Mediterranean Hotspot Research Articles

Identification of climate change hotspots in the Mediterranean

The Mediterranean region has long been identified as a climate change hotspot. However, within the Mediterranean, there are smaller sub-areas that exhibit a higher risk of climate change and extremes. Previous research has often focused on indices based on mean climate values, yet extremes are typically more impactful on humans and ecosystems. This study aims to identify the most vulnerable sub-areas of the Mediterranean as climate change hotspots using two indices: the newly introduced Mediterranean Hotspot Index (MED-HOT) and the well-defined Regional Climate Change Index (RCCI). The MED-HOT focuses on extreme high maximum and minimum temperatures, rainfall, and drought, while RCCI assesses changes in mean climate conditions. By combining these indices, we provide an identification of Mediterranean hotspots, capturing both mean climate shifts and extremes. The spatiotemporal variation of both indices across the Mediterranean region is presented and the 20 subregions are categorized into distinct groups. The results reveal that the southeastern Mediterranean is at high risk according to both indices. Additionally, southern Italy is identified as high risk due to changes in mean climate (RCCI), while the northern part is at risk due to extreme events (MED-HOT). The Iberian Peninsula and Greece are also highlighted as vulnerable areas requiring extra attention.

Investigating a Century of Rainfall: The Impact of Elevation on Precipitation Changes (Northern Tuscany, Italy)

Precipitation is crucial for water resource renewal, but climate change alters their frequency and amounts, challenging societies for correct and effective water management. However, modifications of precipitation dynamics appear to be not uniformly distributed, both in space and time. Even in relatively small areas, precipitation shows the coexistence of positive and negative trends. Local topography seems to be a strong driver of precipitation changes. Understanding precipitation changes and their relationship with local topography is crucial for society’s resilience. Taking advantage of a dense and long-lasting (1920–2019) meteorological monitoring network, we analyzed the precipitation changes over the last century in a sensitive and strategic area in the Mediterranean hotspot. The study area corresponds to northern Tuscany (Italy), where its topography comprises mountain ridges and coastal and river plains. Forty-eight rain gauges were selected with continuous annual precipitation time series. These were analyzed for trends and differences in mean annual precipitation between the stable period of 1921–1970 and the last 30-year 1990–2019. The relationship between precipitation changes and local topography was also examined. The results show the following highlights: (i) A general decrease in precipitation was found through the century, even if variability is marked. (ii) The mountain ridges show the largest decrease in mean annual precipitation. (iii) The precipitation change entity over the last century was not homogenous and was dependent on topography and geographical setting. (iv) A decrease in annual precipitation of up to 400 mm was found for the mountainous sites.

Assessing the Effects of Citizen Climate Literacy and Attitudes on Their ‘Greening’ Behaviour in a Climate Change Hotspot Region of the Eastern Mediterranean

Climate change presents an urgent global challenge, manifesting in rising temperatures and extreme weather events with severe societal impacts. The Eastern Mediterranean, warming faster than the global average, faces immediate repercussions. Climate literacy emerges as pivotal, empowering individuals to comprehend climate science and act accordingly. This study delves into climate literacy, attitudes, and ‘greening’ behaviours in the Eastern Mediterranean hotspot of Greece, based on a survey of 1962 citizens. Findings indicate high climate literacy but lower adoption of ‘greening’ behaviours, especially those involving financial costs. Regression analyses highlight the significant role of climate literacy, concerns about personal impacts, coping appraisal, and trust in institutions in promoting ‘greening’ behaviours. This study underscores the need for multifaceted strategies emphasising financial motivation, trust-building, and societal norm shifts. Socio-demographic disparities, including gender and occupation, highlight areas for targeted interventions. The emphasis on the mental health impacts of climate-related events underscores the need for comprehensive disaster management that addresses not only physical damage but also psychological and social dimensions. Policy implications are discussed, highlighting the potential of expanded climate literacy to catalyse collective action toward sustainability.

Tracking Phenological Changes over 183 Years in Endemic Species of a Mediterranean Mountain (Sierra Nevada, SE Spain) Using Herbarium Specimens.

