The effective implementation and development of conservation schemes to which participation of forest owners is voluntary, requires an understanding of forest owners’ views on measures to safeguard forest biodiversity. The Forest Biodiversity Program for Southern Finland is currently the most important instrument of voluntary forest conservation in Finland. The aim of this study is to explore what kind of methods the forest owners are willing to implement to safeguard biodiversity in their own forests and to identify forest owner groups based on these views. The aim is also to compare forest owners’ values, attitudes, endorsement of an ecological worldview and objectives for forest ownership as well as the background characteristics in these groups. The data were collected in 2015, by a nationwide mail survey sent to 3000 Finnish family forest owners (n = 1035). Five forest owner types were identified: Conservationists, Moderate conservationists, Compensation oriented, Promoters of biodiversity through forest management and Uninterested. Previous experience of implementation of voluntary measures to safeguard biodiversity and positive attitudes towards conservation were important in explaining the willingness to adopt conservation measures. The results can be utilized in developing voluntary conservation programs and in targeting advisory services related to biodiversity protection to different forest owner groups more accurately. The results support the need for flexible voluntary conservation programs, including a large variety of mechanisms to protect nature values in family owned forests.