acreage are alleged to increase as the number of wetland acres increase. On the 

 other hand, the author believes that the average returns to private development 

 and drainage of wetlands exhibits diminishing returns. Carriker believes that 

 high per acre wetlands preservation benefits (coupled with increasing returns 

 to wetlands preservation) underlie the enactment of the Virginia Wetlands Act 

 of 1972. This act seeks to protect ecologically productive Virginia wetlands 

 from development activities. Carriker provides empirical estimates of the dollar 

 values of returns to development activities as well as the per acre social 

 benefits conferred from the use of publicly owned wetlands for various 

 activities, such as recreational saltwater fishing. 



16. Hill, D. 1976. A modeling approach to evaluate tidal wetlands. Pages 

 105-116 in K. Sobel, ed. Transactions: Forty-first North American Wildlife 

 Management Institute. Was,hington, DC. 



The author discusses the amenity values provided by Atlantic estuarine and 

 coastal salt marshes of North America. These benefits are not quantified for 

 a real coastal wetland, but for a computer model of a wetland. The model 

 consists of a set of equations that define uses and values for biological, 

 physical, and chemical functions performed on Hypothetical Bay. Uses and outputs 

 include preservation of certain grasses ( Spartina alterniflora ) ; building and 

 operating a marina; clam, mussel, and sea worm harvesting; cod and flounder 

 harvesting; oyster harvesting; filling in the Spartina acreage; and discharging 

 waste-water into the bay. 



The highest per acre yield is provided by the construction of a marina to 

 support a cod-flounder fishery. But the salt marsh would not support a cod- 

 flounder fishery due to biological and physical constraints. The most valuable 

 feasible benefits provided by the salt marsh are generated by growing certain 

 grasses and harvesting clams and seaworms. Thus some of the uses of Hypothetical 

 Bay can be sustained indefinitely, others cannot. The author imputes preserva- 

 tion benefits for the grasses at $317 per acre for the Spartina alone; the other 

 grasses provide an additional $225 per acre. The model computes the changes in 

 the values of the outputs with changes in the various inputs. 



17. Luken, R.A. 1976. Preservation versus development: an economic analysis 

 of San Francisco Bay wetlands. Praeger, NY. 155 pp. 



Luken assesses the opportunity costs of foregone development for extant 

 San Francisco Bay area wetlands. He does not tackle the difficult problem of 

 imputing quantitative preservation benefits for these wetlands based on such 

 nonmarket wetland outputs as habitat provision for shellfish and finfish. The 

 author finds that only a fraction of these wetlands (49,000 acres out of a total 

 435,000 acres) have high development potential, primarily because of high 

 conversion costs or because the lands are already publicly owned. The latter 

 obstacle (high conversion costs due to public ownership) seems a bit out of place 

 in a study of the optimal allocation of resources. 



18. Friedman, J.M. 1977. The growth of economic values in preservation: an 

 estuarine case study. Coastal Zone Management Journal 3(2): 171-181. 



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