The World s Forests. Change in Forest Area. Environmental Issues & Problems ENV 150. State of the Forest. Guillaume Mauger. Current Topic: Depletion

Transcription

1 Environmental Issues & Problems ENV 150 The World s Forests Guillaume Mauger Current Topic: Depletion Today: Forests Reading & Discussion: Natural Systems Under Stress, (Ch5, Lester Brown, Plan B 2.0) State of the Forest Change in Forest Area World 1900: 5 billion ha. 2000: 3.9 billion ha. -50% tropical/subtropical -50% temperature/boreal Developed countries Gain of 3.6 million ha./yr Developing countries Loss of 13 million ha./yr Land conservation 12% protected, 5% protected from human activities 20% requested by conservation biologists

2 ! Work in groups,! Use the reading from today, and! Use the reading from last night (ch. 6 in the class textbook) First: List the consequences that result from of forest depletion and land degradation. (in economic terms: the costs ). (include impacts to humans and the biosphere). consequences Depletion/degradation of direct-use resources: fuel, wood, pulp, fruits/nuts, etc. Loss of topsoil, erosion Silting of streams, rivers, lakes Loss of soil nutrients Desertification Increased fire risk Regional climate change (not just local!) Release of CO 2 into atmosphere Loss/degradation of habitat Habitat fragmentation -- populations have less ability to adapt, less room to migrate Secondary growth and tree farms are less biologically complex than old growth Premature extinction! Work in groups,! Use the reading from today, and! Use the reading from last night (ch. 6 in the class textbook) Fuelwood Charcoal Lumber Second: Based on the costs we ve just discussed, come up with a list of what makes forests/wilderness valuable. (in economic terms: the ecosystem services ) Forest economic functions Pulp to make paper Rubber Fruits, nuts, meat Livestock grazing Recreation Jobs Medicine Water for hydroelectric power

3 Forest Ecological Functions Ecosystem health -Support energy flow -Support nutrient cycling -Stabilizes soil -Moderate stream flow -Soil filters water -Release oxygen Regulates climate -Evapo-transpiration releases water vapor - Sustains inland precipitation -Store atmospheric carbon Supports biodiversity -Provides habitat -Provides food Valuing Biodiversity Ecosystem Services Provisioning services Food, water, timber, fiber Regulating services Regulation of climate, floods, disease, wastes, and water quality Cultural services Recreation, aesthetic enjoyment, spiritual fulfillment Supporting services Soil formation, photosynthesis, nutrient cycling source: Millennium Ecosystem Assessment, Ecosystems and Human Well-being: Biodiversity Synthesis. Valuing Biodiversity U.S. Forests Use values Direct uses of biodiversity: consumptive - food, medicines, non-consumptive - eco-tourism Subject to trade & commerce, monetary value readily assigned, varies with demand Non-use values Indirectly related to humans, ecosystem services, future options, aesthetics Monetary valuation difficult Intrinsic value Worth in themselves source:

4 ! Work in groups,! Use the reading from today, and! Use the reading from last night (ch. 6 in the class textbook) Logging in WA Third: Is it possible to log sustainably? If so, how? If not, why not? Logging sustainably (?) Options: Clear cutting Strip cutting Selective logging Tree planting gentler cutting techniques (e.g., cut canopy vines) Considerations: Slope Roads: amount / type Status of adjacent land Impact on adjacent land Competing uses of forest (e.g., local communities) What approaches can we take to protecting forests and wilderness areas?

5 Solutions: Agroforestry Solutions: Reduce illegal cutting Integrate trees and agriculture Total - partial ban on logging -Shade -Windbreaks decrease erosion -Trees fix N, decrease the need for fertilizer -Increase wildlife habitat -Carbon sink Solutions: Reducing Demand Waste less wood Make paper and charcoal fuel from fibers that do not come from trees Limit development, urban growth China, New Zealand, Philippines, Sri Lanka, Viet Nam, Thailand Need new methods of enforcement logging bans imposed in the Asia-Pacific region in response to... natural disasters, seldom included strategies that would bring the desired environmental and protection goals. problem: illegal logging persists. -FAO Solutions: U.S. Reserves Executive Office U.S. Dept. of the Interior U.S. Dept. Agriculture National Forest Service (1905) 193 m. acres U.S. Fish and Wildlife National Wildlife refuge (1903) 95 m. acres Bureau of Land Management (1946) National Park Service (1872) 248 m. acres 84 m. acres U.S. Wilderness Society 1935

6 Solutions: Buffer zones and Ecotourism Ecotourism in Costa Rica 8 mega-reserves to sustain 80% of its biodiversity Solutions: sustaining biodiversity hotspots International organizations World Conservation Union (IUCN) Food and Agriculture Organization The Nature Conservancy Forest Trends World Wildlife Federation 34 Hotspots of endangered biodiversity identified by ecologists Wangari Maathai: Greenbelt Movement, Kenya Haiti: Ken Burns: The National Parks