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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Land and water use

Land and Water Use

Part 2


Forestry

Forestry


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


Old growth forests2

Old-Growth Forests


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


Yellowstone 1988

Yellowstone 1988


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


Results of deforestation

Results of Deforestation


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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