The Role of Hydraulic Failure in a Massive Mangrove Die-Off Event

Gauthey, Alice; Backes, Diana; Balland, Jeff; Alam, Iftakharul; Maher, Damien T.; Cernusak, Lucas A.; Duke, Norman C.; Medlyn, Belinda E.; Tissue, David T.; Choat, Brendan

doi:10.3389/fpls.2022.822136

Cited by 5 publications

(2 citation statements)

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“…Mangroves have longer guard cell length for a given stomatal density than other vascular plants (Agduma et al ., 2022). Mangroves are confronted with increasing challenges for survival from global warming, which will result in dramatically increase in VPD, changes that may have led to dramatic die-off events in mangrove forests (Gauthey et al ., 2022). Yet, relatively little is known about the stomatal dynamics of mangroves in response to high VPD, information that would help us to understand the physiological response of mangroves following any hydraulic perturbation.…”

Section: Introductionmentioning

confidence: 99%

Stomatal dynamics are regulated by leaf hydraulic traits and guard cell anatomy in nine true mangrove species

Qie

Zhang

McAdam

et al. 2023

Preprint

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Stomatal regulation is critical for mangroves to survive water deficits and highly fluctuating ambient water availability in the hyper-saline intertidal zone. Despite the importance of stomatal regulation in mangroves very little is known about stomatal sensitivity to vapour pressure deficit (VPD), and the co-ordination of this trait with stomatal morphology and leaf hydraulic traits in these species. We measured the stomatal response to a step increase in vapour pressure deficit (VPD) in situ, stomatal anatomy, leaf hydraulic vulnerability and pressure-volume traits in nine true mangrove species of five families. We aimed to answer two questions: (1) Does stomatal morphology determine stomatal dynamics in response to a high VPD in mangroves and (2) do leaf hydraulic traits influence stomatal sensitivity to VPD in mangroves? We found that the stomata of mangrove plants highly sensitive to VPD, and that species with higher maximum stomatal conductance had slower stomatal responses to an increase in VPD, and that stomatal density and size were correlated with the speed of stomatal closure at high VPD across the closely-related species. We also found that a higher leaf capacitance (Cleaf) and more resistance to leaf hydraulic vulnerability were associated with slower stomatal responses to an increase in VPD. Our results demonstrate that the dynamics of the stomatal response to an increase in VPD are regulated by leaf hydraulic traits and stomatal morphology. Our work provides a quantitative framework to better understand stomatal regulation in mangroves in an environment with highly dynamic water availability.

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Section: Introductionmentioning

confidence: 99%

Stomatal dynamics are regulated by leaf hydraulic traits and guard cell anatomy in nine true mangrove species

Qie

Zhang

McAdam

et al. 2023

Preprint

View full text Add to dashboard Cite

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“…At the same time, salinity is a primary hydrological driver, known to reduce soil water potential, limit root water uptake, increase the risk of xylem cavitation, and impair photosynthesis (Munns, 2002; Perri et al, 2019, 2022; Perri, Entekhabi, & Molini, 2018). A number of studies on mangrove biomass stocks and allometric relations have suggested that aridity and tidal inundation frequency, all‐controlling water salinity, are dominant limiting factors for coastal ecosystems' carbon storage (Adame et al, 2020; Bathmann et al, 2021; Gauthey et al, 2022; Rovai et al, 2021). These effects are analogous to those of water stress in terrestrial forests, and similarly to water stress, they could exert significant controls on species competition and canopy height (Klein et al, 2015; Koch et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Salinity‐induced limits to mangrove canopy height

Perri

Detto

Porporato

et al. 2023

Global Ecol Biogeogr

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AimMangrove canopy height is a key metric to assess tidal forests' resilience in the face of climate change. In terrestrial forests, tree height is primarily determined by water availability, plant hydraulic design, and disturbance regime. However, the role of water stress remains elusive in tidal environments, where saturated soils are prevalent, and salinity can substantially affect the soil water potential.LocationGlobal.Time PeriodThe canopy height dataset provides a global snapshot of the maximum mangrove height geographical distribution for the year 2000. Climate and environmental variables extend over the period 1970–2018.Major Taxa StudiedMangroves.MethodsWe use global observations of maximum canopy height, species richness, air temperature, and seawater salinity—a proxy of soil water salt concentration—to explore the causal link between salinity and mangrove stature.ResultsOur findings suggest that salt stress limits mangrove height. High salinity favours more salt‐tolerant species, narrowing the spectrum of viable traits. Highly salt‐tolerant mangroves have evolved to cope with high salt concentrations in the soil, but this adaptation comes at a cost. They typically have lower rates of photosynthesis and growth, resulting in reduced productivity and smaller stature compared to more salt‐sensitive mangrove species. This suggests a causal link between salinity, biodiversity, and tree height, where high salinity selects for more salt‐tolerant species that tend to be less productive and shorter.ConclusionsWe hypothesize that the salinity‐induced limit to mangrove canopy height is the direct result of a reduction of primary productivity, an increment in the risk of xylem cavitation, and an indirect consequence of the decrease in biodiversity. As sea‐level rise enhances coastal salinisation, failure to account for these effects can lead to incorrect estimates of future carbon stocks in Tropical coastal ecosystems and endanger preservation efforts.

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