1,721,034 research outputs found
Threatened or poorly known? The case of the Mediterranean narrow endemic Valeriana amazonum in Sardinia
Full text linkThe Mediterranean flora is characterized by a high number of narrow endemic plant species that are often restricted to a few small populations. One of these species, Valeriana amazonum, a perennial plant occurring only in the Supramontes region of central eastern Sardinia, is categorized as Critically Endangered on the IUCN Red List because of its restricted range, small population size and an inferred decline caused by several threats. During 2007-2022, we monitored all mature individuals of this plant annually and surveyed ecologically suitable sites for the species. We identified two previously unknown populations and also learnt of two successful translocations carried out independently by an unknown local citizen. As our monitoring data indicate there has been no decline in the number of mature individuals over the period of monitoring, the species' conservation status requires reassessment. We recommend that V. amazonum should be recategorized as Near Threatened as it seems to be poorly known rather than highly threatened. This could also be the case with other narrow Mediterranean endemics, especially those that grow in inaccessible habitats for which long-term studies are needed to assess conservation status
Assessing beach litter trapping efficiency in Mediterranean sandy coasts: A comparative study between typical and invaded embryonic dunes
Full text linkBeach litter is one of the most evident indicators of marine litter pollution, an anthropogenic component that can affect and interact with the habitat of coastal dunes. In this study, we aim to assess the role of the Mediterranean
embryonic dunes in trapping beach litter. Moreover, we investigate if dunes with native vegetation and those invaded by the alien plant C. acinaciformis differ in the trapping of beach litter. To this end, two samplings were carried out in the Tavolara-Punta Coda Cavallo Marine Protected Area, considering four beaches with different morphologies, using a paired sampling method that considers plots in the embryonic dunes and in the same habitat with C. acinaciformis. Our results indicate that plastic is the primary type of beach litter and that its distribution varied across the different beaches; especially, the greatest amount was found on pocket beaches. Based on our results, we can conclude that there are no differences between embryonic dunes with native
vegetation and their invaded form, but the different beach morphologies may play a role in the distribution of beach litter. These findings may support habitat conservation initiatives such as the eradication of C. acinaciformis since it has no additional role in trapping beach litter
Breeding system and inbreeding depression in a translocated population of the endangered plant Dianthus morisianus (Caryophyllaceae)
Full text linkKnow the breeding system of endemic plants is important to design conservation strategies. Translocations are actions to improve the survival prospects of the species, but nowadays there are only a few studies that analyse their success and make a comparison between translocation and the natural populations. Dianthus morisianus is a threatened narrow endemic plant species growing on sand dunes in SW Sardinia (Italy). The objective of this study was to assess the breeding system, the presence of inbreeding depression and pollen limitation, as well as the success of the plant translocation. All these results were compared with those from the single natural population. The breeding system was tested through five pollination treatments and the reproductive success was analysed by the fruit set, seed set, seed weight, germination and mortality rate. The translocated population behaved like the natural one on fruit and seed formation. Autonomous self-pollination was lower than the other treatments regarding fruit set and seed/ovule ratio in the two studied populations. The species is self-compatible and presents partial self-fertility. The selfing rate was higher in the translocated population and the inbreeding depression presented low values for the natural population, while the translocated population presented negative values. Neither of the populations suffered pollen limitation. The species did not present reproductive problems and it is pollinator dependent. Moreover, the translocated population demonstrated high success after five years, as an increase of the population area and new recruited plants was observed; the offspring were able to flower, fruiting and reproduce. This translocation success increases the survival prospects of the species
The unpredictable fate of the single population of a threatened narrow endemic Mediterranean plant
