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Aims Plant mortality associated with the growing frequency and intensity of heatwaves and dry spells is increasingly occurring in various ecosystems worldwide. However, the impacts of extreme events on plant communities of ultramafic soils are still unknown. Here, we describe a first case of plant mortality on serpentine outcrops in Italy following a heat and drought event that occurred between autumn 2016 and summer 2017. Methods Mortality of perennial plants was assessed in thirty plots representing ten major serpentine areas along a SW-NE gradient, with the sparse vegetation of ultramafic soils. Statistical modelling was based on temperature and precipitation data and local site conditions. Results Responses of single species were largely different and not related to their taxonomic position, growth form or level of edaphic specialization for serpentine soils. Notably, obligate serpentine endemics were not less impacted than non-endemics. As expected, species mortality decreased with increasing chromosome number, suggesting higher tolerance and adaptive capacity in taxa of likely polyploid origin. Mortality increased with decreasing number of rainy days and duration of the heatwave and decreased with increasing distance from the Tyrrhenian coastline, reaching 60% in the southern and western areas with a Mediterranean climate. Local site conditions such as increasing soil depth and north-facing aspect significantly increased plant survivorship. Conclusions Our findings show that extreme drought and heat can have a previously unrealized impact on ultramafic plant communities in the short term. Further studies should examine the recovery capacity and resilience of serpentine plants, together with the long term effects.

Main conclusion Odontarrhena is a highly diverse genus of Ni-hyperaccumulators. Here, we demonstrate substantial inability to accumulate Ni in the facultative serpentinophyte O. sibirica , which seems a unique case among the numerous species of the genus that grow on ultramafic soils. Odontarrhena is the most diverse genus of Ni-accumulating plants in W Eurasia, with most taxa growing obligatorily or facultatively on ultramafic soils. A notable exception may be O. sibirica , a facultative serpentinophyte from the E Mediterranean and W Asia in which accumulation ability is still enigmatic. We addressed this issue using observational and experimental methods. Atomic Absorption Analysis of 33 herbarium specimens and plant and soil samples from seven ultramafic and non-ultramafic sites in Greece revealed shoot Ni values always much lower than 1000 µg g −1 , non-significant differences between plants from the two soil types and no relationship with soil pH. Only two Turkish specimens from waste mines had shoot Ni concentration > 1000 µg g −1 . The reasons for this deviating result remain obscure, but may be associated with inherent peculiarities of the local populations. When cultivated together with congeneric Ni-accumulating species on the same natural ultramafic soil, only O. sibirica was unable to accumulate the metal. Although plant growth was stimulated in hydroponics at relatively low NiSO 4 levels (50–150 µM), as typical for hyperaccumulators, Ni-accumulation occurred only at higher concentrations which had a toxic effect. This peculiar combination of Ni-response traits could be the result of a partial evolutionary loss of ability with respect to all other Ni-accumulating congeneric species. For this, O. sibirica could represent a unique model system for further studies on the evolutionary dynamics, physiological mechanisms and genetic control of metal accumulation and homeostasis.

Odontarrhena is a taxonomically difficult genus of the tribe Alysseae, including a number of critical species complexes in the Balkan Peninsula. One of these is O. baldaccii , which was previously included in the inconsistent taxon Alyssum fallacinum but recently shown to be distinct from it. In this paper, we analyzed the still uncertain taxonomic circumscription of O. baldaccii by a comparative analysis of the population from the type locality in Crete and other populations from mainland Greece, which were previously attributed to A. fallacinum or dubitatively included in O. baldaccii s.l. The results supported the separation of these mainland populations in a new distinct species, here described as Odontarrhena stridii , sp. nov. Plant habit, leaf shape and size and silicle shape were the major distinguishing morphological characters. Molecular data also suggested divergence between the two groups of populations, while supporting their phylogenetic affinity. The two species are diploid schizo-endemics with 2 n  = 16, allopatric distribution and specialization for serpentine soils. Shoot Ni concentrations well above 1000 µg g −1 dry weight were confirmed for the Cretan population of O. baldaccii and found for the first time in two populations of O. stridii , which is therefore a new hyperaccumulating species of the Balkan Mediterranean flora. An updated key to the Greek Odontarrhena taxa is provided.

