1,721,005 research outputs found
Notulae alla checklist della flora vascolare italiana 4: 1413-1417
Get PDF1413.Marsilea strigosaWilld. (Marsileaceae)1414.Hypericum androsaemumL. (Hypericaceae)1415.Anthriscus caucalisM. Bieb. (Apiaceae)1416.Deschampsia flexuosa(L.) Trin. (Poaceae)1417.Leersia oryzoides(L.) Sw. (Poaceae
Senecio inaequidens DC. will thrive in future climate: A case study in a Mediterranean biodiversity hotspot
Get PDFMonitoring the expansion of invasive non-native plants under current and future climatic conditions is crucial for understanding biodiversity threats, addressing the ecological impact, and developing effective management strategies. This study focuses on modelling the expansion and distribution of Senecio inaequidens DC. on the island of Sardinia (Italy) to address these environmental challenges. The objectives were to identify bio-climatically suitable areas under current conditions, project potential future distribution, and evaluate invasion dynamics on the island to localize suitable areas for effective management strategies.
Species data were collected from 1991 to the present, supplemented by global databases and analyzed using an ensemble species distribution model approach. This approach utilized presence data, high-resolution current bioclimatic variables (40 m2), developed explicitly for our study area, and two future scenarios derived from the newly Coupled Model Intercomparison Project Phase 6 (CMIP6) under Shared Socio-economic Pathways (SSP2–4.5 and SSP5–8.5 for 2040 and 2060).
The ensemble model’s findings suggest a close alignment between the currently documented occurrences of S. inaequidens and its bio-climatically suitable habitats in Sardinia. Moreover, predictions indicate high biocli- matic suitability for S. inaequidens in the western and southwestern coastal regions, contrasting with its known occurrences at higher altitudes. Notably, the model also forecasts high bio-climatic suitability across most small islands surrounding the region and in central-east Sardinia, potentially indicating habitats at lower altitudes compared to current records.
Under the SSP2–4.5 scenario, suitable areas are expected to nearly double by 2040 and more than double by 2060, compared to current conditions. Under the SSP5–8.5 scenario, the increase in suitable habitats is projected to be about 83.31% by 2040 and more than double by 2060. These results highlight the species’ ability to thrive under climate change, with a more pronounced range expansion under the pessimistic management regime (SSP5–8.5) than under the intermediate one (SSP2–4.5), particularly in the central region of the island. This expansion under the more severe management scenario is particularly alarming as it reflects limited imple- mentation of environmental management policies.
The study underscores the potential ecological risk posed by S. inaequidens due to its potential range expansion and ability to invade different habitat types, from coastal regions to mountainous areas, under current and future scenarios. Based on these findings, we propose targeted management actions for monitoring and eradicating the species, leveraging prior information and local experiences to mitigate its impact
Advancing forest mapping: Pretraining strategies and deep-ensemble based uncertainty for predicting evergreen broad-leaved cover from Sentinel-2 time series
Get PDFThe distribution changes of evergreen broad-leaved tree and shrub species (EVE) at the border of Mediterranean and temperate forests due to climate change and land-use changes necessitates accurate mapping techniques to support biodiversity monitoring and climate adaptation strategies. Remote sensing time series provide valuable data for vegetation analysis, yet functional-level mapping in mixed forests remains challenging due to limited observation data. To tackle this limitation, the present study investigates pretraining strategies for mapping EVE cover in selected Italian forest areas using Sentinel-2 time series and a probabilistic Convolutional Neural Network. Additionally deep ensemble-based uncertainty estimation is used to further enhance the interpretability of the output. We compare three model training strategies: (i) direct training on up-to-date but limited field data, (ii) supervised pretraining on a larger, diverse forest vegetation database before fine-tuning, and (iii) self-supervised pretraining on large-scale unlabeled time series before fine-tuning. Our results demonstrate that pretraining on contextually similar datasets in combination with a spatial split of training and validation data significantly enhances predictive performance and generalization to unseen regions in a cross-validation experiment. Additionally, we assess epistemic and aleatoric uncertainty to improve interpretability and identification of out-of-distribution predictions. This study highlights the benefits of pretraining and uncertainty quantification for large-scale remote sensing applications with limited availability of labeled data
Alien Plants in the Hortus Botanicus Karalitanus (HBK): Current and Future Threats to the Biodiversity of Sardinia, Italy
