What Are the Major Threats to Forest Ecosystems?

Forests vary in Their Make-Up, Age, and Origins

• Old-growth or primary forest (36%): Uncut, or not disturbed for several hundred years

  • Ecological niche: Reservoirs of biodiversity

• Second-growth forest (60%): Secondary ecological succession

• Tree plantation (tree farm, commercial forest- 4%): May supply most industrial wood in the future. 1 or 2 species of the same age

  • Violate sustainability & biodiversity

  • Depletion of nutrients from topsoil

Major Ecological and Economic Sevices Provided by Forests

• Ecological Services

  • Support energy flow and chemical cycling

  • Reduce soil erosion

  • Absorb and release water

  • Purify water and air

  • Influence local and regional climate

  • Store atmospheric carbon

  • Provide numerous wildlife habitats

• Economic Services

  • Fuelwood

  • Lumber

  • Pulp to make paper

  • Mining

  • Livestock grazing

  • Recreation

  • Jobs

Major Tree Harvesting Methods

• Selective cutting: Intermediate-aged or mature trees are cut singly or in small groups

• Clear-cutting: Removal of all trees from an area. Most efficient for logging operations to harvest trees and cost

• Strip cutting: Clear-cutting a strip of trees along the contour of the land

Clear Cutting Forests

• Advantages

  • Higher timber yields

  • Maximum profits in the shortest time

  • Can reforest with fast-growing trees

  • Suitable for tree species needing full or moderate sunlight

• Disadvantages

  • Reduce biodiversity

  • Habitat destruction and fragmentation

  • Increase water pollution

Fire

• Surface fires: Usually burn leaf litter and undergrowth. May provide food in the form of vegetation that sprouts after fire

• Crown fires: Extremely hot so it burns whole trees, kill wildlife, and increase soil erosion

Insects, and Climate Change Threaten Forest Ecosystems

• Introduction of foreign diseases and insects

  • Accidental

  • Deliberate

• Global warming: Rising temperatures, trees become more susceptible to diseases and pests, drier forests have more fires, increase in greenhouse gases

Deforestation

• Tropical forests: Especially in Latin America, Indonesia, and Africa. The main reason for 8,000 tree species are threatened with extinction (10% of the world rate)

• Boreal forests: A coniferous forest consisting primarily of pine, spruce, and larch trees. That is in Alaska, Canada, Scandinavia, and Russia

Major Causes of Destruction of Tropical Forests

• Crop/timber exports

• Poverty

• Population growth

• Roads

• Fires

• Cash crops

• Logging

• Tree plantations

How Should We Manage and Sustain Forests?

Certifying Sustainably Grown Timber

• Collins Pine: Owns and manages protective timberland

• Forest Stewardship Council: Developed a list of environmentally sound practices. Also certifies manufacturers of wood products

Forest Fire Strategies

• Prescribed Fires: Carefully planned & monitored. Set small contained surface fires to remove flammable small trees and underbrush

• Allow fires on public lands to burn

  • Removes flammable underbrush & smaller trees

• Protect structures in fire-prone areas: Eliminate the use of flammable construction materials. Thinning a zone of 60m (200ft) around fire-prone areas

• Thin forests in fire-prone areas: Clear away small fire-prone trees & underbrush under environmental controls. Can leave-behind slash.

  • Slash: Highly flammable debris

Sustaining Tropical Forests

• Prevention

  • Protect the most diverse and endangered areas

  • Educate settlers about sustainable agriculture and forestry

  • Subsizide only sustainable forest use

  • Reduce poverty

  • Slow population growth

• Restoration

  • Encourage regrowth through secondary succession

  • Rehabilitate degraded areas

  • Concentrate farming and ranching in already cleared areas

How Should We Manage and Sustain Grasslands?

Grasslands- Ecological Services

• Soil formation

• Erosion control

• Chemical cycling

• Storage of atmospheric CO2 in biomass

• Maintenance of biodiversity

Rangelands and Pastures

• Rangelands: Unfenced grasslands in temperate and tropical climates that provide forage for animals

• Pastures: Managed grasslands and fences meadows used for grazing livestock

• Overgrazing of rangelands: Reduces grass cover, leads to erosion of soil by water and wind, the soil becomes compacted and enhances invasion of plant species that cattle won’t eat.

How Should We Manage and Sustain Parks and Natural Reserves?

Threats to National Parks

• Parks in developing countries

  • Greatest biodiversity

  • 1% protected against

    • Illegal animal poaching

    • Illegal logging and mini

• The biggest problem may be a popularity

  • Noise

  • Congestion

  • Pollution

  • Damage or destruction to vegetation and wildlife

• Damage from nonnative species

• Native species are sometimes killed or removed

• Threatened islands of biodiversity

  • Air pollution

Solution

• Integrate plans for managing parks and nearby federal lands

• Add new parkland near threatened parks

• Buy private land inside parks

• Locate visitor parking outside parks and provide shuttle buses for people touring heavily used parks

• Increase federal funds

• Get private donations

• Limit visitors

• Increase employees (park rangers)

Protecting Wilderness Is an Important Way to Preserve Biodiversity

• Wilderness can be described as land officially designated as having no serious disturbance from human activities

• Wilderness Act of 1964: Protects undeveloped lands, 2% of the lower 48 protected, mostly in the West.

What is the Ecosystem Approach to Sustaining Biodiversity?

Protecting Global Biodiversity Hot Spots Is an Urgent Priority

• 34 biodiversity hot spots rich in plant species

  • 2% of the earth’s surface, but 50% of flowering plant species and 42% of terrestrial vertebrates

  • 1.2 billion people

• Drawbacks of this approach

  • May not be rich in animal diversity

  • People may be displaced and/or lose access to important resources

Protecting Ecosystem Services Is Also an Urgent Priority

• U.N. Millennium Ecosystem Assessment: Identify key ecosystem services. Human activities degrade or overuse 60% of the earth’s natural services

We Can Share Areas We Dominate With Other Species

• Reconciliation ecology: Invent and maintain habitats for species diversity where people live, work, and play

• Community-based conservation: Belize and the black howler monkeys protects vital insect pollinators