Ecosystem ecology, landscape ecology, regional and global biogeochemical cycling, ecological applications of remote sensing and geographic information systems. Current research includes studies of ecosystem controls over biophysical fluxes (CO2, water and energy) within global grasslands and semiarid lands utilizing remotely sensed spectral data in conjunction with simulation models; scaling site-level ecology to landscape and regional scales in the alpine; quantitative methods that link spatial patterns and ecological processes at broad spatial and temporal scales.