Georgia’s coastal marshes could help create a template to combat greenhouse gases Sink your hand into a pile of marsh mud and you’ll find an array of plant material, nutrients and minerals. The colors you see can change depending on the soil and where you found it. It’s these color changes that form the basis of a new project launched by scientists at the University of Georgia. By using a specially made sensor to detect color variations in the soils of Georgia’s marshes, the team plans to develop a system that calculates the amount of carbon captured in the ground. “The idea is, we’re going to get lots of spectral readings—whether it’s from a satellite or from a drone or another sensor near the ground, as well as other indicators that affect it, such as the amount of acidity in the soil or the salinity—and add all this information into a machine-learning algorithm,” said Lori Sutter, a research scientist at the UGA Warnell School of Forestry and Natural Resources. Sutter is working with researchers in UGA’s geography, computer science and civil engineering departments to develop the process. “The goal is to be able to say, if you get a certain spectral response under specific environmental conditions, you’ll get this much carbon–not only at the surface, but belowground as well.” The project is funded through the National Science Foundation’s Signals in the Soils program, which aims to find innovative, collaborative solutions using sensor data. By incorporating light-sensing technology with satellite capabilities, said Sutter, the process could open doors to new ways of calculating carbon storage in marshes. The result could give us a whole new way of looking at the marshes that dot our coastlines. The process of breaking down plant materials in a marsh (or wetland) is different than in a typical yard or a forest, where insects and microorganisms get to work immediately to break down discarded leaves and branches. In a coastal salt marsh, cord grass pulls carbon dioxide out of the air and holds it in the plants’ tissue. When grasses eventually fall into the mud, the presence of water makes it more difficult for microorganisms to decompose the plant matter than in upland systems, trapping more carbon in the ground. This trapped carbon is a good thing, which is why coming up with a way to measure it could add a new dimension to wetlands management in Georgia and elsewhere. For now, the project is focusing on three different areas of marshes on Georgia’s coast: An inland site near Savannah, a coastal site near Brunswick and an island marsh off Sapelo Island. This will allow researchers to measure the potential differences between the various types of marshes. The first step in the project involves developing a sensor that can rise and fall with the tides, reading the color spectrum of the ground when it settles on the mud. At the same time, the team will fly a drone above the sample area to gather similar spectral readings, overlapping that information with what’s gathered by a passing satellite. When these images are combined with additional environmental data such as salinity or acidity, said Sutter, the result could give the team a formula for devising carbon content that can be applied to any wetland. “The idea of measuring carbon isn’t new, but the process is novel,” added Sutter. “Because usually you go out and sink a PVC pipe into the ground, bring the soil back to the lab and measure the amount of carbon in each slice. But if we’re able to measure the carbon content remotely, it lowers the cost and makes it more accessible so that broad areas could be evaluated with confidence.” Sutter’s lab specializes in measuring detailed levels of carbon and nutrients in soils, and this project capitalizes on that skill. But it also takes things a step further by pushing into the realm of machine learning. The result, though, could open a new avenue for capturing carbon or incentivizing wetland restoration projects. “The Signals in the Soils program is for transformative science, which to me feels high risk. But if we can make this work, it’s high risk, high reward,” added Sutter.
