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Transcript
APES REVIEW Chapter 23 1. Definitions Old Growth Forests- uncut forests or regenerated forests that have not been seriously disturbed by human activities or natural disasters for at least several hundred years Second Growth Forests- stands of trees resulting from secondary ecological succession after the trees in tan area have been removed by human activities such as clear cutting for timber or conversion to cropland or natural forces such as fire, hurricanes, or volcanic eruption Tree Plantations/ Tree Farms- managed tracts with uniformly aged trees of one species that are harvested by clear cutting as soon as they become commercially valuable Even Aged Management- involves maintaining trees in a given stand at about the same age and size Uneven-aged Management- involves maintaining a variety of tree species in a stand at many ages and sizes to foster natural regeneration Selective cutting- intermediate ages or mature trees in an uneven aged forest are cut singly or in small groups Shelterwood Cutting- which removes all mature trees in two or three cuttings over a period of about 10 years Seed Tree Cutting- harvests nearly all a stand’s trees in one cutting, leaving a few uniformly distributed seed producing trees to regenerate the stand Clear Cutting- removes all of the trees from an area in a single cutting Strip Cutting- clear cutting variation that can allow a sustainable timber yield without widespread destruction 3. Major Uses of Land World: Forest, Rangeland and Pasture, Desert, Cropland, Tundra and Wetlands, Urban United States: Forest, Rangeland and Pasture, Croplands, Desert and Tundra and Wetlands, Parks and Wildlife Refuge and Wilderness, Urban 4. Federal Lands in United States 35% of United States land is managed by the Federal Government. The five major types of public lands that the US controls are: Oil Reserves Coal reserves Natural gas reserves Commercial forests Hard rock minerals Four Principles that govern use of public land: - Protecting biodiversity, wildlife habitats and ecological functioning of ecosystems -No one should receive subsidies of tax breaks for using or extracting resources on public land -The American people deserve fair compensation for the use of their property -All users or extractors of resources on public lands should be fully responsible for any environmental damage they cause. 8. Old Growth v. Second Growth v. Tree Plantations Old Growth Forests- uncut forests or regenerated forests that have not been seriously disturbed by human activities or natural disasters for at least several hundred years Second Growth Forests- stands of trees resulting from secondary ecological succession after the trees in tan area have been removed by human activities such as clear cutting for timber or conversion to cropland or natural forces such as fire, hurricanes, or volcanic eruption Tree Plantations/ Tree Farms- managed tracts with uniformly aged trees of one species that are harvested by clear cutting as soon as they become commercially valuable 10. Harvesting Trees Selective cutting- intermediate ages or mature trees in an uneven aged forest are cut singly or in small groups Shelterwood Cutting- which removes all mature trees in two or three cuttings over a period of about 10 years Seed Tree Cutting- harvests nearly all a stand’s trees in one cutting, leaving a few uniformly distributed seed producing trees to regenerate the stand Clear Cutting- removes all of the trees from an area in a single cutting Strip Cutting- clear cutting variation that can allow a sustainable timber yield without widespread destruction Advantages of Selective Cutting Reduces crowding Encourages growth of younger trees Maintains an uneven aged stand of trees of different species Allows natural regeneration from the surrounding trees Can help protect site from soil erosion and wind damage Can be used to remove diseased trees Allows a forest to be used for multiple purposes Disadvantages of Selective Cutting High Grading- cutting and removing only the largest and best specimens of the most desirable species o Reduction of forest canopy Advantages of Clear Cutting Increases timber yield per hectare Permits reforesting trees with genetically improved stocks of fast growing trees Shortens the time needed to establish a new stand of trees Takes less skill and planning than other harvesting methods Usually provides the maximum economic return in the shortest time Often is the best way to harvest tree plantations and stands of some tree species that need full or moderate sunlight for growth Disadvantages of Clear Cutting Leaves moderate to large forest openings Eliminates most recreation value for several decades Reduces biodiversity, disrupts ecosystem processes and destroys and fragments some wildlife habitats Makes nearby trees more vulnerable to being blown down by windstorms Leads to severe soil erosion, sediment water pollution and flooding when done on steep slopes 14. Forest Fires Surface Fires- burn only undergrowth and leaf litter on the forest floor Crown Fires- may start on the ground but eventually burn whole trees and leap from treetop to tree top. Ground Fires- surface fires that go underground and burn partially decayed leaves or peat. Benefits- some fires burn away flammable ground material and help