Phenological studies have a crucial role in the global change context. The Mediterranean basin constitutes a key study site since strong climate change impacts are expected, particularly in mountain areas such as Sierra Nevada, where we focus. Specifically, we delve into phenological changes in endemic vascular plants over time by analysing data at three scales: entire massif, altitudinal ranges, and particular species, seeking to contribute to stopping biodiversity loss. For this, we analysed 5262 samples of 2129 herbarium sheets from Sierra Nevada, dated from 1837 to 2019, including reproductive structure, complete collection date, and precise location. We found a generalized advancement in phenology at all scales, and particularly in flowering onset and flowering peak. Thus, plants flower on average 11 days earlier now than before the 1970s. Although similar trends have been confirmed for many territories and species, we address plants that have been studied little in the past regarding biotypes and distribution, and which are relevant for conservation. Thus, we analysed phenological changes in endemic plants, mostly threatened, from a crucial hotspot within the Mediterranean hotspot, which is particularly vulnerable to global warming. Our results highlight the urgency of phenological studies by species and of including ecological interactions and effects on their life cycles.

Floristic Richness in a Mediterranean Hotspot: A Journey across Italy.

Species richness is a fundamental property of biodiversity patterns and is properly expressed by the species-area relationship (SAR), namely the increase in the number of species with the area. Here, we studied and explored the species-area relationship with respect to vascular plant species in Italy and compared vascular plant richness among Italian administrative regions. Concerning the entire vascular flora (native and alien), the best-performing formula is the Arrhenius' Power function: S = c Az. The constants of this function are c = 241.2 and z = 0.281. The best-performing formula concerning just native (c = 245.2 and z = 0.263) and alien (c = 10.1 and z = 0.404) richness is the Power function as well. The floristically richest Italian regions considering the entire flora are Liguria, Friuli Venezia Giulia, and Trentino-Alto Adige, which are also the regions that are richest in alien flora unfortunately. Regions of particular naturalistic interest are Abruzzo, Valle d'Aosta, and Molise, because only these three regions exhibit native floristic richness that is higher than expected, and this is coupled with an alien floristic richness that is lower than expected. On the contrary, four regions (Lombardia, Veneto, Toscana, and Emilia-Romagna) show potentially severe conservation problems due to biological invasions since they experience native floristic richness that is lower than expected, with an alien floristic richness that is higher than expected. This study offers for the first time the 'c' and 'z' constants specifically calibrated at the national level for Italian vascular flora. The availability of such constants allows the calculation of the number of expected species for a given area to be investigated, providing a robust starting hypothesis for floristic studies.

Updating and enhancing the Protected Areas Network of Palestine: A step towards biodiversity conservation

The Protected Area Network (PAN) in Palestine has undergone a comprehensive evaluation and revision to ensure its effectiveness in conserving biodiversity. This re-evaluation was necessary as the previous PAN lacked clear rationale and included areas designated for non-biological reasons. The evaluation process involved analysing the 50 areas in the previous PAN, as well as conducting Marxan analysis and incorporating new data based on IUCN criteria. The evaluation process led to eliminating, combining and adjusting areas, resulting in a revised PAN consisting of 28 areas. This updated PAN represents all vegetation types and phytogeographical zones in Palestine, effectively protecting key ecoregions in the Mediterranean hotspot. The revision of the PAN has increased the total protected land mass from 9 per cent to 9.98 per cent. This expansion provides additional areas where biodiversity can thrive undisturbed, ensuring the long-term survival of species and ecosystems. The updated PAN was adopted at the highest level of government, signifying the importance and commitment to biodiversity conservation in Palestine. This achievement demonstrates the progress made by Palestine in safeguarding its natural heritage.

The importance of university campuses for the avian diversity of cities

In a world of increasing urban areas and their subsequent negative effect on biodiversity, university campuses arise as environmentally friendly designs that can help enhancing biodiversity. However, current information on the topic is mainly based on single-campus studies, taxonomic diversity variables (e.g., species richness), and specific geographic regions like Asia or North America. Multi-campus comparisons, studies on other components of biodiversity (e.g., functional or phylogenetic diversity) and biodiversity information from other regions of the world are needed to generalize the previous findings. In this study, we try to fill in these gaps by simultaneously investigating taxonomic, functional, and phylogenetic diversity of bird communities on 15 university campuses of Spain, which is located within the Mediterranean hotspot of biodiversity where no previous study on this topic have been conducted. We compared campus areas with other randomly selected urban areas to test whether university campuses hold higher levels of bird diversity than non-campus areas. We also analyzed other environmental variables (e.g., green and building cover in and around campuses) to identify whether their influence in university campuses varies from other urban areas. Our results show that taxonomic diversity was higher within university campuses compared to other areas, but this pattern was not confirmed for functional and phylogenetic diversity. We found that grass cover, buildings, and the green area around the study areas have different associations with taxonomic, functional, or phylogenetic diversity respectively in campuses or non-campus areas. Our findings highlight the importance of university campuses for the conservation of Mediterranean urban biodiversity and support their use as relevant resources for promoting nature conservation among citizens.

