Sustaining Biodiversity: The Ecosystem ApproachChapter 9

WHAT IS THE MOST THREATENED ECOSYSTEM?

WHY?

Three big ideasThe 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.

WHAT ARE THE MAJOR THREATS TO FOREST ECOSYSTEMS?Section 9-1

Forests vary in their age, make-up, and originsNatural and planted forests occupy about 30% of the Earths 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 originsA 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 servicesHow do they contribute to economies?

What services do they provide?

Unsustainable logging is a major threat to forest ecosystemsMethods of harvesting trees:Selective cutting. Clear-cut. Strip cutting.

Unsustainable logging is a major threat to forest ecosystemsThe 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.

Three major tree harvesting methods

Aerial view showing clear-cut logging, Washington state

How about forest fires are they good or bad?!?!

Fire can threaten or benefit forest ecosystemsSurface fires usually 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 ecosystemsReleases 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 fires are 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.

Surface fires and crown fires

Almost half of the worlds forests have been cut downDeforestation is the temporary or permanent removal of large expanses of forest for agriculture, settlements, or other uses. Human activities have reduced the earths 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 worlds remaining intact forests will have been logged or converted to other uses within two decades, if not sooner.

Almost half of the worlds forests have been cut downClearing large areas of forests, especially old-growth forests, has important short-term economic benefits, but it also has a number of harmful environmental effects.The net total forest cover in several countries changed very little or even increased between 2000 and 2007. Some due to natural reforestation by secondary ecological succession on cleared forest areas and abandoned croplands, or the spread of tree plantations.Concern about the growing amount of land occupied by commercial tree plantations, because replacement of old-growth forests by these biologically simplified tree farms represents a loss of biodiversity, and possibly of stability, in some forest ecosystems.

Harmful effects of deforestation

Forest cover in the U.S.

CASE STUDY: Many Cleared Forests in the United States Have Grown BackForests that cover about 30% of the U.S. land area provide habitats for more than 80% of the countrys wildlife species and supply about two-thirds of the nations surface water.Today, forests in the U.S. cover more area than they did in 1920, primarily due to secondary succession.Every year, more wood is grown in the U.S. than is cut and the total area planted with trees increases.Protected forests make up about 40%.Since the mid-1960s, an increasing area of the nations remaining old-growth and fairly diverse second-growth forests has been cut down and replaced with biologically simplified tree plantations.

Tropical forests are disappearing rapidlyTropical forests cover about 6% of the earths land area.

At least half of the worlds known species of terrestrial plants and animals live in tropical forests.

Brazil has more than 30% of the worlds remaining tropical rain forest in its vast Amazon basin.

At the current rate of global deforestation, 50% of the worlds 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

HOW SHOULD WE MANAGE AND SUSTAIN FORESTS?Section 9-2

We can manage forests more sustainablyCertification 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 grow and harvest trees more sustainably

Ways to protect tropical forests and use them more sustainably

HOW SHOULD WE MANAGE AND SUSTAIN GRASSLANDS?Section 9-3

Left of fence: overgrazed landRight: lightly grazed land

Restoration via secondary ecological succession

HOW SHOULD WE MANAGE AND SUSTAIN PARKS AND NATURE RESERVES?Section 9-4

CASE STUDY: Stresses on U.S. Public ParksThe 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?!?

Costa Ricas eight megareserves

CASE STUDY: Costa RicaA Global Conservation LeaderTropical forests once completely covered Costa Rica, but between 1963 and 1983 much of the countrys 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 RicaA Global Conservation LeaderThe countrys 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 worlds highest deforestation rates to having one of the lowest.

CASE STUDY: Controversy over Wilderness Protection in the United StatesConservationists 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.

WHAT IS THE ECOSYSTEM APPROACH TO SUSTAINING BIODIVERSITY?Section 9-5

Biodiversity hotspots

Here are four ways to protect ecosystemsMost biologists and wildlife conservationists believe that the best way to keep from hastening the extinction of wild species through human activities is the ecosystems approach, which protects threatened habitats and ecosystem services.

Here are four ways to protect ecosystemsFour-point plan of the ecosystems approach:Map the worlds terrestrial and aquatic ecosystems and create an inventory of the species contained in each of them and the ecosystem services they provide.Locate and protect the most endangered ecosystems and species, with emphasis on protecting plant biodiversity and ecosystem services.Seek to restore as many degraded ecosystems as possible.

Protecting global biodiversity hotspots is an urgent prioritySome biodiversity scientists urge adoption of an emergency action strategy to identify and quickly protect biodiversity hotspots, areas especially rich in plant species that are found nowhere else and are in great danger of extinction .These hotspots cover only a little more than 2% of the earths land surface, they contain an estimated 50% of the worlds flowering plant species and 42% of all terrestrial species. These hotspots are home for a large majority of the worlds endangered or critically endangered species, and one-fifth of the worlds population.