prevent more destructive fires, release vulnerable mineral nutrients tied up in slowly decomposing litter and undergrowth, increase the activity of underground nitrogen fixing bacteria, stimulate germination of certain tree seeds, and help control pathogens and insects Pros of Prescribed Fires: Keep down flammable ground litter in fire adapted forests as part of the natural ecological cycle of succession and regeneration Cons of Prescribed Fires: Require careful planning and monitoring to keep them from getting out of control Pros/Cons of Allowing Natural Fires to Burn: They have been allowed as long as they do not threaten human lives, park or forest service facilities, private property, or endangered wildlife. Pros/Cons of Cutting Trees to Thin Forests: Promoted by Logging Companies Increase chances of severe fires: o Most dangerous fuel is unwanted waste material or slash left behind after a forest is cut. o Will not reduce the fire hazard because larger are difficult to ignite. Shrubs and small trees fuel most fires. 28. Fuelwood Crisis Fuelwood Crisis- crisis because a lot of people in developing countries are not getting enough fuelwood to meet basic needs Developing Countries can reduce the severity of fuelwood crisis by: Planting more growing fuelwood trees or shrubs Burning wood more efficiently Switching to other fuels 33. Nature Reserve System -It should contain a mixture of large and small reserves because it can protect a variety of species and communities against a number of different threats. -The best shape for a nature reserve us a circular reserve because the circular shape allows better protection of the interior area that is further away from the edges of the reserve. -Pros and cons of establishing large reserves or several small reserves: Large Reserves: -Only way to maintain viable populations of large, wide ranging populations such as panthers, elephants and grizzly bears -Sustain more species base on the species area curve -Minimize the area of outside edges exposed to natural disturbances, invading species, and human disturbances from nearby developed areas -Provide greater habitat diversity than small reserves Several well placed medium sized: -Variety of habitats and thus preserve more biodiversity than a single large reserve of the same area -May better protect more populations of endemic species with small ranges than a single large reserve -Are less likely to be simultaneously devastated, by a single even such as a flood, fire, disease, or invasion by a nonnative species than a singe large reserve. -It is better to have a heterogeneous reserve with a variety of habitats than a homogenous reserve because nature is rarely at equilibrium state and undergoes continuous change. A heterogeneous reserve provides a variety of habitat patches (patch dynamics) of different sizes, shapes, and successional stages and can allow species in disturbed patches to move to undisturbed patches. -Pros and Cons of establishing corridors between nature reserves: +Help support more species +Allow migration of vertebrates that need large ranges +Permit migration of individuals and populations when environmental conditions in a reserve deteriorate +Help preserve animals that must make seasonal migrations to obtain food +Enable some species to shift their ranges if global warming makes their current ranges uninhabitable -Threaten once isolated populations by allowing the movement of pest species, disease, fire and exotic species between reserves -Increase exposure of migrating species to natural predators, human hunters and pollution -Costly to acquire, protect, and manage 37. Wilderness Wilderness: Areas of undeveloped land affect primarily by the forces of nature when man is a visitor who does not remain. Importance: We need wild places where people can experience the beauty of nature and observe natural biological diversity, and enhance their mental and physical health by getting away from noise, stress, development, and large numbers of people. Pros and Cons of protecting more wilderness: +Provide mostly undisturbed habitats for wild plants and animals, especially those that need a large range +Help protect diverse biomes from damage +Provide a natural laboratory in which we can discover more about how nature works in the few remaining areas not seriously disturbed by human activities. Three Ways to manage wilderness: 1) Easily accessible, popular areas that have trails, bridges, hikers’ huts, outhouse, assigned campsites, and extensive ranger patrols 2) Large, remote wilderness areas used only by people who get a permit by demonstrating their wilderness skills 3) Undisturbed biologically unique areas with no human entry allowed 38. Ecological Restoration Restoration: involves trying to return a particular degraded habitat or ecosystem to a condition as similar as possible to its pre-degraded state. Rehabilitation: involves any attempt to restore at least some of a degraded system’s natural species and ecosystem functions Replacement: involves replacing a degraded ecosystem with another type of ecosystem. Four basic steps in carrying out ecological restoration or rehabilitation: -Mimic nature and natural processes and let nature do most of the work, wherever possible -Recreate important ecological niches that have been lost -Rely on pioneer species and natural ecological