Chapter 18 Land Resources

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Chapter 18Land Resources
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Overview of Chapter 18

• Land Use
• World land use
• US land use
• Wilderness Park and Wildlife Refuges
• National Parks
• Wildlife Refuge
• Forests
• Forest management
• Deforestation
• Rangeland and Agricultural Land
• Wetlands and Coastal Areas
• Conservation of Land Resources

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Land Use- Worldwide
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Land Use- United States
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Land Use- United States

• 55 of US land is privately owned
• Remainder of land is owned by government
• Most federally owned land is in Alaska and 11
  western states

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Managing Public and Private Land

• Public Planning and Land Use
• Land use decisions are complex and have multiple
  effects
• Must take into account all repercussions of
  proposed land use
• Management of Federal Land
• Wide-Use Movement
• Environmental Movement

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Wilderness Parks and Wildlife Refuges

• Wilderness
• A protected area of land in which no human
  development is permitted
• Wilderness Act (1964)
• Set aside federally owned land as part of
  National Wilderness Preservation System
• No development permitted (including roads)
• Managed by NPS, USFS, FWS BLM

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Wilderness

• Some areas have a limited number of permitted
  human guests to reduce impact
• Other problems include invasive species

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National Park System
Yosemite National Park

• Created in 1916
• Currently includes 58 parks
• Primary goal
• Teach people about the natural environment,
  management of natural resources and history of a
  site

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National Park System

• Threats to U.S. Parks
• Crime Vandalism
• Traffic jams
• Pollution of the soil, water and air
• Originating both inside and outside the park
• Resource violations
• Natural Regulation
• Policy to let nature take it course
• No culling wildlife
• No suppressing wildfire

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Wildlife Refuges

• National Wildlife Refuge System (1903)
• Represent all major ecosystems founds in the US
• Mission
• To preserve lands and waters for the conservation
  of fishes, wildlife and plants of the US
• Recreation (including hunting and fishing) are
  permitted
• Cannot impede conservation efforts

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Forests

• Role in Hydrologic Cycle (right)
• Forest Management
• Deforestation
• Forest Trends in the US
• Trends in Tropical Forests
• Boreal Forests

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Forest Management

• Traditional Forest Management
• Low diversity- monocultures (right)
• Managed for timber production
• Ecological Sustainable Forest Management
• Environmentally balanced
• Diverse trees
• Prevent soil erosion
• Preserve watersheds
• Wildlife corridors- unlogged

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Harvesting Trees
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Harvesting Trees - Clearcutting
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Deforestation

• Temporary or permanent clearance of large
  expanses of forest for agriculture or other use
• World forests shrank 90 million acres from
  20002005
• Causes
• Fire
• Expansion of agriculture
• Construction of roads
• Tree harvest
• Insect and disease

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Deforestation

• Results
• Decreased soil fertility
• Uncontrolled soil erosion
• Production of hydroelectric power (silt build up
  behind dams)
• Increased sedimentation of waterways
• Formation of deserts
• Extinction of species
• Global climate changes

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Forest Trends in US

• Most temperature forest are steady or expanding
• Returning stands lack biodiversity of original
  forests
• More than half of US forest are privately owned
  (right)
• Forest Legacy Program
• Conservation easement

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US National Forests

• Managed for multiple uses
• Timber harvest
• Livestock forage
• Water resource and watershed protection
• Mining, hunting, fishing, etc.
• Road building is an issue
• Provides logging companies with access to forest
• Clearcutting is an issue

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Case-In-Point Tongass National Park

• One of worlds few temperate rainforests
• Prime logging area
• Modified 1997 Forest Plan
• Roadless Area Conservation Rule (2000)
• Politics rules government agencies

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Trends in Tropical Forests

• Tropical rainforests (below) and tropical dry
  forests

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Disappearing Tropical Rain Forests

• Population growth
• Cannot account for all of it
• Immediate causes
• Subsistence agriculture
• Commercial logging
• Cattle ranching
• Other causes
• Mining
• Hydroelectric power

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Disappearing Tropical Dry Forests

• Primarily destroyed for fuelwood
• Used for heating and cooking

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Boreal Forests

• Worlds largest biome
• Extensive clearcutting
• Primary source of worlds industrial wood and
  wood fiber

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Rangeland and Agricultural lands

• Rangeland
• Land that is not intensively managed and is used
  for grazing livestock

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Rangeland Degradation and Deforestation

