Plants are a powerful proxy for global tidal marsh methane fluxes

Area of Science:

• Environmental Science
• Ecology
• Climate Science

Background:

• Methane (CH4) emissions from tidal marshes can negate their climate benefits.
• Current understanding of CH4 emission drivers is limited, with salinity showing poor predictive power.
• Accurate quantification of CH4 fluxes is crucial for global carbon accounting.

Purpose of the Study:

• To identify reliable predictors of global tidal marsh methane (CH4) fluxes.
• To compare the predictive performance of plant species versus salinity for CH4 emissions.
• To develop improved models for estimating CH4 fluxes in tidal marshes.

Main Methods:

• Compiled data from 87 studies, including 2,094 CH4 flux measurements.
• Utilized random forest and generalized additive modeling to analyze relationships.
• Investigated the influence of plant species, salinity, latitude, and season on CH4 fluxes.

Main Results:

• Plant species alone explained 62% of CH4 flux variability, outperforming salinity.
• A multiproxy model including plant species, latitude, season, and salinity explained 71% of variability.
• Plant functional type alone explained 54% of CH4 flux variability, highlighting plant influence.
• Methane emissions from polyhaline marshes can offset 1-39% of carbon sequestration, depending on plant species.

Conclusions:

• Plant species is the most significant predictor of global tidal marsh methane emissions.
• A plant-based approach substantially enhances the accuracy of CH4 flux estimations.
• This research provides a more robust framework for global carbon accounting in tidal marshes.