Landward and seaward fluxes and soil properties

Sampling was conducted at a two sites within a monospecific Avicenna marina mangrove stand in Thuwal, Saudi Arabia, on the eastern coast of the Central Red Sea (22.340787°N, 39.087991°E). The landward sampling location was approximately 150 m inland from the coast with soil cores were collected over two years, from April 2021 to May 2023, on a monthly basis, except when this was prevented by logistical challenges. The sampling site was either inundated with tidal waters (wet) and measured flux from the sea-air interface or without overlying water (dry) measuring flux from the soil-air interface. The seaward sampling location had cores collected in a narrower time window between September and October 2022, with weekly sampling for two consecutive weeks, followed by a two-week break and a further two weeks of sampling. All collection efforts were with tidal inundation (wet). Two sets of cores were collected during every sampling event. The first set of cores comprised four large clear PVC cylinders inserted into the soil to a depth of 10 cm and retrieved without disturbing the soil layers. These were incubated for 24 hours, with measurements taken at 0 hours (control), 12 hours (under light conditions), and 24 hours (under dark conditions). CO₂, CH₄, δ¹³C-CO₂, and δ¹³C-CH₄ was measured with G2201-i CRDS analyser (Picarro, Santa Clara, California USA). Fluxes were converted from ppm to μmol m^-2 d^-1by the equations shown the the raw datasheet. The second set of scores were collected immediately next to the large cores and used to assess the physical and chemical properties for the top 3 cm of soil, including conductivity, total carbon (TC), total organic carbon (C_org), total nitrogen (TN), bulk density (BD), and water content (WC).The dataset summarizes all variables, with the average, SD, SE, median, min and max values. Separate datasheets show variables across all sites, each site, and split the data into wet and dry sampling conditions. Additional details of sample processing and analysis can be found in: J Breavington, A Steckbauer, C Fu, M Ennasri, and CM. Duarte. 'Dynamics of CO2 and CH4 fluxes in Red Sea mangrove soils'.