9415987 Goldstein This U.S.-Brazil Cooperative Science Program supports travel expenses related to the visits of Drs. G. Goldstein, Univ. of Hawaii, F. Meinzer, Hawaiian Sugar Planters Association, and P. Rundel and P. Jackson, Univ. of California Los Angeles, to Brazil. They will be working with Dr. A. Franco, of the Univ. of Brasilia and his students, on determining the extent of temporal and spatial partitioning of soil water and nutrient resources among representative woody plant species of a cerrado of central Brazil. They also propose to examine related above ground processes, such as long term water use efficiency, nitrogen use efficiency, and other ecophysiological parameters as measures of resource use and competition. Stable hydrogen isotope techniques will be used to address the question of soil water resource partitioning. Stable nitrogen isotopes will be used to distinguish modes of nitrogen acquisition among species (i.e. nitrogen fixers from non fixers). To integrate below ground and above ground processes, stable carbon isotopes will be used to assess long-term intrinsic water-use efficiency. Gas exchange measurements will be used to determine the mechanisms by which variation in water use efficiency is achieved. Representative woody plant species with different patterns of leaf production and other characteristics will be selected for the study. ***
