Rain events decrease boreal peatland net CO2 uptake through reduced light availability.

Area of Science:

• Ecology
• Environmental Science
• Climate Science

Background:

• Boreal peatlands are significant global carbon sinks.
• Carbon dioxide (CO2) exchange is sensitive to water availability and drought.
• Sphagnum moss, crucial for peat formation, relies on wet conditions.

Purpose of the Study:

• Investigate how daytime rain events affect net ecosystem exchange of CO2 (NEE) in peatlands.
• Determine if environmental changes during rain modify the NEE response.
• Assess the impact of rainfall timing and characteristics on peatland carbon uptake.

Main Methods:

• Analyzed an 11-year dataset of eddy covariance and meteorological measurements.
• Utilized half-hourly data from Degerö Stormyr, a boreal peatland in northern Sweden.
• Examined the relationship between rain events, environmental factors, and CO2 exchange.

Main Results:

• Daytime rain events consistently reduced peatland CO2 sink strength.
• Reduced light availability was the primary driver of decreased CO2 uptake.
• An average rain event decreased net CO2 uptake by 0.23-0.54 gC m(-2).

Conclusions:

• Reduced light during rain events is more impactful than water availability on NEE.
• Peatland CO2 uptake is highly sensitive to altered rainfall patterns and cloud cover.
• This highlights a critical, overlooked factor in peatland carbon cycle dynamics.