Time to refine the geography of biodiversity hotspots by integrating molecular data: The Mediterranean Basin as a case study

Three decades ago, worldwide biodiversity hotspots were founded on the distributions of continental plants and vertebrates. Here, we question the timeliness of refining the geography of hotspots by basing their definition on more taxa, thanks to the molecular data available for hyper-diverse organisms such as insects, fungi and marine biota.To do so, we assess the temporal dynamic of molecular data acquisition and the geography of knowledge about lineages currently included or not into hotspot definition. Using the Mediterranean Basin hotspot as a case study, we examine the taxonomic and geographical facets of 175,828 DNA sequences distributed over 21,552 species, and 13,001 indexed biodiversity publications. We reveal a deeply fractured repartition of biodiversity research efforts within the hotspot regarding both barcoding efforts and publication activity, the northern side of the Mediterranean concentrating 84.16 % of the publications and 75.99 % of the public DNA sequences. In addition, 57.55 % of the sequences belong to lineages which were excluded from hotspots definition, with highly congruent geographical patterns among marine and continental lineages.Based on this analysis, we suggest 1) using the uneven geography of knowledge to rebalance sampling efforts towards poorly known regions within the Mediterranean hotspot, 2) handling the molecular corpus of orphan lineages to feed forthcoming multi-taxa biodiversity assessment initiatives, in order to 3) refine the geography of conservation stakes within the hotspot by identifying sub-hotspots of global diversity and 4) fusing a broad range of marine and continental taxa in global biodiversity mapping.

Alien Macroalgal Rearrangement in the Soft Substrata of the Venice Lagoon (Italy): Impacts, Threats, Time and Future Trends

Non-native species are a concern for aquatic environments both for the ecosystem biodiversity and from the economical point of view. The Venice Lagoon is a Mediterranean hotspot of alien introductions and macroalgae are probably the most represented systematic category. For this reason, alien macroalgal distribution and variation were monitored in late spring-autumn surveys, carried out in 2011, 2014, 2018 and 2021 in the soft bottoms of the entire lagoon (87 common stations). Overall, 21 taxa were recorded; three of them (i.e., Acanthosiphonia echinata, Caulacanthus okamurae, Osmundea oederi) are well-established recent introductions for the lagoon, which has increased the total number of non-native species to 33. Ulva australis, previously reported as Ulva laetevirens, is the most abundant species and it is replacing Ulva rigida, especially in the less eutrophic areas. The invasive Gracilariopsis vermiculophylla, an engineering species colonizing the eutrophic choked areas especially in the central lagoon, is instead decreasing. Other abundant established taxa are now dominant components of the lagoon biomass, whereas many others are rare or have small sizes that make their biomass negligible. Overall, these species do not represent serious threats to the environment, but they rather increase biodiversity, with some of them having positive effects on ecosystem services.

Understanding the motivations and implications of climate emergency declarations in cities: The case of Italy

This study investigates the climate emergency declaration (CED) movement in cities and its effects and synergies with local climate planning. Urban areas are experiencing a wide range of climate-induced extreme events, particularly those located in the Mediterranean hotspot. The focus is on Italian cities, which have only recently become key players in climate planning. The method is based on the collection, analysis, and comparison of data on CEDs and local climate plans (LCPs), integrated with information on city membership in climate networks, to extrapolate key performance indicators of the CED movement. The results show that the CED movement can motivate municipalities to become more ambitious in climate action. As of February 2021, the “climate emergency” movement was supported by 105 Italian cities geographically concentrated in the northern regions (66.7%). The motivation behind a CED is often attributable to local populations calling for concrete climate action (91.1% referred to the Fridays for Future movement) but also to a greater perception of the impacts of climate change (85.6% referred to the Special Report on Global Warming of 1.5 °C). Networking plays an important role (85 cities in the Covenant of Mayors). Interestingly, 36 cities (34.3%) were not engaged in local climate planning previously, but the CED shows now they see the urgency to act. 24.4% cities aim at carbon neutrality in their CEDs (most with local adaptation aspirations), with a much smaller fraction of cities doing so in LCPs and generally lower ambition in terms of greenhouse gas emission reduction targets.

