Ch. 1— Summary and Options for Congress • 5 



Pholo credit: H litis 



A dense stand of Zea diploperennis in Sierra de Manantalan, 

 Jalisco, Mexico. This ancient wild relative of corn could 

 be worth billions of dollars to corn growers around the 

 world because of its resistance to seven major diseases 

 plaguing domesticated corn. 



functions that depend on the complex interac- 

 tions of ecosystems and the species that sup- 

 port them. 



Diverse wetlands provide productive and pro- 

 tective processes of economic benefit. Millions 

 of waterfowl and other birds of economic value 

 depend on North American wetlands for breed- 

 ing, feeding, migrating, and overwintering. 

 About two-thirds of the major U.S. commer- 

 cial fish, crustacean, and mollusk species de- 

 pend on estuaries and salt marshes for spawn- 

 ing and nursery habitat. Wetlands temporarily 

 store flood waters, reducing flow rates and pro- 

 tecting people and property downstream from 

 flood and storm damage. One U.S. Army Corps 

 of Engineers' estimate places the present value 

 of the Charles River wetlands (in Massachu- 

 setts) for its role in controlling floods at $17 mil- 

 Hon per year. Although placing dollar values 

 on such ecosystem services is problematic and 

 reflects rough approximations, the magnitude 

 of the economic benefit stresses the importance 

 of these often overlooked values. 



Humans also value diversity for reasons other 

 than the utility it provides. Esthetic motivations 

 have played important parts in promoting ini- 



tiatives to maintain diversity. Cultural factors, 

 as reflected in the way Americans identify with 

 the bald eagle or the American bison or how 

 plants and animals form a fundamental aspect 

 of human artistic expression, illustrate these 

 values. 



Forces that contribute to the worldwide loss 

 of diversity are varied and complex. Histori- 

 cally, concern for diversity loss focused on com- 

 mercial exploitation of threatened or endan- 

 gered species. Increasingly, however, attention 

 has been focused more on indirect threats that 

 are nonselective and more fundamental and 

 sweeping in scope. 



Most losses of diversity are unintended con- 

 sequences of human activity. Air and water pol- 

 lution, for example, can cause diversity loss far 

 from the pollution's source. The decline of sev- 

 eral fish species in Scandinavia and the near 

 extinction of a salmon species in Canada have 

 been attributed to acidification of lakes due to 

 acid rain. Population growth in itself may not 

 be intrinsically threatening to biological di- 

 versity. A populous country like Japan is an 

 example of how a high standard of living, ap- 

 propriate government policies, and a predom- 

 inantly urbanized population can limit the rate 

 of ecosystem disruption. However, when pop- 

 ulation growth is compounded by poverty, a 

 negative impact is characteristic. In many trop- 

 ical developing countries, high population grovvrth 

 and the practice of shifting agriculture employed 

 by peasant farmers are considered the great- 

 est threats to diversity. 



This report assesses the potential of diversity- 

 maintenance technologies and the institutions 

 developing and applying these technologies. 

 But maintaining biological diversity will de- 

 pend on more than applying technologies. Tech- 

 nologies do not exist to re-create the vast 

 majority of ecosystems, species, and genes that 

 are being lost, and there is little hope that such 

 technologies will be developed in the foresee- 

 able future. Therefore, efforts to maintain diver- 

 sity must also address the socioeconomic, po- 

 litical, and cultural factors involved. 



