Extending conservation area networks is one of the most important measures in the struggle against biodiversity loss. Many areas with high conservation effect locate in privately owned land so establishing new protected areas on private land is often seen necessary. In many countries, protection of private land has traditionally been top-down controlled and landowners have had little or no power to affect conservation decisions. A good example is European Union’s Natura 2000 programme that led to conservation conflicts locally. To avoid conflicts and to increase acceptability of new protected areas located in privately owned land, many voluntary and incentive-based conservation measures have been already widely applied. Many scientific papers report of successful protection through voluntary measures and celebrate their ability to make conservation socially more acceptable. However, voluntary measures do not affect only the social aspects of conservation, but also the biodiversity representation, by limiting the different options for protection. We studied the second phase of Finnish Peatland Conservation Programme that was originally planned to be implemented as a statutory programme enabling land expropriations, but was later changed as a programme of voluntary protection. We constructed three structurally different spatial prioritization analyses for three different scenarios: 1. Total acceptance; the analysis removes all the opposed peatlands from the solution despite their biodiversity representation. 2. Partial acceptance; the analysis considers landowners’ resistance as a continuous variable seeking a balance between resistance and biodiversity’s irreplaceability, while trying to maximize biodiversity representation with connectivity considerations. 3. Forced protection; the analysis maximises biodiversity representation and connectivity without considering landowners’ resistance to protection. Preliminary results show that demanding landowners’ total acceptance in peatland protection means a solution with significantly lower biodiversity representation for legal protection than the two other solutions. Instead, considering landowners’ acceptance partially leads to the solution that enables protection of practically as much biodiversity as forced protection. Our study shows that when high quality substitutive areas do not exist, categorical consideration of landowners’ resistance to protection leads to inefficient use of conservation resources. To avoid this, the ecologically most valuable areas should be allowed to be protected in spite of landowners’ opinion. Our results also indicate that a great deal of landowners’ resistance can be considered without a major decline in biodiversity representation in the solution, if conservation planners integrate landowners’ opinions as part of a planning process from the very beginning.