Peatland Carbon Balance: Water Table & Decomposition (2D)

Hydrology

Water table depth 40 cm

Soil temperature 12.0°C

Peat & Vegetation

Vegetation productivity 1.00×

Peat organic-carbon content 45%

Live Readout

GPP uptake

0 g C/m²/yr

Decomposition

0 g C/m²/yr

Net carbon balance

0 g C/m²/yr

Peatland state

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Model time

0.0 yr

Cumulative Δ carbon

0 g C/m²

How it works

A peatland's net carbon balance is the tug-of-war between two real fluxes:

GPP  = NPP_max · prod · f_moisture(WT)
f_moisture = exp(-(WT-WTopt)²/2σ²)  [×exp(WT/18) if WT<0, flooded]

Decomp = k_aero·Q10·C_cm·A_active(WT)  +  k_anaero·Q10·C_cm·D_anox

A_active(WT) = L·(1 - exp(-max(0,WT)/L))   (O2-limited aerobic pool)
Q10 = 2.0^((T-10)/10)                       (temperature response)

Net balance = GPP − Decomp
  Net > 0  →  peat accumulates  →  CARBON SINK
  Net < 0  →  peat oxidises     →  CARBON SOURCE

This is the documented peatland mechanism: a high water table keeps peat waterlogged and anoxic, so decomposition is slow (10–50× slower than in oxygen) and the peatland banks carbon for millennia. Drain it — lower the water table — and a thickening aerobic (oxic) layer decomposes fast, flipping the same peat column from a multi-century carbon sink into an active CO₂ source. Warmer soil accelerates decomposition further via a Q10 response; richer, denser peat (higher %C) has more carbon exposed to that oxic layer per centimetre drained.

Cross-section — brown = oxic (aerobic) peat above the water table, releasing CO₂ bubbles; blue-grey = waterlogged (anoxic) peat below it, decomposing far more slowly.
Flux bars — instantaneous GPP (green, carbon in) vs. total decomposition (orange, carbon out).
Balance trace — net flux over simulated model-years; the shaded band flips from green (sink) to orange (source) exactly when GPP crosses decomposition.

Oxic (aerobic) peat Waterlogged (anoxic) peat GPP / net sink Decomposition / net source