Observational studies suggest that local thunderstorms over land are more intense than those over the ocean.  Diverse characteristics of land surfaces, such as a higher surface Bowen ratio, increased spatial and temporal heterogeneity, and higher aerosol concentrations have been proposed as potential drivers of the land-ocean convective intensity difference, but the relative importance of each of these characteristics remains unclear.  Here, we use high-resolution simulations with a cloud-system resolving model in the idealised state of radiative-convective equilibrium (RCE) to assess how characteristic features of the land surface influence the intensity of local thunderstorms. We confirm previous results demonstrating that simulations with imposed high and low surface Bowen ratio (SBR) over a homogeneous surface show no difference in high percentile updraft velocity, suggesting that cloud-base heights by themselves do not sufficiently explain the differences in intensity of thunderstorms over land and ocean surfaces. We further investigate how spatial heterogeneity in SBR and surface roughness affect convective intensity within our idealised RCE state, with a particular focus the effects of heterogeneity of different scales on the cloud size distribution.