ENVIRONMENTAL SCIENCE 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

http://www.greenbeltmovement.org/ Watch second video

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

Old growth forest in the US state of Washington’s Olympic National Forest Fig. 9-2, p. 180

rapidly year round so rotation cycle can be 6-10 years. 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. 9-3, p. 180

ital Forests Ecological Economic Services Services 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 Forests Ecological Services Economic Services Support energy flow and chemical cycling Fuelwood Lumber Reduce soil erosion Pulp to make paper Absorb and release water Purify water and air Mining Figure 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? Livestock grazing Influence local and regional climate Store atmospheric carbon Recreation Provide numerous wildlife habitats Jobs Fig. 9-4, p. 181

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

Estimated annual global economic values of some ecological services provided by forests compared to the raw materials they produce (in billions of dollars). Fig. 9-A, p. 181

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 grazing New highway Highway Cleared plots for agriculture Old growth Figure 9.5: Natural capital degradation: Building roads into previously inaccessible forests is the first step to providing timber, but it also paves the way to fragmentation, destruction, and degradation of forest ecosystems. Fig. 9-5, p. 182

(a) Selective cutting Clear stream Major tree harvesting methods. If you were cutting trees in a forest you owned which method would you choose and why? (a) Selective cutting Figure 9.6: Major tree harvesting methods. Question: If you were cutting trees in a forest you owned, which method would you choose and why? Clear stream Fig. 9-6, p. 182

(b) Clear-cutting Muddy stream Figure 9.6: Major tree harvesting methods. Question: If you were cutting trees in a forest you owned, which method would you choose and why? Muddy stream Fig. 9-6, p. 182

(c) Strip cutting Cut 1 Uncut year ago Dirt road Cut 3–10 years ago Figure 9.6: Major tree harvesting methods. Question: If you were cutting trees in a forest you owned, which method would you choose and why? Clear stream Fig. 9-6, p. 182

Clear cut logging in the US state of Washington Fig. 9-7, p. 182

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

Type of fire? Surface fires usually burn only undergrowth and leaf litter on a forest floor. Fig. 9-8, p. 183

Type of fire? Fig. 9-8, p. 183

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 Deforestation= temporary or permanent removal of large expanses of forest for agriculure, settlements, or other uses

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? Such clearing of trees, which absorb carbon dioxide as they grow, contributes to projected climate change. It also dehydrates the soil by exposing it to sunlight. The dry topsoil can then blow away, which can lead to irreversible ecological tipping point beyond which a forest cannot be reestablished in the area. Fig. 9-9, p. 184

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 km2 per year Some second-growth forests Tropical forests once covered at least twice as much land area as they do today Brazil, for example, has more than 30% of world’s remaining tropical rain forest in its vast Amazon basin Second growth forests do not have same biodiversity as old-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 Government subsidies can accelerate deforestation by reducing the costs of timber harvesting, cattle grazing, and establishing vast plantations of crops such as soybeans and oil palms

Natural Capital Degradation Major Causes of the Destruction and Degradation of Tropical Forests Basic Causes Secondary Causes Not valuing ecological services Crop and timber exports Government policies Poverty Population growth Roads Fires Settler farming Cash crops Cattle ranching Logging Tree plantations Cattle ranching Tree plantations Logging Cash crops Settler farming Figure 9.11: Major interconnected causes of the destruction and degradation of tropical forests. The importance of specific secondary causes varies in different parts of the world. Question: If we could eliminate the basic causes, which if any of the secondary causes might automatically be eliminated? Fires Roads Fig. 9-11, p. 186

What’s going on in this picture? Brazil’s Amazon basin What’s going on in this picture? Large areas of tropical forest in Brazil’s Amazon basin are burned each year to make way for cattle ranches, plantation crops, and small scale farms. Fig. 9-12, p. 187

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

Kenaf Solutions: Pressure to cut trees to make paper could be greatly reduced by planting and harvesting a fest-growing plant known as kenaf. USDA calls kenaf “the best option for paper making in the US” Fig. 9-14, p. 189

Ways to Reduce Tropical Deforestation Debt-for-nature swaps Conservation concessions Gentler logging methods Encourage use of wood substitutes

Solutions Sustaining Tropical Forests Prevention Restoration Protect the most diverse and endangered areas Encourage regrowth through secondary succession Educate settlers about sustainable agriculture and forestry Subsidize only sustainable forest use Rehabilitate degraded areas Protect forests with debt-for-nature swaps and conservation concessions Figure 9.15: Ways to protect tropical forests and use them more sustainably (Concept 9-2). Questions: Which three of these solutions do you think are the most important? Why? Certify sustainably grown timber Reduce poverty Concentrate farming and ranching in already-cleared areas Slow population growth Fig. 9-15, p. 190

