Citation:

Jones, K B., J D. Wickham, AND A C. Neale. USE OF THRESHOLDS IN LANDSCAPE ASSESSMENTS. Presented at Making the Linkages Through the Use of Environmental Indicators A Regional/State/Tribal and Office of Research and Development Science Topic Workshop, Kansas City, MO, May 17-20, 2004.

Impact/Purpose:

The primary objectives of this research are to:

Develop methodologies so that landscape indicator values generated from different sensors on different dates (but in the same areas) are comparable; differences in metric values result from landscape changes and not differences in the sensors;

Quantify relationships between landscape metrics generated from wall-to-wall spatial data and (1) specific parameters related to water resource conditions in different environmental settings across the US, including but not limited to nutrients, sediment, and benthic communities, and (2) multi-species habitat suitability;

Develop and validate multivariate models based on quantification studies;

Develop GIS/model assessment protocols and tools to characterize risk of nutrient and sediment TMDL exceedence;

Complete an initial draft (potentially web based) of a national landscape condition assessment.

This research directly supports long-term goals established in ORDs multiyear plans related to GPRA Goal 2 (Water) and GPRA Goal 4 (Healthy Communities and Ecosystems), although funding for this task comes from Goal 4. Relative to the GRPA Goal 2 multiyear plan, this research is intended to "provide tools to assess and diagnose impairment in aquatic systems and the sources of associated stressors." Relative to the Goal 4 Multiyear Plan this research is intended to (1) provide states and tribes with an ability to assess the condition of waterbodies in a scientifically defensible and representative way, while allowing for aggregation and assessment of trends at multiple scales, (2) assist Federal, State and Local managers in diagnosing the probable cause and forecasting future conditions in a scientifically defensible manner to protect and restore ecosystems, and (3) provide Federal, State and Local managers with a scientifically defensible way to assess current and future ecological conditions, and probable causes of impairments, and a way to evaluate alternative future management scenarios.

Description:

Identification and use of thresholds are potentially important additions to interpretations of ecological monitoring data. However, there are a number of issues related to defining and using thresholds in interpreting ecological data. Most of these issues center around the paucity of long-term data to establish thresholds or phase transitions in important ecological functions, as well as the fact that ecosystems and their associated processes change over time. In this presentation, we discuss issues related to the establishment of ecological thresholds.

Recent development in landscape assessment approaches provides a way to evaluate ecological conditions where both arbitrary and ecosystem-based thresholds are used. In this presentation, we demonstrate these approaches through case studies from the eastern United States. The approach permits an extension of thresholds developed for streams to the broader watershed or landscape context.

Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

Record Details: