Author Olivier Delettre, discusses their recently published article: Identity of ecological systems and the meaning of resilience. This article proposes four definitions of resilience, each one refers to the maintenance of a different type of identity and to a different level of persistence of ecological systems.
This article is part of an upcoming cross-journal Special Feature, with Journal of Animal Ecology: Reconciling resilience across ecological systems, species and subdisciplines.
Resilience is polysemic (i.e. has multiple definitions) in ecology but some authors have already define it in its broadest sense as “the capacity of a system to persist in the face of disturbance“. The need to specify the system (resilience -of what?) and the disturbance (resilience -to what?) in order to give a meaning to the concept is generally admitted. However, little has been said about the meaning of the term persist. Yet, a system can persist in different ways and it can significantly impact the meaning of resilience. Therefore, a clarification of the different types of persistence associated with the concept of resilience could shed light on its polysemy.
By defining persistence as the “maintenance of the identity” of the system, we asserted that the multiple definitions of the identity concept was the source of different levels of persistence in ecology. We distinguished four levels of persistence:
- Persistance as maintenance in the neighbourhood of a local equilibrium state (point or trajectory), i.e. maintenance of local state identity.
- Persistance as maintenance in a global stable state (basin of attraction), i.e. maintenance of global state identity
- Persistance as maintenance of the existence regardless of the state (avoidance of extinction), i.e. maintenance of numerical identity
- Persistance as maintenance of the type even if the existence is lost, i.e. maintenance of typological identity
Throughout the twentieth century, ecologists have used the resilience concept to refer to each of these four levels of persistence without acknowledging them. We highlighted these four distinct uses of ecological resilience from an historical review and this work leaded to the formulation of four definitions that enlighten the polysemy of the concept in ecology :
- Engineering resilience: the capacity of an ecological syste to maintain its local state identity in spite of disturbance.
- Ecological resilience: the capacity of an ecological syste to maintain its global state identity in spite of disturbance.
- Meta-regime resiliece: the capacity of an ecological syste to maintain its numerical identity in spite of disturbance.
- Typological resilience: the capacity of an ecological syste to maintain its typological identity in spite of disturbance.
These four definitions should not be seen as different levels or degrees of resilience but rather regarded as different types of behaviour that could more or less satisfactorily characterize a system depending on the process whereby persistence is achieved, the disturbance and the scale considered, as well as the research question and the management objectives of the author.
Although it would be better if the ecologists community agreed on the terms, the essential thing is that each author situates his or her particular use of the resilience concept in order to give the clues necessary to understand the term in the context of his or her work. This article therefore did not aim to introduce new terms or concepts but simply to shed light on existing uses of the resilience concept in order to facilitate its clarification in ecology.
Olivier Delettre University of Paris, France.
You can read the full article online: Identity of ecological systems and the meaning of resilience
You may also be interested in the other articles in our cross-journal Special Feature on Ecological Resilience.