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

What happens to overgrazed rangeland? Overgrazed (left) and lightly grazed (right) rangeland Fig. 9-16, p. 191

Manage Rangelands Sustainably Practice rotational grazing Fence out riparian zone areas Suppress invader plants Herbicides Mechanical removal Controlled burning Short-term trampling

In the mid-80s cattle had degraded the vegetation and soil on this stream bank alongside the San Pedro River in Arizona Fig. 9-17, p. 191

Within 10 years, the area was restored through natural regeneration after grazing and off-road vehicle use were banned 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 1995 - reintroduced in Yellowstone, 124 by 2008 Positive ripple effect after reintroduction

The Gray Wolf and Yellowstone National Park : After becoming almost extinct in much of the US, the gray wolf was listed And protested as an endangered species in 1974. Despite intense opposition from ranchers, hunters, miners, and loggers, 31 members of this keystone species were reintroduced to Yellowstone National Park in 1995 and 1996. In 2008, there were about 124 gray wolves in the park. Fig. 9-B, p. 193

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

Costa Rica Panama Figure 9.18: Solutions: Costa Rica has consolidated its parks and reserves into eight zoned megareserves designed to sustain about 80% of the country’s rich biodiversity. Green areas are protected reserves and yellow areas are nearby buffer zones, which can be used for sustainable forms of forestry, agriculture, hydropower, hunting, and other human activities. Pacific Ocean National parkland Buffer zone Fig. 9-18, p. 194

Protecting Wilderness Protects Biodiversity Preserves biodiversity Centers for evolution

Case Study: Controversy over Wilderness Protection in the U.S. 1964 Wilderness Act Ten-fold increase from 1970 to 2008 4.6% 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 Map and inventory the world’s terrestrial and aquatic ecosystems Locate and protect the most endangered ecosystems, with a focus on biodiversity 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

34 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. 34 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. Fig. 9-19, p. 196

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

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 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. TThe 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. Fig. 9-21, p. 199

Overfishing Fishery Fishprint 157% overfishing 90% of large open-ocean fishes have disappeared since 1950

Collapse of Canada’s 500 year old Atlantic cod fishery off coast of Newfoundland Graph illustrating the collapse of Canada’s 500 year old Atlantic cod fishery off the coast of Newfoundland. Beginning in the late 1950s, fishers used bottom trawlers to capture more of the stock, reflected in the sharp rise in this graph. This resulted in extreme overexploitation of the fishery, which began a steady fall throughout the 1970s, followed by a slight recovery in the 1980s, and total collapse by 1992, when the site was closed to fishing. Despite a total ban on fishing, the cod population has not recovered. This has put at least 20, 000 fishers and fish processors out of work and severely damaged Newfoundland’s economy. Fig. 9-22, p. 200

Case Study: Industrial Fish Harvesting Methods Trawler fishing Purse-seine fishing Longlining Drift-net fishing

Major commercial fishing methods Fish farming in cage Trawler fishing Spotter airplane Sonar Purse-seine fishing Drift-net fishing Figure 9.23: Major commercial fishing methods used to harvest various marine species. These methods have become so effective that many fish species have become commercially extinct. Long line fishing Float Buoy lines with hooks Deep sea aquaculture cage Fish caught by gills Fig. 9-23, p. 201

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

Solutions Managing Fisheries Fishery Regulations Bycatch Set catch limits well below the maximum sustainable yield Use wide-meshed nets to allow escape of smaller fish Improve monitoring and enforcement of regulations Use net escape devices for seabirds and sea turtles Economic Approaches Ban throwing edible and marketable fish back into the sea Sharply reduce or eliminate fishing subsidies Aquaculture Charge fees for harvesting fish and shellfish from publicly owned offshore waters Restrict coastal locations for fish farms Certify sustainable fisheries Control pollution more strictly Protect Areas Depend more on herbivorous fish species Figure 9.24: Ways to manage fisheries more sustainably and protect marine biodiversity. Questions: Which four of these solutions do you think are the most important? Why? Establish no-fishing areas Establish more marine protected areas Nonnative Invasions Kill organisms in ship ballast water Rely more on integrated coastal management Consumer Information Filter organisms from ship ballast water Label sustainably harvested fish Dump ballast water far at sea and replace with deep-sea water Publicize overfished and threatened species Fig. 9-24, p. 202

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.