• Overgrazing leaves ground barren
• Animals exceed their carrying capacity
• Land degradation
• Natural or human-induced process that decreases
  future ability of land to support crops or
  livestock
• Desertification
• Degradation of once fertile land into
  nonproductive desert

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Rangeland Trends in US

• Make up 30 of total US land area
• 2/3 privately owned
• Pressure from developers to subdivide
• Public rangeland managed by
• Taylor Grazing Act (1934)
• Federal Land Policy and Management Act (1976)
• Conditions of public rangeland are slowly
  improving
• Grazing fees is an issue

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Agricultural Land

• US has 300 million acres of prime farmland

• Much is being overtaken by suburban sprawl
• Parking lots
• Housing developments
• Shopping malls

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Wetlands

• Lands that are usually covered with water for at
  least part of the year
• Have characteristic soils and water-tolerant
  vegetation
• Benefits
• Habitat for migratory waterfowl and wildlife
• Recharge groundwater
• Reduce damage from flooding
• Improve water quality
• Produce many commercially important products

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Wetlands

• Human activity that threatens wetlands
• Drainage for agriculture or mosquito control
• Dredging for navigation
• Construction of dams, dykes or seawalls
• Filling in for solid waste disposal
• Road building
• Mining for gravel, fossil fuels, etc.
• Shrinking 58,500 acres per year

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Restoring Wetlands

• No Net Loss of Wetlands
• Development of wetlands is allowed if
  corresponding amount of previously converted
  wetland is restored
• Not all wetland restorations are successful

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Coastlines

• Coastal wetlands
• Provide food and habitat for many aquatic animals
• Historically regarded as wasteland

• US starting to see importance of protecting this
  environment
• Retaining seawalls (right)

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Coastal Demographics

• Many coastal areas overdeveloped
• 3.8 billion people live within 150km of coastline
• 6.4 billion people will likely live there by 2025

• United States
• 14 of 20 largest US cities along coast
• 19 of 20 most densely populated countries along
  coasts

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Conservation and Land Resources

• All types of ecosystems must be preserved
• Four criteria of importance
• Areas lost or degraded since European
  colonization
• Number of present examples of a particular
  ecosystem (or the total area)
• Estimate of the likelihood that a given ecosystem
  will lost a significant area or be degraded in
  next 10 years
• Number of threatened and endangered species
  living in the ecosystem

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Conservation and Land Resources
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Soil and Mineral Resources

• Types of rocks
• Igneous
• Sedimentary
• Metamorphic

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Igneous

• Igneous rocks (?fire-formed?)from hardened magma
  and lava
• a) intrusivecoarse-grained igneous rocks below
  the surface
• b) extrusivefine-grained igneous rocks above the
  surface

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Sedimentary

• Sedimentary rocks (?settling)from sediment,
  being compacted and cemented
• a) compactionweight pressing the pieces together
• b) cementation minerals gluing the pieces
  together
• c) types of sediment sand, silt, clay, gravel,
  bone chips, pieces of shells,

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Sedimentary Cont

• Formation
• a) clasticfrom sediment compaction and
  cementation
• b) chemicalfrom water-soluble minerals
• temperatures
• c) organicfrom plant or animal remains (coal,
  limestone)

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Metamorphic

• Metamorphic rocks (?changed form)from
  temperature and pressure
• extremes, and chemical change
• 1) formation
• a) metamorphisma change in rock
• b) contact metamorphismaffects a small area
  local heating
• c) regional metamorphismaffects a large area
  tectonics

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Rock Cycle

• rock cyclechanges in rock forms, from one type
  to another type, by different
• 1) formation of igneous rock
• a) melting and cooling any existing rock
• b) hardening of magma or lava
• 2) formation of sedimentary rock weathering and
  erosion to form sediment compaction and
  cementation
• 3) formation of metamorphic rock heating and
  pressurizing any existing rock

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Soil

• A. Soil characteristics
• 1) Soil profiles
• a) horizonshorizontal soil layers
• b) soil profilevertical slices through soil
  layers

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How is Soil Formed?

• How is soil formed?Soils are dynamic, forming
  continuously over a long period of time. Soil
  types differ, depending on the parent materials
  from which they came and from the surrounding
  environment. The way in which soil forms depends
  on
• parent material
• climate
• topography
• living organisms
• time

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Soil Components

• Soil is a natural medium made up of five major
  components
• mineral particles clay, silt, sand and gravel
• organic matter decaying plant and animal
  material
• water
• air
• living organisms (soil biota) ranging from
  bacteria, fungi and earthworms
• A healthy soil should have a balance of these
  components.

