How environmental managers perceive and approach the issue of invasive species: the case of Japanese knotweed s.l. (Rhône River, France)

We would like to thank Springer for publishing our article. The final publication is available at http://link.springer.com/article/10.1007%2Fs10530-015-0969-1International audienceStudying the perceptions of stakeholders or interested parties is a good way to better understand behaviours and decisions. This is especially true for the management of invasive species such as Japanese knotweed s.l. This plant has spread widely in the Rhône basin, where significant financial resources have been devoted to its management. However, no control technique is recognized as being particularly effective. Many uncertainties remain and many documents have been produced by environmental managers to disseminate current knowledge about the plant and its management. This article aims at characterizing the perceptions that environmental managers have of Japanese knotweed s.l. A discourse analysis was conducted on the printed documentation produced about Japanese knotweed s.l. by environmental managers working along the Rhône River (France). The corpus was both qualitatively and quantitatively analysed. The results indicated a diversity of perceptions depending on the type of environmental managers involved, as well as the geographicalareas and scales on which they acted. Whereas some focused on general knowledge relating to the origins and strategies of colonization, others emphasized the diversity and efficacy of the prospective eradication techniques. There is a real interest in implementing targeted actions to meet local issues. To do so, however, these issues must be better defined. This is a challenging task, as it must involve all types of stakeholders

Scientific basis for the management of Japanese Knotweed s. l. : performances of the hybrid complex Fallopia in response to environmental constraints

La croissance d'une plante est un processus dynamique qui répond aux différentes caractéristiques de l'environnement. La baisse de production de biomasse induite par les différents stress, les perturbations ou la compétition détermine la tolérance des plantes à ces contraintes. Dans le cas d'une plante invasive, caractériser cette tolérance est crucial pour déterminer les habitats sensibles et rechercher des moyens de prévention ou de lutte. Les taxa du genre Fallopia sont ici étudiés dans le cadre de l'invasion du département de la Loire. Leurs réponses au stress nutritif, salin, et à une perturbation sont associées aux conditions environnementales favorisant ou limitant l'invasion. Les résultats obtenus apportent des éléments de réflexion sur les mécanismes à l'origine de l'invasion par les renouées et sur l'efficience de différentes méthodes de lutte et de prévention de l'invasionPlant growth is a dynamic process that responds to environmental characteristics. The decrease of the plant biomass production induced by various stresses, disturbance, or competition, determines the tolerance to these constraints. In the case of invasive plants, assessing this tolerance is crucial to determine invasibility and to find prevention or control methods. The taxa of the genus Fallopia are here considered in the context of the invasion of the Loire department. Their responses to nutrient stress, salt stress, and disturbance are associated with environmental conditions favouring or limiting the invasion. The results give some evidences about mechanisms implied in the success of Fallopia spp and about the effectiveness of different prevention or control method

Gestion des renouées : peut-on ou doit-on changer de perspectives ?

International audienceLes savoirs scientifiques, les représentations et les pratiques associées à la gestion des milieux naturels évoluent, il est donc intéressant d'examiner si les réponses données à certaines questions sont toujours les mêmes, si elles convergent entre différents individus ou différentes disciplines, ou si ces questions n'ont plus lieu d'être et que d'autres émergent. Ici, c'est l'opinion d'une écologue et celle d'une géographe qui s'expriment, à la seule fin de proposer des questionnements et des pistes de réflexion parmi ceux qui animent aujourd'hui les échanges autour de la gestion des renouées

Gestion des renouées : peut-on ou doit-on changer de perspectives ?

International audienceLes savoirs scientifiques, les représentations et les pratiques associées à la gestion des milieux naturels évoluent, il est donc intéressant d'examiner si les réponses données à certaines questions sont toujours les mêmes, si elles convergent entre différents individus ou différentes disciplines, ou si ces questions n'ont plus lieu d'être et que d'autres émergent. Ici, c'est l'opinion d'une écologue et celle d'une géographe qui s'expriment, à la seule fin de proposer des questionnements et des pistes de réflexion parmi ceux qui animent aujourd'hui les échanges autour de la gestion des renouées

Bases scientifiques pour un contrôle des renouées asiatiques (performances du complexe hybride Fallopia en réponse aux contraintes environnementales)

La croissance d'une plante est un processus dynamique qui répond aux différentes caractéristiques de l'environnement. La baisse de production de biomasse induite par les différents stress, les perturbations ou la compétition détermine la tolérance des plantes à ces contraintes. Dans le cas d'une plante invasive, caractériser cette tolérance est crucial pour déterminer les habitats sensibles et rechercher des moyens de prévention ou de lutte. Les taxa du genre Fallopia sont ici étudiés dans le cadre de l'invasion du département de la Loire. Leurs réponses au stress nutritif, salin, et à une perturbation sont associées aux conditions environnementales favorisant ou limitant l'invasion. Les résultats obtenus apportent des éléments de réflexion sur les mécanismes à l'origine de l'invasion par les renouées et sur l'efficience de différentes méthodes de lutte et de prévention de l'invasionPlant growth is a dynamic process that responds to environmental characteristics. The decrease of the plant biomass production induced by various stresses, disturbance, or competition, determines the tolerance to these constraints. In the case of invasive plants, assessing this tolerance is crucial to determine invasibility and to find prevention or control methods. The taxa of the genus Fallopia are here considered in the context of the invasion of the Loire department. Their responses to nutrient stress, salt stress, and disturbance are associated with environmental conditions favouring or limiting the invasion. The results give some evidences about mechanisms implied in the success of Fallopia spp and about the effectiveness of different prevention or control methodsPARIS-Museum Hist.Naturelle (751052304) / SudocSudocFranceF

Gestion des renouées : peut-on ou doit-on changer de perspectives ?

