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Sustaining Biodiversity: The Ecosystem Approach. Chapter 9. What is the most threatened ecosystem? Why?. Three big ideas. The economic value of ecological services are far greater than the value of raw materials obtained from those systems.
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Three big ideas • The economic value of ecological services are far greater than the value of raw materials obtained from those systems. • We can sustain terrestrial biodiversity by protecting severely threatened areas, protecting remaining undisturbed areas, restoring damaged ecosystems, and sharing with other species… • We can sustain aquatic biodiversity by establishing protected sanctuaries, managing coastal development, reducing water pollution, and preventing overfishing.
Section 9-1 What are the major threats to forest ecosystems?
Forests vary in their age, make-up, and origins • Natural and planted forests occupy about 30% of the Earth’s “tree-friendly” land surface. • Two major types based on their age and structure: • Old growth forest • Second-growth forest
Forests vary in their age, make-up, and origins • A tree plantation (tree farm, commercial forest), is usually made up of how many species?What ages of trees? How diverse? Good or Bad? • Forests provide important economic and ecological services. • Help with global warming… HOW?
The short rotation cycle of cutting and regrowth of a monoculture tree plantation
Forests provide many important economic and ecological services What services do they provide? How do they contribute to economies?
Unsustainable logging is a major threat to forest ecosystems • Methods of harvesting trees: • Selective cutting. • Clear-cut. • Strip cutting.
Unsustainable logging is a major threat to forest ecosystems • The first step in harvesting trees is to build roads for access and timber removal, but they can cause the following problems: • Increased erosion and sediment runoff into waterways. • Habitat fragmentation. • Loss of biodiversity. • Forest exposure to invasion by nonnative pests, diseases, and wildlife species.
Fire can threaten or benefit forest ecosystems • Surface firesusually burn only undergrowth and leaf litter on the forest floor. • Kills seedlings and small trees but spares most mature trees and allows most wild animals to escape. • Burns away flammable ground material and may help to prevent more destructive fires. • Frees valuable mineral nutrients tied up in slowly decomposing litter and undergrowth.
Fire can threaten or benefit forest ecosystems • Releases seeds from the cones of lodgepole pines. • Stimulates the germination of certain tree seeds (e.g. giant sequoia and jack pine). • Helps to control tree diseases and insects. • Crown firesare extremely hot fires that leap from treetops, burning whole trees. • Can destroy most vegetation, kill wildlife, increase soil erosion, and burn or damage human structures in their paths.
Almost half of the world’s forests have been cut down • Deforestation is the temporary or permanent removal of large expanses of forest for agriculture, settlements, or other uses. • Human activities have reduced the earth’s original forest cover by about 46%, with most of this loss occurring in the last 60 years. • If current deforestation rates continue, about 40% of the world’s remaining intact forests will have been logged or converted to other uses within two decades, if not sooner.
Tropical forests are disappearing rapidly • Tropical forests cover about 6% of the earth’s land area. • At least half of the world’s known species of terrestrial plants and animals live in tropical forests. • Brazil has more than 30% of the world’s remaining tropical rain forest in its vast Amazon basin. • At the current rate of global deforestation, 50% of the world’s remaining old-growth tropical forests will be gone or severely degraded by the end of this century.
Major underlying and direct causes of the destruction and degradation of tropical forests
Section 9-2 How should we manage and sustain forests?
We can manage forests more sustainably • Certification of sustainably grown timber and of sustainably produced forest products can help consumers. • Removing government subsidies and tax breaks that encourage deforestation would also help.
Ways to protect tropical forests and use them more sustainably
Section 9-3 How should we manage and sustain grasslands?
Section 9-4 How should we manage and sustain parks and nature reserves?
CASE STUDY: Stresses on U.S. Public Parks • The U.S. national park system, established in 1912, includes 58 major national parks, along with 335 monuments and historic sites. States, counties, and cities also operate public parks. What are the problems?!?
