Impacts of biodiversity-dependent ecosystem service debts on the safe operating space of social-ecological systems: a theoretical modelling study.

The rapid environmental changes of the Anthropocene create legacy effects that may shape future Earth system responses. One significant legacy effect is the species extinction debt caused by past habitat destruction. As biodiversity underpins ecosystem services vital to human societies, social-ecological systems may, in turn, be subjected to biodiversity-dependent ecosystem service debts. While biodiversity-dependent ecosystem service debts have been quantified with analytical approaches, less attention has been paid to their potential impact on social-ecological system trajectories. We performed a theoretical study of a dynamical systems model that includes the possibility of biodiversity-dependent ecosystem service debts emerging from past habitat destruction. Our results suggest that these debts reduce systems' safe operating spaces and create environmental tipping points associated with critical transitions in system states. These transitions, however, may include long transients of apparent stability, making it difficult to identify cause and effect. Notably, biodiversity-dependent ecosystem service debts may drive initial phases of apparent recovery after disturbance, still followed by system collapse. Our theoretical findings highlight the need to consider biodiversity-dependent ecosystem service debts for sustainable management of social-ecological systems. Furthermore, these results suggest that social-ecological systems' safe operating spaces cannot be reliably inferred from recent observations of apparent system stability.