Juri Nascimbene

Large-scale patterns of epiphytic lichen species richness: Photobiont-dependent response to climate and forest structure

Lichens are composite organisms consisting of a symbiotic association of a fungus with a photosynthetic partner. Although the photobiont type is a key life-history trait, tests of the potential differential role of the main photobiont types in shaping large-scale patterns of lichen species richness are still absent. The aim of the study was to test the influences of forest structure and climate on epiphytic lichen species richness across Italy and to see whether these relationships change for groups of species sharing different photobiont types. Regional species richness of epiphytic lichens divided into three main photobiont types (i.e. chlorococcoid green algae, cyanobacteria, and Trentepohlia algae) was retrieved for each of the 20 administrative regions. Multiple linear regression was used to quantify the effect of climate and forest structure, and their potential interaction, on the regional species richness for the three photobiont types, accounting also for the effect of regional area. Regional species richness was associated with both climate and forest structure variables but the relationships with both factors were largely photobiont dependent. Regional area and precipitation were the only predictors included in all the models, confirming the strong dependence of lichens on atmospheric water supply, irrespective of the photobiont type. Number of species with chlorococcoid green algae were further positively associated with cover of high forest, whilst lichens with Trentepohlia were further enhanced by warm temperatures. Cyanolichen species richness was only related to area and precipitation. Our study shed light on the relative importance of climate and forest structure on lichen species richness patterns at the macroscale, showing a differential response of the photobiont types to various environmental determinants. This differential response suggested that the current and future impacts of global change on lichens cannot be generalized and that species richness response will be likely dependent on the photobiont type.

Forest plant diversity is threatened by Robinia pseudoacacia (black-locust) invasion

The effects of black-locust invasion on plant forest diversity are still poorly investigated. Vascular plants are likely to be influenced by increasing nutrient availability associated with the nitrogen-fixing activity of black-locust, whereas it is not clear if, along with stand aging, black-locust formations regain forest species. The main aim of the present study was to test whether the increase of black-locust stand age promoted a plant variation in mature stands leading to assemblages similar to those of native forests. Therefore, plant richness and composition of stands dominated by native trees were compared with pure black-locust stands of different successional stages. Our study confirmed that the replacement of native forests by pure black-locust stands causes both plant richness loss and shifts in species composition. In black-locust stands plant communities are dominated by nitrophilous species and lack many of the oligothrophic and acidophilus species typical of native forests. Plant communities of native forests are more diverse with respect to pure black-locust stands, suggesting that black-locust invasion also causes a homogenization of the plant forest biota. We did not detect differences across the successional gradient of black-locust stands, and mature stands do not recover the diversity of plant species which are lost by the replacement of the native forests by black-locust. Accordingly some efforts in reducing the negative impacts of black-locust invasion on plant forest biota should be focused at least in those areas where conservation is among management priorities, such in the case of habitats included in the Habitat Directive (92/43 ECE).

Oak forest exploitation and black-locust invasion caused severe shifts in epiphytic lichen communities in Northern Italy

In the last two centuries, native European oak forests have undergone a dramatic decline related to increasing human pressure for agriculture and urbanization. Oak forests were either completely eradicated and transformed into agricultural landscapes or replaced by second-growth formations. Intensive forest management and the replacement of native forests with production forests or arable lands are recognized amongst the main threats to many lichens in Europe. In this study, we used historical information on the epiphytic lichen biota which was hosted in a native oak-dominated forest of Northern Italy to identify shifts of lichen communities due to the changes in land use which occurred during the last two centuries. We also compared the epiphytic lichen communities inhabiting remnant oak forests with those found in the habitats that have replaced native forests: black-locust forests and agrarian landscapes. Almost all the species sampled during the 19th century are now extinct. The loss of native habitat and the subsequent invasion by black locust were probably the most influential factors which affected the composition of lichen communities, causing the local extinction of most of the species historically recorded. Despite the fact that oak remnants host only a few species which were historically recorded, and that they currently are the lichen poorest habitat in the study region, they host lichen assemblages differing from those of black-locust forests and agrarian stands. In these habitats lichen assemblages are mainly composed of species adapted to well-lit, dry conditions and tolerating air pollution and eutrophication. This pattern is likely to be common also in other lowland and hilly regions throughout Northern Italy where oak forests are targeted among the habitats of conservation concern at the European level. For this reason, a national strategy for biodiversity conservation and monitoring of lowlands forests should provide the framework for local restoration projects.

Lichen diversity on stumps in relation to wood decay in subalpine forests of Northern Italy

Although several studies demonstrated the importance of dead wood for lichen conservation in N-Europe and N-America, the lichen biota on dead wood was poorly studied in the Alps, where stumps represent one of the main available dead wood type. This work aims at evaluating species richness and composition of lichens in relation to the decay of stumps in subalpine forests of the Italian Alps. Differences in species richness between three decay stages were tested using a one-way ANOVA, while the pattern of species composition was evaluated with non-metric multidimensional scaling and an Indicator Species Analysis. Overall, 69 species were found and wood decay proved to be an important factor influencing lichen communities on stumps in our subalpine forests. Despite the fact that the mean number of species per stump did not differ between the three decay stages and lichen communities broadly overlapped, a main pattern of species turnover was identified across wood decay process as well as some indicator species for each decay stage. During the decay process, lichen communities change functional and ecological composition as an adaptive response to the continuous change of substrate. Since stumps host several nationally rare species, which are related to different stages of decay, they could have a relevant role in lichen conservation in managed forests where other types of dead wood are normally absent.

