Abstract

Naturalness is a scientific concept that can be evaluated and quantified Intactness or integrity of ecosystems can be defined and assessed in similar ways. Three indices of naturalness are proposed: the degree to which the system would change if humans were removed; the amount of cultural energy required to maintain the functioning of the system as it currently exists; and the complement of native species currently in an area compared with the suite of species in the area prior to settlement. These indices are complementary and provide a conceptual framework for evaluating naturalness. The latter two can be quantified.