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Chapter 18Chapter 18Land ResourcesLand Resources
Overview of Chapter 18Overview of Chapter 18
o Land UseLand Use• World land useWorld land use• US land useUS land use
o Wilderness Park and Wildlife RefugesWilderness Park and Wildlife Refuges• National ParksNational Parks• Wildlife RefugeWildlife Refuge
o ForestsForests• Forest management Forest management • DeforestationDeforestation
o Rangeland and Agricultural LandRangeland and Agricultural Lando Wetlands and Coastal AreasWetlands and Coastal Areaso Conservation of Land ResourcesConservation of Land Resources
Land Use- WorldwideLand Use- Worldwide
Land Use- United StatesLand Use- United States
Land Use- United StatesLand Use- United States
o 55% of US land is privately owned55% of US land is privately ownedo Remainder of land is owned by governmentRemainder of land is owned by government
• Most federally owned land is in Alaska and 11 Most federally owned land is in Alaska and 11 western stateswestern states
Managing Public and Private Managing Public and Private LandLand
o Public Planning and Land UsePublic Planning and Land Use• Land use decisions are complex and have Land use decisions are complex and have
multiple effectsmultiple effects• Must take into account all repercussions of Must take into account all repercussions of
proposed land useproposed land use
o Management of Federal LandManagement of Federal Land• Wide-Use MovementWide-Use Movement• Environmental MovementEnvironmental Movement
Wilderness Parks and Wildlife Wilderness Parks and Wildlife RefugesRefuges
o WildernessWilderness• A protected area of land in which no human A protected area of land in which no human
development is permitteddevelopment is permitted
o Wilderness Act (1964)Wilderness Act (1964)• Set aside federally owned land as part of Set aside federally owned land as part of
National Wilderness Preservation SystemNational Wilderness Preservation System• No development permitted (including No development permitted (including
roads)roads)
o Managed by NPS, USFS, FWS & BLMManaged by NPS, USFS, FWS & BLM
WildernessWilderness
o Some areas have a limited number of Some areas have a limited number of permitted human guests to reduce permitted human guests to reduce impactimpact
o Other problems include invasive Other problems include invasive speciesspecies
National Park SystemNational Park System
o Created in 1916Created in 1916o Currently includes 58 Currently includes 58
parksparkso Primary goalPrimary goal
• Teach people about Teach people about the natural the natural environment, environment, management of management of natural resources and natural resources and history of a sitehistory of a site
Yosemite National ParkYosemite National Park
National Park SystemNational Park System
o Threats to U.S. ParksThreats to U.S. Parks• Crime & VandalismCrime & Vandalism• Traffic jamsTraffic jams• Pollution of the soil, water and airPollution of the soil, water and air
• Originating both inside and outside the parkOriginating both inside and outside the park• Resource violationsResource violations
o Natural RegulationNatural Regulation• Policy to let nature take it coursePolicy to let nature take it course• No culling wildlifeNo culling wildlife• No suppressing wildfireNo suppressing wildfire
Wildlife RefugesWildlife Refuges
o National Wildlife Refuge System (1903)National Wildlife Refuge System (1903)o Represent all major ecosystems founds Represent all major ecosystems founds
in the USin the USo MissionMission
• To preserve lands and waters for the To preserve lands and waters for the conservation of fishes, wildlife and plants of conservation of fishes, wildlife and plants of the USthe US
o Recreation (including hunting and Recreation (including hunting and fishing) are permitted fishing) are permitted • Cannot impede conservation effortsCannot impede conservation efforts
ForestsForests
o Role in Hydrologic Role in Hydrologic Cycle (right)Cycle (right)
o Forest Forest ManagementManagement
o DeforestationDeforestationo Forest Trends in Forest Trends in
the USthe USo Trends in Tropical Trends in Tropical
ForestsForestso Boreal ForestsBoreal Forests
Forest ManagementForest Management
o Traditional Forest Traditional Forest ManagementManagement• Low diversity- monocultures Low diversity- monocultures
(right)(right)• Managed for timber Managed for timber
productionproduction
o Ecological Sustainable Ecological Sustainable Forest ManagementForest Management• Environmentally balancedEnvironmentally balanced• Diverse treesDiverse trees• Prevent soil erosionPrevent soil erosion• Preserve watershedsPreserve watersheds• Wildlife corridors- unloggedWildlife corridors- unlogged
Harvesting TreesHarvesting Trees
Harvesting Trees - ClearcuttingHarvesting Trees - Clearcutting
DeforestationDeforestation
o Temporary or permanent clearance of Temporary or permanent clearance of large expanses of forest for agriculture large expanses of forest for agriculture or other useor other use
