Trees play a key role in the structure and function of many ecosystems worldwide. In the Mediterranean Basin, forests cover approximately 22% of the total land area hosting a large number of endemics ...(46 species). Despite its particularities and vulnerability, the biodiversity of Mediterranean trees is not well known at the taxonomic, spatial, functional, and genetic levels required for conservation applications. The WOODIV database fills this gap by providing reliable occurrences, four functional traits (plant height, seed mass, wood density, and specific leaf area), and sequences from three DNA-regions (rbcL, matK, and trnH-psbA), together with modelled occurrences and a phylogeny for all 210 Euro-Mediterranean tree species. We compiled, homogenized, and verified occurrence data from sparse datasets and collated them on an INSPIRE-compliant 10 × 10 km grid. We also gathered functional trait and genetic data, filling existing gaps where possible. The WOODIV database can benefit macroecological studies in the fields of conservation, biogeography, and community ecology.
Warm drylands represent 19% of land surfaces worldwide and host ca. 1100 tree species. The risk of decline due to climate aridification of this neglected biodiversity has been overlooked despite its ...ecological and societal importance. To fill this gap, we assessed the risk of decline due to climate aridification of tree species in warm drylands based on spatialized occurrence data and climate models. We considered both species vulnerability and exposure, compared the risk of tree species decline across five bioregions and searched for phylogenetic correlates. Depending on the future climate model, from 44% to 88% of warm drylands' tree species will undergo climate aridification with a high risk of decline even under the most optimistic conditions. On a regional scale, the rate of species that will undergo climate aridification in the future varies from 21% in the Old World North, to 90% in Australia, with a risk of decline confirming the high level of risk predicted at the global scale. Using generalized linear mixed models, we found that, species more exposed to climate aridification will be more at risk, but also that species vulnerability is a key driver of their risk of decline. Indeed, the warm drylands specialist species will be less at risk due to climate aridification than species being marginal in warm drylands. We also found that the risk of decline is widespread across the main clades of the phylogeny and involves several evolutionary distinct species. Estimating a high risk of decline for numerous tree species in all warm drylands, including emblematic dryland endemics, our work warns that future increase in aridity could result in an extensive erosion of tree biodiversity in these ecosystems.
Based on spatialized occurrence data and multiple climate models we assessed the risk of decline due to future climate aridification of tree species in warm drylands. Depending on the climate model, from 44% to 88% of warm drylands' tree species will undergo climate aridification with a high risk of decline even under the most optimistic conditions. Species more exposed to climate aridification and being at their aridity niche margins in warm drylands will be more at risk. Species highly at risk of decline are found in all evolutionary lineages and all dry regions of the world.
•Dracaena draco is able to germinate from 12°C to 33°C•Dracaena draco requires moist and dark conditions to germinate•Native Dracaena draco occurrences are in areas with temperatures below optimum
...The Canary Islands dragon tree (Dracaena draco (L.) L. subsp. draco) is an endangered Tertiary relict species endemic to the Canary and Madeira archipelagos. Based on an ex-situ experiment under controlled conditions, we investigated its germination response to both constant and alternating temperatures, moisture levels (water potential), exposure to light, and desiccation. We found that suitable temperatures for germination (> 5% of germinated seeds) range from 12.1°C to 32.8°C (thermal germination niche limits) and optimal temperatures (> 95% of germinated seeds) range from 16.6°C to 28.3°C. Light exposure and water potential below 0 MPa drastically decreased germination performance while seed desiccation pre-treatments and alternating temperatures had slightly negative effects. Comparing the spatial projection of the thermal germination niche with actual occurrences of D. draco subsp. draco revealed that native populations are mainly distributed in areas where temperatures are colder than the optimum for germination. For native populations, germination rate is predicted to reach 78% on average based on temperature requirements. Our results suggest that niche conservatism and adaptation are involved in shaping the germination requirements of the dragon tree.
