Lichens and bryophytes were sampled in managed and abandoned plots, in 95 trees, in north and south sides and at two heights in Galicia (NW Spain). The studied groups exhibited opposing reactions to these management practices; bryophytes suffered adverse effects in managed stands, experiencing reduced cover and species richness compared to abandoned orchards, while lichens displayed heightened cover and species diversity. The size of trees, included as a covariate in our analyses, displayed no significant impact on the overall species richness of lichens or bryophytes, although it did influence the cover of specific functional traits. These differing outcomes may be linked to alterations in environmental conditions brought by management interventions. Furthermore, the study uncovered divergent responses within the taxonomic and functional composition of epiphytic communities. Different species and functional groups exhibited varying reactions to changing environmental conditions, making predictions a complex endeavour. In conclusion, this research emphasizes the need for management strategies that account for the diverse ecological requirements of different species and functional groups since no single management regime will suit all species or functional groups.

Potential implications of shortened rotation length for forest birds, bryophytes, lichens and vascular plants: An example from southern Swedish production forests

The rotation lengths of intensively managed production forests may be altered to achieve a variety of goals, with correspondingly implications for biodiversity. Here we consider the potential implications of shortened rotation times for biodiversity in planted monocultures of the two most common production tree species in Sweden, Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). To do so we surveyed bird, bryophyte, epiphytic lichen and vascular plant diversity in 80 and 55-year-old stands; stand ages which approximate present-day and potential future rotation lengths in this region respectively. We found clear differences in the species communities of the 55 compared to the 80-year-old stands for both understory species and epiphytes, but not for birds. Nevertheless, bird species richness was still highest in the 80-year-old Norway spruce dominated stands. Dead wood amount was also highest the 80-year-old Norway spruce stands. Highest species richness of epiphytic lichens was found in 80-year-old Scots pine stands. However, 55-year-old Scots pine stands had a higher understory species richness and diversity than the older Scots pine stands, including a larger number of open land species. The 80-year-old forest stands examined may be considered old with respect to production forest rotation lengths in Sweden but are relatively young when comparing stand ages of unmanaged natural forest stands. Nevertheless, our results indicate that shortening the rotation time of Scots pine and Norway spruce, in this part of Sweden from 80 to 55 years, could have important consequences for forest biodiversity. These consequences are primarily inferred from the likely implications from shortened rotations for lichens community composition and diversity in both Norway spruce and Scots pine stands, as well as impacts on understory plant species in Norway spruce stands.

Recovery kinetics of epiphytic lichen diversity after dieback during a continuously wet season

Epiphytic lichens are considered sensitive indicators of environmental change. Excess water is known to depress their photosynthesis, but the effect of long-lasting rain on species richness of epiphytic lichens is rarely reported. By annually repeated records of macrolichen species richness on tree trunks over a period of 33 years that included one long rainy season in year 2000, a strong decline in macrolichen richness on tree trunks was detected after the unusually wet autumn. Afterwards, the lichen richness slowly recovered, but had not yet fully recovered 19 years after the dieback. Thereby, long rainy periods can cause lasting depression in epiphytic lichen richness, and continuous rain should be considered a possible threat to lichens in regions like northern Europe where global change predicts enhanced rainfall frequency.

Warming decreases desert ecosystem functioning by altering biocrusts in drylands

Abstract Warming and precipitation fluctuations are changing desert ecosystems in global drylands. However, the effects of climate change on keystone species such as cryptogamic biocrust in drylands remain relatively under‐investigated, even though biocrusts play a vital role in desert ecosystems. We conducted a long‐term experiment (14 years) to simulate the responses of two main types of biocrusts to warming coupled with reduction in precipitation that was achieved by open‐top chambers (OTCs) to simulate the predicted warming and precipitation decreasing under climate change scenario. We also conduct a structural analysis to evaluate the resulting changes in desert ecosystem functioning (carbon and nitrogen cycling). Neither warming and corresponding rainfall reduction treatments had a negative effect on lichen species richness, but both treatments reduced lichen cover and biomass. The negative effects of warming on moss‐dominated crusts were much greater than those on lichen‐dominated crusts. Although mosses and lichens had varying degree responses to warming, the loss of mosses and decreased lichen cover and biomass, as well as the shortening of the wet time, resulted in a reduction in carbon and nitrogen fixation, soil enzyme activity and water‐holding capacity of biocrusts and topsoil. These impacts collectively change the water balance of drylands and weaken the hydrological and biogeochemical function of biocrusts. Synthesis and applications: Results from this long‐term experiment suggest that the ecosystem C and N cycling and water balance of global drylands may be highly impacted by climate change, in part because of the response of biocrusts, which contribute an important implication for both dryland restoration and earth system dynamics.

