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International audience; Aims Assigning vegetation plots to vegetation units is a key step in biodiversity management projects. Nevertheless, the process of plot assignment to types is usually non-standardized, and assignment consistency remains poorly explored. To date, the efficiency of automatic classification programs has been assessed by comparing them with a unique expert judgment. Therefore, we investigated the consistency of five phytosociology expert judgments, and the consistency of these judgements with those of automatic classification programs. Location Mainland France. Methods We used 273 vegetation plots distributed across France and covering the diversity of the temperate and mountainous forest ecosystems of Western Europe. We asked a representative panel of five French organizations with recognized expertise in phytosociology to assign each plot to vegetation units. We provided a phytosociological classification including 228 associations, 43 alliances and eight classes. The assignments were compared among experts using an agreement ratio. We then compared the assignments suggested by three automatic classification programs with the expert judgments. Results We observed small differences among the agreement ratios of the expert organizations; a given expert organization agreed with another one on association assignment one time in four on average, and one time in two on alliance assignment. The agreement ratios of the automatic classification programs were globally lower, but close to expert judgments. Conclusions The results support the current trend toward unifying the existing classifications and specifying the assignment rules by creating guiding tools, which will decrease inter-observer variation. As compared to a pool of phytosociology experts, programs perform similarly to individual experts in vegetation unit assignment, especially at the alliance level. Although programs still need to be improved, these results pave the way for the creation of habitat time series crucial for the monitoring and conservation of biodiversity.

National audience

International audience; Natura 2000 is a European network of sites dedicated to the conservation of vulnerable habitats. The definitions of Natura 2000 habitats are mainly based on plant communities. We investigated if the increase of the dominance of warm-adapted species observed in plant communities, described as thermophilization, had already led to measurable changes in Natura 2000 forest habitats. We created 5701 pairs of neighboring forest plots by gathering plots surveyed before 1987 and after 1997 to reflect historical and recent climatic conditions. A Natura 2000 habitat type was assigned to each vegetation plot using an automatic classification program. We calculated a temperature index that synthesized the temperature range of each habitat, and compared the habitat temperature indexes of the recent and historical plots of each pair. We highlighted a significant overall shift of 4.8% ± 1.78 (CI 95%) of the pairs toward warmer habitats over the studied period. While the shift was not significant in lowlands, 11.1% ± 3.0 (CI 95%) of the pairs evolved toward warmer habitats in highlands. The excess of pairs with a warmer habitat in the recent period was interpreted as thermophilization of Natura 2000 forest habitats. Therefore, global warming has been strong enough to induce actual changes at the coarse-grained habitat resolution specifically targeted by public policies. The absence of significant results in lowlands suggests the existence of unrealized potential habitat changes, which can be considered as a climatic debt. These results call for differential prioritization levels and implementations of public policies for nature conservation in lowlands and highlands.

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. The previous versions of the expert system and related reports were produced within a contract from the European Environment Agency to Wageningen Environmental Research and Masaryk University. The opinions expressed are those of the contractor and do not represent the Agency's official position. EVA data management and preparation of this paper were supported by the Czech Science Foundation (project no. 19-28491X to MC, LT, IK, TP, CM, JDa, MH, PN, DZ, GB, AJ, AKu, ZL and DV). IB and JAC were supported by the Basque Government (project no. T936-16). TB, ET, and LK were supported by the Ministry of Science and Higher Education of the Russian Federation (TB and ET project no. AAAA-A18-118052590019-7; LK project no. AAAA-A19-119012490096-2).

Habitat conservation status : proposals of definitions and concepts for its assessment at a Natura 2000 site level. Assessing the conservation status of habitats is now a key part in the management plan of protected areas. The transposal of the Habitats-Fauna-Flora directive (92/43/CEE) (Habitats directive) in French law provides a regulatory frame for assessing the conservation status of habitat at a Natura 2000 site level. French Museum of Natural History has been asked to develop methods for Natura 2000 managers in order to standardize evaluations. Focusing on the concept of habitat and its evaluation, we propose definitions in order to fill some identified gaps and precise the concept of conservation status assessment. The need for habitat classification system is mentioned, as well as the advantages and the limits of this tool. Considering the habitat as a complex system under the general systems theories, its conservation status means the status of its components, but also of their interactions among them and with the environment. Assessing the conservation status implies the assessment of the structure, composition and functions of a habitat, which are interdependent. With the need for evaluation comes the need of making choices, which implies to define the «optimal selected state» as a long-term aim, and the «chosen favourable status» as an operational target for managers. These choices are enlightened by scientific evidences in a socio-economic and cultural context bounded by the Habitats directive. We discuss the impact of the habitat’s dynamics and succession on the establishment of the different conservation status. Finally, some key methodological choices are discussed, especially the role of species in the assessment of habitat and the connections between evaluation and management., Depuis une vingtaine d’années, l’évaluation de l’état de conservation des habitats est devenue un élément important des plans de gestion d’espaces naturels. La transposition de la Directive Habitats-Faune-Flore (92/43/CEE) (DHFF) dans le code de l’environnement fournit un cadre réglementaire pour l’évaluer à l’échelle d’un site Natura 2000. Le Muséum national d’Histoire naturelle (MNHN) a été chargé de proposer des méthodes à l’intention des gestionnaires afin de standardiser les évaluations et produire un diagnostic utile à la gestion. En se centrant sur la notion d’habitat (terrestre et marin) et sur son évaluation, nous proposons dans cet article des définitions afin de combler certaines lacunes identifiées et de préciser le concept d’état de conservation. La nécessité de se situer dans le cadre d’une typologie est évoquée avec ses avantages et ses limites. En considérant l’habitat comme un système complexe selon les théories générales des systèmes, son état de conservation traduit l’état de ses composantes ainsi que de leurs interactions, entre elles et avec l’environnement. Évaluer l’état de conservation implique ainsi d’évaluer la structure, la composition et les fonctions d’un habitat, qui sont interdépendantes. La nécessité d’évaluer amène à faire des choix, il s’agit de définir «l’état optimal souhaité» comme objectif théorique à long terme, et «l’état favorable choisi» comme proposition de cible opérationnelle pour les gestionnaires. Ces choix de seuils doivent être éclairés par des éléments scientifiques, tout en s’insérant dans le contexte socio-économique et culturel pris en compte par la DHFF. Nous discutons également de l’influence de la dynamique des habitats sur la définition des états de conservation. Enfin, certains choix méthodologiques clés sont présentés, notamment la place des espèces dans l’évaluation des habitats et les liens possibles entre diagnostic et gestion., Maciejewski Lise,Lepareur Fanny,Viry Déborah,Bensettiti Farid,Puissauve Renaud,Touroult Julien. État de conservation des habitats : propositions de définitions et de concepts pour l’évaluation à l’échelle d’un site Natura 2000. In: Revue d'Écologie (La Terre et La Vie), tome 71, n°1, 2016. pp. 3-20.

International audience

International audience