PNNL

Abstract

The science of plant hydraulics has long sought to understand the fundamental mechanisms of how water moves through plant 4 vascular systems (Dixon & Joly, 1895). Over the last 50 yr, advances in our understanding of embolism formation (Tyree & 5 Sperry, 1989), hydraulic segmentation (Zimmermann, 1978), and refilling (Sperry et al., 1987) were generated both through novel measurements (Scholander et al., 1965; Sperry et al., 1988; Alder 7 6 et al. 1997) andmodel development (Tyree&Sperry, 1989; Sperry et al., 1998). This knowledge provided a foundation of mechanistic understanding that has impacted fields of study from crop physiology to the global hydrologic cycle (Fig. 1; Sperry et al., 2003; Tang et al., 2015; Peters-Lidard et al., 2019). Scientific advances in our understanding of plant hydraulics and its implications for plant function have arguably accelerated over the last two decades. New empirical (Holbrook et al., 2001; Choat et al., 2015) and modeling (Christoffersen et al., 2016; Sperry et al., 2016; Venturas et al., 2018; Kennedy et al., 2019; Mencuccini 8 et al., 2019) approaches have been applied to tackle some of our largest challenges, and different perspectives have been integrated to better understand the entire vascular system (e.g. carbon 9 metabolismand xylemhydraulics;H€oltt€a et al., 2009; Secchi et al., 2011).