Siyuan Ye Liujuan Xie Ken Krauss Lixin Pei Samantha K. Chapman Hans Brix Edward A. Laws Hongming Yuan Shixiong Yang Xigui Ding Shucheng Xie Pan Zhou 2023 <h3 class="c-article__sub-heading" data-test="abstract-sub-heading">Aims</h3><p>Coastal salt marshes are productive ecosystems that are highly efficient carbon sinks, but there is uncertainty regarding the interactions among climate warming, plant species, and tidal restriction on C cycling.</p><h3 class="c-article__sub-heading" data-test="abstract-sub-heading">Methods</h3><p>Open-top chambers (OTCs) were deployed at two coastal wetlands in Yancheng, China, where native<span>&nbsp;</span><i>Phragmites australis</i><span>&nbsp;</span>(<i>Phragmites</i>) and invasive<span>&nbsp;</span><i>Spartina alterniflora</i><span>&nbsp;</span>(<i>Spartina</i>) were dominant, respectively. Two study locations were set up in each area based on difference in tidal action. The OTCs achieved an increase of average daytime air temperature of ~ 1.11–1.55&nbsp;°C. Net ecosystem CO₂<span>&nbsp;</span>exchange (NEE), ecosystem respiration (<i>R</i>_<i>eco</i>), CH₄<span>&nbsp;</span>fluxes, aboveground biomass and other abiotic factors were monitored over three years.</p><h3 class="c-article__sub-heading" data-test="abstract-sub-heading">Results</h3><p>Warming reduced the magnitude of the radiative balance of native<span>&nbsp;</span><i>Phragmites</i>, which was determined to still be a consistent C sink. In contrast, warming or tidal flooding presumably transform the<span>&nbsp;</span><i>Spartina</i><span>&nbsp;</span>into a weak C source, because either warming-induced high salinity reduced the magnitude of NEE by 19% or flooding increased CH₄<span>&nbsp;</span>emissions by 789%. Remarkably, native<span>&nbsp;</span><i>Phragmites</i><span>&nbsp;</span>affected by tidal restrictions appeared to be a consistent C source with the radiative balance of 7.11–9.64&nbsp;kg CO₂-eq m^–2<span>&nbsp;</span>yr^–1<span>&nbsp;</span>because of a reduction in the magnitude of NEE and increase of CH₄<span>&nbsp;</span>fluxes.</p><h3 class="c-article__sub-heading" data-test="abstract-sub-heading">Conclusions</h3><p>Tidal restrictions that disconnect the tidal hydrologic connection between the ocean and land may transform coastal wetlands from C sinks to C sources. This transformation may potentially be an even greater threat to coastal carbon sequestration than climate warming or invasive plant species in isolation.</p> application/pdf 10.1007/s11104-023-06160-x en Springer Tidal restriction likely has greater impact on the carbon sink of coastal wetland than climate warming and invasive plant article