Unprecedented but understudied: A brief review of climate-induced forest decline in Central Chile

Abstract

Mediterranean-type ecosystems (MTEs) are among the most biodiverse and climate-vulnerable ecosystems globally. Rising temperatures, combined with more frequent and intense droughts, have driven widespread forest decline across all five MTE regions, accounting for 48% of globally documented forest mortality events. Among these, Central Chile has experienced the most severe climatic anomalies, including a persistent megadrought since 2010, two hyperdroughts in 2019 and 2021 with precipitation deficits exceeding 75%, and recurrent spring and summer heatwaves. These unprecedented conditions position Central Chile as a potential worst-case scenario for the future of MTEs worldwide. This review synthesises current knowledge on climate-induced forest decline in Central Chile, summarising recent research conducted across multiple spatial and ecological scales. Emerging evidence reveals a regional forest decline characterised by reduced productivity, radial growth declines, impaired seedling establishment, and widespread canopy browning. While these responses are comparable to those observed in other MTEs, the ecological implications of hyperdroughts and regional warming for forest resilience remain poorly understood. Despite growing research efforts, critical knowledge gaps persist regarding forest mortality rates, regeneration dynamics, and the physiological mechanisms underlying tree survival and mortality. We identify key research priorities, including the need for quantified mortality data, mechanistic understanding of decline processes, assessment of post-disturbance ecological dynamics, and integrative approaches that link plot-based observations with remote sensing and modelling. Addressing these gaps is essential to evaluate changes in productivity, species composition, and the long-term trajectory of Chilean MTEs, while contributing to a broader predictive understanding of forest resilience in Mediterranean-type ecosystems globally.