The Time of Emergence (ToE) of the Andean Mediterranean sclerophyllous forest of Quillaja saponaria (Mol.) and Lithraea caustica (mol.) Hox. & Arn

Abstract

Climate change has intensified in recent decades, leading to increasingly severe droughts. This trend will continue due to the emissions and increasing concentration of greenhouse gas (GHG). One of the main direct climate change consequences is the modification and alteration of the dynamics and function of forest ecosystems, having effects ranging from physiological alterations in plants to definitive changes in their geographical distribution. Mediterranean ecosystems are particularly threatened, where the sclerophyllous forest of central Chile that is considered a biodiversity hotspot, is no exception. Despite that sclerophyllous species present drought adaptation mechanisms, there is no certainty of the climatic minimum thresholds in which it develops, or when climate changes will exceed these thresholds, causing definitive changes in its distribution. To evaluate these changes on the Andean Mediterranean Sclerophyllous Forest vegetation belt of Quillaja saponaria and Lithraea caustica, the forest was divided into six quadrants with similar climates. In each quadrant, a critical threshold ​​of a simplified water balance (SWB) was defined where the forest has historically developed. The SWB is considered to be a limiting factor in the forest development. Then, the Time of Emergence (ToE) of the forest is estimated, as the time when climate change projections exceed the critical thresholds, by using CMIP6 General Circulation Models (GCM), under SSP2-4.5 (moderate) and SSP5-8.5 (pessimistic) scenarios. Results indicate that the forest would begin to be displaced between 2060 and 2080 under the SSP5-8.5 scenario, particularly in the Talagante, Isla de Maipo, Paine, and Doñihue area, while no distribution changes are presented under SSP2-4.5 scenario.