Ch. 2— Importance of Biological Diversity • 51 



Photo credit: M.A. Altieri 



Two intercropping systems — fava beans and brussels sprouts, and wild mustard and brussels sprouts — demonstrate 



the benefits of diversity to agriculture. Botti systems benefit the brussels sprouts crop: wild mustard acts as a trap crop 



of flea beetles, and fava beans fix nitrogen with possible benefits to brussels sprouts yields. 



produced in the United States is domesticated). 

 New and incipient forage crops include Bahia 

 grass, desmodium, and several of the wheat- 

 grasses. Red deer and aquaculture species such 

 as catfish, hardshell clam, and the giant fresh- 

 water prawn, are among the newly domesti- 

 cated livestock. Loblolly pine, slash pine, 

 Parana pine, and balsa are some of the new tim- 

 ber domesticates (73,74). 



Domestication of wild species increases the 

 economic benefits of wild species by improving 

 product quality and by raising yields. It can also 

 make a valuable contribution to rural develop- 

 ment in areas that are marginal for conven- 

 tional crops and livestock. Nepal's Department 

 of Medicinal Plants has organized the farming 

 of two native species [Rauvolfia serpentina and 



Valeriana wallichii] for example, and it is in- 

 vestigating propagation of several other wild 

 species that are sources of drugs, perfumes, and 

 flavors for export. Scientists in Zambia and Bot- 

 swana are working on the domestication of 

 mungongo tree, whose fruits are used for food 

 and oil and whose wood is valued for carvings 

 (74). 



Genetic Diversity 



Health and long-term productivity of wild re- 

 source species— from game animals to timber 

 trees to food and sport fish— depend on genetic 

 diversity within and among the harvested pop- 

 ulations. If the best individuals (biggest animals, 

 tallest trees) are harvested before they repro- 



