Explanation of beta diversity in European alpine grasslands changes with scale

The importance of environmental difference among sites and dispersal limitations of species to the explanation of diversity differs among biological systems and geographical regions. We hypothesized that climate and then dispersal limitation will predominantly explain the similarity of alpine vegetation at increasing distances between pairs of regions at subcontinental extent. We computed the similarity of all pairs of 23 European mountain regions below 50 degrees N after dividing the species lists of each region by calcareous or siliceous substrates. Distance decay in similarity was better fitted by a cubic polynomial than a negative exponential function, and the fit was better on calcareous than on siliceous substrate. Commonality analysis revealed that the proportion of explanation of beta diversity by climatic difference had unimodal patterns on a gradient of increasing distance between regions, while explanation by dispersal limitation had consistently rising patterns on both substrates. On siliceous substrate, dispersal limitation explained more of the variation in beta diversity only at longer distances, but it was predominant at all distances on calcareous substrate. The steeper response to distance at 2600 km may indicate dispersal limitation at different temporal scales, and the uptick in the response to distance at the longest distances may reflect how isolated some regions have been before and since the last glacial maximum

Post-glacial determinants of regional species pools in alpine grasslands

[Aim] Alpine habitats support unique biodiversity confined to high-elevation areas in the current interglacial. Plant diversity in these habitats may respond to area, environment, connectivity and isolation, yet these factors have been rarely evaluated in concert. Here we investigate major determinants of regional species pools in alpine grasslands, and the responses of their constituent species groups.[Location] European mountains below 50° N.[Time period] Between 1928 and 2019.[Major taxa studied] Vascular plants.[Methods] We compiled species pools from alpine grasslands in 23 regions, including 794 alpine species and 2,094 non-alpines. We used species–area relationships to test the influence of the extent of alpine areas on regional richness, and mixed-effects models to compare the effects of 12 spatial and environmental predictors. Variation in species composition was addressed by generalized dissimilarity models and by a coefficient of dispersal direction to assess historical links among regions.[Results] Pool sizes were partially explained by current alpine areas, but the other predictors largely contributed to regional differences. The number of alpine species was influenced by area, calcareous bedrock, topographic heterogeneity and regional isolation, while non-alpines responded better to connectivity and climate. Regional dissimilarity of alpine species was explained by isolation and precipitation, but non-alpines only responded to isolation. Past dispersal routes were correlated with latitude, with alpine species showing stronger connections among regions.[Main conclusions] Besides area effects, edaphic, topographic and spatio-temporal determinants are important to understand the organization of regional species pools in alpine habitats. The number of alpine species is especially linked to refugia and isolation, but their composition is explained by past dispersal and post-glacial environmental filtering, while non-alpines are generally influenced by regional floras. New research on the dynamics of alpine biodiversity should contextualize the determinants of regional species pools and the responses of species with different ecological profiles.The authors thank Daniela Gaspar for support in GIS analyses. B.J.-A. thanks the Marie Curie Clarín-COFUND program of the Principality of Asturias-EU (ACB17-26), the regional grant IDI/2018/000151, and the Spanish Research Agency grant AEI/ 10.13039/501100011033. J.V.R.-D. was supported by the ACA17-02FP7 Marie Curie COFUND-Clarín grant. G.P.M. was funded by US National Science Foundation award 1853665. C.M. was funded by grant no. 19-28491 of the Czech Science Foundation.Peer reviewe

EUNIS Habitat Classification: Expert system, characteristic species combinations and distribution maps of European habitats