o World forests shrank 90 million acres World forests shrank 90 million acres from 2000–2005from 2000–2005
o CausesCauses• FireFire• Expansion of agricultureExpansion of agriculture• Construction of roadsConstruction of roads• Tree harvestTree harvest• Insect and diseaseInsect and disease
DeforestationDeforestation
o ResultsResults• Decreased soil fertilityDecreased soil fertility• Uncontrolled soil erosionUncontrolled soil erosion• Production of hydroelectric power (silt build Production of hydroelectric power (silt build
up behind dams)up behind dams)• Increased sedimentation of waterwaysIncreased sedimentation of waterways• Formation of desertsFormation of deserts• Extinction of speciesExtinction of species• Global climate changesGlobal climate changes
Forest Trends in USForest Trends in US
o Most temperature Most temperature forest are steady or forest are steady or expandingexpanding
o Returning stands lack Returning stands lack biodiversity of original biodiversity of original forestsforests
o More than half of US More than half of US forest are privately forest are privately owned (right)owned (right)• Forest Legacy ProgramForest Legacy Program• Conservation easementConservation easement
US National ForestsUS National Forests
o Managed for multiple usesManaged for multiple uses• Timber harvestTimber harvest• Livestock forageLivestock forage• Water resource and watershed protectionWater resource and watershed protection• Mining, hunting, fishing, etc.Mining, hunting, fishing, etc.
o Road building is an issueRoad building is an issue• Provides logging companies with access to Provides logging companies with access to
forestforest
o Clearcutting is an issueClearcutting is an issue
Case-In-Point Tongass National ParkCase-In-Point Tongass National Park
o One of world’s few One of world’s few temperate temperate rainforestsrainforests
o Prime logging areaPrime logging areao Modified 1997 Modified 1997
Forest PlanForest Plano Roadless Area Roadless Area
Conservation Rule Conservation Rule (2000)(2000)
o Politics rules Politics rules government government agenciesagencies
Trends in Tropical ForestsTrends in Tropical Forests
o Tropical rainforests (below) and tropical Tropical rainforests (below) and tropical dry forestsdry forests
Disappearing Tropical Rain Disappearing Tropical Rain ForestsForests
o Population growthPopulation growth• Cannot account for Cannot account for
all of itall of ito Immediate causesImmediate causes
• Subsistence Subsistence agricultureagriculture
• Commercial loggingCommercial logging• Cattle ranchingCattle ranching
o Other causesOther causes• MiningMining• Hydroelectric powerHydroelectric power
Disappearing Tropical Dry Disappearing Tropical Dry ForestsForests
o Primarily destroyed for fuelwoodPrimarily destroyed for fuelwood• Used for heating and cookingUsed for heating and cooking
Boreal ForestsBoreal Forestso World’s largest biomeWorld’s largest biomeo Extensive clearcuttingExtensive clearcutting
• Primary source of world’s industrial wood Primary source of world’s industrial wood and wood fiberand wood fiber
Rangeland and Agricultural landsRangeland and Agricultural lands
o RangelandRangeland• Land that is not intensively managed and is used Land that is not intensively managed and is used
for grazing livestockfor grazing livestock
Rangeland Degradation and Rangeland Degradation and DeforestationDeforestation
o Overgrazing leaves ground barrenOvergrazing leaves ground barren• Animals exceed their carrying capacityAnimals exceed their carrying capacity
o Land degradationLand degradation• Natural or human-induced process that Natural or human-induced process that
decreases future ability of land to support decreases future ability of land to support crops or livestockcrops or livestock
o DesertificationDesertification• Degradation of once fertile land into Degradation of once fertile land into
nonproductive desertnonproductive desert
Rangeland Trends in USRangeland Trends in US
o Make up 30% of total US land areaMake up 30% of total US land area• 2/3 privately owned2/3 privately owned
o Pressure from developers to subdividePressure from developers to subdivideo Public rangeland managed by:Public rangeland managed by:
• Taylor Grazing Act (1934)Taylor Grazing Act (1934)• Federal Land Policy and Management Act Federal Land Policy and Management Act
(1976)(1976)
o Conditions of public rangeland are Conditions of public rangeland are slowly improvingslowly improving• Grazing fees is an issueGrazing fees is an issue
Agricultural LandAgricultural Land
o US has 300 million acres of prime US has 300 million acres of prime farmlandfarmland
o Much is being Much is being overtaken by overtaken by suburban suburban sprawlsprawl• Parking lotsParking lots• Housing Housing
developmentsdevelopments• Shopping mallsShopping malls
WetlandsWetlands
