Presentation on theme: "ENVIRONMENTAL SCIENCE 13e CHAPTER 9: Sustaining Biodiversity: The Ecosystem Approach."— Presentation transcript:
ENVIRONMENTAL SCIENCE 13e CHAPTER 9: Sustaining Biodiversity: The Ecosystem Approach
Wangari Maathai and the Green Belt Movement Began in Kenya in 1977 Organizes poor women in rural Kenya 50,000 members protect forests Planted 20 million trees –Fruits –Building materials –Firewood Similar programs in 30 African countries 2004: Nobel Peace Prize
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9-1 What Are Major Threats to Forest Ecosystems? Concept 9-1 Ecologically valuable forest ecosystems are being cut and burned at unsustainable rates in many parts of the world.
Types of Forests Forests cover 30% of earth’s land surface Old-growth forests: uncut or regenerated primary forest that has not been seriously disturbed by human activities or natural disasters for several hundred years or more Second-growth forests: a stand of trees resulting from secondary ecological succession. Develop after trees have been removed by human activities such as clear cutting for timber or cropland or by natural forces such as fire, hurricanes, or volcanic eruption Tree plantation; tree farm; commercial forest
Fig. 9-2, p. 180 Old growth forest in the US state of Washington’s Olympic National Forest
Fig. 9-3, p. 180 Short (25- to 30- year rotation cycle of cutting and regrowth of a monoculture tree plantation in modern industrial forestry. In tropical countries, trees grow more rapidly year round so rotation cycle can be 6-10 years.
Fig. 9-3, p. 180 Old growth or second growth forest are clear cut to provide land for growing most tree plantations
Fig. 9-4, p. 181 pFigure 9.4: Major ecological and economic services provided by forests (Concept 9-1). Question: Which two ecological services and which two economic services do you think are the most important? ital Fuelwood Lumber Pulp to make paper Mining Livestock grazing Recreation Jobs 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 Ecological Services Economic Services Forests
Science Focus: Putting a Price Tag on Nature’s Ecological Services Estimated value of earth’s ecological services –$33.2 trillion per year –$4.7 trillion per year for forests This is hundreds of times the economic value Need to start factoring values into land use Ecological services can be a sustainable source of ecological income
Fig. 9-A, p. 181 Estimated annual global economic values of some ecological services provided by forests compared to the raw materials they produce (in billions of dollars).
Harvest Methods Step one: build roads –Erosion –Invasive species –Open up for human invasion Step two: logging operations –Selective cutting: intermediate aged or mature trees in an uneven aged forest are cut singly or in small groups (Fig 9-6a) –Clear cutting: remove all the trees from an area –Strip cutting: involves clear cutting a strip of trees along the contour of the land within a corridor narrow enough the allow natural regeneration within a few years
Cleared plots for agriculture New highway Old growth Highway Cleared plots for grazing Fig. 9-5, p. 182
Clear stream (a) Selective cutting Fig. 9-6, p. 182 Major tree harvesting methods. If you were cutting trees in a forest you owned which method would you choose and why?
Muddy stream (b) Clear-cutting Fig. 9-6, p. 182
Cut 1 year ago (c) Strip cutting Uncut Clear stream Uncut Cut 3–10 years ago Dirt road Fig. 9-6, p. 182
Fig. 9-7, p. 182 Clear cut logging in the US state of Washington
Forests and Fires Surface fires –Burn only undergrowth and leaf litter –May kill seedlings and small trees but spare most mature trees; allow most wild animals to escape –Cool fire –Ecological benefits: help prevent more destructive fires, free mineral nutrients, release certain seeds and stimulate germination of some tree seeds, help control diseases and insects
Crown fires –Burn the entire tree –Hot fire –Occur in forests with lack of surface fires
Fig. 9-8, p. 183 Type of fire?
Fig. 9-8, p. 183 Type of fire?
Loss of Original Forests Deforestation Over past 8,000 years, human activities have reduced the earth’s forest by 46%, most of this loss since since 1950 Most in tropical areas, developing countries Estimated loss of 40% intact forests within next 20 years
Fig. 9-9, p. 184 Extreme tropical deforestation in Chiang Mai,Thailand. What do you think will happen to the dried out topsoil when the winds come? How does the term ecological tipping point apply here?
Fig. 9-10, p. 184
Good News on Forests 2000–2007 net total forested area stabilized or increased Most of the increase due to tree plantations Net loss of terrestrial biodiversity
Return of Forests in the United States (1) U.S. forests –Cover ~30% of land –Contain ~80% of wildlife species –Supply ~67% of nation’s surface water Forest cover greater now than in 1920 Secondary succession
Return of Forests in the United States (2) Second- and third-growth forests fairly diverse More wood grown than cut 40% of forests in National Forest System Some forests transformed into tree plantations
Tropical Forests Cover 6% of earth’s land area Habitat for 50% of terrestrial plants and animals –Vulnerable to extinction – specialized niches Rapid loss of 50,000–170,000 km 2 per year Some second-growth forests
Causes of Tropical Forest Deforestation and Degradation Population growth and poverty Economic reasons –Logging –Ranching –Farming Government subsidies Fires raise temperatures and reduce rainfall
Fig. 9-11, p. 186 Natural Capital Degradation Not valuing ecological services Crop and timber exports Government policies Poverty Population growth Roads Fires Settler farming Cash crops Cattle ranching Logging Tree plantations Basic CausesSecondary Causes Settler farming Cattle ranching Tree plantations Cash crops Logging Roads Fires Major Causes of the Destruction and Degradation of Tropical Forests
Fig. 9-12, p. 187 Brazil’s Amazon basin What’s going on in this picture?