The non-native Quercus rubra does not substitute the native Quercus robur and Q. petraea as substrate for epiphytic lichens and bryophytes

Climate change will cause alterations in tree species ranges. Non-native tree species are likely to be increasingly used in production forests, due to their often better adaptation to a warmer climate and their lower susceptibility to pests and pathogens. Trees form an important habitat for numerous species, many of which are more or less specialised regarding tree species. Thus, the tree-associated flora and fauna may be heavily impacted if non-native trees replace native ones. Risk assessments from the introduction of non-native trees must rest on a solid knowledge base, including insights into the potential of such trees to function as biodiversity substitutes, i.e. to host similar biodiversity as closely related native tree species. In a study in temperate Sweden, we inventoried epiphytic lichens and bryophytes on ten random trees in each of 28 stands (14 stands of North American red oak Quercus rubra and 14 stands of native oak Q. robur/petraea), to compare species richness and composition. Overall, 101 lichen taxa and 35 bryophyte taxa were identified, and we found a generally higher diversity for native oak. The regional species richness (gamma diversity) for both lichens and bryophytes was higher in native oak than in red oak, and the lichen species richness at stand level (alpha diversity) was nearly significantly higher. Lichen composition differed between the two oak species, while there was no difference for bryophytes. More lichens were strongly associated with native oak than red oak, while most bryophyte species were generalists with no specific preference for either oak taxa. Bark structure was an important explanatory variable separating the lichen epiphytes, with species preferring smooth bark largely confined to red oak. In conclusion, our study suggests that substituting native oak with red oak could have adverse consequences for epiphytic lichen populations associated with native oak, resulting in a decline of several species. However, certain lichen and bryophyte species were exclusively found on Q. rubra, implying that incorporating a proportion of red oak stands in southern Swedish landscapes may enhance diversity. Further research is needed to explore the overlap between species associated with Q. rubra and other deciduous tree species that possess similar smooth bark. Our findings indicate that red oak may not be an appropriate alternative host tree for epiphytic lichens typically found on native oak, while the implications for bryophytes remain less clear.

How does understory vegetation diversity and composition differ between monocultures and mixed plantations of hybrid poplar and spruce?

Although monocultures are important for timber production, they are often associated with lower biological diversity than mixtures. Thus, mixed plantations have been suggested as a way to enhance biodiversity because of their inherent compositional diversity. However, the effects of monocultures versus mixtures on understory diversity and composition can vary in different ecosystems. The objective of this study was to assess how monocultures and mixed plantations influence understory vegetation diversity and composition in the boreal forest region of southern Quebec. We sampled plantations established with deciduous Populus trichocarpa Torrey & A. Gray × balsamifera L. and P. maximowiczii Henry × balsamifera L. and coniferous Picea abies (L.) Karst. and Picea glauca (Moench) species planted in monocultures and in mixed plantations on abandoned farmlands and a forest site. We assessed understory vegetation diversity and composition in each canopy type (coniferous, deciduous, mixed) and in each plantation type. We evaluated bryophyte and lichen diversity and composition specifically in tree microhabitats: soil, tree bases, and tree trunks. We found that vascular plant and lichen species richness was similar in all plantation types, while bryophyte species richness was higher in spruce monocultures and in mixed plantations compared to poplar monocultures. Our results also highlight how land-use history influenced vascular plant composition as abandoned farmland sites were composed of more ruderal vascular plants, while the previously forested site was composed of species found in natural forests. In the context of reforestation and plantations, our study suggests mixing spruce with poplars to maximize understory vegetation diversity as the addition of spruce in mixed plantations promoted the establishment of terrestrial bryophytes, while poplars favored the establishment of epiphytic lichens.