International audienceLes savoirs scientifiques, les représentations et les pratiques associées à la gestion des milieux naturels évoluent, il est donc intéressant d'examiner si les réponses données à certaines questions sont toujours les mêmes, si elles convergent entre différents individus ou différentes disciplines, ou si ces questions n'ont plus lieu d'être et que d'autres émergent. Ici, c'est l'opinion d'une écologue et celle d'une géographe qui s'expriment, à la seule fin de proposer des questionnements et des pistes de réflexion parmi ceux qui animent aujourd'hui les échanges autour de la gestion des renouées

Using Constrained Optimization to Understand, Predict and Control Knotweed Spread

International audienceIn this paper, we describe an open computational sustainability problem that aims at understanding, predicting and controlling the spatial spread of knotweeds which exhibit exceptionalinvasive capacities

Invasion by Fallopia spp. in a French upland region is related to anthropogenic disturbances

Within Europe, mountain ecosystems are generally less invaded by exotic plant species than are lowland areas. This pattern is commonly attributed to climatic harshness, which limits invasive species presence, and higher propagule pressure and rates of disturbance in lowlands, which favours dissemination. However, the extent to which anthropogenic and natural disturbances contribute to invasive species presence in mountain and lowland environments remains unclear. We conducted field observations in a lowland and an upland region in France and measured environmental variables, estimated the natural and anthropogenic disturbance of plots invaded by Fallopia spp. and compared them to non-invaded plots. Based on generalised linear mixed models, the predictors of Fallopia spp. presence in the upland area only included anthropogenic elements such as the presence of a road or trail and frequentation by humans, whereas both anthropogenic parameters and natural components (light penetration, slope, presence of a road and of a watercourse) were retained as predictors for the lowland region. We calculated the odds of Fallopia spp. presence for the increase of one unit of each predictor. We conclude that the spread of Fallopia spp. in upland areas was mainly linked to human activity whereas dissemination of the species occurred both through humans and in natural ways in lowland areas, and this may be due to a more recent colonisation in the mountains. We therefore advise stakeholders to undertake actions in mountain areas to specifically limit the dissemination of exotic species by humans and to monitor areas of high invasion risk by exotic species, such as areas neighbouring trails and roads highly frequented by humans

Écologie chimique : quelles applications pour la gestion des renouées ?

International audienceUne des pistes de recherche les plus récentes concernant la gestion des espèces végétalesinvasives porte sur les capacités des plantes à produire des composés chimiques inhibantla croissance ou le développement d’autres végétaux. Cet article décrit les enjeux,quelques recherches menées en France et les défis posés par cette démarche

The importance of biotic factors in predicting global change effects on decomposition of temperate forest leaf litter

International audienceIncreasing atmospheric CO(2) and temperature are predicted to alter litter decomposition via changes in litter chemistry and environmental conditions. The extent to which these predictions are influenced by biotic factors such as litter species composition or decomposer activity, and in particular how these different factors interact, is not well understood. In a 5-week laboratory experiment we compared the decomposition of leaf litter from four temperate tree species (Fagus sylvatica, Quercus petraea, Carpinus betulus and Tilia platyphyllos) in response to four interacting factors: elevated CO(2)-induced changes in litter quality, a 3 degrees C warmer environment during decomposition, changes in litter species composition, and presence/absence of a litter-feeding millipede (Glomeris marginata). Elevated CO(2) and temperature had much weaker effects on decomposition than litter species composition and the presence of Glomeris. Mass loss of elevated CO(2)-grown leaf litter was reduced in Fagus and increased in Fagus/Tilia mixtures, but was not affected in any other leaf litter treatment. Warming increased litter mass loss in Carpinus and Tilia, but not in the other two litter species and in none of the mixtures. The CO(2)- and temperature-related differences in decomposition disappeared completely when Glomeris was present. Overall, fauna activity stimulated litter mass loss, but to different degrees depending on litter species composition, with a particularly strong effect on Fagus/Tilia mixtures (+58%). Higher fauna-driven mass loss was not followed by higher C mineralization over the relatively short experimental period. Apart from a strong interaction between litter species composition and fauna, the tested factors had little or no interactive effects on decomposition. We conclude that if global change were to result in substantial shifts in plant community composition and macrofauna abundance in forest ecosystems, these interacting biotic factors could have greater impacts on decomposition and biogeochemical cycles than rising atmospheric CO(2) concentration and temperature