PNNL

The Science

Coastal woody-plant mortality is globally widespread and appears to be increasing, with consequences on many ecosystem resources. Yet our predictive capacity of coastal plant loss is relatively undeveloped and untested, leaving the future of coastal ecosystems uncertain. This study reviewed the physiological, ecological, and geomorphological mechanisms by which coastal woody-plant mortality manifests. In the study, the team proposed a testable framework as a road map for future research.

The Impact

Recent observations of increasing coastal plant mortality have raised fears over the future of coastal ecosystems and the services they provide. This paper provides a framework from which science questions can be pursued and hypotheses tested, both empirically and numerically. From this framework emerges the result that hydraulic failure and carbon starvation are both likely to drive mortality under anomalous water exposure to both fresh and saltwater. Results from the study should spur more integrated, targeted research on coastal woody-plant mortality.

Summary

In this study, researchers reviewed the processes and mechanisms by which rising water levels induce mortality of coastal woody plants. The loss of root function due to hypoxia and salinity triggers a series of mechanisms that lead to increasing likelihood of hydraulic failure and carbon starvation, with hydraulic failure dominating early phase mortality and carbon starvation dominating after multiple years of water exposure. Model and empirical approaches to testing the hypotheses are highlighted.

Funding

NGM, BBL, NW, JPM, MW, and VB were supported by the Department of Energy, Biological and Environmental Research Program Coastal Observations, Mechanisms, and Predictions Across Scales (COMPASS). KWK was supported by the USGS Climate R&D Program. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. MCB thanks the Australian Research Council for support (DP180102969).