Paper No. 4
Presentation Time: 8:45 AM
ECOSYSTEM RESPONSE TO HYDROLOGIC STRESS—STUDIES IN AUSTRALIA AND THE UNITED STATES
WELTI, Nina D., University of Natural Resources and Life Sciences, Institute of Hydrobiology and Aquatic Ecosystem Management, Max Emanuel-Straße 17, Vienna, 1180, Austria, JAKEMAN, Anthony John, The Fenner School of Environment and Society, The Australian National University, Building 48A, Linnaeus Way, Canberra, 0200, Australia, LOCKINGTON, David, University of Queensland, Brisbane, 4072, Australia and HUNT, Randall J., Wisconsin Water Science Center, U.S. Geological Survey, 8505 Reaseach Way, Middleton, WI 53562, nina.welti@boku.ac.at
Ecosystem response curves are one way to represent how ecological systems respond to hydrologic stress. There are multiple ecosystem response curves for any given area under hydrologic stress, any of which may be an important determinant in a societal decision. Ecological response curves may respond in piecewise linear fashion, or as a continuous function in stress and response. Response curves may be a step-function where a threshold is passed and the change happens quickly and may or may not be reversible, following the concepts of ecosystem stability and resilience. Cumulative stress may build up to this “tipping point” which can cause a change or set of changes which could occur non-linearly. However, societal (and policy) decisions involve more than abiotic quantification of water storage and flow. A more encompassing ecohydrological view facilitates a more rounded policy framework that has flexibility to accommodate multiple social drivers, and one that can accommodate an "ecosystem improvement" rather than single species improvement.
Previous work by the US Geological Survey at the Northern Temperate Lakes research site will demonstrate the non-linearity and impact of ground-surface water interactions on the ecosystem. This talk will present upcoming studies in southeastern Australia and midwestern United States in which ecosystem response functions will be generated based on various biotic parameters, with the ultimate goal of incorporation into a policy framework at the catchment scale. In the proposed projects, hydrology and ecology will be evaluated together in order to fully understand the multiple impacts and thresholds which impact ecosystem responses to water-related stressors. By comparing water-rich areas with water-poor areas, it is our goal to demonstrate the variability of ecosystem responses.