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.

Lichen diversity of coarse woody habitats in a Pinus-Larix stand in the Italian Alps

In the European Alps, subalpine forests are important for lichen diversity conservation at multiple levels. However, the potential role of coarse woody debris (CWD) has been only marginally considered in the previous literature. The aims of this case study are (i) to provide a first evaluation of the effects of different types of CWD (stumps, logs, and snags) and wood decay on lichen diversity in Pinus-Larix forests in the Italian Alps, and (ii) to increase the knowledge of the lichen biota on CWD in Italy. Seventy-eight species were found, including 12 nationally rare and 10 calicioid species; Placynthiella hyporhoda is new to Italy. Different types of CWD in different decay stages had significantly different lichen communities. Snags seem to be particularly effective for conservation, since they host the highest number of nationally rare species. Our survey suggests that CWD could be an important substratum for several nationally rare species, indicating that further surveys at a regional scale are urgently required in order to evaluate the role of CWD for lichen diversity conservation in the Alps.

A multi-taxon approach reveals the effect of management intensity on biodiversity in Alpine larch grasslands.

In the Alps, larch grasslands form one of the most pleasing aspects of the landscape. However, their effectiveness in contributing to biodiversity conservation may depend on the intensity of their management. We used a multi-taxon approach to evaluate the effects of the intensification of management practices and those of abandonment on the biodiversity of the main autotrophic organisms hosted in this habitat, including vascular plants, bryophytes, and lichens. The study was carried out in the eastern part of South Tyrol, in the Italian Alps, where the diversity patterns of these three organismal groups were compared among intensively managed, extensively managed, and abandoned stands. The management intensity was found to strongly influence the biodiversity of the organisms, with a general pattern indicating the best conditions in extensively managed stands. Both abandonment and management intensification were detrimental to biodiversity through different mechanisms that led to species loss or to major shifts in species composition. However, the most negative effects were related to management intensification, mainly due to the high nitrogen supply, providing evidence for the increasing impact of eutrophication on Alpine environments.

Monitoring H2S air pollution caused by the industrial exploitation of geothermal energy: the pitfall of using lichens as bioindicators.

This study showed that NH(3) emitted from geothermal power plants affects the surrounding epiphytic lichen vegetation and diversity, confounding the interpretation of lichen diversity counts in terms of air pollution by H(2)S. The presence of nitrophytic lichen species around geothermal installations, determined by NH(3), caused relatively high diversity values that were not related with the levels of air pollution by H(2)S. It is recommended that in the presence of NH(3) emission, nitrophytic species are excluded from the calculation of lichen diversity values.

Influences of tree age and tree structure on the macrolichen Letharia vulpina: A case study in the Italian Alps

Abstract Tree age and tree structure are important determinants for epiphytic lichen communities, affecting substrate stability, light availability, and propagule dispersal. However, little is known about the relative importance of these 2 factors on many species. This work aims to evaluate the importance of tree age and tree structure in explaining the within-stand frequency of the macrolichen Letharia vulpina. The study was carried out in 2 larch–stone pine forests in the Eastern Italian Alps. The frequency of Letharia was evaluated using a standard sampling method. To explain the within-stand frequency of Letharia, tree age and several variables related to tree structure were considered. Multiple ordinary least square regression was applied to clarify the influence of the set of variables. Several partial regressions were then computed to evaluate the relative importance of each significant predictor. The frequency of Letharia increases with increasing tree age, tree diameter, and first branch height. Tree age is the most important variable, accounting for one third of the total explained variation, although tree structure also has a significant effect on lichen frequency. Due to its dispersal limitations and old-tree dependence Letharia is proposed as a suitable indicator of forest continuity. The results may be of interest for conservation purposes, since the frequency of Letharia may be enhanced by protecting old trees. Nomenclature: Nimis & Martellos, 2003.

How much would it cost to monitor farmland biodiversity in Europe

To evaluate progress on political biodiversity objectives, biodiversity monitoring provides information on whether intended results are being achieved. Despite scientific proof that monitoring and evaluation increase the (cost) efficiency of policy measures, cost estimates for monitoring schemes are seldom available, hampering their inclusion in policy programme budgets. Empirical data collected from 12 case studies across Europe were used in a power analysis to estimate the number of farms that would need to be sampled per major farm type to detect changes in species richness over time for four taxa (vascular plants, earthworms, spiders and bees). A sampling design was developed to allocate spatially, across Europe, the farms that should be sampled. Cost estimates are provided for nine monitoring scenarios with differing robustness for detecting temporal changes in species numbers. These cost estimates are compared with the Common Agricultural Policy (CAP) budget (2014-2020) to determine the budget allocation required for the proposed farmland biodiversity monitoring. Results show that the bee indicator requires the highest number of farms to be sampled and the vascular plant indicator the lowest. The costs for the nine farmland biodiversity monitoring scenarios corresponded to 0·01%-0·74% of the total CAP budget and to 0·04%-2·48% of the CAP budget specifically allocated to environmental targets. Synthesis and applications. The results of the cost scenarios demonstrate that, based on the taxa and methods used in this study, a Europe-wide farmland biodiversity monitoring scheme would require a modest share of the Common Agricultural Policy budget. The monitoring scenarios are flexible and can be adapted or complemented with alternate data collection options (e.g. at national scale or voluntary efforts), data mobilization, data integration or modelling efforts.