liifriuliulion — (^iir Ltviii!:; Rtwi'iirccs 



overview of national programs such as the Gap policy makers better protect our resources. 

 Analysis Program, which scientists hope will 

 pro\e useful in acquiring data to help resource 



Biodiversity: 



A New 

 Challenge 



by 



Edward T. iMRoe 



National Biological Service 



Resource managers at many state and federal 

 agencies are in the middle of a fundamental 

 change in the practice and objectives of conser- 

 vation. Traditional management has been 

 directed toward maintaining, usually for harvest 

 purposes, populations of individual species 

 such as ducks, deer, or salmon. Increasingly, 

 however, resource managers are recognizing the 

 critical importance of conserving biological 

 diversity, or biodiversity. 



In its simplest terms, biological diversity is 

 the variety of life at all levels: it includes the 

 array of plants and animals: the genetic differ- 

 ences among individuals; the communities, 

 ecosystems, and landscapes in which they 

 occur: and the variety of processes on which 

 they depend. Conserving biological diversity 

 poses dramatic new problems for comprehen- 

 sive inventory and monitoring: what should be 

 measured or monitored? 



Biodiversity is important for many reasons. 

 Its value is often reported in economic terms: 

 for example, about half of all medicinal drugs 

 (Keystone Center 1991; Wilson 1992) come 

 from — or were first foinid in — natural plants 

 and animals, and therefore these resources are 

 critical for their existing and as yet undiscov- 

 ered medicinal benefits. Additionally, most 

 foods were domesticated from wild stocks, and 

 interbreeding of different, wild genetic stocks is 

 often used to increase crop yield. Today we use 

 but a small fraction of the food crops used by 

 Native cultures: many of these underused plants 

 may become critical new food sources for the 

 expanding human population or in times of 

 changing environmental conditions. 



But biodiversity has an even greater impor- 

 tance: it is the great variety of life that makes 

 existence on eaith possible. As a simple exam- 

 ple, plants convert carbon dioxide to oxygen 

 during the photosynthctic process: animals 

 breathe this fresh air. releasing energy and pro- 

 viding the second level of the food chain. In 

 turn, animals convert oxygen back to carbon 

 dioxide, providing the building blocks for the 

 formation of sugars during photosynthesis by 

 plants. Microbes (fungi, bacteria, and proto- 

 zoans) break down the carcasses of dead organ- 

 isms, recycling the minerals to make them 

 available for new life; along with some algae 

 and lichens, they create soils and improve soil 

 fertility. 



Biodiversity provides the reservoir for 

 change in our life-support systems, allowing 

 life to adapt to changing conditions. In a natur- 

 al population, for example, some individuals 

 will be more resistant to drought or disease or 



cold; as the environment changes, from season 

 to season, year to year, or over longer periods, 

 and as plagues come and go, these differences 

 among individuals allow at least some members 

 of the population or species to survive and 

 reproduce. This diversity is the basis not only 

 for short-term adaptation to changing condi- 

 tions, but also for long-term evolution as well. 



Like air, water, and soils, biological diversi- 

 ty is part of the capital upon which all life 

 depends. The need for this diversity is greatest 

 in times of environmental stress when plants, 

 animals, and microbes must develop new char- 

 acteristics or strategies for survival. As we look 

 at the problems of the globe today — global cli- 

 mate change, decreases in the ozone shield and 

 increasing ultraviolet radiation, losses of natur- 

 al habitats, and pervasive pollution in our 

 streams and oceans — we must recognize that 

 we. as a form of life on earth, need the ability to 

 change in order to cope with new stresses. 



Humans cannot survive in the absence of 

 nature. We depend on the diversity of life on 

 earth for about 259f of our fuel (wood and 

 manure in Africa. India, and much of Asia); 

 more than 5(J% of our fiber (for clothes and 

 construction); almost 50% of our medicines; 

 and. of course, for all our food (Miller et al. 

 1985). As previously stated, biodiversity pro- 

 duces other benefits: plants produce oxygen for 

 our atmosphere; microbes break down wastes, 

 recycle nutrients, and build the fertility of our 

 soils. One reason our highways are not littered 

 with the carcasses of dead dogs, cats, skunks, 

 armadillos, and deer is biodiversity, in the form 

 of the many scavengers and microbes that we 

 don't often think about, but which play an 

 essential role in the cycle of life. Even species 

 often viewed as ""repulsive," such as vultures 

 and maggots, play critical roles in our lives. 



Some people believe that because extinction 

 is a natural process, we therefore should not 

 worry about endangered species or the loss of 

 biodiversity. Certainly extinction is natural; it 

 usually occurs as newer forms of life evolve. 

 But under the forces of population growth, tech- 

 nology, and special interests, humans have dri- 

 ven the rate of extinctions today to about 100 

 times — two orders of magnitude — the natural 

 rate. Even worse, the rate of extinction is still 

 increasing and will be 100 to 1,000 times faster 

 yet in the next 55 years (Miller et al. 1985); sci- 

 entists today predict that between now and 

 2030, half the expected lifetime of a child bom 

 today, the Earth will lose between a quarter and 

 a third of all existing species. And this is in the 

 absence of new forms of life to replace them. 



