The implementation of nature conservation policy in the EU is often based on contracts between public authorities and landowners. We model these contracts in the presence of adverse selection and moral hazard when the outcome is uncertain. The results show that agents, who have high probability to reach a higher level of conservation, should be offered a contract where transfers depend on the final outcome with a bonus for a high state. When conservation measures are correlated with forest management, we show that the contractual measures involve distorded tranfers. Finally, we analyze the payment mechanisms used in France and Denmark and show that these mechanisms result in overcompensation and underperformance since they do not take the problem of moral hazard and natural variability into account.