Hydraulic failure and tree size linked with canopy die-back in eucalypt forest during extreme drought

Globally, drought is one of the most important factors affecting the composition, structure and function of forests (Reichstein et al., 2013). In 2019, Australia experienced its driest and hottest year on record, with many parts of the country undergoing their third consecutive year of drought (Bureau of Meteorology, 2020). These unprecedented conditions resulted in the occurrence of massive canopy die-back events, i.e. foliar death (Atlas of Living Australia, 2020), and record-breaking wildfires across forests and woodlands in eastern Australia (Boer et al., 2020; Nolan et al., 2020a). Extreme drought events such as these are becoming more frequent as increasing temperatures and evaporative demand lead to longer and more intense droughts under climate change (Trenberth et al., 2014; Dai & Zhao, 2017; Miralles et al., 2019). The increased incidence of drought has raised concerns that climate change may lead to broad scale tree mortality in many regions, as the pace of climate change outstrips the capacity of trees to acclimate or adapt to greater drought stress (Brodribb et al., 2020).