9-2 How Should We Manage and Sustain Forests? Concept 9-2 We can sustain forests by emphasizing the economic value of their ecological services, removing government subsidies that hasten their destruction, protecting old- growth forests, harvesting trees no faster than they are replenished, and planting trees.
Fig. 9-13, p. 188
Management of Forest Fires (1) Fire suppression in all types of forests Increased amounts of underbrush Increased probability of crown fires
Management of Forest Fires (2) Prescribed fires Allow some fires to burn Thin vegetation from forests Thin around vulnerable homes Decrease flammability of homes
Science Focus: Certifying Sustainably Grown Timber Forest Steward Council certification of forest operations –Environmentally sound practices –Sustainable yield harvest –Minimal erosion from operations –Retention of dead wood for wildlife habitat
Trees and Paper Many trees are cut for paper production Alternatives –Pulp from rice straw and agricultural residues (China) –Kenaf (U.S.) –Hemp
Fig. 9-14, p. 189 Kenaf
Ways to Reduce Tropical Deforestation Debt-for-nature swaps Conservation concessions Gentler logging methods Encourage use of wood substitutes
Fig. 9-15, p. 190 Sustaining Tropical Forests Protect the most diverse and endangered areas Educate settlers about sustainable agriculture and forestry Subsidize only sustainable forest use Protect forests with debt-for-nature swaps and conservation concessions Certify sustainably grown timber Reduce poverty Slow population growth Encourage regrowth through secondary succession Rehabilitate degraded areas Concentrate farming and ranching in already-cleared areas Prevention Solutions Restoration
9-3 How Should We Manage and Sustain Grasslands? Concept 9-3 We can sustain the productivity of rangeland by controlling the number and distribution of grazing livestock and by restoring degraded grasslands.
Grasslands Provide important ecological services Second most used and altered ecosystem by humans 42% grazed by cattle, sheep, and goats – rangeland (open) and pasture (fenced) Overgrazing
Fig. 9-16, p. 191 What happens to overgrazed rangeland?
Manage Rangelands Sustainably Practice rotational grazing Fence out riparian zone areas Suppress invader plants –Herbicides –Mechanical removal –Controlled burning –Short-term trampling
Fig. 9-17, p. 191
9-4 How Should We Manage and Sustain Parks and Nature Reserves? Concept 9-4 We need to put more resources into sustaining existing parks and nature reserves and into protecting much more of the earth’s remaining undisturbed land area.
National Parks >1,100 national parks in 120 countries Only 1% of parks in developing countries are protected –Local people invade parks to survive –Logging –Mining –Poaching
Problems Protecting National Parks Illegal logging Illegal mining Wildlife poaching Most parks too small to protect large animals Invasion of nonnative species
Stresses on U.S. National Parks 58 major national parks Biggest problem is popularity Damage from nonnative species Threatened islands of biodiversity Need $6 billion for overdue repairs
Nature Reserves Occupy a Fraction of Earth 12% of earth’s land protected Only 5% fully protected – 95% reserved for human use Need for conservation –Minimum 20% of land in biodiversity reserves –Protection for all biomes
Solutions for Protection “Ecological insurance policy” Buffer zones around protected areas Locals to manage reserves and buffer zones United Nations: 531 biosphere reserves in 105 countries
Science Focus: Reintroducing the Gray Wolf to Yellowstone National Park Reduced to a few hundred in lower 48 by 1973 Keystone species Restoration proposal angered ranchers, hunters, loggers reintroduced in Yellowstone, 124 by 2008 Positive ripple effect after reintroduction
Fig. 9-B, p. 193 The Gray Wolf and Yellowstone National Park
Case Study: Costa Rica Superpower of biodiversity Conserved 25% of its land, 8 megareserves Government eliminated deforestation subsidies Paid landowners to maintain and restore tree coverage Boosts ecotourism
Fig. 9-18, p. 194 Panama Costa Rica Buffer zone National parkland Pacific Ocean
Case Study: Controversy over Wilderness Protection in the U.S Wilderness Act Ten-fold increase from 1970 to % of U.S. land protected, 75% of that in Alaska
9-5 How Can We Help to Sustain Terrestrial Biodiversity? Concept 9-5 We can help to sustain terrestrial biodiversity by identifying and protecting severely threatened areas (biodiversity hotspots), rehabilitating damaged ecosystems (using restoration ecology), and sharing with other species much of the land we dominate (using reconciliation ecology).
