Policies aiming at improving biodiversity often consist of costly agri-environmental schemes, i.e. subsidized grazing or mowing of semi-natural areas. However, these practices have widely been found to be insufficient to mitigate biodiversity loss. Rewilding, i.e. restoring natural processes in self-sustaining biodiverse ecosystems, has been proposed as an alternative and is hypothesized to be a more cost-efficient approach to promote biodiversity conservation. Rewilding requires the availability of large natural areas which are not allocated for farming, forestry, and infrastructure to avoid potential conflicts over the use of the area. We perform an ex-ante private cost–benefit analysis of the establishment of four large nature reserves for rewilding in Denmark. We analyse the economic effects of changing from summer grazing in nature areas in combination with cultivated fields and forestry to the establishment of nature reserves in four case areas. We consider two scenarios involving conversion of agriculture and forestry areas into natural areas in combination with either extensive year-round cattle grazing or rewilding with wild large herbivores. In two case areas, it appears possible to establish large nature areas without incurring extra costs. Additionally, rewilding further reduces costs compared to year-round cattle grazing. Two opposing effects were dominant: increased economic rent occurred from the shift from summer grazing to year-round grazing or rewilding, while cessation of agriculture and forestry caused opportunity costs.

旨在改善生物多样性的政策通常包括成本高昂的农业环境计划，即对半自然地区的放牧或割草提供补贴。然而，人们普遍发现这些做法不足以减轻生物多样性的丧失。野化，即恢复自我维持的生物多样性生态系统中的自然过程，已被提议作为替代方案，并被认为是促进生物多样性保护的更具成本效益的方法。重新野化需要提供未分配给农业、林业和基础设施的大片自然区域，以避免该区域使用方面的潜在冲突。我们对丹麦建立四个大型自然保护区进行了事前私人成本效益分析。我们在四个案例地区分析了自然地区夏季放牧与耕地和林业相结合转变为建立自然保护区的经济影响。我们考虑两种情景，将农业和林业地区转变为自然地区，并结合全年广泛的牛放牧或野生大型食草动物的野化。在两个案例区域中，似乎可以在不产生额外成本的情况下建立大型自然区域。此外，与全年放牧相比，野化进一步降低了成本。两个相反的影响占主导地位：从夏季放牧转向全年放牧或重新野化导致经济租金增加，而农业和林业的停止则导致机会成本。