Nutrient Cycling - Biogeochemical Carbon & Nitrogen Dynamics

Ecosystem Type

Biome

Climate Conditions

Temperature (°C)

15°C

Soil Moisture (%)

50%

Atmospheric CO₂ (ppm)

420 ppm

Microbial Parameters

Microbial C:N Ratio

8:1

Carbon Use Efficiency

0.40

Decomposition Rate

0.05

Nitrogen Inputs

N Deposition (kg/ha/yr)

N Fixation Rate

0.20

Perturbations

Plant C

Litter C

Soil Organic C

Microbial C

NH₄⁺

NO₃⁻

Carbon & Nitrogen Pool Dynamics

Flux Diagram (kg/ha/yr)

Mineralization vs Immobilization

C:N Ratios & Limitation

Total C (t/ha)

Total N (kg/ha)

NPP (g C/m²/yr)

Soil Resp (g C/m²/yr)

Net N Min (kg/ha/yr)

N Limited?

Litter C:N

Critical C:N

Biogeochemical Coupling (MIMICS-CN Model Concepts)

Mineralization: Microbes release excess N as NH₄⁺ when litter C:N is below the critical ratio. Immobilization: Microbes take up inorganic N when litter C:N exceeds critical ratio (C:N > ~25). Critical C:N = Microbial C:N / Carbon Use Efficiency. Temperature accelerates decomposition and N mineralization in high-latitude ecosystems.