As a research focused in studies of conservation-induced displacement, ethnobiology has much to contribute towards generating more holistic understandings of the impacts of protected areas upon the lives of resource-dependent peoples around the globe. This paper presents the findings of a case study undertaken in Núcleo Itariru (Southern São Paulo state, Brazil), a unit of Serra do Mar State Park and the site of habitation for a population of approximately 700 peasants. Beginning in 2006, with the enactment of a new conservation initiative, peasants effectively became economically displaced, restricted from access to the natural resources upon which they base their lives and livelihoods. Utilizing ethnobotanical methods, in the form of a freelisting exercise and traveling herbarium survey, the study investigated local environmental knowledge systems as a means of evaluating the human/ landscape relationship in the locale. This paper highlights the value of such an approach for assessing the social and environmental dimensions of displacement, as a supplement to participant observation and ethnographic interviews, and for informing more sustainable conservation policies.