Pier Luigi Nimis

Monitoring with Lichens — Monitoring Lichens

Widespread changes in natural and managed environments in the last century have been associated with rapid development of technology with the capacity for massive destruction of natural environments. This has been accompanied by large-scale natural disasters such as floods and droughts and by large-scale technical failures such as Chernobyl, impacting greatly on human existence and welfare. It is the impact on social conditions that has led to increasing interest in maintaining environmental quality and ensuring that human activities do not threaten the ecosystem on which we depend. The threats to human health by water and air pollution led to early research on bioindicators in order to map and monitor the effects of pollution on selected organisms. However the range of objectives to which biomonitoring is applied has grown steadily from water quality and atmospheric pollution to heavy metal accumulation, climate change, and to environmental issues involving management of natural resources such as the effects of fragmentation and habitat alteration, effects of development on biodiversity as well as assessing conservation practices for rare or endangered species.

A review on usnic acid, an interesting natural compound.

Abstract. Lichens are a world-widespread consortium of fungal and photosynthetic partners. Usnic acid is one of the most common and abundant lichen metabolites, well known as an antibiotic, but also endowed with several other interesting properties. This review summarises the most relevant studies on usnic acid, focusing on a number of biological activities in different fields. On the basis of the existing literature, usnic acid seems to be an exclusive lichen product. No synthetic derivatives more effective than the natural form are known. Both the (+) and (–) enantiomers of usnic acid are effective against a large variety of Gram-positive (G+) bacterial strains, including strains from clinical isolates, irrespective of their resistant phenotype. Of particular relevance is the inhibition of growth of multi-resistant strains of Streptococcus aureus, enterococci and mycobacteria. The (+)-usnic acid enantiomer appears to be selective against Streptococcus mutans without inducing perturbing side effects on the oral saprophyte flora. On the other hand, the (–)-usnic acid enantiomer is a selective natural herbicide because of its blocking action against a specific key plant enzyme. Other recognised characteristics of usnic acid are ultraviolet absorption and preserving properties. The toxicology, the in vitro anti-inflammatory effects and the mechanism of action of usnic acid need to be investigated in greater detail in order to reach clinical trials and to allow further applications. Furthermore, more research is needed to make possible intensive lichen culture, in order to produce large quantities of lichen substances for pharmaceutical, cosmetic and agricultural purposes. Some biological aspects, i.e. the possible biological roles of usnic acid, are discussed.

Biomonitoring of trace elements with lichens in Veneto (NE Italy).

The concentrations of 13 elements in peripheral parts of the epiphytic lichen Xanthoria parietina were measured at 200 stations of Veneto (NE Italy). For each element, two maps are presented, showing, respectively, geographic patterns and deviations from background levels. The results are summarized by a map, showing the joint distribution of elements with concentrations close to Italian backgrounds, and of those strongly deviating from background levels. The results allow selection of high-risk areas for instrumental monitoring.

Lichens as Biomonitors of Sulphur Dioxide Pollution in La Spezia (Northern Italy)

Lichens epiphytic on olive trees were used as biomonitors of sulphur dioxide pollution in La Spezia (Northern Italy). The method adopted was designed to avoid subjectivity at all stages, from the sampling strategy to data analysis. Thus, lichen data are expressed by an index that does not depend on any sensitivity scale; data analysis relies on multivariate methods of classification and ordination, and the pollution maps have been produced by automatic mapping programmes. The index, based on the frequency of species within a sampling grid, showed a very high statisti- cal correlation with pollution data measured by recording gauges. The results of classification and ordination indicate that Parmelia caperata is the species with a distribution best related to the lichen index. The quality of air pollution data obtained from biomonitors is discussed.

The performance of two lichen species as bioaccumulators of trace metals.

The concentrations of 16 metals were measured in peripheral and central parts of the foliose epiphytic lichens Parmelia caperata and Xanthoria parietina collected in north-east Italy. Relevant intra- and interspecific variability was shown by multivariate analysis (classification and ordination) of the matrix of metals and samples. The central, older parts of the thalli contained significantly higher amounts of most metals in both species. Significative differences were also found between peripheral parts of the two species, with higher concentrations of Fe and Al in Xanthoria, and Cd and Zn in Parmelia. An inter-species comparison of several hundred Italian measurements confirmed the higher affinity of Parmelia for Cd and Zn, but not that of Xanthoria for Fe and Al. In order to enhance data quality in biomonitoring studies, it is suggested to analyse only peripheral parts of the lichens, and to avoid the joint use of Parmelia and Xanthoria when monitoring Cd and Zn.

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.

DNA Barcoding as an Effective Tool in Improving a Digital Plant Identification System: A Case Study for the Area of Mt. Valerio, Trieste (NE Italy)

Background Identification keys are decision trees which require the observation of one or more morphological characters of an organism at each step of the process. While modern digital keys can overcome several constraints of classical paper-printed keys, their performance is not error-free. Moreover, identification cannot be always achieved when a specimen lacks some morphological features (i.e. because of season, incomplete development or miss-collecting). DNA barcoding was proven to have great potential in plant identification, while it can be ineffective with some closely related taxa, in which the relatively brief evolutionary distance did not produce differences in the core-barcode sequences. Methodology/Principal Findings In this paper, we investigated how the DNA barcoding can support the modern digital approaches to the identification of organisms, using as a case study a local flora, that of Mt. Valerio, a small hill near the centre of Trieste (NE Italy). The core barcode markers (plastidial rbcL and matK), plus the additional trnH-psbA region, were used to identify vascular plants specimens. The usefulness of DNA barcoding data in enhancing the performance of a digital identification key was tested on three independent simulated scenarios. Conclusions/Significance Our results show that the core barcode markers univocally identify most species of our local flora (96%). The trnH-psbA data improve the discriminating power of DNA barcoding among closely related plant taxa. In the multiparametric digital key, DNA barcoding data improves the identification success rate; in our simulation, DNA data overcame the absence of some morphological features, reaching a correct identification for 100% of the species. FRIDA, the software used to generate the digital key, has the potential to combine different data sources: we propose to use this feature to include molecular data as well, creating an integrated identification system for plant biodiversity surveys.

Bryophytes as indicators of radiocesium deposition in northeastern Italy

Abstract Samples of moss carpets growing in forest vegetation have been used to map radioactive fallout in northeastern Italy. The main factors affecting data variability are the inclination of the carpets, water absorbing power, and their thickness. The best suited bioindicator proved to be Ctenidium molluscum. The results indicate that these carpets were able to intercept most of the radiocesium deposited after the Chernobyl accident, and that the removal half-time in the survey area is of ∼ 46 months.

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.

Ecological Phytogeography of the Southern Yukon Territory (Canada)

This paper analyzes the relations between the present distribution of boreal plants and their ecological requirements. Based on a survey carried out in the southern Yukon (Canada), a large, phytogeographically interesting region whose vegetation was rather poorly known, the paper includes a classification of the vegetation into community types, their ecological characterization on the basis of direct data, and a phytogeographic analysis based on the world ranges of all relevant vascular plant species. Multivariate methods of classification and ordination were used in extensive vegetational, ecological and phytogeographic coordinated analyses to study the correlation between some major ecological factors and the frequencies within communities of species with similar world distribution.