How many broadleaved trees are enough in conifer plantations? The economy of land sharing, land sparing, and quantitative targets

1. For biodiversity conservation to be an effective and significant social investment, non-marketed values of biodiversity conservation and its associated opportunity costs should be evaluated in monetary terms. 2. In this study, we measured the willingness to pay (WTP) for bird abundance using a choice experiment (CE) based on the random utility model. We performed a cost–benefit analysis to identify the optimal proportion of broad-leaved trees in conifer plantations on a volume basis to maximize the social benefits of bird conservation and wood production. 3. The results suggested that respondents to the CE were not satisfied with their current situation and preferred an increase in bird abundance. However, the estimated WTP indicated diminishing returns of bird conservation. More specifically, WTP first greatly increased before gradually experiencing decreasing marginal values, reaching its peak, and finally decreasing slightly with increasing bird abundance. 4. Optimization analyses...