We study the management of a natural resource that supports ecosystems as well as human needs. The reduction in the resource base poses a threat of occurrence of catastrophic ecological events, such as the sudden collapse of the natural habitat, that lead to severe loss of biodiversity. The event occurrence conditions involve uncertainty of various types, and the distinction among these types affects the optimal exploitation policies. When uncertainty is due to our ignorance of some aspects of the underlying ecology, the isolated equilibrium states characterizing optimal exploitation for many renewable resource problems become equilibrium intervals, giving rise to hysteresis phenomena. Events triggered by genuinely stochastic environmental conditions maintain the structure of isolated equilibria, but the presence of event uncertainty shifts these equilibrium states relative to their position under certainty.