Despite increasing metals and metalloids (MM) human-driven soil contamination, how it simultaneously alters biodiversity and ecosystem functioning remains unknown. We used a wide gradient of a ...170-year-old MM soil multi-contamination in Mediterranean scrublands to assess the effects of soil multi-contamination on multiple plant biodiversity facets, microbial communities and ecosystem multifunctionality (EMF). We found an overall positive effect of plant biodiversity on EMF mediated by microbial communities, and allowing offsetting the negative impacts of MM soil multi-contamination, especially on soil water holding capacity and nitrogen content. The diversity of distant plant lineages was the key facet promoting EMF by enhancing microbial communities, whereas the subordinate species richness altered EMF. By developing a holistic approach of these complex relationships between soil multi-contamination, plant biodiversity, microbial communities and ecosystem functioning, our results reveal the potential of plant biodiversity, and especially the diversity of evolutionary distant species, to offset the alteration of ecosystem functioning by MM soil multi-contamination. In this worldwide decade of ecosystems restoration, our study helps to identify relevant facets of plant biodiversity promoting contaminated ecosystem functioning, which is crucial to guide and optimize management efforts aiming to restore ecosystems and preserve human health.
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•Biodiversity promotes ecosystem functioning in contaminated Mediterranean scrubland.•Microbial communities mediate plant biodiversity effects on ecosystem functioning.•Phylogenetic diversity improves contaminated Mediterranean scrublands functioning.•Mediterranean scrublands have a good potential to restore contaminated ecosystems.
Drylands represent about 41% of Earth’s land area, host more than 1,500 tree species and support more than 20% of the world’s human population. Trees are key to the functioning of numerous dryland ...ecosystems and contribute to goods and services for many local human communities, but many are threatened by global changes. From this perspective, mapping tree species assemblages of drylands can provide valuable information for conservation. To our knowledge, warm drylands, including hot deserts, have never been subject to a comprehensive tree biodiversity analysis independent of administrative boundaries or pre-defined regions. Our study aimed to address this gap by redefining warm drylands based on climate data and delineating bioregions using tree species assemblages at the global scale. We based the analyses on aridity and temperature data and a co-occurrence network approach using more than 1,000 tree species. Our data are mined from the Desert Trees of the World database, the Global Biodiversity Information Facility database, and the African Plant Database. This new delimitation of warm drylands reveals eight bioregions, covering about 19% of Earth’s land area across all continents. These are: North America, two bioregions in South America, the southern Mediterranean Basin and Macaronesian islands, the Saharo-Sindian region and the Horn of Africa, Southern Africa, the Socotra archipelago, and Australia. These bioregions have very distinct tree species assemblages, as well as high rates of endemism. This original diversity is found under a wide range of aridity conditions both within and between bioregions, offering the opportunity to anticipate different responses of tree assemblages face to future climate change among the world’s warm drylands. It will aid in conservation, restoration, and rehabilitation strategies involving the use of native trees among the most threatened regions worldwide.
Prospero seisumsianum (Ruksans & Zetterl.) Yıldırım, a species recently described in southeastern Turkey, was recorded for the first time in the flora of Iraq based on samples collected from the ...Amadya and Duhok areas (northern Iraq). Our contribution here will be to find out more about its description, cytology, and chorology. The specimen collected from the Mesopotamian dry plain differs slightly from those collected from the mountainous Zagros forest area, but converges after a cultivation period. Both are treated here as P. seisumsianum and have the same genome size (2C = 8.77 ± 0.24 pg) corresponding to a diploid level. Three chromosome counts gave the same 2n = 2x = 14 karyotype. We hypothesize here that all the historical mentions of P. ?autumnale? in Iraq actually correspond to P. seisumsianum. Comparative morphological description, genome size, ecological niche, and biogeography of the related taxa, and a revised key for Prospero taxa from the Irano-Anatolian enlarged to its Mediterranean border are given in the present study.
Mediterranean temporary pools are threatened ecosystems that host a unique plant community, mostly composed of annual species with large and long-lived seed banks. The longevity of their seed bank, ...the scarcity of their habitat, the small size of their populations and the low frequency of above-ground vegetation result in a low probability of detection of these species. The discovery of new populations of such rare species are thus important for our understanding of the ecology of the temporary pool ecosystem. Lythrum thesioides M.Bieb., 1808 is a very rare annual species of temporary pools and river banks which was thought to be extinct in the South of France until 1998. Here, we review the distribution of the species and report the recent discovery of a population during a targeted search combining historical data on wetland occurrence on a particular geological substrate. We present new information on its autecology, pollen morphology and the karyotype. Only three populations are currently known worldwide for Lythrum thesioides, and only one of these has favorable management conditions. Thus, we outline new conservation perspectives in the context of a targeted search project and the conservation management of one population.
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