Aim: The EUNIS Habitat Classification is a widely used reference framework for European habitat types (habitats), but it lacks formal definitions of individual habitats that would enable their unequivocal identification. Our goal was to develop a tool for assigning vegetation‐plot records to the habitats of the EUNIS system, use it to classify a European vegetation‐plot database, and compile statistically‐derived characteristic species combinations and distribution maps for these habitats. Location: Europe. Methods: We developed the classification expert system EUNIS‐ESy, which contains definitions of individual EUNIS habitats based on their species composition and geographic location. Each habitat was formally defined as a formula in a computer language combining algebraic and set‐theoretic concepts with formal logical operators. We applied this expert system to classify 1,261,373 vegetation plots from the European Vegetation Archive (EVA) and other databases. Then we determined diagnostic, constant and dominant species for each habitat by calculating species‐to‐habitat fidelity and constancy (occurrence frequency) in the classified data set. Finally, we mapped the plot locations for each habitat. Results: Formal definitions were developed for 199 habitats at Level 3 of the EUNIS hierarchy, including 25 coastal, 18 wetland, 55 grassland, 43 shrubland, 46 forest and 12 man‐made habitats. The expert system classified 1,125,121 vegetation plots to these habitat groups and 73,188 to other habitats, while 63,064 plots remained unclassified or were classified to more than one habitat. Data on each habitat were summarized in factsheets containing habitat description, distribution map, corresponding syntaxa and characteristic species combination. Conclusions: EUNIS habitats were characterized for the first time in terms of their species composition and distribution, based on a classification of a European database of vegetation plots using the newly developed electronic expert system EUNIS‐ESy. The data provided and the expert system have considerable potential for future use in European nature conservation planning, monitoring and assessment

Approche syntaxonomique et écologique des formations à Genévrier thurifère (Juniperus thurifera L.) dans les Alpes françaises

The thuriferous juniper (Juniperus thurifera L.) phytosociology of the western part of Mediterranean Basin and French Alps has been well studied. Its distribution within the French Alps is crescent shaped. It follows the last glacial maximum delimited by the French pre-Alps range (from the Bauges mountain to the Tinée region) ; some scattered populations persist along the dry continental valleys of Oisans and High-Durance. Our work is to draw up a syntaxonomic synthesis and a cartography of French alpine populations. Thuriferous juniper of the supramediterranean range belongs to the class of White oak (Quercus pubescens Willd.) and associated shrubs vegetation (Querco roboris-Fagetea sylvaticae : Quercion pubescenti-sessiliflorae ; and Crataego monogynae-Prunetea spinosae : Berberidion vulgaris). In mesomediterranean range it belongs closely to the Evergreen Oak (Quercus ilex L.) class (Quercetea ilicis : Quercion ilicis), but in dry valleys of the mountain range it belongs to the class of Pino sylvestris-Juniperetea sabinae : Juniperion thuriferae described from Spain and indicated in the French phytosociological nomenclature (Bardat et al. 2004).Le Genévrier thurifère (Juniperus thurifera L.) des montagnes de l’ouest de la Méditerranée a fait l’objet de plusieurs études phytosociologiques sur l’ensemble des Alpes françaises. Sa répartition dessine un croissant continu allant du sud du massif des Bauges à la Tinée épousant l’ancien front glaciaire, quelques stations colonisent les vallées internes de l’Oisans et la Haute Durance. Une analyse de 213 relevés phytosociologiques stratifiés réalisés sur l’ensemble de son aire alpine française, couplée à une analyse des conditions climatiques nous permet de proposer une cartographie et une synthèse syntaxonomique de ses populations. À l’étage de végétation supraméditerranéen inférieur, le Genévrier thurifère ne fait qu’effleurer la série du Chêne vert (Quercus ilex L.) de la classe du Quercetea ilicis et de l’alliance du Quercion ilicis, alors qu’à l’étage supraméditerranéen et méditerranéo-montagnard il domine dans l’aire du Chêne pubescent (Quercus pubescensWilld.) avec ou sans le Buis (Buxus sempervirens L.) qui correspond à la classe du Querco roboris-Fagetea sylvaticae et de l’alliance du Quercion pubescenti-sessiliflorae. Les formations primaires arbustives associées de la classe du Crataego monogynae-Prunetea spinosae et de l’alliance du Berberidion vulgaris se retrouvent sur l’ensemble de sa répartition alpine alors que dans l’étage montagnard des Alpes internes sèches, les pinèdes sylvestres à Genévriers spp. appartiennent à la classe oro-méditerranéenne du Pino sylvestris-Juniperetea sabinae et de l’alliance du Juniperion thuriferae décrite d’Espagne et indiquée comme présente en France par le Prodrome des végétations de France (Bardat et al. 2004) et des cahiers d’habitats Natura 2000.Garraud Luc, Abdulhak Sylvain. Approche syntaxonomique et écologique des formations à Genévrier thurifère (Juniperus thurifera L.) dans les Alpes françaises. In: Ecologia mediterranea, tome 40 n°1, 2014. pp. 61-73