Mediterranean university campuses enhance butterfly (Lepidoptera) and beetle (Coleoptera) diversity

Human population growth is causing an expansion of urban areas, a phenomenon known to deeply impact on the Earth’s biodiversity. Therefore, it is key to understand how to conceal urban development with biodiversity conservation. In this context, university campuses can play an important role as they usually present a large array of different environments and green areas, crucial aspects for promoting urban biodiversity as well as human-nature interactions. Several studies have analyzed the biodiversity of university campuses, however, there are still important taxonomic (e.g., insects) and geographical biases (e.g., Mediterranean hotspot) in our current understanding of these urban areas. Insects are fundamental in many ecosystems as pollinators, prey, pest controllers or decomposers among others. This further increases the need to study this group in the urban context. In this study, we have investigated diurnal Lepidoptera and ground-dwelling Coleoptera in three university campuses and three non-campus areas of the city of Granada (Spain). We used spatial and temporal replicates for each area in order to explore whether university campuses hold higher levels of insect biodiversity (e.g., species richness or common species) than other nearby urban areas. In addition, we investigated the potential influence of several additional predictors on insect diversity such as type of land cover, vegetation origin, management intensity, and distance to the outskirts. Our results suggest that Lepidoptera species and Coleoptera families are more diverse in university campuses than in other urban areas, showing also a positive association with the proportion of bare soil and herbaceous cover. Furthermore, they also seem to be benefited from low vegetation management intensity whereas Coleoptera are favored by native vegetation providing clear management recommendations in order to promote such animal groups in cities. Our study indicates that university campuses are important urban areas to preserve insect biodiversity but also highlights the heterogeneity of response among insect groups.

Assessing Resilience Components in Maritime Pine Provenances Grown in Common Gardens

Knowledge acquisition on the response of tree species to drought in the Mediterranean hotspot is an important step to guide adaptation strategies to climate change impacts, e.g., assisted migration. We assessed the resilience components—i.e., resistance, recovery, and resilience—to drought in 2003 in five provenances of maritime pine planted in four common gardens in Sardinia, and analysed the possible influence of climate variables on these indices. The provenances showed differences in growth rate but not in the components of resilience. Among the provenances, Corsica was the most productive, while Tuscany was the least. One of the two provenances from Sardinia (Limbara) showed good performance in terms of tree growth in the comparatively drier site. The resilience components were influenced by prevailing environmental conditions at the common garden sites. In the relatively drier sites, trees showed the lowest resistance but the highest recovery values. However, two sites, which had the lowest stand density, showed the opposite trend during the drought year, probably due to moderate thinning. Predictive models showed different probability in the response of resilience components to climate variables. Resistance and resilience had a similar pattern, both being positively related to temperature, while recovery showed an opposite trend. The models’ results indicate a noticeable adaptation of maritime pine to the drought conditions of Sardinia, though the age factor should be considered as well. Despite only minor differences among provenances being found, environmental conditions and management practices at the common gardens were important in determining tree growth patterns. This study suggests that the provenance of Corsica may provide appropriate material for forest plantations in Mediterranean conditions with mitigation purposes.

