Diurnal branch-level emission rates of biogenic volatile organic compounds (BVOC) including monoterpenes (MT) and sesquiterpenes (SQT) were determined at the University of Michigan Biological Station for the tree species balsam fir (Abies balsamea), red maple (Acer rubrum), red oak (Quercus rubra), paper birch (Betula papyrifera), white pine (Pinus strobus), red pine (Pinus resinosa), trembling aspen (Populus tremuloides), and big tooth aspen (Populus grandidentata). Significant MT emissions were found from four of the eight tree species. MT emissions from three of these were both light- and temperature-dependent and were approximately one order of magnitude greater than light-independent MT emissions. SQT emissions were identified from three of the eight tree species.