Extreme climate variability should be considered in forestry-assisted migration

International audienceRecently, Pedlar et al. (2012) stated that assisted migration in forestry (forestry AM) differs from species-rescue-assisted migration (species rescue AM) because the risks of invasiveness, hybridization with local species, and spread of diseases are minimized in managed forests. The rationale behind this assertion for forestry AM is that it involves the translocation of populations within the existing geographic range of the species, whereas species rescue AM involves the introduction of exotic species. However, while we agree that forestry AM is less risky than species rescue AM for the recipient ecosystem, forestry AM can not only fail but can also incur enormous financial costs. The failure of efforts that involved planting maritime pine (Pinus pinaster Aït) trees in Southwest France (Aquitaine) with seeds from more southerly populations from Portugal for production purposes is a textbook case. The climate variability in Aquitaine includes periods of intense frost that are sufficiently rare (every 10 to 20 years) to be overlooked when establishing tree populations. The frost of the winter of 1985, the most intense frost event since records began with temperatures dropping as low as -22 °C (Boisseaux, 1986), affecting about 350 km2 of tree plantations in the region (Doré & Varoquaux, 2006). The highest mortality related to frost was observed in populations harvested from Leiria in Portugal, for which nearby records show that the absolute minimum temperature was only -7.8 °C in the last 60 years. Climate averages over the last 30 years differ only slightly between Leiria and Aquitaine, which would erroneously suggest that samples from Portugal would have survived in the Aquitaine region. Newly emerging climates (Williams et al. 2007) and the uncertainty related to climate change extreme events (Easterling, 2000) will make the search for southern locations with climatic conditions similar to those of northern populations of trees extremely difficult. Policies of forest adaptation to climate change should account for extreme cold events in the target populations even if climate change will likely decrease the number of extreme cold events (Easterling, 2000), that remain in our opinion, the hidden element behind the maladaptation of southern populations to northern locations

Assortative mating and differential male mating success in an ash hybrid zone population

BACKGROUND: The structure and evolution of hybrid zones depend mainly on the relative importance of dispersal and local adaptation, and on the strength of assortative mating. Here, we study the influence of dispersal, temporal isolation, variability in phenotypic traits and parasite attacks on the male mating success of two parental species and hybrids by real-time pollen flow analysis. We focus on a hybrid zone population between the two closely related ash species Fraxinus excelsior L. (common ash) and F. angustifolia Vahl (narrow-leaved ash), which is composed of individuals of the two species and several hybrid types. This population is structured by flowering time: the F. excelsior individuals flower later than the F. angustifolia individuals, and the hybrid types flower in-between. Hybrids are scattered throughout the population, suggesting favorable conditions for their local adaptation. We estimate jointly the best-fitting dispersal kernel, the differences in male fecundity due to variation in phenotypic traits and level of parasite attack, and the strength of assortative mating due to differences in flowering phenology. In addition, we assess the effect of accounting for genotyping error on these estimations. RESULTS: We detected a very high pollen immigration rate and a fat-tailed dispersal kernel, counter-balanced by slight phenological assortative mating and short-distance pollen dispersal. Early intermediate flowering hybrids, which had the highest male mating success, showed optimal sex allocation and increased selfing rates. We detected asymmetry of gene flow, with early flowering trees participating more as pollen donors than late flowering trees. CONCLUSION: This study provides striking evidence that long-distance gene flow alone is not sufficient to counter-act the effects of assortative mating and selfing. Phenological assortative mating and short-distance dispersal can create temporal and spatial structuring that appears to maintain this hybrid population. The asymmetry of gene flow, with higher fertility and increased selfing, can potentially confer a selective advantage to early flowering hybrids in the zone. In the event of climate change, hybridization may provide a means for F. angustifolia to further extend its range at the expense of F. excelsior

Deciduous Trees and the Application of Universal DNA Barcodes: A Case Study on the Circumpolar Fraxinus

The utility of DNA barcoding for identifying representative specimens of the circumpolar tree genus Fraxinus (56 species) was investigated. We examined the genetic variability of several loci suggested in chloroplast DNA barcode protocols such as matK, rpoB, rpoC1 and trnH-psbA in a large worldwide sample of Fraxinus species. The chloroplast intergenic spacer rpl32-trnL was further assessed in search for a potentially variable and useful locus. The results of the study suggest that the proposed cpDNA loci, alone or in combination, cannot fully discriminate among species because of the generally low rates of substitution in the chloroplast genome of Fraxinus. The intergenic spacer trnH-psbA was the best performing locus, but genetic distance-based discrimination was moderately successful and only resulted in the separation of the samples at the subgenus level. Use of the BLAST approach was better than the neighbor-joining tree reconstruction method with pairwise Kimura's two-parameter rates of substitution, but allowed for the correct identification of only less than half of the species sampled. Such rates are substantially lower than the success rate required for a standardised barcoding approach. Consequently, the current cpDNA barcodes are inadequate to fully discriminate Fraxinus species. Given that a low rate of substitution is common among the plastid genomes of trees, the use of the plant cpDNA “universal” barcode may not be suitable for the safe identification of tree species below a generic or sectional level. Supplementary barcoding loci of the nuclear genome and alternative solutions are proposed and discussed

