Data on the stated willingness to accept collective agri-environmental schemes for biodiversity conservation of European grassland farmers.

We present a data set on the stated willingness to accept collective agri-environmental schemes for biodiversity conservation of farmers managing grassland in six European case studies: Austria (AT), Switzerland (CH), Germany (DE), Estonia (EE), Ireland (IE), and Norway (NO). The survey was conducted between spring 2024 and 2025 and consisted of two parts: 1) a choice experiment; and 2) questions about farmers' and farm characteristics, attitudes, and preferences. In the choice experiment (Part 1), farmers were presented with 10 consecutive choice tasks. Each task consisted of three alternatives, two hypothetical designs for collective biodiversity conservation schemes at the landscape scale and an opt-out option, representing the status quo. The method helps to clarify farmers' policy design preferences and willingness to accept (WTA) collective biodiversity conservation schemes. Non-monetary attributes of the choice experiment included 1) group size (i.e., the number of partners a farmer works in a collective scheme with), 2) monitoring (i.e., execution of the biodiversity monitoring process), and 3) discretion (i.e., responsibility for management decisions at the farm to enhance biodiversity conservation: the farmers or an external consultant). The survey questions (Part 2) collected data on farmers' personal and farm characteristics, production orientation, attitudes towards collaboration, the environment, trust and self-efficacy, their risk, time, and social network preferences, as well as their income satisfaction. To reduce respondents' load, the survey data was matched with farm census data in instances where such data was available (CH, AT, NO).