# Data used in: Variability in methane emissions from stems and buttress roots of Bruguiera gymnorrhiza trees in a subtropical mangrove forest Daniel Epron, Takumi Mochidome, A.T.M. Zinnatul Bassar, Rempei Suwa CH4 fluxes were measured using a cavity-enhanced absorption spectroscopy gas analyser (Li 7810, Li-Cor; Lincoln, USA) with two 6 mm diameter 2 m long PTFE tubes. Changes in the CH4 and CO2 concentrations in the stem chamber were recorded for 4 min at a frequency of 1 Hz. For buttress roots and stem, a polypropylene chamber bases were affixed to the bark surface with neutral seal putty, covering an area of 45 cm2. The stem chambers were closed by affixing a polypropylene lid lined with a silicone rubber gasket. For sediment, a circular chamber made of clear acrylic resin (diameter, 32 cm; height, 14.6 cm) was affixed to PVC collars inserted 10 cm into the sediment. The slopes of the linear variations in CH4 concentration in the chambers over time were used to calculate CH4 emissions, which was expressed per unit area. The experiment was performed in July 2022 in a mangrove forest extending about 1500 m along the intertidal banks of the Miyara River estuary on Ishigaki Island (Japan, 2421'N 12412'E). Trees of B. gymnorrhiza were selected in three plots. Plot #1 and plot #2 are located near the river mouth on the left bank and on the right bank respectively while plot#3 is further upstream on the right bank. Trees were selected to cover a large range of diameter at breast height (DBH), from 10.5 to 61.5 cm. File 24hhours_flux (data used in Figure 5) CH4 fluxes were measured at eight occasions over 24 hours on two trees at four positions (buttress roots and stems) and on three soil collars. Trees were located in plot 1 File Tree_flux.csv (data used in Figure 14) CH4 fluxes were measured once on 15 trees at at least two positions (buttress roots and lower part of the stems) Column names in both files: * Plot ID * Tree ID * DBH: diameter at breast height in cm * Position: root, stem or soil * Height: height of the chamber from the soil in cm * Time: Time and date of CH4 flux measurement * Flux_CH4: Net CH4 flux in nmol m-2 s-1, expressed per unit area of either root, stem or soil covered by the chamber.

The data set provides CH4 flux from buttress roots and stems of individuals of Bruguiera gymnorrhiza of different sizes in Ishigaki Island, Japan. It also provides CH4 flux from trees and sediments over a 24-hour cycle.

Any program that can read .csv files