Context and hierarchy in Aldo Leopold's theory of environmental management

During the 1930s, Aldo Leopold recognized that resource management, activities designed to maximize sustainable production, may damage their larger environmental context. His land ethic can be understood operationally as also requiring environmental management, which shows concern for the ecological context in which resource-producing units are embedded. Leopold introduced this idea metaphorically in Thinking Like a Mountain. He there recognized that human individuals consider their actions in short frames of time whereas the mountain - the larger ecological community - must ‘think’ in the longer frames of ecological time. Theoretically, he expressed this idea by incorporating community ecology into his management model. Leopold's work significantly anticipates hierarchy theory, an important application of general systems theory to ecology. Like Leopold, hierarchy theorists model nature as smaller, fast-changing subsystems embedded in larger, normally slow-changing systems that environ the subsystems. Smaller systems are constrained by the larger system of which they are the parts; individual elements of smaller systems, however, are too short-lived to affect important changes in the larger system. Elements of smaller systems, therefore, affect the larger system only as contributors to trends among their cohorts. Managerially, this implies that environmental management should focus on trends in the behavior of parts and that ‘ecological breakdowns’ such as the dust bowl occur when rapid changes in social trends overbound the parameters of normally slower change in larger systems. The concepts of hierarchy theory, especially the emphasis on levels of dynamically related elements changing in different scales of time, hold promise to make more concrete the important insights of Leopold's land ethic. The hierarchical approach is applied to the problems of nutrient loading in the Chesapeake Bay and its effects on submerged aquatic vegetation. Leopold's land ethic and the hierarchical model both imply that environmental policy must be formed in two distinct stages, with the primary stage determining limits or constraints inherent in ecological systems. Maximizing criteria are then applied to choose among those resource-use plans which fulfill the prior ecologically based constraints.