Estimate logistic K from a resource pool, then headroom and dN/dt at the current N.
| K | – |
| Headroom | – |
| dN | – |
Use this calculator for a back-of-envelope logistic population when you can express a resource stock and how much one individual uses.
The calculation is: K = resource ÷ per-capita use. Headroom is K − N. Instantaneous change is dN = r N (1 − N/K), the discrete snapshot of the logistic equation. r can be negative (decline). If N exceeds K, dN is negative.
Resource and per-capita must use the same unit (kg of forage, litres of water, and so on). This is not a spatial home-range model.
Resource: Total usable stock in one period.
Per capita: How much one individual uses in that same period.
N: Current population.
r: Intrinsic growth rate per time step (e.g. 0.1 is 10% when N is far below K).
K: Carrying capacity in the same units as N.
Headroom: How many individuals fit before K.
dN: Change in N over one time step at the current point.
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