The opportunity of using wave energy converters in a Mediterranean hot spot

The opportunity of using wave energy converter arrays in a hot spot area of the Mediterranean sea was investigated. For this purpose, numerical simulations of wave energy converters together with a simple cost-effective analysis were carried out. The selected study area is one of the most energetic inside the Sicilian channel (Italy). The numerical simulations were performed using the SNL-SWAN (“Sandia National Laboratories – Simulating WAves Nearshore”) spectral model with an unstructured mesh. The power absorbed from thirteen Wave Energy Converter (WEC) devices was computed. In particular, Pelamis, Wave Dragon, Oyster 2, Wavestar, B-HBA, B-OF, Bref-HB, Bref-SHB, F–2HB, F–3OF, F-HBA and F-OWC were investigated. Hydrodynamic stationary simulations of a WEC array parallel to the coastline were carried out in order to choose the best devices for a non-stationary simulation. The devices selected for this simulation are Pelamis, Wave Dragon, Oyster 2, F–2HB, and Bref-HB. The non-stationary simulation was forced with thirty-nine years wave parameters reanalysis from ERA5 by ECMWF (European Centre for Medium-range Weather Forecasts). This simulation has allowed to obtain the capacity factor (CF) and the dissipative effects in the period from 1979 to 2018. Moreover, a preliminary cost-to-benefit analysis was carried out for the best performance WEC array only. Costs, revenues, LCoE (Levelized Cost of Energy), and payback period were therefore computed by means of economic assumptions. The high energy concentration near the coast produces hydrodynamic effects which have as a consequence potential erosion phenomena. A shoreline change analysis of three beaches of the studied coast was carried out. Such an analysis was focused on shoreline retreatment during the last thirty years. On the basis of the presented results, there is a slight economic advantage in installing a Wave Dragon scaled array with the added value of potentially giving beneficial effects on coastal erosion. Nevertheless, from a strictly economic point of view, other renewable resources could give better results (e.g. wind energy). The adopted methodology gives encouraging results that confirm the opportunity to deploy WEC devices in the Sicilian Channel together with devices exploiting other renewable resources.

Conservation biogeography of high‐altitude longhorn beetles under climate change

Abstract High‐altitude insects are expected to be strongly affected by climate change because of their limited range. Phytophagous species will be subject to further threats because of their dependence on host plants. We investigated the impact of climate change on the distribution of Italian high‐altitude longhorn beetles (Cerambycidae) using a maximum entropy approach based on bioclimatic variables. We used 510 presence records for 15 species distributed throughout the Italian Alps and Apennines. Then, we combined climate‐based predictions with vegetation data to predict the future changes in the extent of suitable areas. All species but two will move uphill to track suitable climates and will face a range contraction (with an average loss of 44%) under both climatic change scenarios considered. Suitable vegetation covers, on average, only 56% of the estimated current species ranges, which means that the future distribution will be even more limited. Given the importance of Italian mountains as hubs of diversity in the Mediterranean hotspot, these results are particularly alarming. Conservation actions that can mitigate the effects of climate change on high‐altitude cerambycids should be focused on contrasting habitat loss and degradation through land preservation and the adoption of appropriate forest management practices.

Effects of climate change on the distribution of threatened invertebrates in a Mediterranean hotspot

Abstract The effects of climate change may constitute a major threat factor for endemic and threatened species of invertebrates. A particularly dramatic case can be found in the Iberian Peninsula, because of its high rate of species diversity and endemism. We aim to evaluate the effects of climate change on the distribution of 36 endangered and endemic species of invertebrates within the Iberian Peninsula using species distribution models. We used an ensemble species distribution modelling framework to estimate the species potential distributions under current and future (2050 and 2070) climatic conditions for two different areas: the whole Iberian Peninsula and the current species ranges. We assessed species vulnerability to climate change by calculating three complementary indexes: change in suitable area, persistence in suitable area and turnover in suitable area. Annual mean precipitation was the variable that contributed most to the climatic models. We categorised 25 species as ‘losers’ because they will experience a reduction in their total suitable area under future climatic conditions, six species were categorised as ‘winners’ and six showed contradictory results. Climate change will have several effects on species by changing their suitable distributions and may affect their persistence. Species with narrow distributions associated with mountain ranges will experience the worst future projected conditions, while arid‐adapted species are expected to expand their distributions. Factors assessing the vulnerability of endemic and endangered species can be taken into account to develop strategies that mitigate the negative effects of climate change.

