Fire air pollution weakens forest productivity

Eurek Alert
Fire is an important element of Earth system. Every year, global fires directly emit 2 Pg C (billion-ton carbon) into atmosphere, which is ~20% of total emissions from human activities.
In addition to the carbon emissions, fire plumes also generate air pollutants, including ozone (O3) and fine mode aerosols (e.g., PM2.5, particulate matter less than 2.5 μm in diameter).
It’s well known that these air pollutants may worsen air quality in the local and downwind regions.
However, it’s not known that they also change land carbon budget by influencing photosynthesis of unburned forests.
Recently, a new study in Nature Communications explored the ecological impacts of fire air pollution. Increases in O3 and aerosols have opposite impacts on plant health.
O3 is phytotoxic and reduces plant photosynthesis, while aerosols may promote photosynthesis by enhancing diffuse radiation.
It is unclear what’s the net impacts of these pollutants on biosphere from the same fire.
This study combined three state-of-the-art models and a full set of observations from ground sites, satellites.
, and literature, to quantify the net impacts of fire O3 and aerosols on gross primary productivity (GPP), a metric representing total photosynthesis of forests.