On the use of ecological prices and system-wide indicators derived therefrom to quantify man's impact on the ecosystem

Abstract

Ecological prices and other system-wide, quantitative descriptors of ecosystem functioning are derived from the assumption that ecosystems allocate available resources efficiently among their components. However, ecological prices are not efficiency prices only, and using them does not require one to assume that the ecosystem is completely controlled by Man. The same prices balance flows of different biomasses in a multicomponent system. As such they play the role of exchange prices in a decentralized ecosystem. Properly defined with the help of ecological prices, the resulting ecosystem productivity is no less a significant indicator of ecosystem functioning than the national product is significant for assessing the functioning of an economy. Considerations of the values taken simultaneously by our proposed indicators and by their economic analogs are of much help in judging the desirability of projects with relatively mild environmental repercussions. These values are obtained from an integrated model of a system in which ecological and economic activities are intertwined. However, for the indicators to have an analytical meaning, the methodology should be applied to trace only those dynamic paths during which the system possesses unique, state-dependent, intensive properties. In other cases, a more comprehensive methodology - one which also pays due regard to the viability of the ecosystem - must supplement the analytical approach. This rather comprehensive methodology is scale-dependent and probabilistic in nature. While delineating relations between the structure of the system and its behavior, this method implies that efficiency and viability are two complementary rather than two commensurate attributes of a single entity. An outside observer may be guided by his own values in his attempts to weigh these features, but no inherent property of the system exists that supports his values unequivocally. Nevertheless, this paper proposes an approximation to overcome this difficulty and to estimate a quantitative limit to the rate of substitution between productivity and viability. Such a limit is also an intensive property of the simulated system, and the estimation of its value is shown to be crucial for studying the vulnerability of real ecosystems to severe Man-made disturbances.