1,721,005 research outputs found
Lichens from the aurifodinae of the upper Ticino river valley (N Italy)
Full text linkAurifodinae were open-pit gold mines of the Roman age which left behind them elongated heaps of rounded stones. They are located in lowland semi-natural landscapes, and can be seen as screes at a lower altitude and in a milder climate than typical mountain screes. We investigated the lichen biota of the aurifodinae remains in the upper Ticino river valley (western Po Plain, Northern Italy), in a small, discontinuous, 6.5 ha wide area. Metamorphic siliceous stones prevail, while calcareous stones are rare and scattered. We recorded 35 infrageneric taxa, including three species new to Piemonte: Cladonia conista, C. cryptochlorophaea, and Placidiopsis cinerascens. Several taxa are also new to the submediterranean ecoregion and/or to the Ticino river valley. The function of aurifodinae as a refugium for saxicolous lichens in the lowlands and their potential role in creating wide areas with open dry habitats in the past centuries are discussed
Terricolous lichens of the western Padanian Plain: New records of phytogeographical interest
No full textVery little is known of the earlier lichen flora of the Padanian Plain, the most heavily anthropized and industrialized part of Italy, which is currently extremely poor. Terricolous lichens in particular are the most sensitive to threats, and have almost totally disappeared from the western Padanian Plain. This paper reports new findings of 20 terricolous lichen species, several of which are rare or poorly known in Italy or are of some phytogeographical interest because they are found at lower altitudes than their usual distribution (i.e. Cladonia coccifera, Cladonia uncialis). In addition, Cladonia humilis is new for Lombardy and two other species, Cladonia portentosa and Stereocaulon condensatum, are reported for the second time in the same region. The significance of these species is discussed with regard to their historical records from the same area and their current altitudinal distribution; they were probably much more widespread in the past, but the decline and disappearance of their habitats in lowland areas have been followed by their own disappearance in many localities. A modification of the rarity status of some of these species in the considered phytoclimatic belts, based on the new records, is proposed
Biodiversity and conservation of terricolous lichens and bryophytes in continental lowlands of northern Italy: the role of different dry habitat types
Full text linkIn dry habitats of European lowlands terricolous lichens and bryophytes are almost neglected in conservation practises, even if they may strongly contribute to biodiversity. This study aims at (a) testing the role of heathlands, acidic and calcareous dry grasslands for lichen and bryophyte diversity and conservation in lowland areas of northern Italy characterized by high human impact and habitat fragmentation; (b) detecting the effect of environmental drivers and vegetation dynamics on species richness and composition. Lichens, bryophytes, vascular plants, and environmental variables were recorded in 287 circular plots for 75 sites. Our results indicate that heathlands, acidic and calcareous dry grasslands host peculiar terricolous lichen and bryophyte communities that include several species of conservation concern. Thus, each habitat provides a complementary contribution to lichen and bryophyte diversity in continental lowland landscapes. Furthermore, in each habitat different factors drive species richness and composition with contrasting patterns between lichens and bryophytes. In terms of conservation, our results indicate that management of lowland dry habitats should act at both local and landscape scales. At local scale, vegetation dynamics should be controlled in order to avoid biodiversity loss due to vegetation dynamics and wood encroachment. At the landscape scale, patches of all the three habitats should be maintained to maximize regional diversity
Terricolous lichen communities of Corynephorus canescens grasslands of Northern Italy
No full textIn Italy most of the habitats hosting terricolous lichens are found in the Alps and along the coasts, but some lichen-rich plant communities are also present in the Po Plain. We report a study of terrico-lous lichen communities found in dry grasslands attributed to Spergulo vernalis-Corynephoretum canescentis in the western Po Plain (Northern Italy), in accordance with the Braun-Blanquet approach. Relevés (138) were carried out in several developmental stages of the Corynephorus grassland. They were sorted manually and analyzed using ANOSIM, non-parametric MANOVA and PCA. Indicator species of the groups were found by means of INDVAL and SIMPER analyses and literature. Seven lichen vegetation types were distinguished. These were attributable to 4 described associations: Stere-ocauletum condensati, Cladonietum foliaceae (in which we found 3 subassociations: typicum, cladonietosum furcatae and cladonietosum subrangiformis), Cladonietum mitis and Cladonietum rei, and to one impoverished community (Cetraria aculeata community). Ordination of floristic variables showed several overlaps between communities, underlining the depleted floristic conditions found in the study area, where several species occur in many communities and other species are very rare, and thus play a minor role in the differentiation of the lichen vegetation types. Overlaps are also referable to intermediate conditions between one community and another, reflecting dynamic relationships, with Stereocauletum condensati, Cetraria aculeata community and Cladonietum foliaceae typicum having the most distinct pioneer character and Cladonietum mitis being the most evolved. Ordination of eco-logical variables based on the indices of substrate pH, light and humidity requirements and tolerance to eutrophication showed several overlaps between the communities, found to be from acidophytic to subneutrophytic, from rather to very photophytic, from mesophytic to rather xerophytic and from ani-trophytic to slightly nitrophytic. Rarity in Italy and conservation needs are discussed in detail, also in comparison with the situation of the same communities in central European Corynephorus grasslands. These grasslands and their typical lichen communities are rare in Italy and, though somewhat depleted, they are the habitat of several threatened lichen species at the southern margin of their distribution range. Therefore management plans should always consider both the cryptogamic and the vascular plant communities
