The International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.
This award will support a twenty-two-month research fellowship by Dr. Amy E. Zanne to work with Dr. Mark Westoby at Macquarie University in Australia for eleven months, and with Dr. David Ackerly at the University of California, Berkeley for eleven months.
Existing theory suggests xylem hydraulic conductance (related to vessel diameter) should be negatively related to mechanical strength (related to wood density and vessel wall thickness) and the ability to avoid drought-induced embolisms (air bubbles blocking water flow). It is unclear whether these hydraulic traits are tightly linked to the orthogonal spectra of leaf and twig size or leaf structure and longevity, or whether they represent their own major spectrum of trait variation. This 22-month project quantifies how these traits differ across seasons, annual rainfall, and species biogeographic histories. It also examines relationships between plant hydraulics and these other major spectra. Studies of plant trait spectra form the basis for much of the work in the Westoby and Ackerly labs. The project will be conducted at sites along a coastal to inland rainfall gradient in New South Wales, Australia, and hydraulic traits will be measured during two summer and winter seasons. Many key leaf properties have already been documented at these sites (e.g. leaf lifespan, structure, size, nutrient content, and gas exchange rates), making them ideal locations for this project. The project will entail three steps. First, trait variation will be evaluated relative to site rainfall and season. Second, species plasticity will be examined on seedlings of species from the two sites varying widely in hydraulic properties. Finally, species traits will be compared across sites in Australia based on species biogeographic histories, using analyses from Ackerly's lab. Dr. Westoby will support field and laboratory research in Australia, and Dr. Ackerly will support biogeographic analyses.
This project builds important conceptual bridges between plant hydraulics and other key plant trait spectra and will complement ongoing projects in Australia (Westoby) and California (Ackerly). It will substantially increase understanding of plant responses to changing environments (relevant for predicting global climate change impacts).
