Extensive harvesting of trees during forestry operations dramatically impacts sources and quantities of organic matter and patterns of biodiversity in streams. To minimise these impacts, ‘Best Management Practices’ (BMPs) are used for harvesting, including selective removal of trees and restrictions on harvesting in defined riparian zones. Most research into the effects of (i) timber harvesting and (ii) harvesting BMPs has been done in temperate or boreal regions. However, harvesting BMPs are now widely adopted in forestry practices in other climates with little research to evaluate their effectiveness. We exploited a multiple-paired (control-impact) catchment study to assess the effects of selective harvesting of Eucalyptus spp. and associated BMPs on standing stocks of organic matter, densities of invertebrate detritivores, and composition of invertebrate assemblages in four subtropical streams near Coffs Harbour, New South Wales. Despite differences in the proximity of harvesting to stream among catchments, we found no effect of harvesting on the biomass of detritus or densities of both collector-gatherers and detritivores. At the scale of whole streams, harvesting had no effect on species richness or beta diversity. Among streams, harvesting did not influence species richness. However, effects on beta diversity were inconsistent among streams, apparently associated with their flow regimes (brief decreases in beta diversity in intermittent streams; increased beta diversity in permanent streams). Among within-pool replicates, harvesting had little effect on species richness and variable effects on beta diversity, but only in streams with increasingly intermittent flow. Overall, the lack of major and consistent effects of selective harvesting suggests that the adopted BMPs effectively mitigate impacts in subtropical streams. Nonetheless, a multi-scaled approach to assessing anthropogenic disturbances is necessary because impacts at fine spatial scales are likely to be apparent before broader impacts are detected yet will be missed if not considered in the search for major broad-scale effects.