Bruno Colas

Roadside revegetation practices have evolved significantly in recent decades, spurred by the need for more reliable and cost-efficient operations and escalating concerns regarding biodiversity integration into large land-planning projects. While the use of rich and locally-sourced seed mixtures...

Many countries have legislation intended to limit or offset the impact of anthropogenic disturbance and development on threatened plants. Translocations are often integral to those mitigation policies. When translocation is used exclusively to mitigate development impacts, it is often termed a ‘mitigation translocation.’ However, both the terminology and processes vary regarding interpretation and application, resulting in inconsistent standards, often leading to poorly planned and implemented projects. These mitigation projects rarely achieve the intended ‘no net loss’ of protected species due to issues with timelines and procedures that result in the mortality of translocated individuals. Instead, such projects are often process driven, focused on meeting legislative requirements which enable the development to proceed, rather than meaningful attempts to minimise the ecological impact of developments and demonstrate conservation outcomes. Here, we propose to reframe mitigation translocations as conservation driven, ensuring best practice implementation and hence, a quantified no net loss for impacted species. These methods include redefining the term mitigation translocation to include conservation objectives and outlining issues associated with the mitigation translocation processes worldwide. We also nominate global standards of practice to which all proposals should adhere, to ensure each project follows a trajectory towards quantified success, with genuine impact mitigation. These proposed standards focus on building efficient translocation plans and improving governance to facilitate a transition from project centred to ecology-driven translocation. Employment of these standards is relevant to development proponents, government regulators, researchers, and translocation practitioners and will increase the likelihood of conservation gains within the mitigation translocation sector.

Si la littérature en écologie sur les translocations végétales conservatoires s’est largement développée ces dernières années, très peu d’études sur les conditions pratiques de leur mise en œuvre, dont les aspects économiques, ont été conduites. Pourtant, ces facteurs non strictement biologiques sont importants à considérer, car ils peuvent influencer la faisabilité et l’efficacité des opérations de translocation. À travers une série d’entretiens réalisés auprès des conservatoires botaniques nationaux (CBN), un des acteurs majeurs des translocations végétales, ainsi que quelques acteurs complémentaires, nous faisons le point sur les dimensions réglementaires, organisationnelles et économiques de la pratique des translocations végétales conservatoires en France. Nous avons notamment collecté les coûts économiques de l’implication de six CBN dans 34 opérations de translocations, associés à trois étapes qu’il nous semble intéressant de différencier dans une translocation : la préparation, la translocation proprement dite, et la phase post-translocation. Ce sont les deux phases en amont et en aval de la translocation proprement dite qui impliquent la part la plus importante des coûts. Nous avons également montré que la motivation initiale d’une opération de translocation, c’est-à-dire qu’elle ait lieu dans le cadre de la hiérarchie d’atténuation des projets d’aménagement (éviter, réduire, compenser, accompagner) ou en dehors de ce cadre, n’influe pas significativement sur son coût, ce qui suggère une implication équivalente des acteurs interrogés (au moins économique) dans les deux cas de figure identifiés. Limitée à l’implication des CBN dans cet article, l’analyse des coûts économiques des translocations végétales devrait maintenant être complétée pour les autres acteurs concernés. Le réseau détaillé des acteurs des translocations ainsi que la description des différentes étapes qu’ils sont amenés à rencontrer et que nous proposons dans cet article en constituent un point de départ indispensable.

Although the number of plant translocations has been rapidly increasing for two decades, no study is available to date that examines the directions and distances of plant displacements, which is essential (though not sufficient) information for considering translocations as a management tool to enable species to cope with the consequences of climate change. In this paper, we study the geographical and climatic directions and distances from source to host sites in 638 source‐and‐host site pairs of plant translocations that aimed to achieve viable populations in the last decades in the Western Palearctic (Europe and the Mediterranean). Translocation distances ranged from 0 to 661 km, but were generally short, most (82%) being Synthesis. This study is the first to compare, geographically and climatically, the source sites of biological material and the host sites in translocations of wild plant species to obtain viable populations. Past translocations in the Western Palearctic are in line with mitigating the consequences of global warming on plant species because the host sites were in slightly cooler conditions than the source sites. Despite this, climate considerations seem to have little been taken into account in plant translocation projects and will certainly have to be much more so in a future with rapid anthropogenic climate change.

