RESCRI · Shifts in ecosystems state in Mediterranean landscapes: when, where and how? The interacting effects of multiple disturbances under climate change

The consequences of altered disturbance regimes in the context of global change will be profound. Despite the interacting effects of multiple disturbances and of altered disturbance regimes are extremely difficult to predict, it is becoming increasingly clear that many ecosystems have critical thresholds at which the system shifts abruptly from one state to another. Such behavior has profound implications for ecosystem management and conservation and for the sustained production of ecosystem services.Mediterranean-type ecosystems (MTEs) may be among the most impacted systems by global climate change drivers as a result of increased recurrence in climatically-induced drought events and its interaction with altered fire regimes. Although MTEs vegetation is highly adapted to fire and drought, alteration of such disturbances can promote ecosystems shifts due to crossing of ecosystem thresholds and/or altered system feedbacks. However, little work has been done in MTEs in this respect and the understanding of mechanisms underlying their resilience and the combined and synergistic effects of multiple disturbances need to be better understood.This proposal aims to fill an important scientific knowledge gap by evaluating ecological mechanisms governing system behavior and the occurrence of alternate states in MTEs. The main objectives are i) to increase our capability in predicting changes in ecosystem properties and dynamics and ii) to assess early-warning signals that may indicate proximity to drastic system changes, to aid in the definition of adaptive management policies to successfully address environmental threats. A novel dynamic modeling framework incorporating the stochastic effects of multiple disturbances (fire and drought) and their interaction with vegetation characteristics will be developed. Extensive future scenario-based simulations will serve to identify tipping points that may cause dramatic and surprising shifts in ecosystems’ state.