o Lands that are usually covered with water Lands that are usually covered with water for at least part of the yearfor at least part of the year
o Have characteristic soils and water-Have characteristic soils and water-tolerant vegetationtolerant vegetation
o BenefitsBenefits• Habitat for migratory waterfowl and wildlifeHabitat for migratory waterfowl and wildlife• Recharge groundwaterRecharge groundwater• Reduce damage from floodingReduce damage from flooding• Improve water qualityImprove water quality• Produce many commercially important Produce many commercially important
productsproducts
WetlandsWetlands
o Human activity that threatens wetlandsHuman activity that threatens wetlands• Drainage for agriculture or mosquito Drainage for agriculture or mosquito
controlcontrol• Dredging for navigationDredging for navigation• Construction of dams, dykes or seawallsConstruction of dams, dykes or seawalls• Filling in for solid waste disposalFilling in for solid waste disposal• Road buildingRoad building• Mining for gravel, fossil fuels, etc.Mining for gravel, fossil fuels, etc.
o Shrinking 58,500 acres per yearShrinking 58,500 acres per year
Restoring WetlandsRestoring Wetlands
o No Net Loss of No Net Loss of Wetlands:Wetlands:
o Development of Development of wetlands is allowed if wetlands is allowed if corresponding amount corresponding amount of previously of previously converted wetland is converted wetland is restoredrestored
o Not all wetland Not all wetland restorations are restorations are successfulsuccessful
CoastlinesCoastlines
o Coastal wetlandsCoastal wetlands• Provide food and habitat for many aquatic Provide food and habitat for many aquatic
animalsanimals• Historically regarded as wastelandHistorically regarded as wasteland
o US starting to see US starting to see importance of importance of protecting this protecting this environmentenvironment• Retaining seawalls Retaining seawalls
(right)(right)
Coastal DemographicsCoastal Demographics
o Many coastal areas overdevelopedMany coastal areas overdeveloped• 3.8 billion people live within 150km of coastline3.8 billion people live within 150km of coastline• 6.4 billion people will likely live there by 20256.4 billion people will likely live there by 2025
o United StatesUnited States• 14 of 20 largest US cities along coast14 of 20 largest US cities along coast• 19 of 20 most densely populated countries along 19 of 20 most densely populated countries along
coastscoasts
Conservation and Land Conservation and Land ResourcesResources
o All types of ecosystems must be All types of ecosystems must be preservedpreserved
o Four criteria of importance:Four criteria of importance:• Areas lost or degraded since European Areas lost or degraded since European
colonizationcolonization• Number of present examples of a particular Number of present examples of a particular
ecosystem (or the total area)ecosystem (or the total area)• Estimate of the likelihood that a given Estimate of the likelihood that a given
ecosystem will lost a significant area or be ecosystem will lost a significant area or be degraded in next 10 yearsdegraded in next 10 years
• Number of threatened and endangered Number of threatened and endangered species living in the ecosystemspecies living in the ecosystem
Conservation and Land Conservation and Land ResourcesResources
Soil and Mineral ResourcesSoil and Mineral Resources
o Types of rocksTypes of rocks• Igneous Igneous • SedimentarySedimentary• MetamorphicMetamorphic
IgneousIgneous
o Igneous rocks (―fire-formed‖)—from hardened magma and lava
• a) intrusive—coarse-grained igneous rocks below the surface
• b) extrusive—fine-grained igneous rocks above the surface
SedimentarySedimentary
o Sedimentary rocks (―settling)—from sediment, being compacted and cemented• a) compaction—weight pressing the
pieces together
• b) cementation— minerals gluing the pieces together
• c) types of sediment: sand, silt, clay, gravel, bone chips, pieces of shells,
Sedimentary Con’tSedimentary Con’t
Formation:o a) clastic—from sediment compaction
and cementation
o b) chemical—from water-soluble minerals
o temperatures
o c) organic—from plant or animal remains (coal, limestone)
MetamorphicMetamorphic
o Metamorphic rocks (―changed form)—from temperature and pressure
o extremes, and chemical change1) formation
• a) metamorphism—a change in rock• b) contact metamorphism—affects a small
area; local heating• c) regional metamorphism—affects a large
area; tectonics
Rock CycleRock Cycle
o rock cycle—changes in rock forms, from one type to another type, by different
o 1) formation of igneous rock• a) melting and cooling any existing rock• b) hardening of magma or lava
o 2) formation of sedimentary rock: weathering and erosion to form sediment; compaction and cementation
o 3) formation of metamorphic rock: heating and pressurizing any existing rock
Soil Soil
A. Soil characteristicso 1) Soil profiles
• a) horizons—horizontal soil layers• b) soil profile—vertical “slices” through
soil layers
How is Soil Formed?How is Soil Formed?
