Traditional resource management (TRM) systems in tropical forests can provide insights on sustainable resource use, but despite the growing prevalence of degraded tropical forest habitats, few studies have assessed the relationships between TRM and conservation in these environments. In Hawaii, the traditional gathering of native wild plants used for hula (chants and dance) and lei (garlands) is carried out in forests increasingly dominated by alien invasive species. Ethnographic methods and exploratory experimental harvests were employed to examine: gathering of hula plants in the past and present, ecological impacts of contemporary gathering practices of three important native hula species in alien-dominated forests, and relationships between traditional practices and past and modern conservation. Past gathering traditions included practices to increase and conserve hula plant populations. Harvest of Microlepia strigosa fern fronds significantly decreased M. strigosa cover over the short term. Cover of alien species significantly increased after frond-harvest of Sphenomeris chinensis. Regeneration of the fruit-harvested shrub, Melicope anisata, was significantly negatively correlated with the level of understorey invasive species. These results suggest that in Hawai‘i’s alien-dominated forests, gathering of some species may increase spread of alien invasive species or exacerbate regeneration problems caused by invasive species. However, some expert cultural practitioners have adapted traditional practices to ensure hula plant conservation by incorporating weeding of alien invasive species into their protocols. The re-strengthening and adaptation of traditional Hawaiian knowledge and social institutions to the modern context can provide opportunities to improve conservation of Hawai‘i’s culturally-important native plants and their habitats.