These indicators, while useful, are insufficient for determining how the landscape is responding to water level, hydroperiod, and flow, because major changes in elevation may occur before degradation is reflected in such indicators. For example, a region in western Water Conservation Area 3 (Figure 2-1)– previously classified as “pristine” based on length- to-width ratio and perimeter-area relationships–has now been recognized as being “degraded” because the elevation difference between the ridges and sloughs is now about 20 cm, whereas historically the difference was between 30 and 90 cm (Sklar et al., 2003). To monitor the response of the ridge and slough system, it will be necessary to consider the topographic relationship between ridges and sloughs, as well as area, directionality, and connectivity of the landscape patterns.
Regardless of the mechanism(s) responsible for creation and maintenance of the ridge and slough and tree island patterns, performance measures must be developed so that these patterns can be monitored. Once there is sufficient scientific evidence to establish the role of flow and the flow rates required to maintain these landscape patterns, flow-related performance measures should be developed and added to the MAP. How these new performance measures are incorporated into the Restoration Plan will be a test of the plan’s ability to incorporate new information in a framework of adaptive management.