1,720,966 research outputs found
Knowledge gaps and challenges for conservation of Mediterranean wetlands: Evidence from a comprehensive inventory and literature analysis for Sardinia
Full text linkWetlands are some of the most important ecosystems on Earth. They play a key role in mitigating climate change-related events and filtering polluted water, and provide habitats for a wide range of species. Despite their importance, and numerous regulations that support their conservation, wetlands continue to be destroyed. Recent reports have indicated a progressive decline in ecological character of remaining wetlands. This research reviews and extends the present status of wetland knowledge in Sardinia, the second largest Mediterranean island. For the first time, Sardinian wetlands were comprehensively mapped using satellite images and field validation. Impacts were also assessed. Trends in literature published about Sardinian wetlands since 1900 were then analysed, mainly according to the location(s) and topic(s) studied. In total, 2,501 Sardinian wetland sites were identified. The most common impacts observed in the field were vegetative degradation and water pollution. Of these wetlands, 2,274 have never been the subject of a research paper. Despite recent increases in publication rates, there was a lack of even basic knowledge about many wetlands, especially smaller ones. Larger wetlands have been studied from a range of viewpoints. In the light of these results, suggestions for improved awareness, effective management and conservation of Mediterranean wetlands were established. Future work should be directed to filling gaps in basic information, and to improvements in research and conservation, which might include multidisciplinary approaches in support of more comprehensive conservation management plans
Functional and habitat characteristics associated with nativeness, rarity, and invasiveness in the aquatic vascular flora of Sardinia
Full text linkMediterranean wetlands are of great conservation concern given their high biodiversity, functional value, societal importance, and significant decline during recent decades. Within the contexts of species protection and functional resilience, understanding the biological and environmental factors that influence the composition and diversity of wetland plant communities could help to inform management of these critical systems. To examine such factors, we considered 13 functional and habitat characteristics in explanatory models of the nativeness, rarity, and invasiveness of a comprehensive flora of 224 vascular plant species associated with wetlands in Sardinia. We categorised 59 of the 184 native species as rare and 21 of the 40 non-native species as invasive. Our models revealed some functional and habitat characteristics that are significantly associated with plant species’ nativeness, rarity, and invasiveness in Sardinian wetlands. Specifically, native species generally have smaller flowers than non-native species, while non-native species tend to flower later and reproduce more vegetatively. Rare native species typically occur across a narrower elevation range, have shorter flowering duration, and are less likely to reproduce vegetatively than common species, while invasive species tend to have larger flowers than non-invasive species. The relatively high incidences of rarity and invasiveness in Sardinian wetlands are likely influenced by the intrinsic fragmentation of freshwater environments and profound anthropogenic modifications in the region. In addition, we suggest that differences in reproductive traits may further contribute to species’ rarity and invasiveness in these systems
Investigating Plant–Bird Co-Occurrence Patterns in Mediterranean Wetlands: Can They Reveal Signals of Ecosystem Connectivity?
Full text linkInterspecific biotic interaction is believed to be a fundamental phenomenon in ecology. However, despite the increasing efforts, interaction mechanisms are still not clearly understood. We compiled a database of 323 birds and 844 vascular plants in 30 wetlands from Sardinia. This was complemented with seed dispersal features and plant structures (suitability for nesting), and with site-level traits, such as wetland surface area, distance from the sea, percentage of open water, protection level, and number of human impacts. The percentage of non-random co-occurrences was then measured, and the relative importance of each trait in determining it was modelled. We found that non-random co-occurrences among sites decreased with the site extent and increase with the percentage of open water, bird zoochory was positively correlated with co-occurrences, nesting birds showed higher rates of co-occurrence than non-nesting birds, and plants with habits suitable for nesting displayed more co-occurrences than the rest of the plants. These results are a small contribution to the complex topic of species co-occurrence and connectivity within an ecosystem. Species co-occurrence is a promising but debatable approach that may provide insightful clues to species interactions within ecological systems
Astragalus resilience: Heat shock effect on seed dormancy and germination in endangered species
No full textMany Astragalus species exhibit physical dormancy and understanding
their seed dormancy is crucial for conservation efforts. Previous studies
have revealed that impermeable seed coats inhibit germination in
these species, but little is known about the ecological context of this
dormancy. We focused on Astragalus maritimus and A. verrucosus, two
threatened endemic species in Sardinia living in fire-prone ecosystems,
to explore the ecological implications of heat shock on dormancy release
and germination.We investigated under laboratory conditions the
effects of different heat shock treatments (40–140°C) for varying durations
(5 and 10 minutes), to simulate different fire conditions. Results
showed a reduction of germination compared with control test only at
high heat shock temperatures (120–140°C) in both species. Most seeds
remain dormant (viable, not imbibed seed) after the simulation of fire in
the soil, from 80% at 40°C – 5 min to 20% at 120°C – 5 min for A. verrucosus.
