Long-term nutrient addition increased CH₄ emission from a bog through direct and indirect effects

Area of Science:

• Ecology
• Biogeochemistry
• Environmental Science

Background:

• Peatlands are critical global sources of atmospheric methane (CH4).
• Understanding long-term nutrient deposition effects on peatland CH4 dynamics is crucial but understudied.
• Few long-term fertilization experiments exist to assess aggregated impacts on ecosystem functioning.

Purpose of the Study:

• To investigate the long-term effects of nitrogen (N), potassium and phosphorus (PK), and NPK fertilization on CH4 flux and production in a temperate bog.
• To determine how 16 years of nutrient addition influence CH4 emissions and underlying ecosystem processes.

Main Methods:

• Field measurements of CH4 fluxes were conducted in May-August 2005 and 2015.
• Long-term field treatments included three levels of N, PK, and NPK fertilization.
• Laboratory incubations of peat samples assessed potential CH4 production with and without short-term PK amendment.

Main Results:

• The NPK treatment, with 16 years of high N application, showed significantly higher CH4 flux (50.5 mg CH4 m-2 d-1) compared to the control (8.6 mg CH4 m-2 d-1) in 2015.
• Increased CH4 flux was correlated with wetter conditions resulting from peat subsidence.
• Potential CH4 production in peat incubations was enhanced by PK treatments, both from field application and direct amendment.

Conclusions:

• Long-term NPK fertilization in this temperate bog ecosystem leads to increased CH4 emissions.
• Observed changes are attributed to vegetation shifts, enhanced decomposition, and direct nutrient impacts on microbial CH4 production.
• Nutrient deposition significantly alters peatland functioning and greenhouse gas release.