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SECTION3

LandManagementandConservation

Asthehumanpopulationgrows,theresourcesofmorerurallandareneededtosupportthepopulation.Themaincategoriesofrurallandarefarmland,rangeland,forestland,nationalandstateparks,andwilderness.Throughoutourhistory,wehavesome-timesmanagedtheselandssustainablysothattheywillprovideresourcesindefinitely.Wehavealsosometimesreducedtheirpro-ductivitybyoverusingorpollutingthem.Theconditionofrurallandisimportantbecauseoftheecologicalservicesthatitpro-vides.Theseservicesareespeciallyimportantfortheurbanareasthatrelyontheproductivityofruralland.

Farmlands

Farmland,suchasthatshowninFigure12,islandthatisusedtogrowcropsandfruit.TheUnitedStatescontainsmorethan100millionhectaresofprimefarmland.However,insomeplaces, urbandevelopmentthreatenssomeofthemostproductivefarm-land.ExamplesofplaceswherefarmlandisthreatenedarepartsofNorthCarolina’sPiedmontregionandtheTwinCitiesareaofMinnesota.In1996,theU.S.governmentestablishedanationalFarmlandProtectionProgramtohelpstate,county,andlocal governmentsprotectfarmlandindangerofbeingpavedoverorotherwisedeveloped.

factHedgerows FarmlandformsanimportanthabitatforwildlifeinGreatBritain,whichhasrelativelyfewremainingnaturalareas.Fieldsareseparatedbyrowsofbushescalledhedgerows,whichprovideshelterforavarietyofbirds,mam-mals,reptiles,andinsects.

Figure12�ThisfarmlandnexttothesuburbsofMililani,Hawaii,isusedtogrowavarietyofcrops.

Topic:RangeManagement

SciLinkscode:HE4091

Figure13�ThephotobelowshowsproductiverangelandinthewesternUnitedStates.

Rangelands

Landthatsupportsdifferentvegetationtypeslikegrasslands,shrublands,and desertsand that isnot usedfor farming ortim-berproductioniscalledrangeland.Rangelandscanbearid,likerangelandsinthedesertSouthwest,orrelativelywet,liketherangelandsofFlorida.Themostcommonhumanuseofrange-landisforthegrazingoflivestock,asshowninFigure13.Themostcommonlivestockarecattle,sheep,andgoats,whicharevaluedfortheirmeat,milk,wool,andhides.Nativewildlifespeciesalsograzetheselands.Likefarmland,rangelandisessen-tialformaintainingtheworld’sfoodsupply.Worldpopulation growthmayrequirea40percentincreaseinthefoodproduction ofrangelandfrom1977to2030.

ProblemsontheRangeSomerangelandsintheUnitedStateshavebecomedegradedbypoorlandmanagementstrategies.Mostdamagetorangelandcomesfromovergrazing,orallowingmoreanimalstograzeinanareathantherangecansupport.Whenanimalsovergraze,toomanyoftheplantsareeaten,andthelandcanbecomedegraded.Overgrazingoftenresultsinchangesintheplantcommunity.Lessdesirableplantspeciesmayinvadetheareaandreplacemore-desirableplantspecies.Incasesofsevereovergrazing,allthevegetationthatcoversthelandiseaten.Oncetheplantsaregone,thereisnothingtokeepthesoilfromeroding.

MaintainingtheRangeMuchoftherangelandintheUnitedStatesispubliclandmanagedbythefederalgovernment,whichleasestherangelandtoranchers.MuchoftherangelandintheUnitedStatesisdegraded.ThePublicRangelandsImprovementActof1978wasenactedtoreversethistrendandimprovelandmanagementpractices.

Sustainingtheproductivityofrangelandgenerallymeansreducingovergrazingbylimitingherdstosizesthatdonot

degradetheland.Rangelandisalsoleftunusedforperiodsoftimesothatthevegetationcanrecover.Improvingrangelandthathasbeendegradedbyover- grazingoftenincludesmethodssuchaskillinginvasiveplants,plantingnativevegetation,andfencingareastoletthem recovertothestatetheywereinbeforetheywereovergrazed.Ranchersalsocontrolgrazing bydiggingenoughsmallwaterholesthatlivestockdonotover- grazethevegetationaroundasinglewaterhole.

