DEVAUX Caroline

Questions: Sustaining ecosystem services for society in the face of global change is a major challenge. Resilience, an ecosystem's ability to absorb disturbance and return to its initial functioning, is critical for this. We assessed the resilience of mown subalpine grasslands following restoration management. Using a novel multi-indicator approach, we asked how different taxonomic and functional facets of biodiversity influence resilience mechanisms. We demonstrated this approach for a case study in subalpine grasslands, asking: how resilient are grasslands dominated by Patzkea paniculata and their agronomic services to changing mowing regimes? Location: Villar d'Arene, Hautes-Alpes, Provence-Alpes-Cote d'Azur, France. Boundary area of Ecrins National Park. Methods: A manipulative experiment tested the reciprocal effects of mowing cessation and mowing resumption for 10 years. We analysed floristic composition data following four steps. First, we used the Community Structure Integrity Index (CSII.

AbstractEcosystems provide a variety of ecosystem services (ES), which act as key linkages between social and ecological systems. ES respond spatially and temporally to abiotic and biotic variation, and to management. Thus, resistant and resilient ES provision is expected to remain within a stable range when facing disturbances. In this study, generic indicators to evaluate resistance, potential resilience and capacity for transformation of ES provision are developed and their relevance demonstrated for a mountain grassland system. Indicators are based on plant trait composition (i.e. functional composition) and abiotic parameters determining ES provision at community, meta-community and landscape scales. First the resistance of an ES is indicated by its normal operating range characterized by observed values under current conditions. Second its resilience is assessed by its potential operating range − under hypotheses of reassembly from the community’s species pool. Third its transformation potential is assessed for reassembly at meta-community and landscape scales. Using a state-and-transition model, possible management-related transitions between mountain grassland states were identified, and indicators calculated for two provisioning and two regulating ES. Overall, resilience properties varied across individual ES, supporting a focus on resilience of specific ES. The resilience potential of the two provisioning services was greater than for the two regulating services, both being linked to functional complementarity within communities. We also found high transformation potential reflecting functional redundancy among communities within each meta-community, and across meta-communities in the landscape. Presented indicators are promising for the projection of future ES provision and the identification of management options under environmental change.

The interest of the scientific and political community in ecosystem services and their resilience in the face of ongoing global (environmental or societal) change is growing, as reflected in the number of studies on the subject, the Millennium Ecosystem Assessment report and the establishment of a working group on resilience ("Resilience Alliance"). Definitions of resilience are also very diverse, with concepts such as resistance, specific resilience ("from what to what?"), general resilience, adaptability and transformability, which we appropriated in order to develop a conceptual and methodological framework to study the resilience of ecosystem service provision, in particular with the aim of comparing the resilience potentials of different types of subalpine meadows of the Lautaret Pass (Hautes-Alpes, France) for a set of selected services. We proposed two approaches to evaluate the resilience potential of the different states in which a socio-ecosystem can find itself, considering resilience as the capacity of a system to maintain a stable supply of ecosystem services (resistance component) but also its capacity to adapt (different components according to the degree of adaptation: resilience, transition, transformation). An initial assessment of a set of services of interest in the study area is followed by an initial analysis of the resilience of each of these services specifically, based on the assessment of "operational ranges" for each service, defined as the ranges of values that the said service can take in a given state of the socio-ecosystem. The organizational scale at which these ranges are evaluated links them to the different components of resilience. The results confirm the interest in focusing on the specific resilience of each service, as their resilience profiles are different, i.e. the grasslands with the strongest potentials are not the same from one site to another, although in all cases the resilience potentials are rather strong, in contrast to the other potentials.The second analysis starts from the theoretical assumption that the diversity of response traits (heterogeneity and redundancy) improves resilience. We hypothesized that when response traits are those used to model ecosystem services, the functional diversity of a plant community may be related to its overall resilience in terms of ecosystem services. We have linked several measures of functional diversity to resilience potentials (entropy and functional diversity in their α and β dimensions, redundancy and complementarity of functional groups). However, the results obtained from the analysis of the Lautaret grasslands lead us to refute the hypothesis proposing that the functional diversity of plant communities helps explain the resilience profile of the ecosystem services analyzed, as they do not agree with the resilience profiles found by the operational ranges approach. In the end, we recommend using the operational range approach, which allows us to know the resilience profile of each service, in the context of studies on the capacity of a socio-ecosystem to maintain the provision of its ecosystem services. This approach can be further enriched with a scenario approach that would allow to determine "what" the provision of each service is resilient to.