["Journal of Agricultural Economics, Volume 77, Issue 1, Page 225-243, February 2026. ", "\nABSTRACT\nAlthough both protected areas and agri‐environment schemes (AES) aim to conserve biodiversity, the interaction between the two policy instruments is unknown. We investigate the effects of listing a region as a protected area (a regional nature park) on the uptake of biodiversity conservation AES within the region. Using panel data of all Swiss farms between 2005 and 2020, and survey data on 15 Swiss regional nature parks established between 2008 and 2018, we analyse the effects of park establishment on farmers' adoption of three types of AES for biodiversity conservation (action‐based, result‐based, and agglomeration) in a heterogeneity‐robust difference‐in‐differences framework. Overall, parks significantly increase the adoption of result‐based AES. Moreover, the park effect depends largely on the agricultural baseline where parks are established. In regions with relatively more intensive agricultural production and lower AES adoption beforehand, the establishment of parks increases the adoption of result‐based and agglomeration AES, evidencing synergies between the two policies. Such effects are not observed in regions with more extensive agricultural production and high AES adoption prior to park establishment. Moreover, the effects of park establishment increase over time. Therefore, when introducing a new policy aimed at integrating biodiversity conservation into agriculture, it is important to account for baseline situations and identify synergies between intended and existing policies.\n"]