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ForestLands

Treesareharvestedtoprovideproductsweuseeveryday,suchaspaper,furniture,andlumberandplywoodforourhomes.Inadditiontowoodandpaper,wealsovalueforestproductssuchasmaplesyrupandturpentine.Therearemanyecosystemserv-icesprovidedbyforests;however,oneofthemostimportantistheremovalofCO2fromtheair.

HarvestingTreesPeopleuseenormousamountsofwood.Theworldwideaverageis1,800cm3 ofwoodusedperpersoneachday.However,onaverage,eachpersonintheUnitedStatesusesabout3.5timesthisamount.Thisistheequivalentofeachper-sonintheUnitedStatescuttingdownatreethatis30mtalleveryyear.About1.5billionpeopleindevelopingcountriesdependonfirewoodastheirmainsourceoffuel.

Thetimberindustryclassifiesforestlandsintothreecategories—virginforest,whichisforestthathasneverbeencut;nativeforest,whichisforestthatisplantedandmanaged;andtreefarms,whichareareaswheretreesareplantedinrowsandharvestedlikeothercrops.Thetwomostwidelyusedmethodsofharvestingtreesareclear-cuttingandselectivecutting.ThesemethodsareshowninFigure14.Clear-cuttingistheprocessofremovingallofthetreesfromanareaofland.Clear-cuttinglarge areasdestroyswildlifehabitatandcausessoilerosion.Themainalternativeisselectivecutting,whichisusuallypracticedonsmallerareasownedbyindividuals.Selectivecuttingistheprocessofcuttingandremovingonlymiddle-agedormaturetrees.Selectivecuttingismoreexpensivethanclear-cutting,butselectivecuttingisusuallymuchlessdestructive.

Figure14�Methodsforharvestingtreesincludeclear-cutting(top)and selectivecutting(bottom).

QuickLAB

MeasuringSoilDepthandCompaction

Procedure

1.Findaplotofundisturbedsoilinaforest,meadow,park,orotherundisturbedareanearyourschool.

2.Pressameterstickdownintothe undisturbed soil as far as itwillgo.Recordhowdeepthemeterstickwentintothesoil.Recordhowsoftthesoilwasandhoweasyitwastopressthemeterstickintothesoil.Repeatthisfivetimesinthesameplotofundisturbedsoil.

3.Pour1Lofwaterontotheundisturbedsoil.Useastop-watchtorecordhowlongittakesforthesoiltofullyabsorbthewater.

4.Repeatthisprocedureataplotofdisturbedsoilinabikepath,dirtroad,orotherareawhere thesoilisbareandvegetationhasbeenclearedortrampled.

Analysis

1.Howdidthesoildepthand hardnessintheplotofundis-turbedsoildifferfromthatintheplotofdisturbedsoil?

2.Whichplotabsorbedwaterfaster?

3.Howmightgrazingcattleaffectthedepthandcompactionofanundisturbedplotofland?

4.Howmightclear-cuttingaffectanundisturbedplotofland?

EcofactBurningTreesandCO2 Whentreesarecutandburned,they

releasecarbondioxide. From1850to 1990, deforestationreleasedmorethan100billionmetrictons ofcarbondioxideintotheatmos-phereworldwide.SomescientiststhinkthisadditionalCO2iscon-tributingtoanincreaseinglobaltemperatures.

DeforestationTheclearingoftreesfromanareawithoutreplac-ingthemiscalleddeforestation.Mostcountriesbecomeseverelydeforestedaspopulationsexpandandthedemandforforestproductsincreases.Forestsareclearedtoconvertthelandintofarmland.Peoplealsoclearforeststomakespaceforroads,homes,factories,andofficebuildings.

Deforestationreduceswildlifehabitat,butithasother impacts,too.Forexample,whenforestsareclearedfromhill-sides,soilerosionusuallyresultsiftheareaisnotquicklyplantedwithacovercrop.Withouttreerootstoholdthesoilinplace,soiliseasilywashedorblownintothevalleybelow.InNewYork,forestsonhillsideswereclearedforfarmlandduringthe19thcentury.Plowingalsoincreasedtherateoferosion,andasmuchas90percentofthesoileroded.Then,duringtheGreat Depression,whichwasinthe1930s,hundredsoffarmersinthisarea went bankrupt.The state boughtmany of theseabandoned farms,andlettheforestsregenerate.Today,manyofthesehill-topsarecoveredwithstateforest,whichisusedforrecreation.