Effets d’une crue sur la banque de semences du sol des habitats riverains dans les Alpes du Sud, France

Soil seed banks play a pivotal role in maintaining the diversity of riverine plant communities. However, large floods with a thrust of materials can strongly alter seed bank. To quantify this effect, we studied the differences in floristic composition and species diversity of seed bank before and after floods of an alpine river at the edge of the Mediterranean region : the Durance. Due to construction works on a hydroelectric plant upslope in the Durance valley, the operator released significant amounts of water generating controlled floods. In order to measure the effect on the seed bank of the soil, we collected 30 soil samples from four sites including a control site without flooding. Samples were cultivated in a non-heated greenhouse while maintaining soil stratification. Germination was monitored during three consecutive years. Statistical analyses highlight the effect of the flood on the abundance and the specific composition of the soil seed bank. Analysis of variance showed a marked flood effect. Species richness decreased sharply after flooding and then increased back after one year. Dissimilarity in community composition before and after flood appeared with new species, typical of the different abiotic conditions of the Durance River watershed. This study underlines the potential of the seed bank of different depths of soil to restore vegetation after floods. Interestingly, our study also revealed the presence of seeds of a rare species, Centaurium favargeri, in the seed bank of the soil in two sites, where it was historically present but extinct nowadays. Comparing the established vegetation with the soil seed bank showed a great dissimilarity, with an important diversity of species in the soil seed bank that did not appear in the established vegetation pinpointing the role of environmental factors for germination and establishment.Les banques de semences du sol jouent un rôle primordial pour le maintien de la diversité des communautés des bords de cours d’eau. Or des crues importantes avec un charriage de matériaux peuvent les altérer. Pour quantifier cet effet, nous avons étudié les différences en termes de composition floristique et de diversité spécifique de la banque de semences avant et après crues d’une rivière à régime alpin en marge de la région méditerranéenne : la Durance. Dans le cadre de travaux sur une installation hydroélectrique, l’exploitant a réalisé des lâchers d’eau importants générant des crues contrôlées. Afin de mesurer l’effet sur la banque de semences du sol, nous avons prélevé 30 échantillons de sol sur quatre sites, dont un témoin. Les échantillons ont été mis en culture en conservant la stratification du sol et les germinations ont été suivies pendant les trois années consécutives aux prélèvements. L’effet de la crue sur la richesse et la composition spécifique du stock semencier est marqué. La richesse spécifique diminue après crue puis augmente au bout d’une année. On constate une dissimilarité du cortège d’espèces avant et après crue. Cette étude montre le potentiel de restauration de la banque de semences dans différentes profondeurs du sol. L’échantillonnage confirme la présence d’une espèce rare, Centaurium favargeri, dans la banque de semences du sol. Cette espèce est historiquement présente dans deux des quatre sites étudiés. Les différents épisodes de crue sur la Durance peuvent expliquer le caractère d’espèce à éclipse (espèce qui disparaît puis réapparaît quand les conditions bioclimatiques deviennent favorables). L’étude comparative de la végétation observée et de la végétation potentielle montre une grande dissimilarité : le potentiel semencier dormant est très important et son expression dépend des facteurs environnementaux. Il contient tous les cortèges floristiques possibles sous forme de graines en un même lieu alors qu’une part infime des espèces s’observe sur le terrain.Huc Stéphanie, Saatkamp Arne, Jacob Frédérick, Abdulhak Sylvain. Effets d’une crue sur la banque de semences du sol des habitats riverains dans les Alpes du Sud, France. In: Ecologia mediterranea, tome 45 n°1, 2019. pp. 45-59

