1,720,986 research outputs found
Is vegetation an indicator for evaluating the impact of tourism on the conservation status of Mediterranean coastal dunes?
No full textMediterranean coastal dunes are threatened by several factors; particularly, tourism causes modifications to the vegetation and the disappearance of endemic species. Understanding the dunes' conservation status is crucial for preserving these vulnerable environments through appropriate management strategies. This study was conducted on 17 Sardinian coastal dunes, with different levels of touristic pressure. We focused on endemic plant species and developed a new endemicity index (EI). Our study aimed: 1) to assess the conservation status by applying the diversity indices; 2) to verify if the study sites would reveal a general pattern based on different degrees of human disturbance and 3) to test the effectiveness of the EI index. Four m 2 plots (2 × 2 m) were placed along orthogonal transects to the coastline (446 plots in total), in which all plant species were identified, and their relative abundance was estimated. We found significant differences among the sites for H dune and EI values but no statistically significant differences in the N values. The EI showed the high naturalistic value of Sardinian coastal dunes and allowed us to distinguish the sites with higher anthropic pressure. We found significant differences in the indices among the degrees of human disturbance in the coastal systems. The H dune values were positively related to a medium level of human disturbance, and the EI allowed us to distinguish the sites with varying levels of human disturbance, although it differentiated better those with the highest anthropic pressure. A medium level of human disturbance was positively related to the plant richness and cover, and human trampling could be tolerated by psammophilous vascular plants. Results showed a satisfactory conservation status of Sardinian dune systems and highlighted diversity indices as valuable support for implementing a conservation strategy, compatible with the tourism purposes and the integrated management of the Mediterranean coastal dune systems
Assessing the potential for restoring Mediterranean coastal dunes under pressure from tourism
Full text linkMediterranean dune systems have undergone a large reduction in the last decades. The main factors involved in this process are urbanisation promoting an alteration of dune morphology and changes in plant communities. The most representative coastal dune systems of Sardinia have been selected as a study case and analysed to evaluate their environmental status, vulnerability, and the potential for dune restoration. Thirty coastal-dune systems, ranging from high natural sites to urbanised areas were analysed. A matrix of 35 variables × 30 sites was built to calculate the relationship among dune development (StaDun) and other indices related to the coastal dunes potential to host dunes (BeaPot), the conservation actions and management of coastal-dune systems (CoMan), and the anthropogenic pressure and the transgression capacity of the sand (SurLan). The values obtained for StaDun and Dune restoration potential index (DPR) were clustered. The results highlighted the relationship among StaDun, BeaPot and CoMan indices. The geomorphological and ecological characteristics determine the main factors that influence the presence, typology, and development of dunes in each site. Conversely, StaDun was weakly correlated to SurLan index. The DPR index allowed to discriminate the coastal dunes that required management actions. The first group included well-developed dune systems for which conservation and management actions were not necessary. The second one consisted of sites for which these previous actions and restoration measures were necessary. DPR index provides a tool useful to assess and classify coastal dune areas based on their potential for restoration, and to plan appropriate management actions. Graphical Abstract: [Figure not available: see fulltext.
Recruitment pattern in an isolated small population of the Mediterranean dwarf shrub Satureja thymbra L. and implication for conservation
No full textThe recruitment pattern of Satureja thymbra (Lamiaceae), in a single and isolated population in Sardinia, was experimentally investigated by human-mediated sowing in the field: 12 plants in two habitats (inside and outside of “phrygana” habitat) were randomly selected as the source of seeds and a total of 2160 seeds were buried in two microhabitats, under the canopy and in open areas (3 replicas × 30 seeds × 12 plants × 2 microhabitats). The experiment was monthly monitored over a 2-year period. Germination and recruitment of S. thymbra were extremely low. Significant differences in the interaction among habitat and cohorts in seedling emergence were found. Differences between cohorts are due to the early emergence, which protected seedlings from seasonal drought. Seedling emergence in both microhabitats was recorded, although no significant differences were found. Additionally, significant differences in survived seedlings for habitat and cohort and for the interaction among them were found. The phrygana habitat showed a positive effect on the persistence of S. thymbra, by protecting plants from human disturbance, hence its conservation is essential to increase the population size of S. thymbra. Our findings, increasing the knowledge of the recruitment pattern of S. thymbra, provide also useful information for its conservation
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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