While A. maritimus dormant seeds varying from 84.2% at 40°C – 5
min to 40% 100°C – 10 min. At higher temperatures of heat shock, the
percentage of dead seed increases, A. verrucosus ranged from 55.4% at
120°C – 5 min to 99% at 140°C – 10 min and for A. maritimus this ranges
varied from 54% at 100°C – 10min to 92% 140°C – 10 min. In conclusion,
heat shock caused by fire is not able to break the physical dormancy.
However, they can survival the fire pass and develop soil seed bank that
persists after fires and delay germination until the occurrence of break
dormancy conditions
Effects of temperature and salinity on the seed germination of Limonium strictissimum (Salzm.) Arrigoni in the Mediterranean Basin
No full textSalt stress might be an important factor that decreases the emergence of seedlings and reduces plants’ growth, causing their endangered status. However, the effects of salt stress on the germination of the Mediterranean species are less concern. Limonium strictissimum (Salzm.) Arrigoni, part of the group related to Limonium articulatum (Loisel.) Kuntze, is a Cyrno-Sardinian endemism, which is included in the International Union for Conservation of Nature (IUCN) Red Lists as Endangered (EN). Fresh seeds of L. strictissimum harvested from the only known population in Sardinia and a population in southeastern Corsica were used with the aims to study the effects of temperature and salinity on the seed germination and to evaluate the ability to recover their germination after exposure to salt stress. In both populations, empty fruits with a lower percentage were observed in Sardinia than in Corsica. The seeds showed a high germination capacity, which was not influenced by temperature and did not even differ between the two populations. Compared with non-saline condition, the presence of salt in the substrate, independently of the concentration tested, inhibited seed germination in both populations, with germination percentages never exceeding 40%. The Sardinian population showed a recovery capacity after exposure to high salt stress, always above 50% regardless of the salt concentration and incubation temperature considered. The seeds previously exposed to 125 mM NaCl at 30°C had the lowest recovery percentage (56%), while the highest recovery percentage (84%) was recorded at 25°C with a concentration of 250 mM NaCl. Differently, the Corsican population recorded a higher recovery percentage (54%) in seeds previously exposed to 500 mM NaCl at 20°C, while for the concentration of 125 mM NaCl, the best recovery percentage (11%) was recorded at 30°C. The ability of L. strictissimum to recover germination after salt exposure can be interpreted as an adaptation to the coastal habitats in which it grows. This study provides new insights into the ecophysiology of L. strictissimum seed germination, which could help preserve and implement effective conservation measures for this endangered species with restricted populations
Plant distribution and conservation in mediterranean islands’ lentic wetlands: there is more than aquatic species
Full text linkThis study investigates the distribution and conservation status of plant species in lentic wetlands of Mediterranean islands. Field data on vascular macrophytes were collected from the online national databases of the “Conservation of the island wetlands of the Mediterranean Basin” (MedIsWet). A comprehensive inventory of wetlands was conducted, and information on the main anthropogenic impacts and conservation priorities was compiled. In addition to all vascular hygro- and hydrophytes, we retained information on those species typically adapted to environments with intermittent or temporary wetness. A significant knowledge gap regarding the distribution and conservation of plant species in Mediterranean wetlands was found. A lower endemism rate was observed particularly in coastal wetlands. However, approximately 25% of species, mainly with relatively wide distribution, were identified as endangered or with unknown conservation status. Including all macrophytes adapted to seasonal wetness is crucial when considering wetland conservation efforts. The research emphasised the importance of considering diverse wetland types, including seasonal and permanent, natural and artificial, for effective plant conservation. Artificial wetlands emerged as potential habitats with considerable biodiversity conservation value. This study provides a comprehensive inventory of wetlands and valuable insights into the distribution, ecology, and conservation relevance of aquatic macrophytes in Mediterranean islands. The research enhances our understanding of biogeographic patterns and processes, offers critical information for the management and conservation of Mediterranean island wetlands, and presents a replicable approach that can be applied to other wetland contexts
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
Variations on the Author
Full text link“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
Full text linkWe 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
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