Three Principles to Protect Ecosystems 1.Map and inventory the world’s terrestrial and aquatic ecosystems 2.Locate and protect the most endangered ecosystems, with a focus on biodiversity 3.Seek to restore as many degraded ecosystems as possible
Protecting Global Biodiversity Hotspots 17 megadiversity countries, mostly in tropics and subtropics –Two-thirds of biodiversity Developing countries economically poor and biodiversity rich Protect biodiversity hotspots
Fig. 9-19, p biodiversity hotspots identified by ecologists as important and endangered centers of terrestrial biodiversity that contain a large number of species found nowhere else. Identifying and saving these critical habitats requires a vital emergency response.
Supplement 4, Fig. 2, p. S16
Ecological Restoration Restoration: returning a particular degraded habitat or ecosystem to a condition as similar as possible to its natural state Rehabilitation: turning a degraded ecosystem into a functional or useful ecosystem without trying to restore it to its original condition ex. Removing pollutants and replanting to reduce soil erosion in abandoned mining sites Replacement : replacing a degraded ecosystem with another type of ecosystem ex. A degraded forest could be replaced by a pasture or tree plantation Creating artificial ecosystems : ex. Creating artificial wetlands to help reduce flooding or treat sewage
Science-based Principles for Restoration Identify cause of degradation Stop abuse by reducing factors Reintroduce species if necessary Protect area from further degradation
Case Study: Ecological Restoration of Tropical Dry Forest in Costa Rica One of world’s largest ecological restoration projects Restore a degraded tropical dry forest and reconnect it to adjacent forests Involve 40,000 people in the surrounding area – biocultural restoration Ecotourism
Restoration Ecology Creating new habitats to conserve species diversity in areas where people live, work, play People learn to protect local species and ecosystems Sustainable ecotourism Golden Gate Park in San Francisco
Fig. 9-20, p. 198
9-6 How Can We Help to Sustain Aquatic Biodiversity? Concept 9-6 We can help to sustain aquatic biodiversity by establishing protected sanctuaries, managing coastal development, reducing water pollution, and preventing overfishing.
Impacts on Aquatic Ecosystems (1) Destroyed or degraded by human activities Coastal habitats disappearing 2-10 times faster than tropical forest Rising sea levels will destroy coral reefs and some low islands Ocean floor degradation 150 times larger than area clear-cut annually
Impacts on Aquatic Ecosystems (2) Freshwater habitat disruption –Dams –Water withdrawals from rivers Likely extinction –34% marine fish species –71% freshwater species –Greater than any other group of species
Fig. 9-21, p. 199 Area of ocean bottom before a trawler net scraped it like a gigantic plow.
Fig. 9-21, p. 199 The same area after the trawler scraped the ocean bottom. According to marine biologist Ellie Norse, “Bottom trawling is probably the largest human-caused disturbance to the biosphere.” Trawler fishers disagree and claim that the ocean bottom life recovers after trawling.
Overfishing Fishery Fishprint 157% overfishing 90% of large open-ocean fishes have disappeared since 1950
Fig. 9-22, p. 200 Collapse of Canada’s 500 year old Atlantic cod fishery off coast of Newfoundland
Case Study: Industrial Fish Harvesting Methods Trawler fishing Purse-seine fishing Longlining Drift-net fishing
Fig. 9-23, p. 201 Float Trawler fishing Drift-net fishing Purse-seine fishing Sonar Long line fishing lines with hooks Fish farming in cage Spotter airplane Deep sea aquaculture cage Fish caught by gills Buoy Major commercial fishing methods
Why Is Protection of Marine Biodiversity So Difficult? Human aquatic ecological footprint expanding Not visible to most people Viewed as an inexhaustible resource Most ocean areas outside jurisdiction of a country
Solutions for Marine Ecosystems Protect endangered and threatened species Establish protected marine sanctuaries Marine reserves – work well and quickly Integrated coastal management Protect existing coastal wetlands
Fig. 9-24, p. 202 Managing Fisheries Fishery Regulations Set catch limits well below the maximum sustainable yield Improve monitoring and enforcement of regulations Economic Approaches Sharply reduce or eliminate fishing subsidies Charge fees for harvesting fish and shellfish from publicly owned offshore waters Certify sustainable fisheries Protect Areas Establish no-fishing areas Establish more marine protected areas Rely more on integrated coastal management Consumer Information Label sustainably harvested fish Publicize overfished and threatened species Bycatch Dump ballast water far at sea and replace with deep-sea water Filter organisms from ship ballast water Kill organisms in ship ballast water Nonnative Invasions Depend more on herbivorous fish species Control pollution more strictly Restrict coastal locations for fish farms Aquaculture Ban throwing edible and marketable fish back into the sea Use net escape devices for seabirds and sea turtles Use wide-meshed nets to allow escape of smaller fish Solutions
Three Big Ideas from This Chapter - #1 The economic values of the important ecological services provided by the world’s ecosystems need to be included in the prices of goods and services.
Three Big Ideas from This Chapter - #2 We can sustain terrestrial biodiversity by protecting severely threatened areas, restoring damaged ecosystems, and sharing with other species much of the land we dominate.
Three Big Ideas from This Chapter - #3 We can sustain aquatic biodiversity by establishing protected sanctuaries, managing coastal development, reducing water pollution, and preventing overfishing.