o How is soil formed?How is soil formed?
Soils are dynamic, forming continuously over a Soils are dynamic, forming continuously over a long period of time. Soil types differ, depending long period of time. Soil types differ, depending on the parent materials from which they came on the parent materials from which they came and from the surrounding environment. The and from the surrounding environment. The way in which soil forms depends on: way in which soil forms depends on: • parent material parent material • climate climate • topography topography • living organisms living organisms • timetime
Soil ComponentsSoil Components
o Soil is a natural medium made up of five Soil is a natural medium made up of five major components: major components: • mineral particles: clay, silt, sand and gravel mineral particles: clay, silt, sand and gravel • organic matter: decaying plant and animal material organic matter: decaying plant and animal material • water water • air air • living organisms (soil biota): ranging from bacteria, living organisms (soil biota): ranging from bacteria,
fungi and earthwormsfungi and earthworms
*A healthy soil should have a balance of these *A healthy soil should have a balance of these components.components.
Soil TextureSoil Texture
o Soil texture—classification based on particle size• a) soil separates—rock fragments of
varying size: Sand, Silt, Clay
o Size of sand, silt and clay particleso Name Particle Diameter
• Very coarse sand 2.0 to 1.0 millimeters• Coarse sand 1.0 to 0.5 millimeters• Medium sand 0.5 to .25 millimeters• Fine sand 0.25 to 0.10 millimeters• Very fine sand 0.10 to 0.05 millimeters• Silt 0.05 to 0.002 millimeters• Clay below 0.002 millimeters
LoamLoam
o loam—common soil type: 40% sand, 40% silt, and 20% clay
WeatheringWeathering
o weathering— breaking up of the crust; the wearing down of rock, liberating minerals
• physical (mechanical) weathering—from wind,
water, weather, or other environmental events
o chemical weathering—from chemical reactions
between water and atmospheric gases and bedrock
o biological weathering—from activities of organisms
Soil Erosion and DegradationSoil Erosion and Degradation
o Erosion: movement of soil from one Erosion: movement of soil from one place to another; caused by wind, place to another; caused by wind, usually waterusually water
ErosionErosion
o Usually caused by moving waterUsually caused by moving water• Sheet erosion Sheet erosion • Rill erosionRill erosion
Losing TopsoilLosing Topsoil
o Makes soil less fertile and less able to Makes soil less fertile and less able to hold waterhold water
o Sediment clogs ditches, boat channels, Sediment clogs ditches, boat channels, reservoirs, and lakesreservoirs, and lakes
Causing and Correcting ErosionCausing and Correcting Erosion
1) overcultivation—frequent plowingo a) crop rotation—alternating the type of crops growno b) no-till agriculture—weed control, planting, and covering
upall at once(low-till farming—decrease the amount of tilling)
o c) contour-strip cropping—cultivation along sloping groundo d) shelter belts—“belts” of trees planted around farmland
toreduce wind erosion
o e) problems with fertilizers• inorganic chemical fertilizer does not replenish organic
material mineral content remains high but soil degrades anyway
Erosion Causes and CorrectionsErosion Causes and Corrections
o 2) overgrazing—animals stripping vegetation at a rate too fast for
natural growth patterns to counteract it• a) public lands
• BLM, Bureau of Land Management http://www.blm.gov
• BLM leases grazing land• the acceptable amount of grazing animals is
high
Causes and CorrectionsCauses and Corrections
o 3) deforestation—depletion of forest land• U.N. Food & Agriculture Organization (FAO)
http://www.fao.org• a) causes increased leaching and erosion• b) worst-case scenario—layers above the subsoil
are gone
o 4) the other end of the erosion problem: Where do the particles go?