Aménagement des éco quartiers et de la biodiversité

Face aux changements globaux, au déclin de la biodiversité et à l'augmentation de la population urbaine, la demande des professionnels de la construction pour intégrer la biodiversité dans leurs pratiques est de plus en plus forte. Ma thèse a eu pour objectif de (1) faire un état des lieux de la prise en compte de la biodiversité dans les aménagements urbains et (2) développer de nouveaux outils afin d'aider les aménageurs à améliorer leurs pratiques. Dans une première partie consacrée au bilan biodiversité, (1) nous avons émis des doutes quant à la pertinence de l'utilisation des toitures végétalisées, telles qu'elles sont conçues actuellement, en tant qu'éléments intégrés à un réseau écologique ; (2) l'étude des mesures environnementales mises en place dans 54 éco quartiers européens (principalement en France) a montré que les concepteurs se préoccupaient principalement des bénéfices environnementaux en termes d'énergie, de transport, de déchets et d'eau, et plus rarement de biodiversité ; (3) l'ACV (analyse du cycle de vie), un outil fréquemment utilisés par les aménageurs pour calculer les impacts environnementaux d'un produit (toit vert, bâtiment, quartier) intègre mal la biodiversité dans ses calculs, et son utilisation pour comparer différents éléments verts pourrait uniformiser les pratiques et ainsi conduire à une homogénéisation de la biodiversité et à l'altération du fonctionnement de l'écosystème. Pour aider les aménageurs à mieux considérer la biodiversité dans leurs pratiques, nous avons participé à l'amélioration de l'outil Profil-Biodiversité créé par Frank Derrien et développé notre propre outil (BioDi(v)Strict) basé sur la diversité des habitats et la présence de quatre groupes d'espèces bio-indicatrices afin de traduire au mieux la dynamique écologique d'un site. Ces deux outils ont été appliqués sur un site pilote : la Cité Descartes (à Noisy-le- Grand et Champs-sur-Marne). Dans le but de faire émerger une prise de conscience des différents acteurs locaux sur la nécessité de préserver la biodiversité et les services écosystémiques associés, nous avons développé un outil de concertation pour l'aménagement du territoire (NewDistrict), basé sur une modélisation d'un système multi-agents (SMA) et d'un jeu de rôles autour de l'étalement urbain et ses conséquences environnementales.In a context of global changes, decline of biodiversity and increase of the urban population, the request of urban developers to integrate biodiversity into their practices is increasingly strong. My PhD thesis aimed to (1) make a review of the consideration of biodiversity in urban development, and (2) develop new tools to help developers to improve their practices. In the first part focused on biodiversity review, (1) we have expressed some doubts about the relevance of the use of current green roofs as possible integrated element of an ecological network; (2) The study of environmental measures implemented in 54 European eco-districts (mainly in France) showed that designers appeared to focus primarily on environmental benefits in terms of energy, transport, waste, water, and more rarely on biodiversity conservation; (3) LCA (life cycle analysis), a tool commonly used by developers to calculate the environmental impacts of a product (a green roof , a building or a district) integrates badly biodiversity in its calculations, and its use to compare different green elements could standardize practices which lead to an homogenization of biodiversity associated with the deterioration of ecosystem functioning. To help developers to better consider biodiversity in their practices, we have firstly contributed to the improvement of the tool Profil-Biodiversité created by Frank Derrien, and secondly, we have developed our own tool (BioDi(v)Strict) based on the diversity of habitats and the presence of four groups of bioindicator species to better reflect the ecological dynamic of a site. Both tools have been applied on a pilot site: the Cité Descartes (in Noisy-le- Grand and Champs-sur Marne). Finally, in order to let emerging a collective biodiversity awareness for the different local actors, we have developed a tool (NewDistrict) based on a multi agent system (MAS) model combined with a role-playing game constructed in a context of urban sprawl.PARIS-AgroParisTech Centre Paris (751052302) / SudocSudocFranceF

Integrating Ecology into Land Planning and Development: Between Disillusionment and Hope, Questioning the Relevance and Implementation of the Mitigation Hierarchy

Scientific research on the mitigation hierarchy has steadily increased over the past few years at the international level. While some seek to improve the application of this public action instrument, others point out its shortcomings and risks. This opinion paper—which focuses on the French context—does not provide an exhaustive overview of existing research but instead targets specific issues considered to be a “priority”. We mainly investigate the relevance and implementation of the mitigation hierarchy, especially from an ecological point of view. Part of this paper thus questions the very principle of biodiversity offsetting (BO)—the last resort of the mitigation hierarchy that brings together numerous controversies—and the adequacy of the mitigation hierarchy with the objective of no net loss (NNL) of biodiversity. The general idea underlying this paper is to show how the mitigation hierarchy has been built and based on what values (mainly economic and legal, which leads us to conclude about the lack of ecology in the policy itself). In doing so, we provide a few perspectives as to what should be done to (better) integrate ecology into land use planning and development

Determining the location of protected areas in France: Does “scientific interest” matter?

International audienceProtected areas are one of the main policy instruments used by policymakers to tackle the current biodiversity crisis. While numerous studies highlight the inability of such areas to protect the full range of biodiversity, the procedures by which protected areas are created nevertheless remain understudied. A better understanding of the related policy processes is necessary to overcome the “research-implementation gap” and, hopefully, decrease biodiversity loss. This article seeks to fill this blind spot in conservation by conducting interdisciplinary research at the crossroads of ecology and policy studies. We applied mixed methods (i.e. quantitative and qualitative analysis) to the historical archives of national nature reserve (NNR) projects to identify the weight of scientific statements and other factors involved in the decision-making process. Our results reveal a two-step process. Scientific opinion about NNR projects operates as the primary filter. Then, another triage is made under social, political and economic interests. Such situation challenges the idea that more evidence would lead to better conservation. In our opinion, the key issue is to determine the ways to improve the success of NNR projects rather than improving data and algorithms. In this sense, we call for the implementation of an “informed opportunism” approach and suggest some leads to favor its practical application. This research highlights the importance of interdisciplinary research to reach conservation goals