Land and water use
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Land and Water Use. Part 2. Forestry. Ecological Services. Providing wildlife habitat Carbon sinks Affecting local climate patterns Purifying air and water Reducing soil erosion Providing energy and nutrient cycling. Tree Plantations.

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Land and Water Use

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Ecological services
Ecological Services

  • Providing wildlife habitat

  • Carbon sinks

  • Affecting local climate patterns

  • Purifying air and water

  • Reducing soil erosion

  • Providing energy and nutrient cycling


Tree plantations
Tree Plantations

  • Large, managed commercial farm with uniformly aged trees of one species


Tree plantations1
Tree Plantations

  • Primary uses

  • Trees harvested by clearcutting


Tree plantations2
Tree Plantations

  • Species choice


Tree plantations3
Tree Plantations

Pros

Cons

  • Easy to harvest

  • Economical

  • More wood production

  • Little biodiversity

  • Damage to wetlands

  • Much smaller food webs

  • Little decaying wood


Old growth forests
Old-Growth Forests

  • Have not been seriously impacted by humans

  • Much biodiversity


Old growth forests1
Old-Growth Forests

  • Depletion increases risk of climate change

  • High economic value, but mature slowly

    • Mahogany, oak



Forest fires
Forest Fires

  • Each forest is unique

    • Number of fires

    • Frequency of fires


Changes in forest fires
Changes in Forest Fires

  • Wild fire frequency has increased (4X average 1970-1986)

  • Area burned has increased (7X previous)

  • Wild fire season lengthened by 78 days


Reasons for changes
Reasons for Changes

  • Appears to be linked to spring and summer temperatures

  • Fire management has changed


Crown fires
Crown Fires

  • Occurs where no fires have occurred in long time

  • Extremely hot

  • Burn entire tree

  • Hop from tree to tree

  • Kills wildlife, increases soil erosion, destroys structures



Ground fires
Ground Fires

  • Occur underground and burn partially decayed leaves

  • Common in peat bogs

  • Difficult to detect and extinguish

  • Summer 2008 - Pocosin Lakes National Wildlife Refuge


Surface fires
Surface Fires

  • Burns undergrowth and leaf litter.

  • Kills seedlings and small trees

  • Releases minerals back into soil

  • Stimulates germination

  • Control pathogens and insects


Controlling fires
Controlling Fires

  • Prevention

  • Prescribed burning


Deforestation
Deforestation

  • Conversion of forested areas to non-forested areas


Deforestation1
Deforestation

  • Natural causes

  • Human reasons



Methods to manage and harvest
Methods to Manage and Harvest

  • Selective cutting

  • Strip cutting

  • Clear-cutting


Clear cutting
Clear Cutting

Pros

Cons

  • Practical method for trees that require full or moderate sunlight

  • Genetically improved – resist disease, grow faster

  • Increased economic returns

  • Produces high yield of timber

  • Provides jobs

  • Reduces recreational value of the land

  • Causes soil erosion, water pollution, flooding on steeply sloped surfaces

  • Reduces biodiversity

  • Decaying wood is absent


Effect on hydrologic cycle
Effect on Hydrologic Cycle

  • Decreased evapotranspiration

  • Lessens downwind precipitation

  • Increased runoff to rivers/ocean


Causes of deforestation
Causes of Deforestation

  • Growing number of poor

  • “Open-access property rights”

  • Entrepreneurs


Forest management
Forest Management

  • Forests cover 1/3 world land surface

    • Most forests in N. America, S. America, Russia

  • Forests cover 1/3 of US

    • 2/3 nonfederal


Forest management1
Forest Management

  • Forest Service

    • 1905

    • Agency of USDA

    • Manages public land in national forests and grasslands (193 million acres)

      • Logging, farming, recreation, hunting, fishing, mining, oil/gas extraction, livestock grazing


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