A particularly interesting, difficult and debated issue is how naturalness relates to the author's understanding and treatment of wilderness areas. Ecosystem management and park and wilderness stewardship are some of the last few subject areas in relation to which the authors could say that the term 'naturalness' still plays a direct and indirect role as a common reference and 'guiding principle'. The functional paradigm is developed as an alternative to an unsatisfying paradigm wherein "naturalness" has been the guiding principle. Ecology as a scientific field has close bonds to environmental issues. One may say that environmentalism and ecology have common aspects that share a destiny. 'Ecology' and 'ecological' are often used as normative concepts. In the late nineteenth century there was an agreement that the relationships in ecology could not be understood in terms of mechanistic and passivist conceptions and theories.