Therateofdeforestationisespeciallyhighintropicalrain forests,wherethesoilisrelativelythin.Farmerswhoclearforestsintheseareasmustalwaysmovefromoneplotoflandtoanotherandclearmoreforesteachtimetheymove.Whetherforestsareclearedforfarmingorwood,iftreesarenotreplanted,naturalresourcesaresteadilydepleted.

California’s WildernessCorridors

Californiahasanextraordinaryrangeofhabitats,from coastal islands,whereelephantsealsbreed,tomountains wheresalmon,cougars,bobcats, andbadgersare found.Many of theseanimals liveonwildlifepreservesandotherpubliclandsoronprivateland.

Animalsdonotknowthattheyaresafestiftheystayonpreserves.Manyanimalsnaturallymigrateatdifferenttimesoftheyear.Younganimalsareoftenevictedfromtheirterritoriesbytheirparentsandmustsearchforterritoriesoftheirowntosurvive.Manyanimalsalsoleavetheirterritoriesinsearchofmatesfromotherpopulations.Thisprocessis

important becauseifanimalsrepro-duceonlywithmembersofthespecies thatlive nearby, thepopula-tionbecomesinbredandgeneticdefectsbecomemorecommon.

AsCaliforniabecomesmoreurbanized,however,migrationroutesbetweenonepopulationofanimalsandanotherpopulationareincreasinglyblockedbyhighwaysandhousingdevelopments.

A possiblesolutionistheacquisitionofconservationcorri-dors—thinstripsofprotectedlandthatconnectonepreservewithanotherpreserve.Conservationbiologists haveargued foryearsoverwhethersuchcorridorsare

�ThisdiagramshowssuspectedwildlifecorridorsaroundLosAngeles,California.

366 Chapter14 Land

ReforestationClear-cutforestcanbereplantedorallowedtoregrownaturally,withouthumanintervention.Reforestationistheprocessbywhichtreesareplantedtore-establishtreesthathavebeencutdowninaforestland.Insomeplaces,reforesta-tionishappeningfaster than treesarebeingcutdown. NewEngland,forexample,now containsmoreforestthanitdidacenturyago.Muchoftheoriginalforesthadbeenclearedforfarming, butthelandwasunable tosustainproductivecropsoveralongperiod.Asfarminginthisareabecamelesseco-nomical,farmswereabandonedandtheforestregenerated.Thesameprocesshashappenedinplaceswheresteephillsidesweredeforestedforfarmingordevelopment.Thecostofdeforesta-tion,whichcausedsoilerosion,landslides,andflooding,wastoohigh.So foresthasnow beenallowedto regenerateorhasbeenreplanted.

Somegovernmentsrequirereforestationaftertimberhasbeenharvestedfrompublicland.AreforestationprojectisshowninFigure15.Worldwide,morethan90percentofalltimbercomesfromforeststhatarenotmanagedbyanagencythatmonitorsthehealthofforestecosystems.Manygovernmentsarecurrentlyworkingtoimprovereforestationeffortsandtopromotelessdestructiveloggingmethods.Privateorganizationshavealsoestablishedtree-plantingprogramsonroadsidesandincities.

Figure15�TreeseedlingshavebeenplantedtoreforestthishillsideaspartofareforestationprojectintheFijiIslands.

Nowthereispublicpressuretopreserve232ofthecorridorsthatlinkcriticalhabitats.Votershaveapprovedbondmeasuresthatwillsupplythemoneytobuysomeoftheland,andtheNatureConser-vancyisalsocontributingland.Thequestionofwhetherwildlifecorri-dorspreservespeciesmayfinallybeanswered byCalifornia’s initiative.

CRITICAL THINKING

�CougarsmayneedwildlifecorridorsinordertosurviveinpartsofCalifornia.

1.ApplyingIdeas California’sstateemblemisagrizzlybear,

effectiveinlinkinghabitatsand

protectinganimals.

OnesuchcorridorinCaliforniaistheTenajacorridor,whichcon-nectstheSantaRosaPlateauEcologicalPreserveandthelargerCleveland NationalForest in theSantaAnaMountainssoutheastof

LosAngeles.BiologistPaulBeirstud-

iedthemovementsofapopulationofcougarsintheSantaAnaMountainsbyputtingradiocollarsonmorethan30animalstotracktheirmovements.HefoundthattheanimalsusedtheTenajacorridorandavoidedurbanareas.

whichisaspeciesnolongerfoundinthestate.Whydoyouthinkthebearsdisappeared?

