Fig. 2. Conceptual diagram illustrating the interaction of the range of variability for an ecological condition that reflects the disturbance of ecosystems by biophysical and human forces and their rate of recovery with the range of conditions that are considered socially acceptable. Figure 2A shows a hypothetical set of these relationships for some condition. We recognize four zones relative to the interaction of the two ranges: Zone i, which represents ecological conditions that would occur without investment/intervention to prevent them but that do not have social acceptance; Zone ii, in which the likelihood of occurrence is greater than the likelihood of acceptance; Zone iii, in which the likelihood of occurrence is less than the likelihood of acceptance; and Zone iv, which represents conditions that would not occur without investment/intervention to enable them even though a segment of society wants them. To the degree that the two ranges do not overlap, we can expect social pressure/negotiation to change the shape of the ecological probabilities curve. This negotiation leads to the range of variability actually experienced (Fig. 2B). The exact probability distribution can only be estimated, but there is always uncertainty, hence this distribution is represented by a fuzzy area between the two curves. Looking back in time, Fig. 2B would be called the historical range of variability. Looking forward in time, Fig. 2B would be called the future range of variability. It is important to recognize that the curve produced in Fig. 2B is potentially highly dynamic.