Passive rewilding refers to the spontaneous rewilding of ecosystems when land is left to its own devices. It can be applied intentionally, but the concept also includes cases when (agricultural) land is abandoned. Arguably, as a result of farmland abandonment in Eastern Europe and some other world regions, unintentional passive rewilding currently covers far more land than do other forms of rewilding. Passive rewilding involves no or very little human intervention and does not specify an explicitly desired historical baseline scenario to which the landscape should revert, or include deliberate reintroductions of keystone species.