Comparison of S and J curves. Note that they are similar at low population density. As the population increases, the curves diverge more. The divergence is a measure of environmental resistance. Thus, population growth levels off at K because of environmental resistance.
Environmental resistance can be density independent or density dependent.
G. Environmental Resistance - Density Dependent Population Controls. These are factors whose magnitude is dependent on the size of the population. These operate irrespective of the size of the population. The magnitude of the effect is not related to the size of the population. Check the graph and note the similarity in early S and J curves.