Possibilities and limitations of passive restoration of heavily disturbed sites

Passive restoration, which relies exclusively on natural processes and technical reclamation, which intervenes strongly into the restoration process, represent the extremes of a restoration action continuum. Between the extremes, we consider various degrees of active restoration. We suggest a general scheme to determine which approach to use based on site conditions, landscape context and societal circumstances. We conclude that passive restoration should usually be preferred in smaller sites with low abiotic stress and moderate productivity that are recovering from moderate disturbances. A passive approach may also be preferred in those landscapes that are less altered by humans, where target species are common and both invasive aliens and strong competitive generalists are rare. In such landscapes, passive restoration may succeed even if initial disturbances are intense. Potential of passive restoration has not yet been fully utilised. Passive restoration is viable economically and can produce multiple social and ecological benefits.