Modelling extreme precipitation over the Dinaric Alps: An evaluation of the CNRM‐ALADIN regional climate model

AbstractOne of the Mediterranean hotspots for extreme precipitation is the coastal mountainous eastern Adriatic and Dinaric Alps regions, which are often affected by heavy precipitation events (HPEs) that can cause severe damage. Representing these events at different time scales and projecting their future evolution using regional climate models (RCMs) remains a key modelling challenge. This study evaluates the impact of model configuration on the representation of extreme daily precipitation in an RCM at climatological (1979–2012) and event scales (HPEs). Additionally, the impact of the spectral nudging (SN) technique is analysed. We compare two CNRM‐ALADIN model configurations, and perform several sensitivity tests on specific parameters within a configuration. All simulations are driven by the ERA‐Interim re‐analysis over the Med‐CORDEX domain at 0.11° horizontal resolution. On all examined time scales, model configuration shows a considerable impact on the mean and extreme daily precipitation. The new physical parameterizations of moist processes show improvement at the climatological (precipitation intensity, extreme precipitation and frequency of light precipitation) and event (the occurrence, spatial pattern and structure of HPEs) scales. Extreme precipitation shows limited sensitivity to specific parameters and is highly dependent on HPE. The use of SN improves the temporal variability at climatological scales and the location and occurrence of HPEs. We conclude that extreme precipitation representation in CNRM‐ALADIN is more sensitive to change in the model configuration, particularly in the physical parameterizations, than to the application of SN. This study shows that the development and advancement of physical parameterizations can improve the model representation of extreme precipitation at several time scales and can therefore be considered as a means to reduce uncertainties in future climate projections.

Role of wild rabbits as reservoirs of leishmaniasis in a non-epidemic Mediterranean hot spot in Spain

There is limited information regarding the role of wild mammals in the transmission dynamics of Leishmania infantum. A potential human leishmaniasis hot spot was detected in southern Spain that could not be explained solely by canine leishmaniasis prevalence. The aim of this work was to analyse the involvement of wild rabbits as the main factor affecting this Mediterranean hot spot. A survey of wild rabbits, dogs and sand flies was conducted in the human cases environment. A nearby region without clinical leishmaniasis cases was used as reference control. 51 wild rabbits shot by hunters were analysed by molecular techniques. 1100 sand flies were captured and morphologically identified. Blood collected from patients’ relatives/ neighbours (n = 9) and dogs (n = 66) was used for molecular analysis and serology. In Mediterranean leishmaniasis hot spots such as Montefrío municipality (average incidence of 16.8 human cases per 100,000 inhabitants/year), wild rabbits (n = 40) support high L. infantum infection rates (100%) and heavy parasite burdens (average value: 503 parasites/mg) in apparently normal ear skin directly accessible to sand flies, enabling the existence of heavily parasitized Phlebotomus perniciosus females (12.5% prevalence). The prevalence of infection and median parasite load were very low among rabbits captured in Huéscar (n = 11), a human clinical leishmaniasis-free area for the last 18 years. P. perniciosus was the most abundant Phlebotomus species in all the domestic/peridomestic microhabitats sampled, both indoors and outdoors. Accordingly, leishmaniasis is clustering in space and time at this local scale represented by Montefrío due to the proximity of two competent host reservoirs (dogs and heavily parasitized wild rabbits) associated with overlapping sylvatic and domestic transmission cycles through the main vector, P. perniciosus. We highlight the usefulness of determining the prevalence of infection and parasite burden in wild rabbits as a control leishmaniasis measure with the advantage that the use of the ear offers.

Biogeographic history and environmental niche evolution in the palearctic genus Helianthemum (Cistaceae)

The biogeographic history and the degree of environmental niche conservatism provide essential clues to decipher the underlying macroevolutionary processes of species diversification and to understand contemporary patterns of biodiversity. The genus Helianthemum constitutes an excellent case study to investigate the impact of the geo-climatic changes and the environmental niche shifts on the origins of plant species diversity in the Mediterranean hotspot. It is a palearctic species-rich lineage with c. 140 species and subspecies mostly belonging to three distinct evolutionary radiations, almost confined to the Mediterranean region and occurring across varied environmental conditions. In this work, we studied the ample and rapid diversification of the genus Helianthemum across its whole distribution range by performing phylogenetic reconstructions of ancestral ranges and environmental niche evolution. We observed a striking synchrony of biogeographic movements with niche shifts between the three major clades of the genus Helianthemum, likely related to the geo-climatic events occurred in the Mediterranean Basin since the Upper Miocene. In particular, Late Miocene and Early Pliocene were dominated by episodes of range expansions, the Late Pliocene by range contraction and vicariance events, and Pleistocene by most intense environmental niche shifts and in-situ diversification. Our study also provides evidence for four main environmental niches in Helianthemum (i.e., Mediterranean, subdesert, humid-montane and subtropical-insular) and a tendency toward environmental niche conservatism within different subclades, with few niche shifts mostly occurring from Mediterranean ancestors. The relative longer time spent in Mediterranean areas by the ancestors of Helianthemum suggests that the larger species diversity observed in the Mediterranean (i.e. Northern Africa and Southern Europe) may have been generated by a time-for-speciation effect reinforced by environmental niche conservatism. Overall, our work highlights the role of the Mediterranean Basin as a ‘cradle of diversity’ and an ‘evolutionary hub’, facilitating the environmental transitions and determining the building up of a global plant biodiversity hotspot.

