Exotic, Invasive Plant Species Impact the Ability of Soils to Store Carbon

It turns out that invasive species may be causing even more damage to the environment than first thought. Researchers have found that exotic plants, such as Japanese knotweed, can actually accelerate the greenhouse effect by affecting the ability of soil to store greenhouse gases.

Soil actually stores more carbon than both the atmosphere and terrestrial vegetation combined. This means that soil is a huge part of keeping carbon out of the air and mitigating the impact of global warming. In addition, it also means that the repercussions for how we manage agricultural land and ecosystems to facilitate carbon storage could be dramatic.

That's why the researchers examined the impact of Japanese knotwood and kudzu on soils. These plants are two of North America's most widespread invasive plants.

So what did they find? It turns out that kudzu invasion released carbon that was stored in soils, while the carbon amassed in soils invaded by knotweed was more prone to oxidation and was lost to the atmosphere. These findings, in particular, show that these invasive plants have a large impact on carbon storage.

"Our findings highlight the capacity of invasive plants to effect climate change by destabilizing the carbon pool in soil and shows that invasive plants can have profound influence on our understanding to manage land in a way that mitigates carbon emissions," said Nishanth Tharayil, one of the researchers, in a news release. "Climate change is causing massive range expansion of many exotic and invasive plant species. As the climate warms, kudzu will continue to invade northern ecosystems, and its impact on carbon emissions will grow."

The findings could help create better land-management strategies. In addition, they suggest that it's the chemistry of plant biomass added to soil rather than the total amount of biomass that has the greatest influence on the ability of soil to harbor stable carbon.

Currently, the researchers plan to take a closer look at soil carbon storage and invasion by conducting more studies.

The findings are published in the journal New Phytologist.