Ch. 5— Maintaining Biological Diversity Onsite * 111 



isons and provides a framework for all pro- 

 tected areas. 



Criteria for Selection of 

 Areas To Protect 



Protected areas can be located and managed 

 to protect biological diversity at three levels: 



1. at the ecosystem level: by protecting unique 

 ecosystems, representative areas for each 

 main type of ecosystem in a nation or re- 

 gion, and species-rich ecosystems and cen- 

 ters of endemism; 



2. at the species level: by giving priority to 

 the genetically most distinct species (e.g., 

 families with few species or genera with 

 only one species), and to culturally impor- 

 tant species and endemic genera and spe- 

 cies; and 



3. at the gene level: by giving priority to plant 

 and animal types that have been or are be- 

 ing domesticated, to populations of wild 

 relatives of domesticated species, and to 

 wild resource species (those used for food, 

 fuel, fiber, medicine, construction mate- 

 rial, ornament, etc.). 



Ecosystem Approacii 



Conserving ecosystem diversity maintains 

 not only a variety of landscapes but also broad 

 species and genetic diversity. Indeed, it may 

 be the only approach to conserving the many 

 types of organisms still unknown to science. 



A strategy to maintain ecosystem diversity 

 generally begins with the biogeographic classi- 

 fication system described earlier. The system 

 can be used to identify which ecosystem types 

 need to be acquired or designated to achieve 

 more complete protection of biological diversity. 



The extent to which diverse U.S. ecosystems 

 are represented within protected areas is be- 

 ing assessed on a State-by-State basis by the nat- 

 ural heritage inventory programs of the differ- 

 ent States (see ch. 9). Recent estimates of the 

 proportion of major terrestrial ecosystem types 

 that are not protected in the Federal domain 

 vary from 21 to 51 percent, depending on the 



size and number of each type thought to be 

 needed for adequate protection (13). 



The extent to which the world's terrestrial 

 ecosystems are included in protected areas has 

 been crudely estimated using the Udvardy bio- 

 geographic classification system, which divides 

 the world's land into 193 biogeographical prov- 

 inces. Since each province typically contains 

 many distinct types of ecosystems, the degree 

 to which province locations correlate to pro- 

 tected area locations gives only an approxima- 

 tion of where greater protection is needed. The 

 3,514 protected areas listed by lUCN are located 

 in 178 provinces. The coverage is patchy: sev- 

 eral provinces have few protected areas, which 

 implies that numerous unique ecosystems have 

 yet to be included in the worldwide network 

 of protected areas (see table 5-2) (33). An esti- 

 mate of the cost of completing this network is 

 $1 billion (17). 



Ten provinces have fewer than 1,000 square 

 kilometers protected but more than five pro- 

 tected areas, while another 29 have more than 

 1,000 square kilometers but only five or fewer 

 separate protected areas. Determining the ex- 

 tent of the patchiness requires better figures 

 for analysis, such as accurate estimates of prov- 

 ince sizes. In addition, aquatic and azonal eco- 

 systems (e.g., wetlands and coral reefs) do not 

 fall easily within this system. 



A U.S. effort that helps maintain representa- 

 tive aquatic ecosystems is the Marine Sanctuary 

 Program conducted by the National Oceanic 

 and Atmospheric Administration of the Depart- 

 ment of Commerce. Potential marine sanctuary 

 sites were listed after consultation with scien- 

 tific teams familiar with the different ecologi- 

 cal values of sections of the coastal zone (86). 

 All current and future designations into the ma- 

 rine sanctuaries will be made from the site- 

 evaluation list. Maintenance of community or 

 ecosystem diversity is not a specific objective 

 of the Marine Sanctuaries Program, but if all 

 sites on the list were designated sanctuaries, 

 coastal ecosystem diversity would be signifi- 

 cantly protected. 



An international effort that contributes to con- 

 serving representative ecosystems is UNESCO's 