No full textNarrow endemic plants are highly vulnerable to extinction due to natural factors and human disturbance because of their restricted distribution and few populations. To conserve narrow endemic and threatened plants, is important to know the factors that drive population dynamics. We investigated the factors affecting the population demography of the narrow endemic and threatened Dianthus morisianus, a psammophilous plant with only one small population in Sardinia. Demographic data was analysed by integral projection models (IPMs), and the analysis of population growth rates, elasticities and life table response experiment (LTRE) was performed. Vital rates models show that ramet volume correlates with growth, survival, flowering probability and fruit output. Our results indicate that Dianthus morisianus can be considered a typical long-lived plant with a population dynamic dominated by large ramets. The population growth rate values were always strongly positive; this indicates that the population could increase in the long term and suggests that this plant could be able to recolonise the dune system. However, this scenario seems to contrast with the high risk of extinction reported for this plant; actually the persistence of the unique population of D. morisianus is negatively affected by several factors related to the ecological conditions of coastal dunes and other external factors such as animal grazing and trampling. Conservation actions for this threatened and narrow endemic plant should be focused to strictly protect and to enhance the number of large ramets; this strategy is the key element to increase the population size and to ensure the population persistence
Assessing the global conservation status of the rock rose Helianthemum caput-felis
Full text linkThe assessment of the conservation status of a species is the first step in developing a conservation strategy. IUCN Red Lists assessments are an important starting point for conservation actions and the most commonly applied method for assessing the extinction risk of a species. In this study, the global conservation status of the rock rose Helianthemum caput-felis Boiss. (Cistaceae), a perennial Mediterranean plant, was evaluated using the Red List criteria. The distribution of the species was determined by monitoring historical localities and all other suitable sites along the western Mediterranean coasts for 6 years. For each confirmed locality, the ecological and population parameters and the main threats were recorded; these data were used in a quantitative analysis of the species' extinction risk. Our findings indicate there have been several recent extinctions, and there is a continuing decline in the species' area of occurrence, habitat quality and number of reproductive plants. The main threats are related to human activities. Extinction models indicate a probability of quasi-extinction risk of c. 30% in five generations or c. 45% in three generations, with the species likely to become extinct in seven currently known localities within the next 10 years. Application of the Red List criteria indicates H. caput-felis should be categorized as Endangered. This study confirms that legal protection and passive conservation measures are insufficient to guarantee the persistence of a plant species. Active conservation and management actions are needed to protect this and other threatened species of the Mediterranean Basin
From global to local scale: where is the best for conservation purpose?
Full text linkDemographic analysis of plant populations represents an essential conservation tool allowing to identify the population trends both at global and at the local level. In this study, the population dynamics of Helianthemum caput-felis (Cistaceae) was investigated at the local level by monitoring six populations distributed in Sardinia, Balearic Islands and Ibero-Levantine coast (Alicante). Demographic data for each population were analysed by performing Integral Projection Models (IPMs). Our results showed that, although the local trend of the main basic demographic functions was similar, vital rates and demographic dynamics varied among populations indicating high variability. In fact, asymptotic growth rate in Spanish populations widely varied both between years and populations (some populations growth, decline or strongly decline), while Sardinian populations showed greater equilibrium or a slight increase. Also, the typical pattern of a long-lived species was not supported by the results at the local scale. These results indicated that different populations of the same species can present extremely different population dynamics and support the belief that, for conservation needs, local studies are more informative than global ones: the conservation status of H. caput-felis could notably vary at a small spatial scale and, accordingly, the conservation efforts must be planned at the population level and supported by local analysis
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
Difference between invasive alien and native vegetation in trapping beach litter: A focus on a typical sandy beach of W-Mediterranean Basin
Full text linkBeach litter is one of the most pervasive pollution issues in coastal environments worldwide. In this study, we aim to assess the amount and distribution of beach litter on Porto Paglia beach, its entrapment across psammophilous habitats, and whether the invasive Carpobrotus acinaciformis (L.) L.Bolus plays a different role in trapping litter than native vegetation. To this end, two seasonal samplings (in spring and autumn) were conducted using a paired sampling method that considers plots in all coastal habitats with and without C. acinaciformis. Our results confirm that the main beach litter category is plastic, and that its distribution varies across habitats: the white dune seems to play a greater role in trapping and filtering beach litter, reducing its amount in the backdune. A correlation was found between the Naturalness index (N) and the beach litter amount, supporting the finding that invaded habitats trap beach litter better than native ones
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
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