Transcript Chapter 6
Sustaining Biodiversity: The Ecosystem Approach Chapter 6 Biodiversity - Defined • Speciation – Extinction = Biodiversity – Raw genetic material for further evolution Succession • Highest diversity occurs when there is enough disturbance to prevent the dominant competitors from taking over, but not so much that the community is unable to develop. Human Activities and Biodiversity Habitat Loss and Degradation Greatest threat to species diversity “HIPPO” Habitat destruction Invasive species Population (humans) growth Pollution Over-harvesting Rate = 80 million new people/year + New York City every month + Germany every year + United States every 3.7 years Biodiversity is affected by human population size and resource use Agriculture Economic production and consumption Industry Recreation Global Biodiversity Status Forests Rainforests Grassland Desert Everything 5% of our virgin forests remain uncut 2% of our native grasslands are left in their native state 15% of our redwood forests are old growth Less than 50% of our wetlands remain Their existence being deemed less important than others… Open Season On Wetlands Destruction Begins Menards filling wetlands for new store In Puget Sound, we have lost 70% of our estuaries to farms and development Over 800 miles of Puget Sound shoreline has been armed with bulkheads. Importance of Biodiversity • Intrinsic value – right to exist, to have evolved means they have important roles • Instrumental value – because of their use to us • Existence value – knowing it exists • Aesthetic value – wildlife viewing • Bequest value – willing to pay for its existence Solutions for Protecting Biodiversity Types of US Public Lands • Multiple-use lands: National Forests; National Resource Lands (BLM) • Moderately-restricted use lands: National Wildlife Refuges • Restricted-use lands: National Park System; National Wilderness Preservation System US Public Lands Fig. 11-6 p. 198 Managing US Public Land Conservation biologists support: • Biodiversity and ecological function • No subsidies or tax breaks for use • Public should get fair compensation • Users held responsible for actions • • • • Developers and Resource Extractors Support: Sell public land Cut funding to administer lands Cut old growth forests Drill in the Artic Refuge Ecological and economic services of forests Trade-Offs Logging in U.S. National Forests and other publicly owned lands Advantages Helps meet country’s timber needs Cut areas grow back Keeps lumber and paper prices down Provides jobs in nearby communities Promotes economic growth in nearby communities Disadvantages Provides only 4% of timber needs Ample private forest land to meet timber needs Has little effect on timber and paper prices Damages nearby rivers and fisheries Recreation in national forests provides more local jobs and income for local communities than logging Decreases recreational opportunities * Clear cutting our forests: Advantages and Disadvantages Advantages Higher timber yields Maximum economic return in shortest time Can reforest with genetically improved fast-growing trees Short time to establish new stand of trees Needs less skill and planning Best way to harvest tree plantations Good for tree species needing full or moderate sunlight for growth Trade-Offs Clear-Cutting Forests Disadvantages Reduces biodiversity Disrupts ecosystem processes Destroys and fragments some wildlife habitats Leaves moderate to large openings Increases soil erosion Increases sediment water pollution and flooding when done on steep slopes Eliminates most recreational value for several decades Sustainable Forestry • Several methods can be used to sustain harvests and maintain biodiversity Longer rotations will provide a more stable ecosystem and greater biodiversity Selective logging leaves habitat, minimizing disturbance and Habitat fragmentation and island biogeography Leave snags and downed logs for cavity nesting animals Logging roads like this one have dozens of ditches, culverts and other conduits that dump pollution from clear cut and herbicide-sprayed hillsides directly into streams and rivers. Recent efforts by the forest industry, the tribes and government agency scientists have worked to lessen the impacts of logging roads. Include ecological services in estimating economic value Rainforests harbor the greatest gene pool in the world. The rainforest has nurtured this "pool" to become home for 170,000 of the world's 250,000 known plant species. Tropical Deforestation: Consequences • Rapid and increasing • Loss of biodiversity • Loss of resources (e.g., medicines) • Contributes to global warming Tropical Deforestation: Causes • Population growth • Poverty • Environmentally harmful government subsidies (encourage poor to colonize tropical forests) • Debts owed to developed countries • Low value of ecological services Managing and Sustaining National Parks • • • • • • Inadequate protection Often too small to sustain biodiversity Invasions by nonnative species Too many human visitors Traffic jams and air pollution Better pay for park staff Establishing, Designing, and Managing Nature Reserves • Include moderate to large tracts of land • Involve government, private sector and citizens • Biosphere reserves • Adaptive ecosystem management • Protect most important areas (“hot spots”) • Wilderness areas Ecological Restoration: Basic Principles • • • • • Mimic nature Recreate lost niches Rely on pioneer species Control nonnative species Reconnect small patches Protecting Biodiversity in Washington State • Governor Locke’s Executive Order • Establishment of the Washington Biodiversity Council – Develop 30-year comprehensive prioritized strategy to protect biodiversity – Assess existing and potential landowner incentive program – Develop public education and a web site – By December 31, 2007 Ecosystem Planning in Washington State • Mitigation “banks” • Growth Management Act Critical Area Ordinances • CREP and CRP • Marine Protected Areas • Eco-regional Assessments for Biodiversity