Temperature sensitivity of anaerobic CO2 production in soils of Phragmites australis marshes with distinct hydrological characteristics in the Yellow River estuary

Temperature sensitivity (Q(10)) is important to reveal carbon decomposition responding to climate change. It's remains limited to understand how Q(10) of anaerobic soil organic matter (SOM) decomposition is regulated by soil property in various wetlands with distinct hydrological characteristics. In the present study, samples of soil at the depths of 0-10 cm, 10-20 cm and 20-30 cm were collected in three typical Phragmites australis marshes, including a freshwater marsh (FPa), a no-tidal salt marsh (NTPa) and a tidal salt marsh (TPa), in the Yellow River estuary. The soil samples were incubated at 10 degrees C, 20 degrees C and 30 degrees C, respectively, to determine the rates of anaerobic CO2 production, Q(10) values, and their relations to soil properties. Over 70-d incubation, temperature rise significantly increased the mean rates by 70%-136% (from 10 degrees C to 20 degrees C) and 64%-142% (from 20 degrees C to 30 degrees C) among the marshes, with the mean Q(10) values ranging from 1.61 to 2.66. The rates of CO2 production and Q(10) values were significantly affected by wetland type and soil depth. Among marshes, the Q(10) of the FPa and NTPa soils was higher than that of the TPa soil (for 0-10 cm and 10-20 cm but for 20-30 cm); along soil depths, the Q(10) of the top soil was higher than that of the subsoil (for FPa and NTPa but for TPa). Q(10) was affected by total organic carbon (TOC), salinity and pH, and the effects were different with marshes. TOC was a main factor regulating Q(10) for the freshwater and the no-tidal salt marshes, while salinity and pH were main factors for the tidal salt marsh. The findings highlight an interactive mechanism of soil property and tidal underlying the response of SOM decomposition to temperature change in estuarine wetlands.

Automated summary

The study reveals that wetland type and soil depth significantly affect the Q(10) values of anaerobic soil organic matter decomposition. Different wetland types and soil depths show distinct differences in Q(10) values, and total organic carbon, salinity, and pH have varying impacts on the Q(10) values of the decomposition process.