Payments for Environmental Services (PES) implemented in forest-dependent subsistence-based economies can involve significant restrictions on the traditional use of forest resources. This implies changes in human-nature relations that affect the way people relate to forests, including their perception of why the forest is valuable. Such effect is scientifically relevant since the way people perceive forest values might influence their motivations to implement conservation practices. In this paper, we estimate the impact of a Cambodian PES scheme designed to conserve biodiversity on the perception of forest values and assess the correlation between specific perceived values and conservation behaviors. We conducted a household survey with PES participants (N = 205) and with non-participants living in control villages selected with propensity-score matching (N = 120). Our results show that the program had a significant impact on the perceived forest values, which changed from subsistence-related to money-related values. Our results suggest that these changes have consequences on the program long-term effectiveness, as individuals emphasizing money-related values reported significantly more frequently that they would break conservation rules after an eventual end of payments. We conclude that the PES program changed the way local populations relate to nature, following the pattern of motivation crowding-out described in the social psychology literature.