Trends in water use efficiency, and tradeoffs between growth and function for riparian trees undergoing climatic drying

Organização: Centro de Estudos Florestais e Centro de Ecologia Aplicada Prof. Baeta Neves
Data: 5 de março de 2014 :: 12h30 - 13h30
Local: Sala PF 1.6 (Antigo Auditório de Florestal)

Orador: John Stella, College of Environmental Science and Forestry, State University New York, E.U.A.

Riparian ecosystems in water limited regions are under stress worldwide from river modifications and climate change. Coupled with tree-ring studies, stable isotopes of the common elements of oxygen and carbon hold promise as tracers to understand how changing environmental conditions affect the physiological function of riparian trees over the scale of decades. I will present several recent studies that apply common stable isotope methods within a novel context, semi-arid riparian ecosystems in several tributaries to the Rhône River basin in southeastern France. In the first study, we compared tree-ring growth and source water use for Populus nigra and Fraxinus excelsior within a floodplain that had experienced channel incision and a lowering of the water table. In the second study, we analyzed growth and stable carbon isotopes in riparian P. nigra tree rings to identify shifts in water use associated with forest decline following in-stream gravel mining and meteorological droughts. Together, these combined results indicate that these semi-arid riparian woodlands are vulnerable to multiple physical drivers, but that the severity of impacts is conditioned by interactions between drivers at different scales, including regional climate variability, reach-based hydrogeomorphic alteration, and local lithological controls.