Contribution to the knowledge of lichen flora of inland sand dunes in the western Po Plain (N Italy)
No full textThis paper describes the lichen flora surveyed in inland sand dunes, called dossi, in the western Po Plain (Lombardy region, Italy). Here, lichens were marginally known in comparison with the epigaeous component, but they were never studied before in relation to the epiphytic, epixylic and epilithic components. The floristic list includes 50 species; ecological and chorological analyses were carried out. Thirteen lichen species observed on various substrata were not reported in the lichen list of the Ticino Natural Park, which distances only few kilometres from our study area. Nine species are new for the Po phytoclimatic region and one species, Cladonia portentosa, is new for Lombardy. Particularly interesting are some species related to the Corynephorus grasslands, such as Cladonia sp. pl. and Stereocauloncondensatum, and three species usually absent, at our latitudes, beneath the montane belt: Cladonia digitata, Hypocenomyce scalaris and Parmeliopsis ambigua. These data confirm the importance of inland sand dunes for lichen diversity of the Po Plain. Some preliminary remarks concerning the management of the habitats hosting lichens are given, with particular emphasis to their conservation. Suggested actions include the possibility to keep woody coarse debris, to favour epixylic species, and mechanical disturbance, dispersal of lichen fragments and sheep grazing, to favour epigaeous species
Terricolous lichen communities in Thero-Airion dry grasslands of the Po Plain (Northern Italy): syntaxonomy, ecology and conservation value|Erdflechtengesellschaften in Thero-Airion Trockenrasen der Po-Ebene (Norditalien): Syntaxonomie, Ökologie und Erhaltungswert
No full textTerricolous lichen communities in Thero-Airion dry grasslands of the Po Plain (Northern Italy): syntaxonomy, ecology and conservation value
No full textTerricolous lichen vegetation has been partially studied in Italy so far, particularly in the Po Plain. Here, pioneer acidic Thero-Airion dry grasslands host rich terricolous lichen communities which often include lichen species of conservation concern. Overall, 288 phytosociological releves were carried out with the Braun-Blanquet method using standard plots of 30 cm x 30 cm in lichen-rich stands within Thero-Airion dry grasslands located in 16 localities of the western Po Plain, an area with continental climate. Releves were manually sorted and species composition was analyzed through Principal Component Analysis (PCA) and non-parametric MANOVA. Biological, ecological, chorological and rarity spectra were computed and analyzed with Kruskal-Wallis tests to assess differences among the communities. Nine lichen communities were recognized. One community dominated by Cladonia pulvinata referred to the Pycnothelio-Cladonietum cervicornis. Three communities referred to the Cladonietum foliaceae are dominated respectively by C. foliacea, C. furcata and C. rangiformis. Three communities referred to the Cladonietum rei are dominated respectively by C. rei, C. polycarpoides and C. coccifera. Two communities dominated respectively by C. peziziformis and C. cariosa are referred to an undescribed association, temporarily attributed to the Cladonion rei. All communities significantly differ in the mean ecological indicator values - soil pH, light, aridity, eutrophication, poleotolerance. The communities Pycnothelio-Cladonietum cervicornis, Cladonietum foliaceae (C. foliacea facies) and the C. peziziformis-C. cariosa community are pioneer communities. The Cladonietum rei (C. rei facies) and the Cladonietum foliaceae (C. rangiformis facies) are the more mature communities, respectively in disturbed and undisturbed sites. This study shows that terricolous lichen communities represent an important component of biodiversity in Thero-Airion dry grasslands, due to their diversification in different syntaxa and, in some cases, to their role as microhabitats for lichen species of conservation concern. Thus, our study contributes to the knowledge on Thero-Airion dry grasslands, which is a key component in the choice of management and conservation strategies
Habitat loss, extinction debt and climate change threaten terricolous lichens in lowland open dry habitats
Full text linkHabitat loss is the main driver of biodiversity decline worldwide. An immediate consequence can be extinction debt, i.e. time-delayed extinction of species following habitat loss. We tested extinction debt in terricolous lichen communities in 45 patches of lowland open dry habitats in the western Po Plain (northern Italy) considering richness of four species groups: total, red-listed, rare, and common species. The distance from the currently nearest patch and the annual precipitation correlated – negatively and positively, respectively – with all the groups. Total, red-listed, and rare species were positively related to the oldest available patch extent (1954). Common species were positively related to the current (2020) patch extent. Total and red-listed species were negatively related to the extent difference (1954–2020). Results reveal an extinction debt which has not yet been completely paid and that could be exacerbated by climate change. To counteract this trend, management should conserve habitat patches with the highest species richness, improve connectivity between habitat patches, and provide suitable microrefugia for species with different ecological requirements
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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