succession to facilitate the restoration process -Control or remove harmful species Five techniques for implementing these steps: -Identify what caused the degradation -Eliminate or sharply reduce these factors (reduce toxic soil pollutants, adding nutrients to deplete soil, adding new topsoil and eliminating disruptive nonnative species) -Reintroduce species to restore natural ecological processes, if necessary -Protect the area from further degradation and from the disruptive effects of fires -Monitor restoration efforts, assess success, and use adaptive ecosystem management to modify strategies as needed. APES chapter 24 6. Commercial Fishing Commercial marine fishing can be viewed as a tragedy of the commons because the fish will become over-fished and then there will be no source of food for that specific community, and will also decrease fish production as a whole. We have to make sure that we make fishing a sustainable job. 7. Threat to wetlands Purple Loosestrife is considered a threat if it invades the wetlands because It has no natural enemies in the United States and has now spread to 35 states in the US and reduces wetland biodiversity by displacing native vegetation. 19. Ways to prevent over fishing and protect marine biodiversity: Enacting fishery regulations: set, monitor, and enforce fishery catch limits well below their estimated maximum sustained yields. Divide up fishing quotas based on fairness and inputs for local communities and fishers. Require selective gear that avoids catching unwanted undersized fish. Economic Approaches: Sharply reduce of eliminate fishing subsidies; impose fees for harvesting fish and shellfish from publicly owned and managed offshore waters and use the money for government fishery management; certify sustainable fisheries Bycatch: Reduce bycatch levels by using wider mesh nets to allow smaller species and smaller individuals of that targeted species to escape, outfitting trawling nets with devices to exclude seabirds and sea turtles, having observers on fishing vessels, licensing boats to catch several species instead of only one target species, and enacting laws that prohibit throwing edible and marketable fish back into sea. Protected Areas: Establish no fishing marine areas, seasonal fisher closures and marine protected areas to allow depleted fish species to recover; start by protecting marine habitats that are in food condition or those most likely to benefit form protection instead of using limited funds to protect potentially hopeless cases; strengthen commitment to marine biodiversity protection and integrated coastal management programs that promote both sustainable fishing and the ecological health of marine ecosystems. Nonnative Invasions: Reduce invasions by nonnative species by using heat, disinfectants or pumping nitrogen gas to kill organisms in ship ballast water, developing filters to trap the organisms when ballast water is take into or discharged from a ship, and requiring ships to dump their ballast water at least 200 miles from shore and replace it with deep sea water. Consumer Information: Use labels that allow consumers to identify fish that have been harvested sustainability Aquaculture: Restrict location of fish farms to reduce loss of mangrove forests and other threatened coastal environments; enact and enforce stricter pollution regulations for aquaculture operations; increase production of herbivorous aquaculture fish species that need little or no grain or fish meal in diets. 20. Wetland Policy in US Pros: Federal permit is required to fill or to deposit dredged or fill material into wetlands occupying more than 3 acres This law as helped cut the average annual wetland loss by 80% Cons: Attempts to weaken it by using unscientific criteria to classify areas as wetlands 8% of remaining inland wetlands are under federal protection Protection is weak 21. Sustaining and Restoring Wetlands Enacting and Enforcing laws to protect existing wetlands from destruction and degradation Using comprehensive land use planning to steer developers, farmers and resource extractors away from existing wetlands Using mitigation banking only as a last resort Requiring creation and evaluation of a new wetland before destroying an existing one Restoring degraded wetlands Trying to prevent and control invasions by nonnative species 23. Florida’s Everglades Problems: Natural flow of everglades have been disrupted and diverted with canals, levees and spillways Has 56 endangered or threatened species Runoff from farms has stimulated growth of cattails that have taken over Efforts to deal with problem: Everglade National Park Worlds largest ecological restoration project- carried out between 2000- 2038 o Restore curving flow of river o Remove 250 miles of canals and levees o Allow 240 acres of farmland to flood o Add land to park o Create artificial marshes o Create 18 reservoirs APES chapter 25 1. Definitions Urban or Metropolitan Area- town or city plus its adjacent suburban fringe Rural Area- area with population less than 2,500 Degree of Urbanization- percentage of its population living in an urban area Urban growth- rate of increase of urban populations Village- consists of a group of rural households linked together by custom, culture and family ties City- a much larger group of people with a variety of specialized occupations