L'évaluation géoécologique de l'intérêt patrimonial des sols polygonaux hérités en montagne alpine. L'exemple du Col du Noyer (Massif du Dévoluy, Hautes Alpes, France)

International audienceAt an altitude of 1664 m, the Col du Noyer in the French Dévoluy Mountains, which is accessible in summer by road, is one of the most popular Alpine passes. It was located in an unglaciated area during the last Quaternary ice age and suffered the effects of the severe frost. Polygonal grounds formations have recently been discovered. Our study presents the results of the identification and characterisation of these formations as well as the floristic assemblages that currently occupy them. The analyses, carried out by a multidisciplinary team, consist of photo-interpretation, geomorphological, sedimentological and pedoanthracological studies. They confirm the presence of these inherited polygonal grounds. Floristic surveys reveal that these inherited periglacial formations constitute original habitats, favouring a strong local heterogeneity. The whole constitutes a natural complex requiring protection. Enhancing the heritage value of this site would constitute a means of protecting this complex, which is a rare geomorphological landscape in the Alps: educational both in terms of its understanding and its paleoenvironmental interpretation.À 1664 m d’altitude, le col du Noyer, dans le massif français du Dévoluy, accessible en été par une route, fait partie des cols alpins très fréquentés. Il était disposé en secteur non englacé lors de la dernière glaciation quaternaire et il a subi les effets de l’action du gel intense. Des formes de sols polygonaux ont été récemment découvertes. Notre étude présente les résultats d’identification et de caractérisation de ces formes ainsi que des cortèges floristiques qui les occupent actuellement. Les analyses, menées par une équipe pluridisciplinaire, consistent en travaux de repérage par photointerprétation, en études géomorphologiques, sédimentologiques et pédoanthracologiques. Elles confirment la présence de ces sols polygonaux hérités. Des relevés floristiques révèlent que ces formes périglaciaires héritées constituent des habitats originaux, favorisant une forte hétérogénéité locale. L’ensemble constitue un complexe naturel nécessitant une mise en protection. La valorisation patrimoniale de ce site constituerait un moyen de protéger ce complexe constitué d’un paysage géomorphologique rare dans les Alpes, pédagogique sur le plan de sa lisibilité et de son interprétation paléoenvironnementale

The Geoecological Evaluation of the Heritage Interest of Polygonal Soils Inherited in Alpine Mountains. The Example of the Col du Noyer (Massif du Dévoluy, Hautes Alpes, France)

International audienceAt an altitude of 1664 m, the Col du Noyer in the French Dévoluy Mountains, which is accessible in summer by road, is one of the most popular Alpine passes. It was located in an unglaciated area during the last Quaternary ice age and suffered the effects of the severe frost. Polygonal grounds formations have recently been discovered. Our study presents the results of the identification and characterisation of these formations as well as the floristic assemblages that currently occupy them. The analyses, carried out by a multidisciplinary team, consist of photo-interpretation, geomorphological, sedimentological and pedoanthracological studies. They confirm the presence of these inherited polygonal grounds. Floristic surveys reveal that these inherited periglacial formations constitute original habitats, favouring a strong local heterogeneity. The whole constitutes a natural complex requiring protection. Enhancing the heritage value of this site would constitute a means of protecting this complex, which is a rare geomorphological landscape in the Alps: educational both in terms of its understanding and its paleoenvironmental interpretation

