Marsh plants respond to increased CO2 by growing many small stems, creating a denser wetland that may protect against sea level rise
By Andrea Michelson | 3 October 2019
SMITHSONIAN — Carbon dioxide is textbook plant food. Plants take in carbon dioxide (CO2) and release oxygen, so it’s no surprise that increased CO2 emissions have a steroid-like effect on the world’s flora. However, plants have to take in a balanced diet of carbon dioxide, nitrogen and other nutrients to grow big and tall. The result of a CO2-heavy diet, scientists found, can be an unusual pattern of growth.
A team of researchers at the Smithsonian Environmental Research Center (SERC) working in a marshland on the Rhode River in Edgewater, Maryland, recently took a closer look at how high levels of CO2 affect marsh plant growth. They knew that carbon dioxide has a positive effect on the overall biomass of marsh plants and assumed that individual plants must be producing bigger stems. But the results of the study, recently published in Nature Climate Change, actually showed plants producing smaller but more plentiful stems.
“I don’t think anybody expected this,” lead author Meng Lu says in a press release. “Everyone thought, okay, [plants] increased, biomass increased, so the height, width, all should increase. But that’s not the case in a marsh.”
Lu and his team worked in the Global Change Research Wetland (GCRW) at SERC, where scientists have been experimenting with CO2 enrichment since 1987. Based on three decades of data, they found that the total biomass of marsh sedges growing in high-carbon dioxide chambers increased by 20 percent, but the biomass of individual stems shrunk 16 percent. […]