Exponential and logistic population models
Simple growth equations expose assumptions about density dependence.
Key knowledge
Exponential growth assumes a constant per-capita net growth rate. The logistic model adds a linear reduction of that rate with population size relative to a carrying-capacity parameter. These idealized models help compare density dependence rather than predict every population trajectory.
Values and equations
dN/dt = rN(1 − N/K)
- N
- population size individuals
- t
- time chosen time unit
- r
- constant low-density per-capita net growth rate inverse time
- K
- positive carrying-capacity parameter individuals
Conditions and scope
- The displayed logistic equation assumes a closed population, constant r and K, and immediate homogeneous density dependence.
- Age structure, migration, delays, stochasticity and environmental change can require different models.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Source exponential/logistic equations and equal-resource-access assumption.
2026-10-10 · Checked the standard logistic expression and explicit model limits; no new population fit.
Entry details
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- bio-population-growth-models
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- university-reference.1
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- University reference