Some plants strongly emit biogenic volatile organic compounds (BVOCs), such as isoprene and monoterpenes, in response to intense light and high temperatures. In this study, we collected the BVOCs emitted from the leaves of eight tree species - three deciduous trees that emit isoprene and five evergreen trees that emit monoterpenes - using the leaf-cuvette method with a portable photosynthesis measurement device (LI-6400, Li-Cor), and identified and quantified BVOCs using GC-MS (QP2010 SE, Shimadzu). At the same time, we also measured the net photosynthetic rate. In addition, we analyzed the pigment composition of the leaves for the eight tree species under three different light intensities: dark, low light, and high light. In the calculation of DPS (de-epoxidation state) of the xanthophyll cycle, which is used as an indicator of heat dissipation, differences in the amount of heat dissipation according to the light conditions were observed between species. However, these differences were not related to the differences between isoprene-emitting species and non-emitting species. This rejected the hypothesis that isoprene emission dissipates excess energy instead of heat dissipation. To further examine the relationship between photoinhibition and isoprene, we measured the diurnal variation in isoprene emission rates (nmol m^-2 s^-1) under high light at two field sites for adult trees and saplings of two species that are mainly isoprene-emitting species. At Site 1, we measured isoprene emission rates in the canopy of adult Quercus serrata under controlled light intensity conditions using the LI-6400 LED-controlled chamber. At Site 2, we used the LI-6400 Clear Top Chamber to measure the daily variation in isoprene emission from Populus nigra var. italica under natural fluctuating light. In the case of Populus nigra var. italica, the daily variation in isoprene emission rate was well-synchronized with the daily variation in sunlight intensity and net photosynthetic rate. These results indicate that isoprene synthesis is maintained during periods of high net photosynthetic rate under intense light, both in saplings and adult trees. Both Quercus serrata and Populus nigra var. italica are resistant to photoinhibition under strong sunlight in summer. In the future, we will further clarify the relationship between photoinhibition and isoprene emit.