This study explores attitudes and preferences of Finnish non-industrial private forest owners for voluntary temporary forest conservation. The survey data, collected with the best–worst scaling and discrete choice methods, focus on a conservation program that incentivizes forest owners for biodiversity conservation and carbon sequestration. Forest owners are willing to conserve simultaneously biodiversity and forest carbon. They prefer non-profit organization as implementer of program, suggesting alternative to current implementation of forest conservation by authorities. Forest owners’ interest in forest conservation program increases with shorter contract and higher payment, both aspects being subject to preference heterogeneity. Forest owners differ in terms of the perceived importance of ecological, economic and social aspects of sustainability of forestry. Heterogeneity in attitudes and preferences stems from the size of forest land, gender, freetime home located on forest site, and place of residence.