Design elements of monitoring programs: The necessary ingredients for success.

Natural resource managers must know the condition of resources entrusted to their steward-ship so that they can maintain unimpaired resources and know when to restore impaired ecosystems. Resource monitoring programs should be designed to provide indications of ecosystem health, define limits of normal variation, identify abnormal conditions, and suggest potential agents of abnormal changes. Development of a conceptual model that identifies all ecosystem components and their relationships is the first step in the design of such a diagnostic monitoring program. Design studies, with field testing on each selected system component, are required to determine the parameters to be measured and to establish monitoring protocols. The best approach to diagnostic monitoring appears to be based on the population dynamics of selected species relative to physical and chemical environmental factors. Both management and monitoring of natural ecosystems need to be recognized as experimental endeavors, and thus approached in an iterative fashion with the scientific method to reduce uncertainty and cost.