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Soil Texture

• Soil textureclassification based on particle
  size
• a) soil separatesrock fragments of varying size
  Sand, Silt, Clay

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• Size of sand, silt and clay particles
• 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

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Loam

• loamcommon soil type 40 sand, 40 silt, and
  20 clay

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Weathering

• weathering breaking up of the crust the wearing
  down of rock, liberating minerals
• physical (mechanical) weatheringfrom wind,
• water, weather, or other environmental events
• chemical weatheringfrom chemical reactions
• between water and atmospheric gases and
  bedrock
• biological weatheringfrom activities of
  organisms

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Soil Erosion and Degradation

• Erosion movement of soil from one place to
  another caused by wind, usually water

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Erosion

• Usually caused by moving water
• Sheet erosion
• Rill erosion

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Losing Topsoil

• Makes soil less fertile and less able to hold
  water
• Sediment clogs ditches, boat channels,
  reservoirs, and lakes

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Causing and Correcting Erosion

• 1) overcultivationfrequent plowing
• a) crop rotationalternating the type of crops
  grown
• b) no-till agricultureweed control, planting,
  and covering up
• all at once
• (low-till farmingdecrease the amount of
  tilling)
• c) contour-strip croppingcultivation along
  sloping ground
• d) shelter beltsbelts of trees planted around
  farmland to
• reduce wind erosion
• e) problems with fertilizers
• ? inorganic chemical fertilizer does not
  replenish organic
• material
• ? mineral content remains high but soil
  degrades anyway

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Erosion Causes and Corrections

• 2) overgrazinganimals 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

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Causes and Corrections

• 3) deforestationdepletion of forest land
• U.N. Food Agriculture Organization (FAO)
  http//www.fao.org
• a) causes increased leaching and erosion
• b) worst-case scenariolayers above the subsoil
  are gone
• 4) the other end of the erosion problem Where
  do the particles go?
• displaced sediments can wash into rivers and
  streams

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Irrigation and Salinization

• E. Irrigation and Salinization
• 1) irrigationcontrolled introduction of water to
  an area
• a) flood irrigationdiverted canals
• b) central-pivot irrigationwater pumped from a
  central area
• 2) salinizationsalts accumulating in and on the
  soil, hindering plant growth

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Salinization

• Salinization accumulation of salts
• Stunts crop growth
• Lowers yields
• Kills plants
• Ruins the land
• Cure
• Take land out of production
• Install drainage pipe
• Flush soil with low-salt water

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Soil Conservation

• Conventional-tillage farming
• Land is plowed and soil broken up and smoothed to
  make a planting surface
• Land is usually plowed in fall, left bare in
  winter
• Conservation-tillage farming
• Special tillers break up and loosen subsurface
  soil without turning over topsoil
• Special planting machines inject seeds,
  fertilizers and weed killers into slits make in
  unplowed soil
• Saves fuel, cuts costs, hold more water in soil,
  keeps soil from getting packed down, allows more
  crops to be grown during a season

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Soil Conservation

• Terracing reduces erosion on steep slows
• Retains water and controls runoff
• Good choice for mountains

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Soil Conservation

• Contour Farming on gentle sloping land
• Plowing and planting crops in rows across rather
  than up and down the slope

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Soil Conservation

• Strip Cropping a row crop alternates with
  another crop
• The cover crop traps soil that erodes from the
  row crop
• Catches and reduces water runoff to help prevent
  the spread of pests and plant diseases

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Soil Conservation

• Alley Cropping is a form of intercropping
• Several crops are planted together in strips or
  alleys between trees or shrubs
• Trees provide shade
• Trimmings from trees/shrubs provide mulch (green
  manure)

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Soil Conservation

• Windbreaks
• Forest Farming

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• Riparian Forest Buffers
• Perennial vegetation planted
• between cropland or pastures
• and streams, lakes, wetlands ect
• - Reduces runoff and non-point source pollution
  by trapping sediment, filtering excess nutrients,
  and degrading pesticides

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Maintaining Soil Fertility

• Fertilizers
• Organic
• Animal Manure
• Green manure
• Compost
• Crop Rotation

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Mining

• Surface mining used to retrieve shallow mineral
  deposits
• - Open pit mining

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Surface Mining

• Dredging

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Mining

• Strip Mining

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Mining

• Mountain Top Removal

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Subsurface Mining

• Used to remove ores too deep to be extracted by
  surface mining