Effects of Drying-Rewetting Frequency on Vertical and Lateral Loss of Soil Organic Carbon in a Tidal Salt Marsh

Abstract

Tidal salt marshes, as "blue carbon" ecosystems, play a critical role in mitigation of global climate change since their large soil organic carbon (SOC) pool. Drying-rewetting cycles induced by periodic tides have profound influence on soil carbon cycling in tidal salt marshes. However, the magnitude and mechaanism of the effects of drying-rewetting frequency on SOC loss in tidal salt marshes is still uncertain. Here, we conducted a mesocosm experiment to identify how drying-rewetting frequency changes alter the vertical (CO 2 and CH 4 ) and lateral (dissolved organic carbon) carbon losses of soils in a tidal salt marsh in the Yellow River Delta (YRD). We found that increasing soil moisture inhibited CO 2 emission but stimulated CH 4 emission in a tidal salt marsh. Soil dissolved organic carbon (DOC) was produced in the drying phase and rewetting lead to the loss of DOC. Soil moisture and salinity change induced by drying-rewetting cycles were the critical factors controlling vertical organic carbon loss in a tidal salt marsh. DOC had significant effects on CO 2 emissions. Changes of tidal action and drying-rewetting cycle induced by global change can affect the pathway of carbon loss in a tidal salt marsh.Keywords Tidal salt marshes . Drying-rewetting cycle . CO 2 and CH 4 emissions . Dissolved organic carbon

Responses of soil CO2 and CH4 emissions to changing water table level in a coastal wetland

“…Additionally, the significant correlation between soil CO 2 emission and DOC concentrations (Fig. 5) was consistent with previous studies (Liu et al, 2017;Li et al, 2020) and indicated that CO 2 was mainly contributed from DOC (Chow et al, 2006;Liu et al, 2017). DOC is the most active organic substrate for microorganisms, which can supply energy and nutrients for microbial metabolism and further promote CO 2 production (Kane et al, 2013;Yang et al, 2018b).…”

Short-term effects of soil moisture on soil organic carbon decomposition in a coastal wetland of the Yellow River Delta

“…Numerous field studies and incubation experiments have investigated the response of SOC decomposition to soil water availability, leading to inconsistent results within different ecosystems (Dijkstra & Cheng, 2007;Tao et al, 2018;Shahzad et al, 2019;Li et al, 2020). For example, limited soil moisture in croplands inhibited plant photosynthesis and C fixation (Moyano et al, 2013), which was related to vegetation phenology (Wang et al, 2019).…”

Tidal Flats as a Significant Carbon Reservoir in Global Coastal Ecosystems

“…Coastal infrastructure and urbanization could reduce the accommodation space of coastal habitats, driving or limiting habitat transitions (Schuerch et al, 2018). These strong anthropogenic impacts modify the C cycle (Kuwae et al, 2016) and reduce the frequency of the sediment dryrewetting process, which will increase the loss of sediment C (Li et al, 2020). However, the impact of global habitat loss on C emissions from tidal flats is still unquantified.…”