CASE STUDY: Costa Rica—A Global Conservation Leader • Tropical forests once completely covered Costa Rica, but between 1963 and 1983 much of the country’s forests were cleared to graze cattle. • Costa Rica is a superpower of biodiversity, with an estimated 500,000 plant and animal species. • Costa Rica now has a system of nature reserves and national parks that, by 2010, included about a quarter of its land. • Costa Rica now devotes a larger proportion of its land to biodiversity conservation than does any other country
CASE STUDY: Costa Rica—A Global Conservation Leader • The country’s largest source of income is its $1-billion-a-year tourism industry, almost two-thirds of which involves ecotourism. • To reduce deforestation, the government has cut subsidies for converting forest to rangeland. • The government pays landowners to maintain or restore tree cover. • Between 2007 and 2008, the government planted nearly 14 million trees. • Went from having one of the world’s highest deforestation rates to having one of the lowest.
CASE STUDY: Controversy over Wilderness Protection in the United States • Conservationists have been trying to save wild areas from development since 1900. • The Wilderness Act (1964) allowed the government to protect undeveloped tracts of public land from development as part of the National Wilderness Preservation System. • Only about 2% of the land area of the lower 48 states is protected, most of it in the West.
Section 9-5 What is the ecosystem approach to sustaining biodiversity?
Section 9-6 How can we help to sustain aquatic biodiversity?
Ways to manage fisheries more sustainably and protect marine biodiversity
Three big ideas • The economic value of ecological services… • We can sustain terrestrial biodiversity by … • We can sustain aquatic biodiversity by…
Human activities are destroying and degrading aquatic biodiversity • Human activities have destroyed or degraded a large portion of the world’s coastal wetlands, coral reefs, mangroves, and ocean bottom, and disrupted many of the world’s freshwater ecosystems. • Rising sea levels are likely to destroy many coral reefs and flood some low-lying islands along with their protective coastal mangrove forests. • Loss and degradation of many sea-bottom habitats caused by dredging operations and trawler fishing boats.
Human activities are destroying and degrading aquatic biodiversity • In freshwater aquatic zones, dam building and excessive water withdrawal from rivers for irrigation and urban water supplies destroy aquatic habitats, degrade water flows, and disrupt freshwater biodiversity. • The deliberate or accidental introduction of hundreds of harmful invasive species threatens aquatic biodiversity. • Thirty-four percent of the world’s known marine fish species and 71% of the world’s freshwater fish species face premature extinction.
Overfishing: gone fishing; fish gone • A fishery is a concentration of a particular wild aquatic species suitable for commercial harvesting in a given ocean area or inland body of water. • The fishprint is defined as the area of ocean needed to sustain the consumption of an average person, a nation, or the world. • Fifty-two percent of the world’s fisheries are fully exploited, 20% are moderately overexploited, and 28% are overexploited or depleted.
Overfishing: gone fishing; fish gone • Overharvesting has led to the collapse of some of the world’s major fisheries. • When overharvesting causes larger predatory species to dwindle, rapidly reproducing invasive species can more easily take over and disrupt ocean food webs.
CASE STUDY: Industrial Fish Harvesting Methods • Industrial fishing fleets dominate the world’s marine fishing industry, using global satellite positioning equipment, sonar fish-finding devices, huge nets and long fishing lines, spotter planes, and gigantic refrigerated factory ships that can process and freeze their catches. • Trawler fishing is used to catch fish and shellfish by dragging a funnel-shaped net held open at the neck along the ocean bottom. • Purse-seine fishing, is used to catch surface-dwelling fish by using a spotter plane to locate a school; the fishing vessel then encloses it with a large net called a purse seine.
CASE STUDY: Industrial Fish Harvesting Methods • Longlining involves lines up to 130 kilometers (80 miles) long, hung with thousands of baited hooks to catch open-ocean fish species or bottom fishes. • Drift-net fishing catches fish with huge drifting nets that can hang as deep as 15 meters (50 feet) below the surface and extend to 64 kilometers (40 miles) long. • Drift-nets can trap and kill large quantities of unwanted fish, called bycatch, along with marine mammals, sea turtles, and seabirds. • Almost one-third of the world’s annual fish catch by weight consists of bycatch species, which are mostly thrown overboard dead or dying.
We can protect and sustain marine biodiversity • Protecting marine biodiversity is difficult for several reasons. • The human ecological footprint and fishprint are expanding so rapidly into aquatic areas that it is difficult to monitor the impacts. • Much of the damage to the oceans and other bodies of water is not visible to most people.