No full textBotanical gardens have historically introduced alien species for agronomic, medicinal, and ornamental purposes, but they also contribute to plant invasions. The Hortus Botanicus Karalitanus (HBK) is a historic botanical garden stablished in 1866, as an acclimatisation arboretum for tropical plants, by the University of Cagliari. This study inventoried alien vascular plants in the HBK that showed some degree of spontaneity, analysing their status, origin, life form, introduction pathways, reproductive strategies, and presence in Sardinian habitats. A focus on invasive species and their historical introduction based on their first records on the island and in the HBK was made. Field surveys from 2015 to 2024 allowed us to identify 146 alien taxa, primarily neophytes (83%), 45% of which were naturalised and 12% were invasive. Ornamental plants contributed to 70% of introductions, while accidental taxa (weeds and hitchhikers, 61%) were the most invasive. Seed reproduction was the most common way of propagation (41%). About the diffusion in Sardinia, 25% of taxa had no records in nature outside the HBK, 39% were found only in anthropogenic habitats, and 36% in natural habitats. Among them, 8% were invasive in both the HBK and Sardinia, with wetlands being the most affected (5%). However, only 3% of common invasive species were first recorded in the HBK. The results highlight the role of the HBK in alien species spread and early detection, aiding in invasion management and biodiversity conservation in Sardinia
The Endemic Vascular Flora of Sardinia: A Dynamic Checklist with an Overview of Biogeography and Conservation Status
Get PDFThe vascular flora of Sardinia has been investigated for more than 250 years, with particular attention to the endemic component due to their phylogeographic and conservation interest. However, continuous changes in the floristic composition through natural processes, anthropogenic drivers or modified taxonomical attributions require constant updating. We checked all available literature, web sources, field, and unpublished data from the authors and acknowledged external experts to compile an updated checklist of vascular plants endemic to Sardinia. Life and chorological forms as well as the conservation status of the updated taxa list were reported. Sardinia hosts 341 taxa (15% of the total native flora) endemic to the Tyrrhenian Islands and other limited continental territories; 195 of these (8% of the total native flora) are exclusive to Sardinia. Asteraceae (50 taxa) and Plumbaginaceae (42 taxa) are the most representative families, while the most frequent life forms are hemicryptophytes (118 taxa) and chamaephytes (106 taxa). The global conservation status, available for 201 taxa, indicates that most endemics are under the ‘Critically Endangered’ (25 taxa), ‘Endangered’ (31 taxa), or ‘Least Concern’ (90 taxa) IUCN categories. This research provides an updated basis for future biosystematics, taxonomic, biogeographical, and ecological studies and in supporting more integrated and efficient policy tools
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Distribution, floristic and ecological characterization of Sardinian Gymnospermae communities
Get PDFA complete analysis of the distribution, ecology and floristic composition of the natural pine woods of Sardinia, belonging to Pinus halepensis Mill., P. pinaster Ait. subsp. pinaster and P. pinea L., was for the first time produced in Sardinia by means of aerial photographs, literature, Local Ecological Knowledge (LEK) and phytosociological surveys carried out within the areas where the three pine species are considered native or putative native. The phytosociological work allowed the description of two new associations for P. halepensis woods, located in the south-western coastal area, as well as the confirmation of a previously described one on the island of San Pietro, which is currently in a more mature stage than its original description. A new association related to P. pinaster subsp. pinaster woods was described in north-eastern Sardinia, with two new sub-associations. Finally, a new association for P. pinea woods on coastal dunes of the south-western Sardinia.
The diachronic study of pine woods’ decrease and subsequent recovery represents an important step in the analysis of how human impact and land use change can influence the vegetation dynamics of pioneer species with restricted distribution ranges in insular contexts. In this respect, the help of local people and toponymy was crucial for trying a reconstruction of the loss happened in recent times. The method here applied can be an example for further research on rare and declining species.
We improved the knowledge of the distribution, ecology and threats of Taxus baccata L. populations in Sardinia as well, by analysing climatic factors, to define yew’s ecological niche and the species potential distribution in the island. In this study, we found 234 different localities were T. baccata grows or was known in recent times, then confirming how the potential distribution is similar to the real one. On the other hand, we highlighted that in many localities the presence of the species is today related to isolated to scattered old individuals.
Many factors are driving this species to become more and more rare in the Mediterranean environments. We selected 40 sites, a part of which are characterised by the presence of T. baccata old-growth woods, then compared these woods with others where human impact and mean dimensions of the samples identify them as younger formations. This comparison was useful to understand which of the structural features are significantly differentiating old-growth stands with yew from younger ones, and can therefore have a methodological value. The places where the species still thrives today are subject to a long pressure by overgrazing and are often the remnants of wider populations reduced by practices such as wildfires, cuttings, and subsequent reforestations. This work increases the knowledge in relation to the health of the species and its distribution in Sardinia. Moreover, it represents a crucial point for its conservation since it shows how future conservation measures seem to be necessary to preserve the most endangered populations. In managed forests, silvicultural systems should be able to maintain, restore or develop structural attributes useful to a reprise of yews free of competition of alien naturalised taxa. Moreover, the application of protection protocols can represent an effective tool for the characterisation of the old growth stands with yews, in order to plan better management and conservation measures
- …
