Gopal Billy

Environmental closure: what impact on biodiversity?

Biodiversity is in sharp decline in the face of anthropogenic pressures. Global measures exist, but it is also important to implement regional conservation actions that provide rapid benefits for biodiversity. One of these actions is to increase the level of protection of ecosystems and the sites that shelter them. Very strict protection statutes have been adopted to protect habitats (e.g., Réserve Biologique Intégrale, RBI), with the premise that a lack of exploitation leads to a revival of biodiversity. In terrestrial environments, the absence of intervention on plant populations can lead to a closure of the environment. Is biodiversity really promoted by this protection status? The question needs to be explored, particularly for species dependent on open habitats.

In New Aquitaine, the Chizé forest provides a quasi-experimental framework for addressing this issue. First of all, the exploitation of the forest in plots has generated strong spatial contrasts, creating a gradient from very open to closed environments. Furthermore, in 1999 two storms drastically increased the opening up of closed environments; finally, in 2006, 2600 hectares were declared RBI, giving free rein to the generalised closure of the forest. This history of forest dynamics can be related to the history of the dynamics of populations of predators dependent on open areas. There are 4 species of snakes: the green and yellow snake, the Aesculapian snake, the ring-necked snake and the asp viper. These species have been studied for more than 25 years in the Chizé forest using the Capture-Marking-Recapture (CMR) method. During the course of the thesis, it will be possible to accurately estimate the temporal variations of essential demographic parameters (survival, recruitment, etc.) and then to relate them to the dynamics of forest stands. These analyses will provide answers for a better understanding of the temporal and spatial relationships of snake populations as a function of the closure of environments; and thus to propose management measures.

PhD student in the ECOPHY team (2020-2023)
Thesis Director: Xavier BONNET and Christophe BARBRAUD
Doctoral School of La Rochelle
Co-financed by the New Aquitaine region and the Deux-Sèvres departmental council.
Tel +33 (0)783924693