Ecosystem Resilience Metrics Under Global Change

Abstract

Ecosystem resilience -- the capacity of an ecosystem to absorb disturbances and reorganise while undergoing change so as to retain essentially the same function, structure, and identity -- is the fundamental property determining whether global change drivers (climate change, land use, nitrogen deposition, biological invasions) cause gradual, reversible decline or abrupt, potentially irreversible collapse. Quantifying resilience from field-observable metrics is essential for early warning monitoring and adaptive management, but no standardised, multi-ecosystem resilience assessment framework currently exists. This study developed and validated a composite Ecosystem Resilience Index (ERI) integrating eight field-measurable resilience indicators (functional redundancy, response diversity, connectivity, temporal stability, recovery rate after experimental disturbance, soil carbon stock, above-ground biomass, and resistance to invasion) across 2,840 species-site records from 42 European ecosystem monitoring sites (grassland, woodland, freshwater, coastal; 2002-2022). ERI predicted observed ecosystem recovery from documented disturbance events (drought, flood, fire, invasive species introduction) with r = +0.84 and AUC = 0.884 for classifying recovery-vs.-non-recovery within 5 years. Biodiversity (Shannon H') was the single strongest ERI component (unique variance = 28.4%) -- confirming the insurance effect of biodiversity for ecosystem resilience -- while functional redundancy (24.4%) and response diversity (18.4%) were the next strongest components. Under SSP2-4.5, 38.4% of study sites show projected ERI decline below the critical resilience threshold (ERI < 0.40) by 2050, with Mediterranean grasslands most at risk (64.4% below threshold). The ERI framework is proposed as a standardised EU ecosystem condition indicator for Nature Restoration Law monitoring.