Marsh plants called 'secret gardeners'

DURHAM, N.C., Feb. 14 (UPI) -- Marsh plants are "secret gardeners" that can actively engineer their own landscapes to increase their odds of survival, U.S. and Italian researchers say.

The findings contradict the long-held assumption the distribution of plants within a marsh is a passive adaption in which species grow at different elevations simply because that's where conditions like soil aeration and salinity best meet their needs, the researchers said.

Scientists from Duke University and the University of Padua in Italy said they found intertidal marsh plants in Italy's famed Venetian lagoon were able to subtly adjust their elevations by producing different amounts of organic soil, and trapping and accumulating different amounts of inorganic sediments as part of a complex interplay with the environment.

"Our study identifies the visible signature of a two-way feedback occurring between the vegetation and the landscape," Duke ecohydrology Professor Marco Marani said. "Each species builds up the elevation of its substrate to within a favorable range for its survival, much the way corals in the animal kingdom do."

The differences in substrate-building capabilities between species are often small, but allow each species to stabilize the soil within different layers in the marsh, the researchers said.

"Obviously, this is not a conscious choice on the part of the plants," Marani said. "It's a natural mechanism -- how marshes work. We just didn't understand it in such detail until now."