Manon Hess [1], doctorante à la Tour du Valat, vient de publier dans la revue Applied Vegetation Science., [2] un nouvel article dans le cadre de sa thèse co-encadrée par la Tour du Valat et l’Institut Méditerranéen de Biodiversité et d’Écologie marine et continentale (IMBE) sur le renforcement des capacités de résistance des communautés végétales restaurées à l’invasion, dans le cadre des activités de la Tour du Valat sur la restauration écologique (en savoir plus [3]).
Cet article reprend les résultats d’une expérimentation en serre réalisée à la Tour du Valat entre 2017 et 2018. Cette expérimentation s’intéresse à l’influence de l’interaction entre l’âge d’une communauté végétale, sa densité de semis et sa composition sur sa résistance à l’invasion. Grâce à des modèles hiérarchiques multi-états habituellement utilisés pour les études de Capture-Marquage-Recapture, il a été mis en évidence que la germination et la survie des trois plantes invasives testées sont négativement corrélées à une forte production de biomasse aérienne de la communauté receveuse.
Restaurer une communauté native productive (ici, en incluant des espèces productives dans le semis) et lui donner le maximum d’avance sur l’invasive (par exemple, en revégétalisant le plus rapidement possible après perturbation) apparait comme une solution efficace pour réduire significativement le succès d’invasion.
Résumé :
Questions
Giving a time advance to restored native plant species has recently been considered a promising way to improve their persistence and reduce invasion success (i.e., through priority effects). However, little is known about the influence of the elapsed time between seeding and invasion and its interaction with other characteristics such as species composition and density, despite the fact that it could substantially help developing effective management strategies.
Methods
In a pot experiment, we simulated invasion by three major invasive species (Ambrosia artemisiifolia , Bothriochloa barbinodis , and Cortaderia selloana ) in soil covered with recipient communities differing in species composition (one, three or nine species), density (700 or 2,778 seeds/m2), and time advance (established one or five months previously). We assessed early invasion success by measuring seedling emergence and survival over six months.
Results
Early invasion success was mainly explained by recipient community’s time advance and composition (or their interaction), while density had limited influence. Polycultures (three or nine species) showed generally greater invasion resistance, most likely due to high above‐ground biomass essentially produced by two species. Species composition interacted with time advance in two ways: (a) Bothriochloa barbinodis seedling emergence was impacted by composition only in communities having five months of advance, suggesting that the contribution of species composition to invasion resistance varies according to the age of the community, and (b) Ambrosia artemisiifolia and Cortaderia selloana survival was affected by time advance in polycultures only, which produced much more biomass than monocultures, implying that a greater head start provides a competitive advantage only if it allows a sufficient increase in biomass production.
Conclusions
Implementing revegetation as soon as site clearance work is over, as well as establishing productive native species may help reduce invasion success. How much of an advantage recipient community time advance represents depends on biomass production.
Référence bibliographique : Hess M.C.M., Buisson E., Fontes H., Bacon L., Sabatier F., Mesléard F., Marrs R. 2020. Giving recipient communities a greater head start and including productive species boosts early resistance to invasion. Applied Vegetation Science Online:avsc.12502. DOI : http://dx.doi.org/10.1111/avsc.12502 [2]