• displaced sediments can wash into rivers and streams
Irrigation and SalinizationIrrigation and Salinization
o E. Irrigation and Salinization• 1) irrigation—controlled introduction of
water to an area• a) flood irrigation—diverted canals• b) central-pivot irrigation—water pumped from a
central area• 2) salinization—salts accumulating in and
on the soil, hindering plant growth
SalinizationSalinization
o Salinization = accumulation of saltsSalinization = accumulation of salts• Stunts crop growthStunts crop growth• Lowers yieldsLowers yields• Kills plantsKills plants• Ruins the landRuins the land
o Cure: Cure: • Take land out of productionTake land out of production• Install drainage pipeInstall drainage pipe• Flush soil with low-salt waterFlush soil with low-salt water
Soil ConservationSoil Conservation
o Conventional-tillage farmingConventional-tillage farming• Land is plowed and soil broken up and smoothed to Land is plowed and soil broken up and smoothed to
make a planting surfacemake a planting surface• Land is usually plowed in fall, left bare in winterLand is usually plowed in fall, left bare in winter
o Conservation-tillage farmingConservation-tillage farming• Special tillers break up and loosen subsurface soil Special tillers break up and loosen subsurface soil
without turning over topsoilwithout turning over topsoil• Special planting machines inject seeds, fertilizers Special planting machines inject seeds, fertilizers
and weed killers into slits make in unplowed soiland weed killers into slits make in unplowed soil• Saves fuel, cuts costs, hold more water in soil, Saves fuel, cuts costs, hold more water in soil,
keeps soil from getting packed down, allows more keeps soil from getting packed down, allows more crops to be grown during a seasoncrops to be grown during a season
Soil ConservationSoil Conservation
o Terracing: reduces erosion on steep Terracing: reduces erosion on steep slowsslows• Retains water and controls runoffRetains water and controls runoff• Good choice for mountainsGood choice for mountains
Soil ConservationSoil Conservation
o Contour Farming – on gentle sloping Contour Farming – on gentle sloping landland• Plowing and planting crops in rows across Plowing and planting crops in rows across
rather than up and down the sloperather than up and down the slope
Soil ConservationSoil Conservation
o Strip Cropping: a row crop alternates Strip Cropping: a row crop alternates with another cropwith another crop• The cover crop traps soil that erodes from The cover crop traps soil that erodes from
the row cropthe row crop• Catches and reduces water runoff to help Catches and reduces water runoff to help
prevent the spread of pests and plant prevent the spread of pests and plant diseasesdiseases
Soil ConservationSoil Conservation
o Alley Cropping: is a form of Alley Cropping: is a form of intercroppingintercropping• Several crops are planted together in strips Several crops are planted together in strips
or alleys between trees or shrubsor alleys between trees or shrubs• Trees provide shadeTrees provide shade• Trimmings from trees/shrubs provide mulch Trimmings from trees/shrubs provide mulch
(green manure)(green manure)
Soil ConservationSoil Conservation
o Windbreaks:Windbreaks:
o Forest Farming:Forest Farming:
o Riparian Forest Buffers:Riparian Forest Buffers:• Perennial vegetation planted Perennial vegetation planted
between cropland or pasturesbetween cropland or pastures
and streams, lakes, wetlands ectand streams, lakes, wetlands ect
- Reduces runoff and non-point source - Reduces runoff and non-point source pollution by trapping sediment, filtering pollution by trapping sediment, filtering excess nutrients, and degrading pesticidesexcess nutrients, and degrading pesticides
Maintaining Soil FertilityMaintaining Soil Fertility
o FertilizersFertilizers• Organic:Organic:
• Animal ManureAnimal Manure• Green manure Green manure • CompostCompost
o Crop RotationCrop Rotation
MiningMining
Surface mining – used to retrieve shallow Surface mining – used to retrieve shallow mineral depositsmineral deposits
- Open pit mining: - Open pit mining:
Surface MiningSurface Mining
o DredgingDredging
MiningMining
o Strip Mining Strip Mining
MiningMining
o Mountain Top RemovalMountain Top Removal
Subsurface MiningSubsurface Mining
o Used to remove ores too deep to be Used to remove ores too deep to be extracted by surface miningextracted by surface mining
