Deforestation and Loss of Biodiversity

Three General Types of ForestsTropicalTemperatePolar

Old Growth ForestsVirgin (uncut) forests and forests that have not been disturbedExamples: forests of Douglas firs, giant sequoia, and coastal redwoodsUses: habitat for wildlife species, and standing dead trees(snags) and fallen logs decay and add nutrients to the soil

Second Growth ForestsStands of trees resulting from secondary successionExamples: most of the forests in the U.S. and approximately 40% of tropical forests

Economic Importance of Forests

Provide lumber for housingBiomass for fuelwoodPulp for paperMedicines and moreWorth more than $300 billion a year

Ecological Importance of Forests

Slows runoff Reduce amount of sediment in streamsInfluence climateVital to global carbon cycleProvide wildlife habitat

Threats to Forest Ecosystems

Unsustainable loggingClear cuttingSelective cuttingStrip cutting

FireSurface firesCrown firesThe Age of Mega-Fires

Threats to Forest Ecosystems con’t

Insects and diseaseNonnative species introduced accidently and deliberatelyCausing billions of dollars in damage and loss

Climate ChangeLoss of species as temperatures riseFor example: alpine tundra in VA

Tropical ForestsLocation: equatorial Latin America, Africa, and AsiaTypes: rainforests, tropical deciduous forests, dry and very dry deciduous forests

Importance of Tropical Forests

Supplies 50% of the world’s annual harvest of hardwood50%-90% of terrestrial species found thereProvides hundreds of food products(coffee, tea, cocoa, spices, nuts, chocolate & fruits)Natural latex rubber, resins, dye, & essential oils

Importance of Tropical Forests Continued

Contain the active ingredients for ¼ of the world’s prescription drugsStrains of rice, wheat, and corn developed from wild tropical plants

Impact of DeforestationLoss of biodiversity (plants and animals)ErosionLoss of climate control

Causes of Tropical Deforestation

Population growth and povertyPolicies of governmental and international lending agencies

Degradation of a Tropical Forest

Degradation of a tropical forest always begins with a road, usually one cut by a logging company.

Other Reasons for Degradation

LoggingPeasant farmingCattle ranchingCash cropsMiningDamsTree plantations