Species–area relationship in lichens tested in protected areas across Italy

AbstractThe species–area relationship (SAR) states that species richness increases with the increase of the sampled area, although other factors can influence the pattern. SARs have been tested on many different organisms, but only rarely on lichens. We aimed to test the SAR, across a wide range of area sizes, for three main substratum-related guilds of lichens, namely epiphytic, epilithic and epigaeic. The test was performed using data from lichen inventories carried out in 44 protected areas of various sizes across Italy. We found a positive correlation of species richness with area size for all three guilds, better fitted by the logarithmic function for epilithic lichens and by the power function for epiphytic and epigaeic lichens. Our results support the fundamental role of area size as the main driver for lichen diversity, suggesting that in an area-based conservation framework, larger protected areas are fundamental to support high lichen species richness. However, finer scale investigations are also required to better elucidate whether and how other environmental factors could interact with area size and modify SAR patterns. Exhaustive lichen inventories could be useful information sources to more robustly test such relationships, and therefore better inform conservation practices.

Natura 2000 network enhances the protection of rare epiphytic lichens: evidence from forest sites of Central Italy

AbstractAlthough epiphytic lichens are widely adopted as environmental indicators, they are not yet included among the target species listed in Annex II of the Habitats Directive, to which the system of protected areas of the Natura 2000 network refers. In this work, we aim to test the effectiveness of this system, mainly designed for the conservation of other groups of species, in protecting lichen species richness. For this purpose, we considered a case study (Central Italy) with half of the territory included in protected areas. Statistical differences in species richness and lichen communities were tested between sites located in 16 Protected Areas (PA) and 11 Non-Protected Areas (NPA) using non-parametric tests, multi-response permutation procedures (MRPP), non-metric multidimensional scaling (NMDS) and Indicator Species Analysis (ISA). Despite the broad overlap between epiphytic lichen communities of NPAs and PAs and a similar number of total and common species, PAs contain a significantly higher number of nationally rare and extremely rare species, including cyanolichens. These results are also confirmed by the indicator analysis. Although the Natura 2000 network does not explicitly address the conservation of lichens, the protected areas in our study can play a role in protecting the diversity of epiphytic lichens, especially nationally rare and endangered species. However, the future inclusion of red-listed epiphytic lichens among the target species of Annex II of the Habitats Directive would be welcome to better protect these organisms on a European level.

Effects of root plates, pits and mounds following windthrow events on the biodiversity of plants and lichens in Central European mountain forests

Windthrows lead to the formation of a characteristic land microtopography and they provide new habitats and substrata for species. The present study is novel, because it concerns different taxonomic groups of organisms and effects of various variables on species composition, richness and abundance within root plate-pit-mound (RPM) complexes. For the first time we studied lichens, liverworts, mosses and vascular plants on RPM complexes across major vegetation types, from deciduous to coniferous forests. We analyzed 164 RPM complexes which included in total 268 components: 115 root plates, 80 pits and 73 mounds. Besides the vegetation types and component types the following variables were also considered: dimensions (area, size), age (decomposition degree), species of the uprooted tree, shade, and elevation. The research revealed that root plates, pits and mounds had their own indicator species, but the key factors for the species composition were the species of uprooted trees and the vegetation type. Furthermore, the type of component and the vegetation type were also the most main variables determining the richness and abundance of the studied taxonomic groups of species. Analyses revealed the greatest species richness and abundance of lichens on root plates, and the highest richness of liverworts and vascular plants in pits. The type of component had no effect on the species richness of mosses. However, they were most abundant on mounds. The response of individual groups to the vegetation types and other variables varied. Findings from the study indicated that the presence of uprooted trees with different features (size and age, species of uprooted tree) is important for the biodiversity of mountain forests. We recommend leaving uprooted trees in forest communities for natural colonization, preferably large objects. Moreover, in managed forests a mosaic of forest communities that mimic the structure of natural unmanaged forests should be supported.

