Capitalized Value (at 5% interest rate) ($/acre)

2000 7000 18,000 5600 50,000


68,000 83,000

Source: Adapted from Gosselink, J. G., E. P. Odum, and R. M. Pope. 1973. The value of the tidal marsh. Working Paper No. 3. Urban and Regional Development Center, University of Florida, Gainesville, FL.

H. T. Odum even suggested how the calculation could be used to estimate losses in the life-support system due to pollution. Using a human population figure from the late 1960s and an average global ecosystem metabolism, he calculated that

Each human's portion of the earth's life-support system is 1.7 X 10E5 g oxygen or 4 times this amount of energy (6.8 ¥ 10E5 kcal) processing by the system daily. Every time someone discharges about 380 pounds of organic waste per day he has diverted the life-support fraction of one person. If the substances are toxic, the amplifier destructive action is much greater. Large storages of oxygen and carbon in air and sea protect us from immediate difficulty with them, but we use their flows as an index to our disturbance of nature.

The life-support calculation approach was used in a classic paper on valuation of coastal wetlands (Gosselink et al., 1973). This paper was important because it provided the first comparison of different methods for calculation of ecosystem values (Table 8.5). The life-support approach provided the highest estimate of value. Of particular interest, the life-support value was higher than the component summations of individual values. This result attracted criticism from economists (i.e., King et al., 1979) and, in particular, an interesting exchange of opinions is recorded among Shabman and Batie (1978, 1980) and H. T. Odum (1979) and E. P. Odum (1979b). H. T. Odum and Hornbeck (1997) provide a review of the issue of saltmarsh valuation and update the early calculations by incorporating emergy analysis. The basic difference of opinion seems to be that some workers feel that the life-support

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