Invasive plants help prevent climate change by becoming ecosystem engineers

One study found that some invasive species could contribute to the fight against climate change by storing "blue carbon". These "ecosystem engineers" have been found to enhance the carbon storage potential of a given ecosystem by growing larger and faster than the native species they use. In some cases, the biomass of ecosystems and their carbon storage potential increased by 117%.

Much research on carbon storage has focused on terrestrial biomass such as forests. However, the potential of coastal environments, such as mangroves and salt marshes, is increasingly being studied in relation to its role in climate change. These marine ecosystems have the potential to store carbon about 40 times faster than forests, but they are rapidly disappearing. Approximately 3,000 square miles are lost each year.

According to the Blue Carbon Initiative, humans are largely responsible for destroying these ecosystems. This includes aquaculture, agriculture, exploitation of mangrove forests and pollution. When blue carbon ecosystems are damaged, carbon is sent back into the atmosphere, potentially contributing to climate change.

Understanding carbon storage systems is important for future climate change models. Knowing how much different ecosystems the planet will absorb will enable scientists to better predict the planet's adaptation to the greenhouse gas emissions we produce.

On May 14, 2009, mangroves and coral reefs grow off the national marine park of Bunaken Island, north of Sulawesi. ROMEO GACAD / AFP / Getty Images

The latest research paper, published in Biology of global change, is a meta-analysis with data from 104 studies. These compared the blue carbon ecosystems where invasive species had been introduced to those where no invasion had occurred. The team was able to determine the amount of biomass of plant origin and the carbon storage potential.

The results produced a mixed bag. They found that where invasive animal species were introduced, biomass was almost halved. "Introduced animals will essentially eat, stomp, cut and destroy biomass," said Ian Davidson, senior author of the Smithsonian Environmental Research Center (SERC), in a statement.

Invasive plants have told a different story. When the newly introduced plant was very different from the already present flora, such as the algae invading a herbarium, the biomass had been reduced by about a third. But where an invasive plant resembled what already existed, biomass increased considerably.

This wetland of Maryland is covered with invasive reeds of Phragmites, light-brown stems that grow higher than native grasses. Gary Peresta / Smithsonian Center for Environmental Research

"When" ecosystem engineers "get into the system, not only do they help create a habitat, but they seem to do it more aggressively and more effectively," Davidson said. These examples include a new type of mangrove invading a mangrove forest or a reed species growing in a salt marsh. Compared to native species, invaders experienced much faster and larger growth, increasing the potential for blue carbon storage.

Scientists do not advocate the introduction of invasive species in marine environments to enhance the blue carbon storage potential. Instead, they state that results can be used in conservation strategies to balance invasive species management, carbon storage, and ecosystem function.

The co-author of the study, Christina Simkanin, explained: "We are discussing the best way to manage systems already impacted by humans, and functions that you want to preserve or that you judge most important. "

The authors of the study were not immediately available for comment.