Resurvey studies of terricolous bryophytes and lichens indicate a widespread nutrient enrichment in German forests

AbstractQuestionsVegetation resurveys, both single studies and meta‐analyses, have predominantly been based on vascular plant data while bryophytes and lichens have largely been neglected. Our study aims to fill this gap and addresses the following research questions: has the overall species richness of terricolous bryophytes and lichens in forests changed over time? Which are the winners and losers among single species and ecological species groups? Do the results give a signal of the impact of nutrient enrichment, of changes in the light regime and of climate change?LocationDeciduous and coniferous forests in Germany.MethodsWe compiled 35 single resurvey data sets, including 1096 plots in total (each sampled twice). The time interval between initial surveys and resurveys ranged from 10 to 65 years. The differences between old and new plots were analysed with respect to the frequency of single species, total species richness, and the absolute and relative numbers of taxa in the species groups. Trend scores of species were related to ecological indicator values to identify the main environmental drivers behind the observed changes.ResultsTotal species richness did not systematically change, while pleurocarpous mosses had increased at the expense of acrocarpous mosses and, in coniferous forests, of lichens. Weak changes were generally observed in deciduous forests on base‐rich soils. In coniferous forests and in deciduous forests on acid soils, species with high nitrogen demand and high shade tolerance had increased, whereas those being typical for more infertile and open forest sites had decreased. There were trends towards a larger share of taxa with a more oceanic distribution.ConclusionsThe changes in the vegetation of terricolous bryophytes and lichens in the studied forests indicate nutrient enrichment and increasingly shady conditions in forests on acid soils, likely caused by nitrogen deposition and shrub layer closure.

Performance evaluation and applicability of Lichens GO, a citizen science-based protocol for urban air quality monitoring

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%).

Remote sensing in mapping biodiversity – A case study of epiphytic lichen communities

In boreal forests, European aspen (Populus tremula L.) is a keystone species that hosts a variety of accompanying species including epiphytic lichens. Forest management actions have led to a decrease in aspen abundance and subsequent loss of suitable habitats of epiphytic lichens. In this study, we evaluate the environmental responses of epiphytic lichen species richness and community composition on aspen, focusing on the potential of remote sensing by combined hyperspectral imaging and airborne laser scanning to identify suitable habitats for epiphytic lichens. We measured different substrate and habitat parameters in the field (e.g., aspen diameter and bark pH) and by remote sensing (e.g., mean canopy height and tree species composition of the surrounding forest) in the study area in Southern Finland that includes protected and non-protected forest. We used linear regression and the Hierarchical Model of Species Communities (HMSC) to compare how the different parameters explain and predict lichen species richness and community composition, respectively. We show that coarse predictions of epiphytic lichen community composition can be made using parameters extracted from remote sensing data. Estimated mean canopy height, tree density, dominant tree species and tree species diversity of the stand predicted the species community on aspens slightly better than field parameters. Remote sensing variables calculated over a larger area (30 m radius) always outperformed the same variables calculated over a smaller area (10 m radius) in predicting community composition, highlighting the cost-efficiency of remote sensing compared to covering a similar area with on-ground measurements. These results are encouraging for the prospects of using remote sensing data to direct field inventories and to map potential high-biodiversity habitats. Aspen bark pH was the only parameter affecting species richness regardless of whether the forest was protected or not, whereas, interestingly, the effects of tree diameter, height and furrow depth were only significant in protected areas. Our results also underline the importance of protected areas, since they hosted a higher tree-specific number of epiphytic lichen species, and red listed species, than non-protected areas.

Phorophyte specificity of lichen community, with ecological taxation in Suruli watershed, Southern Western Ghats

The Lichens is an essential component of all kinds of ecosystems. They are one of the flora's dominant components, and it accumulates about eight percent of the terrestrial ecosystem. India is an assorted vegetative tropical country. Four major ecological factors produce several microclimatic niches for the growth of lichens in the Western Ghats. First attempt to correlate the lichen population and species richness with the natural and silviculture challenges. During collection, surprisingly uninformed rainfall has observed in the summer season too. Eco-lichenological ranks premeditatedly founded on altitude, geo-specificities, substrates or habitats and morpho-types. The environmental variables revealed that the lichen density was more about spring to summer (27.3 to 25.5%), 23.5 to 18.5% during the winter and late autumn periods. The luxuriant growth of lichen thalli has notified on the rainy and Autumn seasons. Meanwhile, the crustose group of fruiting bodies flourished during the summer season. The terrestrial forest habits occurring on the cryptogamic and phanerogamic plants, including lichens. Most forests hold with the tribal and ethnic community; they suffered from terrestrial human and motor vehicle movements and forest fires, landslides, and more, including endangered species. Natural and manmade forestation practises to be regulating to conserve forest and dependences.

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.

