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#S-shaped curve

5 public questions tagged with this topic.

The graph of logistic growth includes a phase called:

Positive acceleration is a recognized portion of a sigmoid logistic trajectory: early in growth, the absolute increment rises as more reproducing individuals are added. However, lag phase is also commonly named in descriptions of logistic curves, making this item non-unique as written. After the inflection near K/2, negative acceleration leads toward the upper asymptote or stationary phase. Logistic predictions depend on assumptions that managers should not overlook. Carrying capacity changes with habitat and climate, and removing individuals may alter age structure, social organization, or genetic diversity. Thus an algebraic optimum is a benchmark, not a guarantee that a real harvested or conserved population will behave identically. The key idea is the direction of the trade-off or feedback, because that direction determines the population-level outcome. Field evidence should therefore be compared with the model assumptions before extending the conclusion to every species, habitat, or time period. Interpreting the example at the appropriate population scale keeps the causal mechanism distinct from a simple correlation or an absolute rule.

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 11

The shape of the logistic growth curve is:

The logistic growth curve is S-shaped when population size is plotted against time. Growth begins slowly if the population is small, accelerates as the number of reproducing individuals rises, then decelerates as density-dependent limitation intensifies. Population size eventually approaches carrying capacity, producing the upper flattening of the sigmoid rather than the continually steepening J shape of exponential growth. The logistic model is a deliberately simplified, density-regulated model. It assumes a constant intrinsic rate and carrying capacity, no time delay, and no age or spatial structure. Its value lies in exposing the feedback mathematically; real populations can oscillate, overshoot, or track a changing K when those assumptions fail. This causal chain is what makes the keyed content ecologically meaningful rather than merely definitional. This interpretation connects individual-level processes with measurable changes in survival, reproduction, recruitment, or abundance across the population. Field evidence should therefore be compared with the model assumptions before extending the conclusion to every species, habitat, or time period.

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 11