Abstract
The degree of naturalness of ecosystems has often been evaluated with respect to dependence on culture in native and introduced plants and in types of vegetation. The concept of “potentially natural vegetation” is briefly discussed. There are no longer any absolutely natural ecosystems on Earth, but a gradient from near-natural to entirely man-made ecosystems is outlined. The six degrees proposed are (1) near-natural, (2) mildly modified, (3) semi-natural: managed but with native species, (4) semi-cultural: not totally man-made but with species selected by man, (5) cultural: entirely man-made except for weeds and some animals, (6) near- sterile: some urban and industrial sites. Changes in impact are frequent, chiefly toward greater impact but in some cases lesser, through less intense management or abandonment. In the latter case, long-lasting residual effects of the former impact may prevent or slow down development toward truly “potentially natural vegetation”.

This publication has 5 references indexed in Scilit: