Processes and mechanisms of coastal woody‐plant mortality

Abstract

Observations of woody plant mortality in coastal ecosystems are globally widespread, but the overarching processes and underlying mechanisms are poorly understood. This knowledge deficiency, combined with rapidly changing water levels, storm surges, atmospheric CO 2 , and vapor pressure deficit, creates large predictive uncertainty regarding how coastal ecosystems will respond to global change. Here, we synthesize the literature on the mechanisms that underlie coastal woody-plant mortality, with the goal of producing a testable hypothesis framework. The key emergent mechanisms underlying mortality include hypoxic, osmotic, and ionic-driven reductions in whole-plant hydraulic conductance and photosynthesis that ultimately drive the coupled processes of hydraulic failure and carbon starvation. The relative importance of these processes in driving mortality, their order of progression, and their degree of coupling depends on the characteristics of the anomalous water exposure, on topographic effects, and on taxa-specific variation in traits and trait acclimation. Greater inundation exposure could accelerate mortality globally; however, the interaction of changing inundation exposure with elevated CO 2 , drought, and rising vapor pressure deficit could influence mortality likelihood. Models of coastal forests that incorporate the frequency and duration of inundation, the role of climatic drivers, and the processes of hydraulic failure and carbon starvation can yield improved estimates of inundation-induced woody-plant mortality.

Modeling strategies and data needs for representing coastal wetland vegetation in land surface models

“…Although terrestrial woody plant communities sequester carbon at lower rates compared with the rapid rates driven by sediment accumulation in coastal ecosystems (Rogers et al ., 2019), they accumulate large amounts of carbon within living woody biomass with slow turnover (Smart et al ., 2020). The combination of large C pools and low salinity tolerance makes upland coastal forests another important PFT to include in simulations of sea level rise (Smith & Kirwan, 2021; McDowell et al ., 2022). The same salinity response function approaches used for salt‐tolerant species could be applied for freshwater and terrestrial forest PFTs, with much lower salinity thresholds (Fig.…”

Ghosts of dry seasons past: Legacy of severe drought enhances mangrove salinity tolerance through coordinated cellular osmotic and elastic adjustments

“…Salinity (ppt) at each site are from , 2006). Additionally, loss of turgor and cell volume can impact structural integrity, cellular function and carbon gain, and eventually lead to cell death (Guadagno et al, 2017;Lamacque et al, 2020;Lambers & Oliveira, 2019;McDowell et al, 2022;Nguyen, Meir, Wolfe, et al, 2017;Sapes & Sala, 2021).…”

Unveiling resilience mechanisms of Quercus ilex seedlings to severe water stress: Changes in non-structural carbohydrates, xylem hydraulic functionality and wood anatomy

“…Indeed, extensive holm oak diebacks have been recently observed following severe drought episodes (Colangelo et al, 2018;Encinas-Valero et al, 2021;Ogaya et al, 2015Ogaya et al, , 2020Pasquini et al, 2023). Therefore, improving our understanding of the mechanisms underlying holm oak decline and mortality is required to predict Q. ilex forest loss and suggest management measures for its conservation (Gentilesca et al, 2017;McDowell et al, 2022). Previous studies have shown that Q. ilex displays an isohydric behaviour under water stress because it tightly controls stomatal conductance, thus preventing leaf dehydration and embolism formation in xylem vessels (David et al, 2007;Limousin et al, 2022;Nardini et al, 2014;Vaz et al, 2010).…”