The beautiful Venetian plant with a secret climate superpower

Venice’s landmarks are teeming with tourists — so many, in fact, that the city has had to put restrictions in place, like banning guides from using loudspeakers. But just outside the famous canals and resplendent architecture lies an ecosystem teeming with less abhorrent life forms: the Venetian Lagoon. For millennia, its marshes have sheltered a multitude of flora and fauna and for centuries protected the city from invasions by its enemies.

Now, protecting this habitat, and other habitats like it, can help protect people and the planet. By walking the wetlands and sampling plants, the researchers identified a carbon-capturing powerhouse, known as sea lavender, of the genus Limonium. By restoring these biomes, conservationists would not only strengthen local biodiversity, but also ensure its ability to trap this planet-warming gas. “Salt pans are not just sites of carbon sequestration,” said Tegan Blount, a geoscientist at the University of Padua in Italy, lead author of a new paper describing the research. “Their conservation also protects many other ecosystem services, which are of vital importance locally and globally. »

On the surface, sea lavender is a marvel. True to its name – although it’s not technically lavender – it produces pretty purple flowers that attract pollinators, supporting biodiversity. Unlike terrestrial lavender, Limonium tolerates salty, waterlogged conditions, allowing it to thrive in the wetlands of the Venice Lagoon. “In summer, salt marsh meadows are tinged purple with an undulating mass of sea lavender flowers, teeming with bees and other insects,” Blount said.

Although Limonium is nice to look at, these researchers were more interested in what lies beneath the ground. Instead of a network of fine filaments, sea lavender’s mature rhizome system grows like a hand reaching out of the ground, with foliage growing from fingertips to the surface. (That’s them in the photo.)

This impacts Venetian marshes in several ways. With its robust root system and foliage, sea lavender anchors waterlogged soil, generates organic matter and traps sediment, reducing erosion and habitat loss in the face of pressures such as sea level rise. It can also create a more stable and conducive environment for other salt-tolerant species, further enhancing biodiversity. “So this can also be a stepping stone,” Blount said.

Even after it dies, the root system of this wonderful plant can persist for long periods of time, continuing to shape the mud. The study found that, compared to other swamp species in the region, such as those in the genera Sarcocornia and Juncus, Limonium creates much more biomass below ground than above and significantly improves the organic carbon content of sediments. In fact, sea lavender can hold 12 times more biomass underground than that growing on the surface.

By protecting these ecosystems, sea lavender can thrive alongside other species, so conservationists wouldn’t need to constantly care for it, Blount said. Limonium species also grow all over the world, from the coasts of North America to Africa to Asia. The restoration of these habitats would therefore benefit biodiversity while improving carbon sequestration and storage. Additionally, healthy wetlands help absorb the force of storm surges from hurricanes, mitigating the flooding of coastal cities.

Properly restored, coastal ecosystems can be self-sustaining. In contrast, infrastructure such as sea walls are expensive to build and maintain, particularly as ocean levels rise. If they have enough space to infiltrate inland, wetlands can adapt. “These systems can keep pace with sea level rise, provided they can migrate backward,” said Emily Landis, global director of climate adaptation and resilience at The Nature Conservancy, who was not involved in the study. “This means they can still provide that critical benefit in adaptation and flood reduction.” »

They also bring economic benefits when conservationists work with indigenous communities to determine how they use these ecosystems. Subsistence fishing, for example, can be done in a measured manner to ensure that pool populations do not collapse, which would be terrible for both the ecosystem and the humans who depend on it. “They know how to take care of their coastline,” Landis said. “They know what’s sustainable.”

In the Venetian lagoon, fishermen have long used fishing valleysessentially ponds that function as artificial ecosystems. This provides shelter for baby fish to grow large enough to be harvested. Removing animals from these habitats may seem counterproductive, but in some ways it provides an incentive to protect these areas. “So conservation is not only about preserving the environment, but also getting something back in return,” said Alice Stocco, an ecologist at Ca’ Foscari University in Venice, who studies valli da pesca but was not involved in the new paper.

The value of sea lavender therefore lies not only in the amount of carbon it captures in the Venetian lagoon, but also in the habitats – and therefore economic and ecological benefits – it provides. “An ecosystem – nature in general – has its own value, which is intrinsic and sometimes cannot be measured,” Stocco said. “Healthy ecosystems enable healthy people. »