Floristic knowledge and georeferenced information about vascular plant species distribution in southern Tuscany (Italy) are still poor for supporting effective biodiversity conservation efforts. A dataset of georeferenced floristic collections from Southern Tuscany, which was developed by the first author between 1989 and 2024, is provided and briefly commented on. The dataset includes data for 4535 herbarium specimens, mostly unpublished, currently preserved in the Herbarium Centrale Italicum at the Natural History Museum of Florence (FI). The specimens belong to 1766 species and subspecies in 122 families of vascular plants. Each record is associated with a Unique Identifier (UID) and information on the collection locality, date, collector(s), and geographical coordinates (WGS84 geodetic datum). Many specimens were collected in areas that were poorly investigated, documenting new sites for several uncommon or phytogeographically relevant taxa. The dataset includes two specimens of Euphorbia meuselii Geltman, a forest herb endemic to Southern Italy and new to the flora of Tuscany. Overall, this dataset allows a relevant advancement in the floristic knowledge of central Italy.

An anomalous event of drought and heat occurred in central Italy during the summer of 2017. Based on the SPI (Standardized Precipitation Index) and data from the European Space Agency, this event started in November 2016 and was characterized by a strong reduction of precipitation and soil moisture, especially in lowland areas with Mediterranean climate. The aim of this case report were to describe the impact of this event on representative forest communities in central Italy, to analyze the different responses of deciduous and evergreen tree and shrub species in contrasting environmental conditions and to assess their subsequent capacity of recovery or, if not, mortality. Trees suffered severe impacts consisting of widespread crown defoliation, leaf desiccation, crown dieback and whole tree mortality. Deciduous tree species (Fagus sylvatica, Quercus pubescens, Quercus cerris) shed their leaves during the summer, but apical buds and twigs were preserved. This allowed these species to produce new shoots in the following year (2018) and to restore the canopy closure of the stands. Mediterranean evergreen broadleaves, such as Quercus ilex and Phillyrea latifolia suffered of total or partial crown desiccation with wilting leaves and branch dieback. These species partially resprouted in 2018 from axillary and latent buds. The case presented here is discussed within the wider context of the impacts of climate change on Mediterranean forests. Future research directions should include an effective forest monitoring system that combines terrestrial and remote sensing surveys, ad hoc field climate change experiments and silvicultural trials from the perspective of proactive management for the adaptation of forests to future climatic conditions.

The new species Silene isabellae is described and illustrated from the Skënderbëut mountain range of central Albania. It grows on the ultramafic mountain slopes around Qafë Shtamë, in the understorey of open Pinus nigra forests and in the rocky grasslands above the forest belt, at 1000–1600 m a.s.l. Silene isabellae is a serpentine endemic likely belonging to section Elisanthe (Fenzl ex Endl.) Ledeb. and shows affinities with the widespread European species S. noctiflora L. It is sharply distinct from the latter species in habit, stem and leaf pubescence, morphology, and biology of the flowers and length of the carpophore. Moreover, the ecology of the two taxa is also contrasting, being S. noctiflora a synanthropic-ruderal, mostly in lowlands. Weaker similarities were also observed with the south European subalpine taxa of the group of S. vallesia L. of section Auriculatae (Boiss.) Schischk., though these are not likely to reflect a real systematic affinity.

Despite their biogeographical relevance, the trait space exploited by endemic plants of Mediterranean forests remains largely unknown. Understanding their functional divergence from widespread congeners is key to explaining their restricted distribution, ecology, and resource-use strategies. Here, we analyzed interspecific variability in leaf economic traits capturing plant strategies of resource-use such as leaf area (LA), specific leaf area (SLA), leaf mass per area (LMA), leaf dry matter content (LDMC), leaf nitrogen content per unit dry mass (Nmass) and carbon to nitrogen ratio (C:N ratio), across 45 endemic taxa of Mediterranean forests. The influence of environmental variables and the phylogenetic signal of traits were examined to identify the main drivers. Next, we performed paired comparisons in 27 endemic-non endemic pairs, with allopatric, parapatric and sympatric distribution. Overall, trait variability within endemics was remarkably ample, reflecting their diversity in functional types, phylogenetic relationships and biogeographical contexts. Endemics were widely distributed along the resource use gradient associated with LA, LMA and Nmass. Herbaceous taxa showed more resource-acquisitive trait values and prevalence of C and R strategies, while woody endemics were more resource-conservative and stress-tolerant. Traits showed a phylogenetic signal of variable intensity depending on the metrics, with Pagel's λ approaching the Brownian model for LA and LMA. Environmental factors variously influenced trait variation. LA decreased with temperature and depended on forest type, while LDMC decreased with latitude and precipitation. LMA increased with temperature and varied with ecoregion and forest type, while Nmass decreased with latitude and increased with precipitation. Species pairs analysis revealed a negative effect of the endemic condition on LA, but positive on LMA. Compared with widespread congeners, this pointed to a lower acquisitive ability and stronger resource conservation attitude, also confirmed by CSR strategies. Differences in LA and LMA within allopatric and parapatric pairs were larger than in sympatric pairs, suggesting the role of vicariance in key leaf trait divergence. In advancing our understanding of the functional and ecological characteristics of Mediterranean endemic forest plants, this study may help to predict the effects of the increasing pressures to their habitat and support strategies for their conservation.

