Priority maps for biodiversity conservation are increasingly aimed at their implementation by local governments in their land use decision making. However, these biodiversity planning products usually rely on the implicit assumption that biodiversity and related concepts are the appropriate ones for communicating the need to safeguard nature. We investigated the level of understanding of the terms “biodiversity” and “sustainability” of decision makers in four South African coastal municipalities and identified the prevalent frames of interpretation they held regarding nature conservation in land use planning. We demonstrate that understanding of the term “biodiversity” is very limited; however, the term is well linked to the natural environment. Conversely, the concept of “sustainability” is clearly established—but only marginally connected to nature. The frame analysis showed that the preservation of nature is regarded as fundamentally in opposition to socio-economic development. Conservation is frequently interpreted as being a socially unjust endeavor, disrespectful toward people and lacking realism. We use these insights to provide recommendations on how conservationists should proceed to reframe biodiversity issues in order to more effectively mainstream conservation plans into local land-use decision making.