Improved simulation of poorly drained forests using Biome-BGC.

Area of Science:

• Ecology
• Biogeochemistry
• Ecosystem Modeling

Background:

• Boreal and terrestrial biogeochemical cycling heavily rely on forested wetlands and peatlands.
• Existing forest process models are typically designed for upland systems, lacking accuracy for poorly drained environments.

Purpose of the Study:

• To enhance the Biome-BGC ecophysiological process model for improved simulation of poorly drained forests.
• To incorporate key hydrological and physiological processes specific to wetland conditions.

Main Methods:

• Modified Biome-BGC to include lateral water inflow, variable drainage, anoxic soil effects on decomposition, stomatal closure in flooded soils, and bryophyte growth.
• Parameterization of model changes using published data.
• Validation of ecosystem-level model performance against field data from the northern BOREAS site.

Main Results:

• Simulations showed reduced decomposition and vascular plant growth in poorly drained forests compared to well-drained ones.
• Integrated bryophyte photosynthetic response aligned with published data.
• Simulated net primary production, biomass, and soil carbon accumulation generally agreed with field measurements.

Conclusions:

• The modified Biome-BGC model offers improved simulation capabilities for poorly drained forests, particularly regarding bryophyte contributions and carbon cycling.
• Model sensitivity analyses highlighted oxygen restriction and stomatal closure as key factors influencing net primary production in these environments.
• The model's limitations include an inability to simulate true wetlands with prolonged flooding and associated processes like organic soil formation and water table dynamics.