Plant community age as a measure of sensitivity of ecosystems to disturbance

A method is outlined based on sound ecological principles which provides an objective evaluation of the ecological cost of human activities in natural ecosystems. The cost is judged in terms of the potential time needed to replace destroyed terrestrial vegetation. The approach involves, firstly, the development of a classification for all terrestrial vegetation types within a region of study. However, an existing classification may be used and, when necessary, modified to suit the purposes desired. Secondly, after the major types are identified, they are assigned an ordinal rating which is proportional to their age of development. Finally, once a study region has been evaluated the fractional area of each class is multiplied by its rating and the products are summed for any given unit area, e.g. 2/sup 2/ kilometers. The latter information, which defines the ecological sensitivity of a region on a unit area basis, can be mapped and thus provide a sound basis for land-use planning decisions. While the method provides an objective evaluation of the landscape it is recognized that other criteria must also be considered in making any comprehensive planning proposals.