The Structure and Functioning of Dryland Ecosystems—Conceptual Models to Inform Long-Term Ecological Monitoring

Miller, Mark

The National Park Service (NPS) has undertaken the task of developing long-term ecological monitoring programs for 32 ecoregional networks of parks that have significant natural resources. As part of this effort, each network will select “vital signs” that are intended to represent the overall health or condition of park ecosystems, known or hypothesized effects of stressors, or elements that have important human values. As an aid to the consideration and selection of vital signs for long-term monitoring in NPS units of the Colorado Plateau region, this report presents a literature synthesis and a set of diagrammatic conceptual models that summarize existing knowledge and hypotheses concerning the structure and functioning of dryland ecosystems. These generalized conceptual models describe functional relationships among key structural components of dryland ecosystems; effects of climate, natural disturbances, and anthropogenic stressors on the functioning of selected ecosystem processes; and how these drivers of ecosystem change interact to produce particular patterns of ecosystem dynamics. Because NPS policies dictate that monitoring data will be used to help sustain the integrity of park ecosystems, conceptual models in this report emphasize common processes and pathways of dryland degradation— with the intent that this emphasis will best highlight ecosystem attributes that should be monitored for purposes of sustaining ecosystem integrity. Although developed to support the identification of long-term monitoring needs in NPS units, information in this report is broadly applicable well beyond NPS management boundaries and should be of use to other organizations or persons involved in management, conservation, and monitoring of dryland ecosystems in the Colorado Plateau or bordering ecoregions.