We can rehabilitate and restore ecosystems that we have damagedAlmost every natural place on the earth has been affected or degraded to some degree by human activities.We can at least partially reverse much of this harm through ecological restoration: the process of repairing damage caused by humans to the biodiversity and dynamics of natural ecosystems.Examples of restoration include:replanting forests

We can rehabilitate and restore ecosystems that we have damagedrestoring grasslandsrestoring coral reefsrestoring wetlands and stream banks reintroducing native species removing invasive speciesfreeing river flows by removing dams.

We can rehabilitate and restore ecosystems that we have damagedFour steps to speed up repair operations include the following:Restoration.Rehabilitation.Replacement.Creating artificial ecosystems.

We can rehabilitate and restore ecosystems that we have damagedResearchers have suggested a science-based, four-step strategy for carrying out most forms of ecological restoration and rehabilitation:Identify the causes of the degradation.Stop the abuse by eliminating or sharply reducing these factors. If necessary, reintroduce key species to help restore natural ecological processes.Protect the area from further degradation and allow secondary ecological succession to occur.

We can share areas we dominate with other speciesReconciliation ecology is the science that focuses on inventing, establishing, and maintaining new habitats to conserve species diversity in places where people live, work, or play.Examples include:Protecting local wildlife and ecosystems can provide economic resources for their communities by encouraging sustainable forms of ecotourism.

We can share areas we dominate with other speciesProtecting vital insect pollinators such as native butterflies and bees by reducing the use of pesticides, planting flowering plants as a source of food for pollinating insect species, and building structures which serve as hives for pollinating bees.Protecting bluebirds within human-dominated habitats where most of the bluebirds nesting trees have been cut down by using nesting boxes and keeping house cats away from nesting bluebirds.

Ways you can help sustain terrestrial biodiversity

HOW CAN WE HELP TO SUSTAIN AQUATIC BIODIVERSITY?Section 9-6

The collapse of Canadas 500-year-old Atlantic cod fishery

Before and after a trawler net

Major commercial fishing methods

Ways to manage fisheries more sustainably and protect marine biodiversity

Three big ideasThe economic value of ecological services

We can sustain terrestrial biodiversity by

We can sustain aquatic biodiversity by

Human activities are destroying and degrading aquatic biodiversityHuman activities have destroyed or degraded a large portion of the worlds coastal wetlands, coral reefs, mangroves, and ocean bottom, and disrupted many of the worlds 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 biodiversityIn 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 worlds known marine fish species and 71% of the worlds freshwater fish species face premature extinction.

Overfishing: gone fishing; fish goneA 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 worlds fisheries are fully exploited, 20% are moderately overexploited, and 28% are overexploited or depleted.

Overfishing: gone fishing; fish goneOverharvesting has led to the collapse of some of the worlds 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 MethodsIndustrial fishing fleets dominate the worlds 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 MethodsLonglining 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 worlds annual fish catch by weight consists of bycatch species, which are mostly thrown overboard dead or dying.

We can protect and sustain marine biodiversityProtecting 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.

We can protect and sustain marine biodiversityMany people incorrectly view the seas as an inexhaustible resource that can absorb an almost infinite amount of waste and pollution and still produce all the seafood we want.Most of the worlds ocean area lies outside the legal jurisdiction of any country and is thus an open-access resource and subject to overexploitation.

We can protect and sustain marine biodiversitySeveral ways to protect and sustain marine biodiversity:Protect endangered and threatened aquatic species. Establish protected marine sanctuaries. Protect whole marine ecosystems within a global network of fully protected marine reserves.

Taking an Ecosystem Approach to Sustaining Aquatic BiodiversityStrategies for applying the ecosystem approach to aquatic biodiversity include:Complete the mapping of the worlds aquatic biodiversity, identifying and locating as many plant and animal species as possible.Identify and preserve the worlds aquatic biodiversity hotspots and areas where deteriorating ecosystem services threaten people and other forms of life.

Taking an Ecosystem Approach to Sustaining Aquatic BiodiversityCreate large and fully protected marine reserves to allow damaged marine ecosystems to recover and to allow fish stocks to be replenished.Protect and restore the worlds lakes and river systems (the most threatened ecosystems of all).Initiate worldwide ecological restoration projects in systems such as coral reefs and inland and coastal wetlands.Find ways to raise the incomes of people who live in or near protected lands and waters so that they can become partners in the protection and sustainable use of ecosystems.

Taking an Ecosystem Approach to Sustaining Aquatic BiodiversityThe harmful effects of human activities on aquatic biodiversity and ecosystem services could be reversed over the next 2 decades if an ecosystem approach is implemented, at a cost one of penny per cup of coffee consumed in the world each year.

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