2.Expressing ViewpointsShouldCaliforniaspendstatemoneytopreservehabitats?Explainyouranswer.

Section3 LandManagementandConservation 367

Figure16�NationalparksintheUnitedStatesareconcentratedintheWest.

Figure17�Biospherereservesareplaceswherehumanpopulationsand wildlifelivesidebyside.

River

Corearea

Bufferzone1

Bufferzone2

Humansettlement

TourismandeducationcenterResearchstation

368 Chapter14 Land

ParksandPreserves

Inthe1870s,agroupofexplorersapproachedCongresswithnewsofamagnificentexpanseoflandinWyomingand Montana.TheseexplorersexpressedtheirconcernthatthislandwouldbedamagedbythedevelopmentthathadchangedthenortheasternUnitedStates.Congressagreedtoprotectthislandbysettingitasideforthepublictouseandenjoy,andthefirstnationalpark—Yellowstone—wascreated.Today,theUnitedStateshasabout50nationalparks,asshowninFigure16.IfyouareaU.S.citizen,youshareownershipoftheselands.

PubliclandsintheUnitedStateshavemanypurposes.Most publiclandsarenotasprotectedasthenationalparksare.Somepubliclandsareleasedtoprivatecompaniesforlogging,mining,andranching.Otherpubliclandsaremaintainedforhuntingandfishing,aswildliferefuges,ortoprotectendangeredspecies.

InternationaleffortsincludetheUnitedNations’sManandtheBiosphereProgram.Thisprogramhassetupseveralhundredpre-servesthroughouttheworldsince1976.Thesepreservesarecalledbiospherereservesandareunusualinthattheyincludepeopleinthemanagementplanofthereserves,asshowninFigure17.

WildernessTheU.S.WildernessAct,whichwaspassedin1964,designatedcertainlandsaswildernessareas.Wildernessisanareainwhichthelandandtheecosystemsitsupportsareprotectedfromallexploitation.Wildernessareasarefoundwithinseveralofthenation’spubliclandsystems.Sofar,474regionscoveringalmost13millionhectares(32millionacres)havebeendesignatedaswildernessintheUnitedStates.Figure18showsanexampleofawildernessarea.Theseareasareopentohiking,fishing,boating(withoutmotors),andcamping.Buildingroadsorstructuresandusingmotorizedequipmentisnotallowedinwildernessareas.

BenefitsofProtectedAreasWithoutnationalandprivateparksandpreservesaroundtheworld,manymorespecieswouldnowbeextinct.Inacrowdedworld,these protectedareasoftenprovidetheonlyplace whereunspoiledforests,deserts,orprairiesremain.Withouttheseareas,theplantsandanimalsthatcansurviveonlyintheseecosys-temswoulddisappear.Theseprotectedareasalsoproviderecreationforpeople.Peoplecancamp,hike,fish,andwatchbirdsandotherwildlifeintheseareas.Wildernessareasalsoserveasoutdoorclassroomsandresearchlaboratorieswherepeoplecanlearnmoreaboutthenaturalworld.

ThreatstoProtectedAreasThereisacon-stantbattleinourworldbetweenourconser- vationeffortsandthegrowingandincreasinglymobilepopulation.Aroundtheworld,morepeoplevisitnationalparksandwildernessareaseachyearandleavetheirmarkontheland.Litterandtrafficjamsthathaveplaguedourcitiesnowplaguemanyofournationalparks.Rangelands,miningandloggingsites,oilandgasdrillingoperations,factories,powerplants,andurbanareasareoftencloseenoughtotheparkstoaffecttheparks.Inaddition,preservedareasareaffected byclimatechangeandbyairandwaterpollu-tion,asaremostotherpartsoftheworld.

Inattemptstoprotectwildernessfrom

damage,limitshavebeensetinsomeareasonthenumberofpeo-plepermittedintheareaatanygiventime.Someareasarecom- pletelyclosedtovisitorstoallowwildanimalstobreed.Inaddition,volunteerprogramsarenowactiveinmanywilderness areas.Volunteershelppickuptrash,buildtrails,controlinvadingorexoticspecies,andhelpeducatethevisitingpublic.

Figure18�IntheUnitedStates,wildernessareas,suchastheHighUintasWildernessareashownhere,aresupposedtobepreserveduntouchedforourownandfuturegenerations.