Environmental Problems, Their Causes, and Sustainability 1

Forests precede civilizations, deserts follow them.FRANÇOIS-AUGUSTE-RENÉ DE CHATEAUBRIANDBiodiversityThis chapter addresses the following questions:■■■■■■■■■■■How have human activities affected the earth’sbiodiversity?What is conservation biology? What roledoes bioinfomatics play in helping sustainbiodiversity?What are the major types of public lands in theUnited States, and how are they used?Why are forest resources important, and how arethey used, managed, and sustained?How should forests in the United States be used,managed, and sustained?How serious is tropical deforestation, and how canwe help sustain tropical forests?What problems do parks face, and how should wemanage them?How should we establish, design, protect, andmanage terrestrial nature reserves?What is wilderness, and why is it important?What is ecological restoration, and why is itimportant?What can we do to help sustain the earth’sbiodiversity?Increase Factors• Middle stages ofsuccession• Moderate environmentaldisturbance• Small changes inenvironmental conditions• Physically diverse habitat• EvolutionDecrease Factors• Extreme environmentalconditions• Large environmentaldisturbance• Intense environmentalstress• Severe shortages ofkey resources• Nonnative speciesintroduction• Geographic isolationFigure 11-2 Factors that tend to increase or decrease theearth’s biodiversity.some extent at least half and probably about 83% ofthe earth’s land surface (excluding Antarctica andGreenland).About 82% of temperate deciduous forests havebeen cleared, fragmented, and dominated becausetheir soils and climate are very favorable for growing11-1 HUMAN IMPACTSON TERRESTRIAL BIODIVERSITYHow Have Human Activities AffectedGlobal Biodiversity? Increasing OurEcological FootprintWe have depleted and degraded some of theearth’s biodiversity and these threats are expectedto increase.Figure 11-2 lists factors that tend to increase or decreasebiodiversity. Many of our activities decreasebiodiversity (Figure 11-3). According to biodiversityexpert Edward O. Wilson, “The natural world is everywheredisappearing before our eyes—cut to pieces,mowed down, plowed under, gobbled up, replaced byhuman artifacts.”Consider a few examples of how human activitieshave decreased and degraded the earth’s terrestrialbiodiversity. According to the results of a 2002 studyon the impact of the human ecological footprint on theearth’s land (Figure 9-12, p. 172), we have disturbed toHuman ActivitiesAgriculture, industry, economicproduction and consumption, recreationDegradation and destructionof natural ecosystemsAlteration of natural chemicalcycles and energy flowsClimatechangeHuman PopulationSize and resource useDirect EffectsChanges in number anddistribution of speciesPollution of air, water,and soilIndirect EffectsLoss ofbiodiversityFigure 11-3 Natural capital degradation: major connectionsbetween human activities and the earth’s biodiversity.http://biology.brookscole.com/miller14195