Key role of small woodlots outside forest in a Mediterranean fragmented landscape

Even if the ecological role of trees outside forests (TOF) is acknowledged, few studies provide an exhaustive census and define their principal characteristics, considering not only the patch size but also the effect of the surrounding land-use type on TOF biodiversity. Using a multiphase sampling design, we provided a map showing the spatial distribution of small woodlots outside forest (SWOF), a type of TOF, embedded in different land-use types in Sardinia, a Mediterranean hotspot of biodiversity conservation. Once located and mapped, we investigated the differences among SWOFs enclosed in different land-use types, in terms of vegetation structure and plant species richness (native and alien), searching for indicator species able to characterize SWOFs located in different land-use types. Hence, we explored the effect of environmental factors and vegetation structure on native and alien contingent in SWOF's plant communities.Our findings indicated that SWOFs were widely spread along the land-use intensification gradient, both in natural and human-modified land-use types. The area covered by SWOFs increased following the gradient of land-use intensification, reaching the highest value in urban zones (0.85%), and the lower in agricultural and natural and semi-natural areas (0.31% and 0.23%, respectively).We found dissimilarities between SWOFs located in different land-use types in terms of species richness, composition and indicator species, both native and alien. Notably, the contribution of alien species to the overall diversity was low both in natural and human-modified land-uses.Nevertheless, alien and native taxa showed different responses to environmental drivers: alien taxa were not affected by landscape variables, while the native ones were significantly influenced by all investigated environmental drivers and by the structural complexity of vegetation.SWOFs embedded in human-altered areas, in particularly in agricultural land-use, show good levels of naturalness: these results indicate that SWOFs represent an opportunity for natural conversion and rewilding of altered ecosystems.Small woodlands outside the forest can be the pillars to build and extend the green infrastructure network in both natural and modified land-uses, delivering important benefits for ecosystem services, and offering nature-based solutions to pamper fragmentation effects.

Intercomparison of the expected change in the temperature and the precipitation retrieved from CMIP6 and CMIP5 climate projections: A Mediterranean hot spot case, Turkey

The performances of a large number of Global Circulation Models (GCMs) belonging to the latest release the Coupled Model Intercomparison Project phase 6 (CMIP6) in comparison with its predecessor CMIP5 are evaluated for monthly precipitation and temperature over Turkey (i.e. climate change hotspot). The ensemble of best top four models from both CMIP simulations is also used to investigate the future climate change under medium and high emissions for short, medium, and long terms. Results show CMIP6 products outperform CMIP5 in terms of accuracy statistics, particularly for precipitation. Overall, CMIP6 indicate less intermodel variability, implying the climate signal obtained via CMIP6 is improved relative to CMIP5. The CMIP6 reduce the error in precipitation and temperature 11% and 6%, respectively while increasing the correlation 13% for precipitation. Correlation is not changed for temperature. The substantial success of CMIP6 mainly manifests itself in the winter precipitation and autumn temperature. A slightly warmer (up to 0.35 °C) climate from the CMIP6 is projected while precipitation change in mean precipitation decline is about 2.5% smaller for CMIP6. However, precipitation changes in maximum decline and increase are more noticeable for CMIP6, addressing the better resolving for future climate variability. The summer warming (up to 6.5 °C) and drying (up to −40%) towards autumn spread across the country. The increased precipitation projection in the winter and spring over the east of the Black Sea Region and north-east of Anatolia may further increase the flood risks in the area.