who depend on a flow of resources from other areas to meet most of their needs and wants Urban Heat Island- the enormous amounts of heat generated by cars, factories furnaces, lights, air conditioners, and heat absorbing dark roofs and roads in cities Ecological Land Use Planning- anticipating a regions present and future needs and problems Zoning- various parcels of land are designated for certain uses 3. Urban or Metropolitan Area- town or city plus its adjacent suburban fringe Rural Area- area with population less than 2,500 Degree of Urbanization- percentage of its population living in an urban area Urban growth- rate of increase of urban populations Village- consists of a group of rural households linked together by custom, culture and family ties City- a much larger group of people with a variety of specialized occupations who depend on a flow of resources from other areas to meet most of their needs and wants 4. Factors that Push/pull people to urban places: Push: Poverty Lack of land Declining agricultural jobs because of the increase of machines Famine War Pull: Jobs Food Housing Better life Entertainment Freedom 7. Major problems of urban poor: Lacking clean water supplies, sewers, electricity and roads Land is not suitable for human habitation They do not have drinking water, sanitation facility, housing, food, health care, schools or jobs Rampant disease Cities bulldoze slums to build up 9. Good News: Since 1920, many of the worst economic problems have been reduced Most people have better working and housing conditions; air and water quality have been improved Better sanitation, water supplies and medical care have reduced death rates and sickness Concentrating people in urban areas have protected countries biodiversity Bad News: Number of cities in Us have deteriorating services, aging infrastructures, budget crunches and rising poverty Urban sprawl is encouraging dependence on cars 10. Urban Sprawl Definition: growth of low density development on the edges of cities and towns that encourages dependence on cars Factors promoting it: Ample land for expansion Federal government loans guarantees for new single family homes for WWII veterans Federal and state government funding of highways that encourage development of the once inaccessible outlying tracts of land Low cost of gas Greater availability of mortgages State and local zoning laws that require large residential lots Harmful Effects: Increased water runoff Contaminated air and water Higher taxes Increased energy use 12. Seven Benefits of Urbanization Lower infant mortality rates Better access to medical care, family planning, education Reducing fertility and slowing population growth Recycling more feasible Per capita expenditures on environmental protection are higher 47% of urban people occupy 2% of land Preserve biodiversity Harmful Effects Not self sustaining Consumer 75% of earths resources Fertile soil and wildlife lost as cities expand Lack of trees Produce little of their own food Water resource problems Pollution Noise pollution Microclimate- urban heat island 15. Four ways cities can grow more food Planting community gardens Using window boxes and balcony planters Creating gardens and greenhouses on roofs Raising fish in aquaculture Urban Heat Island- the enormous amounts of heat generated by cars, factories furnaces, lights, air conditioners, and heat absorbing dark roofs and roads in cities Four ways to counteract heat island: Planting trees Using lighter colored paving and building surfaces Reducing imputes of waste heat into atmosphere Establishing gardens on roofs or large buildings Five ways to reduce noise pollution Modifying noisy activities and devices to produce less noise Shielding noisy devices Moving noisy operations Using anti noise- cancels noise out with another noise Shielding workers from noise 19. Critical, Brazil- model of environmentally sustainable and livable city Sustainable because: Lots of trees- cant cut without a permit City is not build around cars o Transportation planning Buses, bike paths High rise buildings must have shops in lower 2 floors to reduce peoples need to travel Recycling Existing buildings are reused Stiff air and water pollution laws Old buses- traveling technical schools for poor School children have to study ecology Signs along road to present environmental ideas Each poor family is given a plot of land 25. Ways to preserve open space: Small or medium size parks when cities expand Buy land for use as parks Purchase development rights- prohibit certain types of development on environmentally sensitive land Surround city with green belt- an open area used for recreation, sustainable forestry or other nondestructive uses urban growth boundary- line surrounding city beyond which development is not allowed cluster development- high density housing units are concentrated on one portion of a parcel, rest of land is for community shared space greenways- biking, hiking and jogging paths 26. New cities and towns can take the pressure off of overpopulated cities and allow development of more environmentally sustainable cities. Tapiola, Finland: ecological design, beauty and high quality of life Built in 7 sections villages separated by greenbelts o several neighborhoods clustered around shopping and cultural centers o walkways o factories located away from villages