82 • Technologies To Maintain Biological Diversity 



Figure 3-3.— Past and Projected World Population 



AD 



1 



1000 



1200 1400 1600 1800 2000 2100 



Year 



If the current growth in population continues, by the year 2000 

 more than 6 billion people will inhabit the world. With this 

 growth, irreversible environnriental degradation and loss of 

 biological diversity can be expected. 



SOURCE: World Resources Institute and International Institute for Environment 

 and Development, World Resources 1986 (New York: Basic Books, 

 1986), 



nection" by which U.S. and European beef con- 

 sumers are said to be causing loss of diversity 

 in tropical countries where forests are con- 

 verted to pasture. The very difficult task of iden- 

 tifying, measuring, and mitigating such nega- 

 tive economic-ecologic links between nations 

 is increasingly important as the world economy 

 becomes more and more international (30). 



The causal link between human population 

 size and diversity loss is clearer in developing 

 countries where population growth in rural 

 areas continues to be rapid, and land-use regu- 

 lations do not exist or are poorly enforced. Be- 

 tween 1980 and 2000, rural populations are ex- 

 pected to increase by 500 million in the 

 developing world (57) (figure 3-3). Where these 

 people continue to rely on extensive agricul- 

 ture, resource degradation and diversity loss 

 can be expected to accelerate. The harmful im- 

 pacts of population growth are also likely to 

 be exacerbated by development programs that 

 encourage large resettlements of landless peo- 

 ple into deserts or tropical lowlands without 

 providing the means to sustain agricultural 

 productivity in such difficult sites (42). 



CONCLUSION 



Circumstantial Evidence 



Biological diversity is abundant for the world 

 as a whole. More than 10 million species may 

 exist, but after more than 200 years of study, 

 scientists have only named and described some 

 1.7 million. Many of these species contain nu- 

 merous genetically distinct populations, each 

 with a different potential for survival and utility. 



The abundance and complexity of ecosys- 

 tems, species, and genetic types have defied 

 complete inventory or direct assessment of 

 changes. But from events and circumstances 

 that can be measured, it can be inferred that 

 the rate of diversity loss is now far greater than 

 the rate at which diversity is created. 



The circumstantial case is based on the 

 knowledge that each wild species and popula- 

 tion depends on the habitat to which it is 

 adapted. Diverse natural habitats are being con- 

 verted to less diverse and degraded landscapes. 

 On those sites, diversity has been reduced. The 

 sites that remain in a natural or nearly natural 

 condition are often fragmented patches that will 

 not support the diversity of larger areas. 



For domesticated agricultural plants and ani- 

 mals, the concern is genetic diversity, which 

 must be maintained by active husbandry. Farm- 

 ing systems with high genetic diversity are be- 

 ing replaced by new systems with much lower 

 diversity, so husbandry of many genetic types 

 is abandoned. Thus, gene combinations that re- 



