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Common challenges and opportunities in riparian zone management along large Mediterranean-climate river.
Floodplain forests that line river corridors provide critical functions such as flood protection, nutrient filtration, and habitat for wildlife. These areas, called riparian zones, are far more important beyond the small proportion of land area they occupy. Most large European rivers, including the Rhône River in southeastern France, have been greatly altered by agricultural development, riverbank engineering for navigation, and dams that strongly modify natural flow conditions. Over several centuries, these cumulative impacts have severely reduced the extent of riparian zones and have confined them to highly altered river margins. As we understand more about how these critical ecosystems function, and we repurpose river margins as zones of recreation and aesthetic appreciation, we are challenged to restore ecological function while maintaining the economic values that rivers provide.
During my fellowship year with IAS and the Collegium de Lyon, I am investigating the ecological status and management options for the remnant floodplain forests that line the Rhône River. All along its length from Lyon to the Mediterranean Sea, the river’s banks remain highly altered by 19th century navigation walls that trap sediment and now support narrow ribbons of floodplain forest. This is an area of particular conservation value to many stakeholders in the Rhône Basin, including the Compagnie Nationale du Rhône (CNR), EDF, and l’Agence de l’Eau. In collaboration with Hervé Piégay (CNRS) and others at the École Normale Supérieure (Lyon), I am studying these floodplain forests using an approach adapted from my long-term research on the Sacramento River in California (USA), which like the Rhône is highly modified and drains a populated, water-limited region. In both systems I am conducting forest inventories of tree species present, their sizes and ages, and relation to environmental factors such as flooding to understand how the forest is developing in response to both natural and human controls on the river’s flow regime. With this information we plan to work with river managers to identify options that would maximize the forest’s ecological values while maintaining important functions such as flood control, navigation and water for irrigation and hydropower generation.
Beyond the scope of these two rivers, this study presents an opportunity to synthesize larger lessons for river management. How have the very different histories of river development in France and the U.S. manifested as human impacts on the ecosystem? And despite these separate histories and management contexts, are there common ecological principles and goals that we can apply to other large, regulated rivers? Finally how in these scenarios do we account for the accelerated climate changes taking place in both study regions and many others globally?
Ce résident fait partie du programme de mobilité européenne EURIAS
John Stella is an ecologist and Associate Professor of Forest and Natural Resources Management at State University of New York College of Environmental Science and Forestry (SUNY-ESF), and holds an adjunct appointment in Geography at Syracuse University. His research interests focus on riparian ecology and management of river corridors, and his research approaches includes field studies, tree-rings, stable isotope biogeochemistry, and landscape analysis. He earned his Ph.D. in Environmental Science, Policy and Management from the University of California, Berkeley. His research sites are located in semi-arid regions of California and the U.S. Southwest, Mediterranean Europe, and the Adirondack mountains of New York. More information about his research is available at http://www.esf.edu/fnrm/stella/
Stella, J.C., P. Rodríguez-González, S. Dufour, J. Bendix. 2013. Riparian vegetation research in Mediterranean-climate regions: common patterns, ecological processes, and considerations for management. Hydrobiologia 719:291–315. DOI: 10.1007/s10750-012-1304-9
Stella, J. C., J. Riddle, H. Piégay, M. Gagnage, and M. L. Trémélo. 2013. Climate and local geomorphic interactions drive patterns of riparian forest decline along a Mediterranean Basin river. Geomorphology 202:101–114. DOI: 10.1016/j.geomorph.2013.01.013
Bendix, J., and J.C. Stella. 2013. Riparian Vegetation and the Fluvial Environment: A Biogeographic Perspective. In Treatise on Geomorphology 12: Ecogeomorphology (D. Butler and C. Hupp, Eds.). Elsevier, San Diego.
Stella, J.C., J.D. Riddle, J.J. Battles, M.K. Hayden, and A.K. Fremier. 2012. Riparian forest dynamics on a large, regulated river (California, USA): impacts and implications for management. Proceedings of the Integrative Sciences and Sustainable Development of Rivers (IS Rivers) Conference, Lyon, France, 26–28 June 2012. http://www.graie.org/ISRivers/actes/pdf2012/1B109-237STE.pdf
Stella, J.C., M.K. Hayden, J.J. Battles, H. Piégay, S. Dufour, and A.K. Fremier. 2011. The role of abandoned channels as refugia for sustaining pioneer riparian forest ecosystems. Ecosystems 14: 776–790. DOI: 10.1007/s10021-011-9446-6
Harper, E.B., J.C. Stella, A.K. Fremier. 2011. Global sensitivity analysis for complex ecological models: a case study of riparian cottonwood population dynamics. Ecological Applications 21: 1225–1240. DOI:10.1890/10-0506.1
Stella, J.C., J.J. Battles, J.R. McBride, B.K. Orr. 2010. Riparian seedling mortality from simulated water table recession, and the design of sustainable flow regimes on regulated rivers. Restoration Ecology. 18(S2): 284–294. DOI: 10.1111/j.1526-100X.2010.00651.x