Environmental Problems, Their Causes, and Sustainability 1

Should Reserves Be as Large as Possible?Generally, But Not AlwaysLarge reserves usually are the best way to protectbiodiversity, but in some places several well-placed,medium-sized, and isolated reserves can do the job.Large reserves sustain more species and providegreater habitat diversity than do small reserves. Theyalso minimize the area of outside edges exposed tonatural disturbances (such as fires and hurricanes), invadingspecies, and human disturbances from nearbydeveloped areas.However, research indicates that in some locales,several well-placed, medium-sized, and isolated reservesmay better protect a wider variety of habitatsand preserve more biodiversity than a single large reserveof the same area. A mixture of large and smallreserves (Figure 11-21) may be the best way to protecta variety of species and communities against a numberof different threats.Establishing protected habitat corridors between reservescan help support more species and allow migrationof vertebrates that need large ranges. They alsopermit migration of individuals and populations whenenvironmental conditions in a reserve deteriorate andhelp preserve animals that must make seasonal migrationsto obtain food. Corridors may also enable somespecies to shift their ranges if global climate changemakes their current ranges uninhabitable.On the other hand, corridors can threaten isolatedpopulations by allowing movement of pest species,disease, fire, and exotic species between reserves.They also increase exposure of migrating species tonatural predators, human hunters, and pollution. Inaddition, corridors can be costly to acquire, protect,and manage.A buffer zone surrounds and protects the core area.In this zone, emphasis is on nondestructive research,education, and recreation. Local people can also carryout sustainable logging, agriculture, livestock grazing,hunting, and fishing in this buffer zone, as long as suchactivities do not harm the core.Finally, a second buffer, or transition zone, surroundsthe inner buffer. In this zone local people canengage in more intensive but sustainable forestry,grazing, hunting, fishing, agriculture, and recreationthan in the inner buffer zone. Doing this can enlist localpeople as partners in protecting a reserve from unsustainableuses.So far, most biosphere reserves fall short of theideal and receive too little funding for their protectionand management. An international fund to help countriesprotect and manage biosphere reserves wouldcost about $100 million per year—about what theworld’s nations spend on weapons every 90 minutes.What Is Adaptive Ecosystem Management?Cooperation and FlexibilityPeople with competing interests can work togetherto develop adaptable plans for managing andsustaining nature reserves.Managing and sustaining a nature reserve is difficult.One problem is that reserves are constantly changingin response to environmental changes. Another is thatthey are affected by a variety of biological, cultural,Biosphere ReserveWhat Are Biosphere Reserves?A Great IdeaBiosphere reserves have an inner protected coresurrounded by two buffer zones that can be usedby local people for sustainable extraction of resourcesfor food and fuel.In 1971, the UN Educational, Scientific, and CulturalOrganization (UNESCO) created the Man and theBiosphere (MAB) Programme. A major goal of the programis to establish at least one (and ideally five ormore) biosphere reserves in each of the earth’s 193 biogeographicalzones. Today there are more than 425biosphere reserves in 95 countries.Each reserve must be large enough to containthree zones (Figure 11-22). The core area contains an importantecosystem that the government legally protectsfrom all human activities except nondestructiveresearch and monitoring.Tourism andeducation centerCore areaBuffer zone 1Buffer zone 2HumansettlementsResearchstationFigure 11-22 Solutions: a model biosphere reserve. In traditionalparks and wildlife reserves, well-defined boundaries keeppeople out and wildlife in. By contrast, biosphere reserves recognizepeople’s needs for access to sustainable use of variousresources in parts of the reserve.http://biology.brookscole.com/miller14217