The impact of invasive herbivore species may be lower in more diverse plant communities due to mechanisms of associational resistance. According to the “resource concentration hypothesis” the amount and accessibility of host plants is reduced in diverse plant communities, thus limiting the exploitation of resources by consumers. In addition, the “natural enemy hypothesis” suggests that richer plant assemblages provide natural enemies with more complementary resources and habitats, thus promoting top down regulation of herbivores. We tested these two hypotheses by comparing crown damage by the invasive Asian chestnut gall wasp (Dryocosmus kuriphilus) on chestnut trees (Castanea sativa) in pure and mixed stands in Italy. We estimated the defoliation on 70 chestnut trees in 15 mature stands sampled in the same region along a gradient of tree species richness ranging from one species (chestnut monocultures) to four species (mixtures of chestnut and three broadleaved species). Chestnut defoliation was significantly lower in stands with higher tree diversity. Damage on individual chestnut trees decreased with increasing height of neighboring, heterospecific trees. These results suggest that conservation biological control method based on tree species mixtures might help to reduce the impact of the Asian chestnut gall.

Wetlands are among the world’s valuable ecosystems for biodiversity conservation, but they are also among the most threatened habitats, heavily impacted by human pressures and threats. The Mediterranean basin features numerous small lakes, ponds, and pools, whose number and quality are decreasing at an alarming rate, and whose biodiversity is often little or not at all known. As a better knowledge of the biotic components of these minor water bodies is necessary, with this aim a phytosociological survey campaign was carried out in southern Tuscany (central Italy), an area where little information is available on the vegetation of aquatic and palustrine biotopes. Numerous previously unknown water bodies were located and surveyed in this work, while others already known were resurveyed. These investigations allowed us to identify 28 plant communities which can be classified into seven syntaxonomic classes. A new subassociation (Ranunculo ophioglossifolii-Callitrichetum stagnalis subass. ranunculetosum peltati) is described. The identification of the site-associated Natura2000 habitats led to the recognition of five habitats of conservation interest at the national and European level. The results of these investigations will improve the knowledge of the flora and vegetation of these small but valuable natural areas, providing a basis for their conservation.

AIM: Production of wood charcoal is an ancient form of anthropogenic forest use that existed for millennia in Mediterranean countries and only vanished in the last century. As a result, thousands of abandoned charcoal kiln platforms still occur in present‐day woodlands. Because of peculiar light and soil properties, the understorey vegetation at these platforms may differ from the surrounding stands. Our study investigated, for the first time, the effects of abandoned kiln platforms on understorey vegetation diversity, composition and biomass production in forests of a Mediterranean area. LOCATION: Tuscany, central Italy. METHODS: One 3 × 3 m kiln plot on charcoal kiln area and one 3 × 3 m control plot in the surrounding stands were established in 59 representative sites located in three major forest types dominated by evergreen sclerophylls, deciduous oaks and beech. In each plot, diversity and composition of the understorey community were analysed, together with soil factors (content of C, N, C:N ratio, pH) and light conditions (PAR). A 50 × 50 cm frame was randomly placed in each plot to measure biomass production. RESULTS: The charcoal kiln habitat positively affected understorey diversity and above‐ground biomass, as well as the content of C, C:N ratio, pH and light availability. Significant compositional differences between the two plot types occurred, although to a variable extent for the three forest types. Graminoids were more abundant on kiln plots, and 12 indicator species were found for this habitat in deciduous oak forests. Higher values of cover and biomass showed the lack of detrimental effects of wood charcoal accumulation on understorey productivity. CONCLUSIONS: Long‐term wood charcoal production in Mediterranean woodlands has caused long‐lasting effects on the understorey via persistent changes in abiotic factors. Hence, former kiln platforms represent anthropogenic microhabitats that increase biodiversity and fine‐scale heterogeneity of forest ecosystems. Conservation measures are advocated to preserve them against various external threats.