Anthropogenic activities in urban ecosystems induce a myriad of environmental changes compared with adjacent rural areas. These environmental changes can be seen as series of abiotic and biotic selection filters affecting the distribution of plant species. What are the attributes of plant species that compose urban communities, compared with rural communities, as related to their ecological affinities (e.g., to temperature, humidity), and reproductive traits (e.g., entomophily, autogamy, floral morphology)? Using a floristic dataset from a citizen science project recording plant species growing spontaneously in the streets, we analyzed the distribution of species according to their ecological requirements and reproductive traits along an urbanization gradient in the Parisian region. We developed an original floral and pollinator typology composed of five floral and four pollinator morphotypes. The proportion of impervious areas, used as a proxy of urbanization, was measured at different spatial scales, to reveal at which spatial scales urbanization is selecting plant traits. We found significant differences in plant communities along the urbanization gradient. As expected with the warmer and drier conditions of urban areas, species with higher affinities to higher temperature, light and nutrient soil content, and lower atmospheric moisture were over‐represented in urban plant communities. Interestingly, all of the significant changes in plant abiotical affinities were the most pronounced at the largest scale of analysis (1,000 m buffer radius), probably because the specific urban conditions are more pronounced when they occur on a large surface. The proportion of autogamous, self‐compatible, and nonentomophilous species was significantly higher in urban plant communities, strongly suggesting a lower abundance or efficiency of the pollinating fauna in urban environments. Last, among insect‐pollinated species, those with relatively long and narrow tubular corollas were disadvantaged in urban areas, possibly resulting from a reduction in pollinator abundance particularly affecting specialized plant–pollinator interactions.

Urbanisation, associated with habitat fragmentation, affects pollinator communities and insect foraging behaviour. These biotic changes are likely to select for modified traits in insect-pollinated plants from urban populations compared to rural populations. To test this hypothesis, we conducted an experiment involving four plant species commonly found in both urban and rural landscapes of the Île-de-France region (France): Cymbalaria muralis, Geranium robertianum, Geum urbanum and Prunella vulgaris. The four species were grown in four urban and four rural experimental sites in 2015. For each species and each experimental site, plants were grown from seeds collected in five urban and five rural locations. During flowering, we observed flower production and insect–flower interactions during 14 weeks and tested for the effects of experimental site location and plant origin on flower production and on the number of floral visits. The study species had various flower morphology and hence were visited by different floral visitors. The effect of experimental sites and seed origin also varied among study species. We found that (1) insect visits on P. vulgaris were more frequent in rural than in urban sites; (2) for C. muralis, the slope relating the number of pollinator visits to the number of flowers per individual was steeper in urban versus rural sites, suggesting a greater benefit in allocating resources to flower production in urban conditions; (3) as a likely consequence, C. muralis tended to produce more flowers in plants from urban versus rural origin.

Despite recent efforts to develop the science of reintroduction biology, there is still no general and broadly accepted definition of reintroduction success. We investigate this issue based on the postulates (1) that successful reintroduction programs should produce viable populations and (2) that reliable assessments of ultimate success require that populations have reached their regulation phase. We assessed if the viability of these reintroduced populations could be evaluated using the same criteria as for remnant populations, such as the Internation Union for Conservation of Nature (IUCN) Red List criteria. Using modeling, we projected the viabilities of theoretical populations with various life history and environmental characteristics and we tested whether population sizes (criterion D of the IUCN) and other potential predictors are relevant proxies of the risk of extinction (criterion E of the IUCN) in the case of remnant populations with an unknown past history and in the case of reintroduced populations that have reached their carrying capacity. We found that, as for remnant populations, population size can be used as a relevant indicator (although subject to considerable uncertainty) of the viability of reintroduced populations. However, the results demonstrate the importance of the reintroduction failure filter, that is, the fact that the reintroduced populations that have successfully reached their carrying capacity are those with the highest and more stable growth rates, especially if populations have been reintroduced with a few individuals. As a consequence, the general relationship between the current size of a population and its projected viability will, most likely, differ considerably between remnant and reintroduced populations. Overall, our results demonstrate that there are no theoretical limitations on the application of some of the criteria widely used for remnant populations to define reintroduction success, although these criteria are very conservative for reintroduced populations and might be rescaled to account for the demographic filter that early extinction constitutes for these populations.