The spatial organization of dielectric barrier discharges operating at atmospheric pressure in the presence of complex wood substrates was analysed using optical imaging, current–voltage (I–V) characteristics, and optical emission spectroscopy combined with a collisional–radiative model to extract the average electron energy. The structural inhomogeneities of selected wood species produced non-uniform light emission patterns while maintaining homogeneous-like I–V characteristics and spatially uniform average electron energy. Based on a simple electrical model of the discharge, this localization was ascribed, at least partially, to a spatial modulation of the relative dielectric permittivity on 'early' versus 'late' wood affecting the local voltage applied to the gas, and thus the local discharge current.