High carbon dioxide can create 'shrinking stems' in marshes

Researchers investigated the effects of high levels of carbon dioxide on marsh plants.

Researchers investigated the effects of high levels of carbon dioxide on marsh plants. Photo: Gary Peresta/Smithsonian Environmental Research Center

For most plants, carbon dioxide acts like a steroid: the more they take in, the bigger they get. But in a new study, scientists at the Smithsonian Environmental Research Center, Villanova University and other institutions discovered something strange happening in marshes. Under higher levels of carbon dioxide, instead of producing bigger stems, marsh plants produced more and smaller stems.

The results were unexpected. For years, scientists had known that carbon dioxide was increasing the total biomass of marsh plants, so it seemed natural to think individual plants were getting bigger, too.

The researchers worked on a tidal marsh called the "Global Change Research Wetland," home to one of the world's longest-running field experiments on climate change. Inside experimental chambers, ecologists have been increasing carbon dioxide levels for more than 30 years. They're tracking how marsh plants grow in a world with carbon dioxide levels nearly twice as high as today -- levels we could see by the end of the century.

Every year, scientists have harvested the plants in the chambers and measured their total biomass, stems, roots and other key traits. With three decades of data, the biologists realized that in chambers with high levels of carbon dioxide, the total biomass of the marsh sedges increased by 20%.

Richer carbon dioxide was spurring the marsh sedges to grow more stems in thicker clusters. But surprisingly, the individual stems had shrunk by 16%.

"Individual marsh plants become smaller and denser with increases in atmospheric carbon dioxide and nitrogen, increasing overall marsh biomass and elevation," says Betsy von Holle, a program director in NSF's Division of Environmental Biology. "Understanding how marshes might become more resilient has major implications for understanding coastal response to sea level rise." (National Science Foundation)

YOU MAY ALSO LIKE

Salt marshes' capacity to store carbon may be threatened by nitrogen pollution

Deep in the waterlogged peat of salt marshes, carbon is stored at much greater rates than in land ecosystems, serving as an offset to climate change caused by carbon dioxide (CO2) build-up in the atmosphere.

Newly Discovered Comet Is Likely Interstellar Visitor

A newly discovered comet has excited the astronomical community this week because it appears to have originated from outside the solar system.

Hubble Finds Water Vapor on Habitable-Zone Exoplanet for 1st Time

Its size and surface gravity are much larger than Earth’s, and its radiation environment may be hostile, but a distant planet called K2-18b has captured the interest of scientists all over the world.

NASA Satellite Spots a Mystery That's Gone in a Flash

Pops of bright blue and green in this image of the Fireworks galaxy (NGC 6946) show the locations of extremely bright sources of X-ray light captured by NASA's NuSTAR space observatory.

Researchers find two new planets with masses similar to Earth’s near a small neighbouring star

Researchers discovered two Earth-like planets near Teegarden’s Star.

Hubble Views Final Stages of a Star’s Life

New image from the NASA/ESA Hubble Space Telescope shows NGC 5307, a planetary nebula that lies about 10,000 light-years from Earth.