How does cypress knee density relate to methane emissions from floodplain swamps?
6-20 sites covering a range of knee densities, always near cypress trees...except that we'll also have a quadrat in the middle of the beaver pond (John)
Record distance to cypress tree?
Cypress knee density measurement
Count knees in each plot.
Measure knee dimensions?
Methane emission measurement
Use lysimeters to draw up pore water from four points (one per quadrant) in each quadrat, then use headspace equilibration to get a gas sample to run on a gas chromatograph to measure methane.
Regression of sediment methane concentration versus knee density
Guarav - in charge of running gas samples.
John - wearing chest waders to sample gas from the beaver pond.
Soil Coring - Jimmy
We used a slide hammer corer in the center of each 2x2m quadrant, retrieving samples after our corer had traveled 30cm into the ground. After, to retrieve the soil samples, we tilted the corer at approximately 45° and carefully lifted the corer up as to prevent the soil from slipping through. In certain cases when the soil did slip through, we took another sample from an undisturbed area in the vicinity of the center of the quadrant. (To remove the cartridge, we sometimes needed the assistance of a wrench and a grip wrench.) As soil coring caused compaction in the soil, we never retrieved soil samples greater than 15cm in height in the corer’s cylindrical cartridge. In the case that there was soil present in both cartridges, we took one cartridge’s worth of soil that was closest to the surface. We then placed the soil-containing cartridge into a pre-filled jar with water from a designated area of the swamp so that there would be about 5cm of air from the top of the jar after the addition of the cartridge. These jars would be all sealed at once after we obtained all our samples (at 3:40pm) and we placed a new cartridge into the soil corer each time and repeated the process.