Conifer tree species and age as drivers of epiphytic lichen communities in northern European production forests

AbstractThe epiphytic lichen species richness and community composition was compared for 600 living trees distributed within the interior of 60 Scots pine and Norway spruce monoculture stands in southern Sweden. A higher species richness, and more unique species, was found on trees of Scots pine than of Norway spruce, and distinctive communities were associated with the two tree species. Lichen species composition also shifted between the 30-, 55- and 80-year-old stands, although there was no significant difference in species richness between the different age classes. Tree species and age of the stand explained most of the variation in community composition (41%), with additional variance explained by lichen proximity to the ground (6%) and aspect (1%) (northern/southern side of trunk). Scots pine and Norway spruce share many attributes, such as both being conifers with acidic bark properties and having a similar geographical distribution in Fennoscandia. However, our study showed that species richness and community composition can nevertheless diverge in stands dominated by these two tree species. Since the occurrence of red-listed species was low in these stands, we suggest that 80-year rotations are not long enough for the occurrence of the many rare and specialized lichen species that require old forest structures and long forest continuity in this region.

Impacts on tundra vegetation from heavy metal-enriched fugitive dust on National Park Service lands along the Red Dog Mine haul road, Alaska.

The DeLong Mountain Transportation System (DMTS) haul road links the Red Dog Mine-one of the world's largest zinc mines-with a shipping port on the Chukchi Sea in northwest Alaska, USA. The road traverses 32 km of National Park Service (NPS) lands managed by Cape Krusenstern National Monument (CAKR). Fugitive dusts from ore concentrate transport and mining operations have dispersed zinc (Zn), lead (Pb), cadmium (Cd), and metal sulfides onto NPS lands since the mine began operating in 1989. This study assessed the effects of metal-enriched road dusts on the diversity and community structure of lichens, bryophytes, and vascular plants in dwarf-shrub tundra within CAKR. In a Bayesian posterior predictions model, lichen species richness (LSR) was highly correlated to distance from the haul road and was distributed on the landscape consistently with the spatial patterns of Zn, Pb and Cd patterns published earlier in this journal. The mean modeled LSR of the 3000-4000 m distance class was 41.3, and LSR decreased progressively down to 9.4 species in the 0-50 m class. An ordination of 93 lichen species by 91 plots revealed strong community patterns based on distance from the haul road. The major community gradient was highly correlated (r = 0.99) with LSR and negatively correlated with Cd, Pb and Zn (-0.79 < r < -0.74). Ordinations of bryophyte classes showed less response than lichens to distance from the road and heavy metals values, and vascular plant ordination showed less still. Measures of bryophyte health such as the midrib blackening and frond width of Hylocomium splendens were positively correlated with distance from the haul road and negatively correlated with this same suite of elements. A total area of approximately 55 km2 showed moderate to strong impacts on lichens from fugitive dusts. This is equivalent to an area of almost 1 km on both sides of the haul road running 32 km through CAKR.

Red wood ants shape epiphytic lichen assemblages in montane silver fir forests

The Formica rufa group comprises several ant species which are collectively referred to as “red wood ants” (hereafter RWA). These species have key roles in forest ecosystems, where they are ecologically dominant and greatly influence the dynamics of the habitat they colonise. Various studies have shown how their trophic activity may affect other organisms, which include both other invertebrates and plants. We can therefore hypothesize that their presence could affect the taxonomic and functional composition of epiphytes, despite clear information on such an effect is lacking. This study aimed to fill this research gap by evaluating whether the presence of red wood ants could affect the structure and composition of lichen communities. We selected two sites on the Apennine Mountains in Italy, where the red wood ant F. paralugubris was introduced from the Alps more than 50 years ago. In each site, lichen assemblages on Abies alba trees located within the colonised areas were compared to those from nearby, non-occupied areas. The results allowed for the identification of significant effects of F. paralugubris on the structure of lichen communities. Although there was no detectable impact on lichen species richness, a significant difference in their community composition between colonised and control sites was detected. Furthermore, ant presence seemed to be associated with specific lichen functional traits such as asexual reproduction. We argue that RWA could affect the lichen community either directly, e.g., by actively dispersing the species capable of asexual reproduction through their movements on trees (ant-mediated dispersion), or indirectly through herbivore exclusion. Finally, we also observed differences in β-diversity among the colonised and non-colonised sites.