Figure 1.

A general model for incorporating biotic disturbance in ecosystem models. A typical ecosystem model predicts GPP based on enzyme kinetics or light-use efficiency and is closely coupled to transpiration through stomatal regulation. Plants then allocate stored carbon to leaf, root and stem pools minus construction costs (growth respiration, R_g). Maintenance respiration (R_l, R_s and R_r) and turnover then deplete each of these pools to CO₂ and soil organic matter respectively. Biotic disturbances (red font) act by altering one or more of these flux terms (red valves): For leaves and roots this is through a percent (%) acceleration of turnover rates; for sapwood a % hydraulic reduction; for heartwood a % loss of physical strength and for storage a % loss of inputs.