Scientists have long believed that the distribution of plants within a marsh is a passive adaption in which species grow at different elevations because that's where conditions like soil aeration and salinity best meet their needs.
But this team found intertidal marsh plants in Italy's famed Venetian lagoon were able to subtly tune, or 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," said Marco Marani, professor of ecohydrology at Duke's Nicholas School of the Environment and Pratt School of Engineering. "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 finding may help scientists better predict marsh ecosystems' resilience to climatic changes such as sea level rise.
"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."
The study appears this week in the early online edition of the Proceedings of the National Academy of Sciences.
The team used numerical modeling to visualize the dynamic interactions of marsh ecosystems over time, and tested the models against detailed topographical surveys of elevations and distributions of plant species in the Venetian lagoon.
"We've been studying this same marsh for 15 years and, as in similar studies around the world, we were using GPS technology with an accuracy of plus or minus one centimeter in elevation," Marani explained. For the new study, they used a more precise surveying instrument, an electronic theodolite, which measure elevations accurately to within less than one millimeter. "It allowed us to observe differences so subtle that they went unnoticed before," he said.
The differences in substrate-building capabilities between species are often minute, but they allow each species to stabilize the soil within different stable states, or layers, in the marsh. Some species prefer elevations at or below mean sea level; others prefer higher elevations that are less often inundated.
"Interestingly, our models and surveys show that plants make trade-offs when colonizing within their preferential ranges," Marani said. "Entire sections of a species' vegetation patch often are located above the elevation needed for its maximum biomass productivity." This gives it a bit of margin to compensate for external fluctuations, such as the rates of relative sea level rise or sediment availability.
"Essentially," he said, "the species hedges its bet by trading maximum productivity for greater long-term stability."
Scientists have long known that biodiversity plays an important role in a marsh ecosystem's long-term health and survival, "but this paper provides a clear causal link suggesting how and why," he said. "The take-home message is that the more species you have colonizing different levels within a marsh, the more resilient to abrupt change the marsh as a whole will be."
He said that marshes in which an invasive species, such as cordgrass, has pushed out other species will be less resilient to climatic changes.
Marani's co-authors on the new study are Cristina Da Lio and Andrea D'Alpaos of the University of Padova, Italy.
CITATION: "Vegetation engineers marsh morphology through multiple competing stable states," Marco Marani, Cristina Da Lio and Andrea D'Alpaos. Published week of Feb. 11, 2013 in the early online edition of the Proceedings of the National Academy of Sciences. DOI - 10.1073/pnas.1218327110
Tim Lucas | EurekAlert!
Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main
Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
06.12.2016 | Materials Sciences
06.12.2016 | Medical Engineering
06.12.2016 | Power and Electrical Engineering