PARENT SESSION
Symposium #16: Thresholds and non-linear responses in ecosystems: Understanding, sustaining, and restoring complex rangelands.
Sponsored by ESA Rangeland Ecology Section
Organized by: D.D. Breshears and J. Herrick.
Wednesday, August 8, 2001. 1:00 PM to 5:00 PM. Lecture Hall
Managing rangelands: implications of a paradigm shift in the ecology of arid and semi-arid ecosystems.
JOYCE, LINDA1, PYKE, DAVID2, HERRICK, JEFFERY3, 1 2 3
ABSTRACT- Arid and semi-arid ecosystems often exhibit unanticipated non-linear responses to environmental events and to management activities. While the importance of non-linear dynamics and thresholds has been widely documented, most rangeland management is still based upon the classical Clementsian understanding of succession and retrogression. The objectives of this talk are to review how recent ecological theory has been integrated into resource management, to identify the scientific and non-scientific limitations of this integration, and based on these limitations, to define types of research that land managers need to effectively apply modern ecological theory. The concept of multiple states and transitions is being integrated into revisions of the ecological site descriptions of the Natural Resource Conservation Service. The Bureau of Land Management is implementing the concept of thresholds in their qualitative rangeland health assessments. A more complete integration into resource management is limited by a poor understanding of states, transitions and thresholds in many arid and semi-arid ecosystems, and the lack of scientifically-based protocols for selecting management options when uncertainty exists about threshold dynamics. These limitations are compounded by administrative structures and competing resource demands. Ecological research is needed to clearly define environmental factors that control states, transitions, and thresholds for the variety of rangeland ecosystems. Adaptive management is paramount and will require collaboration among scientists and managers to successfully apply these increasingly complex models.
KEY WORDS: multiple states, threshold dynamics, uncertainty, adaptive management