Does reaction-diffusion support the duality of fragmentation effect?

Lionel Roques (1, 1) , Mickaël D. Chekroun (2)

1 BioSP - Biostatistique et Processus Spatiaux
2 CERES-ERTI - Centre d'Enseignement et de Recherche sur l'Environnement et la Societé / Environmental Research and Teaching Institute

There is a gap between single-species model predictions, and empirical studies, regarding the effect of habitat fragmentation per se, i.e., a process involving the breaking apart of habitat without loss of habitat. Empirical works indicate that fragmentation can have positive as well as negative effects, whereas, traditionally, single-species models predict a negative effect of fragmentation. Within the class of reaction-diffusion models, studies almost unanimously predict such a detrimental effect. In this paper, considering a single-species reaction-diffusion model with a removal -- or similarly harvesting -- term, in two dimensions, we find both positive and negative effects of fragmentation of the reserves, i.e. the protected regions where no removal occurs. Fragmented reserves lead to higher population sizes for time-constant removal terms. On the other hand, when the removal term is proportional to the population density, higher population sizes are obtained on aggregated reserves, but maximum yields are attained on fragmented configurations, and for intermediate harvesting intensities.

Mots clés: reaction-diffusion; harvesting; spatial patterns; conservation biology; fragmentation; single-species model

Domaines: Equations aux dérivées partielles [math.AP]; Evolution [q-bio.PE]; Biodiversité et Ecologie; Milieux et Changements globaux

Lionel Roques, Mickaël D. Chekroun. Does reaction-diffusion support the duality of fragmentation effect?. 2009. ⟨hal-00402026⟩