Combinaisons nouvelles requises dans la seconde édition de Flora Gallica

International audience73 combinaisons et noms nouveaux sont proposés en vue de changements taxonomiques dans la seconde édition de Flora Gallic

Anticipating the spatio-temporal response of plant diversity and vegetation structure to climate and land use change in a protected area

Vegetation is a key driver of ecosystem functioning (e.g. productivity and stability) and of the maintenance of biodiversity (e.g. creating habitats for other species groups). While vegetation sensitivity to climate change has been widely investigated, its spatio‐temporally response to the dual effects of land management and climate change has been ignored at landscape scale. Here we use a dynamic vegetation model called FATE‐HD, which describes the dominant vegetation dynamics and associated functional diversity, in order to anticipate vegetation response to climate and land‐use changes in both short and long‐term perspectives. Using three contrasted management scenarios for the Ecrins National Park (French Alps) developed in collaboration with the park managers, and one regional climate change scenario, we tracked the dynamics of vegetation structure (forest expansion) and functional diversity over 100 yr of climate change and a further 400 additional years of stabilization. As expected, we observed a slow upward shift in forest cover distribution, which appears to be severely impacted by pasture management (i.e. maintenance or abandonment). The time lag before observing changes in vegetation cover was the result of demographic and seed dispersal processes. However, plant diversity response to environmental changes was rapid. After land abandonment, local diversity increased and spatial turnover was reduced, whereas local diversity decreased following land use intensification. Interestingly, in the long term, as both climate and management scenarios interacted, the regional diversity declined. Our innovative spatio‐temporally explicit framework demonstrates that the vegetation may have contrasting responses to changes in the short and the long term. Moreover, climate and land‐abandonment interact extensively leading to a decrease in both regional diversity and turnover in the long term. Based on our simulations we therefore suggest a continuing moderate intensity pasturing to maintain high levels of plant diversity in this system.ISSN:0906-7590ISSN:1600-058

Post-glacial determinants of regional species pools in alpine grasslands

Aim Alpine habitats support unique biodiversity confined to high-elevation areas in the current interglacial. Plant diversity in these habitats may respond to area, environment, connectivity and isolation, yet these factors have been rarely evaluated in concert. Here we investigate major determinants of regional species pools in alpine grasslands, and the responses of their constituent species groups. Location European mountains below 50 degrees N. Time period Between 1928 and 2019. Major taxa studied Vascular plants. Methods We compiled species pools from alpine grasslands in 23 regions, including 794 alpine species and 2,094 non-alpines. We used species-area relationships to test the influence of the extent of alpine areas on regional richness, and mixed-effects models to compare the effects of 12 spatial and environmental predictors. Variation in species composition was addressed by generalized dissimilarity models and by a coefficient of dispersal direction to assess historical links among regions. Results Pool sizes were partially explained by current alpine areas, but the other predictors largely contributed to regional differences. The number of alpine species was influenced by area, calcareous bedrock, topographic heterogeneity and regional isolation, while non-alpines responded better to connectivity and climate. Regional dissimilarity of alpine species was explained by isolation and precipitation, but non-alpines only responded to isolation. Past dispersal routes were correlated with latitude, with alpine species showing stronger connections among regions. Main conclusions Besides area effects, edaphic, topographic and spatio-temporal determinants are important to understand the organization of regional species pools in alpine habitats. The number of alpine species is especially linked to refugia and isolation, but their composition is explained by past dispersal and post-glacial environmental filtering, while non-alpines are generally influenced by regional floras. New research on the dynamics of alpine biodiversity should contextualize the determinants of regional species pools and the responses of species with different ecological profiles.Gobierno del Principado de AsturiasAgencia Nacional de Investigación e InnovaciónFundación para el Fomento en Asturias de la Investigación Científica Aplicada y la TecnologíaPrograma Clarín COFUNDDepto. de Farmacología, Farmacognosia y BotánicaFac. de FarmaciaTRUEpu