Messy. Muddy. Mangroves. 2021 Climate Intern Field Update

2021 Climate Intern, Paula Sternberg tells the story of what it’s really like to do field sampling in a mangrove forest, and explains the scientific questions driving her efforts. Read today’s blog to learn more about the efforts behind the data!

Versión en español al final.

Imagine you’re knee-deep in mud in the scorching Baja sun, you’re completely soaked in sweat, it smells of sulfur and decaying matter, and you’re using all of your strength to try to insert a giant metal tube into the ground. . . now that’s science! (Photo 1).

This is exactly what estimating underground carbon stocks looks like in a mangrove forest. That giant metal tube is actually a very helpful tool called a soil corer, and it can give us a vertical profile of what the earth looks like beneath the surface. It also helps us take soil samples at specific depths, which we later analyze to find the percent organic carbon.

Specifically, my team and I are interested in comparing different types of corers that can be used to measure underground carbon. This way, we can directly compare how accurate each coring method is and eventually develop a conversion system that accounts for the disturbances produced by each one.

For this project, we sampled using three different types of corers and one control method (Photo 2). We selected three mangrove forests in La Paz, Baja California Sur and went to work. Once at the forest, we began by coring in the same location with all four methods, taking samples at 15 cm and 40 cm depths. Within each mangrove forest, we repeated the process at different sites in an effort to sample different soil types like mud, peat, clay, and sand.

During the field work, we observed that some corers were more prone to disturb the soil than others. More disturbance during sampling means that the density of the soil may be affected and can later indicate different carbon percentages than that of undisturbed soils. Thus, coring methods that cause the least disturbance during sampling are more representative of the actual soil composition.

Once the samples had been taken and placed into jars, they were left open to dry as much as possible in the sun. When all the field work was finished, we shipped them to the lab for processing and analysis (Photo 3). Here, the samples will be fully dried, ground, acidified, and eventually analyzed for organic carbon composition.