Local-scale Arctic tundra heterogeneity affects regional-scale carbon dynamics

Area of Science:

• Geosciences
• Ecology
• Biogeochemistry

Background:

• Polygonal ground dominates northern Alaska's landscape (65%).
• Tundra landforms influence carbon and nutrient cycling at fine spatial scales.
• Current models often aggregate fine-scale heterogeneity into dominant land cover units for large-scale projections.

Purpose of the Study:

• To assess the impact of tundra heterogeneity on soil carbon dynamics across various spatial scales.
• To determine the necessary spatial scale and landform representation for accurate ecological modeling in the Arctic.

Main Methods:

• Utilized legacy data from Utqiaġvik, Alaska (1973-2016) for model initialization, parameterization, and validation.
• Employed process-based biogeochemical models to simulate soil carbon dynamics.
• Applied hierarchical cluster analysis to an ensemble of 21st-century simulations.

Main Results:

• Simulation uncertainty increased with reduced representation of tundra heterogeneity and coarser spatial scales.
• A minimum of two tundra landforms (dry and wet) and a maximum 4km² spatial scale were identified.
• Uncertainties were minimized to below 10% with appropriate scale and heterogeneity representation.

Conclusions:

• Fine-scale tundra heterogeneity is crucial for accurate soil carbon dynamics modeling.
• Regional to Pan-Arctic ecological models require explicit representation of landscape features.
• Optimizing model scale and heterogeneity is vital for reliable climate change impact projections.