Invasive-plant control can turn a salt marsh from carbon sink to carbon source—at least during recovery
WHAT THE EVIDENCE SAYS
Researchers compared unmanaged Spartina alterniflora marsh with chemical control and cutting plus continuous flooding. Unmanaged marshes showed net carbon uptake of 13.49 Mg C ha−1 yr−1, while both control strategies shifted the system to net carbon release of 1.78–4.94 Mg C ha−1 yr−1. Chemical control increased methane emissions relative to unmanaged marshes; both treatments reduced total and surface soil carbon, and carbon-stability metrics fell sharply.
WHY IT MATTERS / OUR READ
Control can be ecologically justified for native-habitat and biodiversity goals while still carrying a carbon cost. The useful management question is therefore not whether Spartina should be controlled in the abstract, but which method, recovery trajectory and carbon tradeoff fit the site’s objectives. Carbon quantity and carbon stability also need to be kept separate.
CAVEATS / UNCERTAINTY
This is one eastern-China salt-marsh system and the study captures post-control conditions rather than the full long-term recovery trajectory. Carbon consequences do not negate biodiversity or habitat reasons for controlling the invader, and results should not be treated as universal across tidal settings or control methods.
SOURCE
Carbon Balance and Management — primary study
View original evidence ↗
An eastern China study found both herbicide and cutting-plus-flooding control of invasive Spartina reversed net carbon uptake, while the two methods changed methane, soil carbon and carbon stability in different ways.
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