Management and Risk analysis of an Invading plant Species (Ulex europaeus (L.)): how socio-ecological niche with population dynamics modelling under a wide range of climate can help – MARIS

The study of the ecological niche of the species is achieved via several approaches: 1) a correlative approach worldwide to link the presence of gorse to macroscopic factors (eg climate); 2) an in situ experimental approach transplant seedlings along an altitudinal gradient in a native territory and two territories invaded with a micro-meteorological monitoring; 3) an ex situ experiment to test the effect of temperature and drought on growth and survival of seedlings. A study of regrowth after cutting capacity is also made experimental garden gorse different regions. The long-distance seed dispersal by three vectors is studied by experimental and modeling approaches.
Sociological surveys to characterize finely uses and perceptions of the model species by players in several territories in the area of ??origin and invaded zone will be realized. These surveys are based on semi-structured interviews with various actors -public and privés- present in the studied territories.
A theoretical modeling will be performed on the remobilization of the concepts of «Species Distribution Models« mechanistic and those of local-scale models of type Cellular Automata for specifying the hybrid model. Integration into the model the results of socio-ecological data acquired will then be performed. The computer implementation of the model and sensitivity analysis will then be conducted. These analyzes will provide a basis for reflection for the development of the overall risk analysis.
Risk analysis begins with the realization of the system description and mapping of hazardous situations. It will be finalized by the development of scenarios and the development of a prototype of risk management action plan.

Bioclimatic niche species was defined. The temperature driest month is the most limiting factor. Bioclimatic nests have evolved in some regions. The ex situ experiments showed different responses to temperature between home areas and populations invaded. The ability of regrowth, depends on the degree of basal branching of individuals; differences between regions but not between the original and areas invaded. The study of the long-distance seed dispersal by sheep has demonstrated the role of this vector.
The study of social treatment of gorse shows that in areas of origin as those overgrown, there are public management devices gorse. The density of these devices is however very variable: extremely strong on the island of Reunion, where gorse is considered a major invasive species, and very low in the forests of Landes where gorse, although very present is monitored routinely in intensive cultivation. Ownership and effective implementation of these devices is also variable depending on the nature of the areas occupied by gorse and field workers responsible for the technical implementation of management actions.
A «pilot« implementation of population dynamics model at the local level was conducted to evaluate the feasibility of a general scale model of the island of Reunion in which local models are nested. Integrating the results of the long-distance dispersal is underway.
A literature review on the life cycle of the Gorse and the factors limiting or encouraging was realized. This knowledge has been incorporated in a Global Risk Analysis to develop a mapping of hazards, hazardous situations and risks. This work allowed to synthesize the methods of current struggles and the most effective

The climatic niche at the seedling stage will be completed with the results to be obtained in transplant experiments. Dispersal vehicles will also be studied.
Sociological surveys to characterize finely uses and perceptions of the model species by actors in several territories in the area of ??origin and invaded zone are completed.
The modeling task will focus on the end specification of the work of the hybrid model and the integration of the socio-ecological data in the model . The computer implementation of the model and sensitivity analyzes will be conducted.
The overall risk analysis will be finalized by the development of scenarios and the development of a prototype of risk management action plan.
The analysis of risk perceptions will be performed based on the results of sociological analysis performed.

Atlan A., Udo, N. Hornoy, B. & Darrot, C. 2015. Evolution of the uses of gorse in native and invaded regions: what are the impacts on its dynamics and management? La Terre et la Vie-Journal d'Ecologie: 70(sup 12).

Gonzalez M., Connen de Kerillis T., Christina M., Brédoire F., Gire C., Niollet S., Callède L., Dartiail F., Delmotte S. & Bakker M.R. Long distance dispersal of an invasive species by a transhumance sheep herd. August 2016, ECOSUMMIT, Montpellier. (Communication orale)

Udo N., Tarayre T. and Atlan A. 2016. Germination patterns of Ulex europaeus: Comparison between a native and an introduced region. Journal of Plant Ecology.

Van Tilbeurgh V., Udo N., et al. Comment gérer l’ajonc d’Europe sur l’île de La Réunion : l’enrôlement des acteurs dans les dispositifs de gestion. Soumission le 10 juillet à l’atelier de recherche « Aborder les problèmes d’environnement comme des situations de gestion ? ». Décembre 2016, Strasbourg

Udo N., Darrot C., Atlan A. Espèce invasive : un statut public inscrit dans la succession des lectures du monde. Le cas de l’ajonc d’Europe sur l’île de La Réunion. Soumission le 22/05/16 au colloque GdR Invasions Biologiques, Octobre 2016, Marseille

Van Tilbeurgh V., Udo N, Boudes P., Darrot C., Atlan A. Espèces invasives : entre dispositifs publics de gestion environnementale et gestes techniques. Soumission le 30/05/2016 au colloque GdR Invasions Biologiques, Octobre 2016, Marseille

Darrot, C., Boudes, P., Nouvelles perspectives sociologiques sur les biens publics environnemenaux : quelle application aux invasions biologiques . Soumission le 30/5/2016 au GDR « Invasion biologiques », octobre 2016, Marseille

The aim of the MARIS project is to provide a new framework for the sustainable management of risks of biological invasion. Biological invasions and their effects on ecosystem biodiversity and functioning are one of the main causes of global change. The management of invasive species depends on both the knowledge of the ecological characteristics of the target species and of the sociological contexts that control its installation, persistence, the perception and potential spread through dispersal. The MARIS project will use Ulex europaeus (L.), a ‘world invasive species’ outside its native European range, as model species. We will study it in a wide range of ecological and social conditions both in native (French Brittany and Landes of Gascogne) and invaded areas (French Reunion Island, New Zealand and the Spanish Canary Islands). The ecological part of the project will focus on three specific stagers for the control of the population dynamics: recruitment, persistence and dispersal. The climate and soil conditions which favour successful recruitment of seedlings and persistence (seed bank and resprouting) of the species will be assessed in meta-analysis, experiments (using phytotron and common garden) and field surveys. This part of the project will also address the dispersal distance enabled by different vectors (vehicles, sheep and water). The sociological part will focus on analyses of human perceptions and uses of Ulex europaeus. A mechanistic species distribution model will be coupled with existing models to simulate population dynamics at the stand scale to account for local processes at regional scale. To achieve the right balance, the uncertainty of model outputs and the complexity of the local scale model will be weighed against the gain in accuracy provided by the final hybrid model. Field surveys and experimental results as well as information collected on social uses and perception of the species will be included in the model. The global risk analysis framework will be used to combine all the results of the project. Results of the ecological experiments and of the field studies and expert knowledge will be used to define biological thresholds. Sociological field surveys will make it possible to account for the perceptions of the different actors (managers, users) in creating scales for the assessment of risk as well as for drawing up risk management plans. Economic data on the cost of the Ulex europaeus eradication programme in the literature will be used to propose a pragmatic sustainable management to control its expansion.