Vegetation emits large quantities of biogenic volatile organic compounds (BVOC). At remote sites, these compounds are the dominant precursors to ozone and sec-ondary organic aerosol (SOA) production, yet current field studies show that atmospheric models have difficulty in cap-turing the observed HO x cycle and concentrations of BVOC oxidation products. In this manuscript, we simulate BVOC chemistry within a forest canopy using a one-dimensional canopy-chemistry model (Canopy Atmospheric CHemistry Emission model; CACHE) for a mixed deciduous forest in northern Michigan during the CABINEX 2009 campaign. We find that the base-case model, using fully-parameterized mixing and the simplified biogenic chemistry of the Re-gional Atmospheric Chemistry Model (RACM), underesti-mates daytime in-canopy vertical mixing by 50–70 % and by an order of magnitude at night, leading to discrepancies in the diurnal evolution of HO x , BVOC, and BVOC oxidation products. Implementing observed micrometeorological data from above and within the canopy substantially improves the diurnal cycle of modeled BVOC, particularly at the end of the day, and also improves the observation-model agreement for some BVOC oxidation products and OH reactivity. We compare the RACM mechanism to a version that includes the Mainz isoprene mechanism (RACM-MIM) to test the model sensitivity to enhanced isoprene degradation. RACM-MIM simulates higher concentrations of both primary BVOC (iso-prene and monoterpenes) and oxidation products (HCHO, MACR+MVK) compared with RACM simulations. Addi-tionally, the revised mechanism alters the OH concentrations and increases HO 2 . These changes generally improve agree-ment with HO x observations yet overestimate BVOC oxida-tion products, indicating that this isoprene mechanism does not improve the representation of local chemistry at the site. Overall, the revised mechanism yields smaller changes in Published by Copernicus Publications on behalf of the European Geosciences Union. 8830 A. M. Bryan et al.: Modeling in-canopy chemistry during CABINEX 2009 BVOC and BVOC oxidation product concentrations and gra-dients than improving the parameterization of vertical mix-ing with observations, suggesting that uncertainties in verti-cal mixing parameterizations are an important component in understanding observed BVOC chemistry.