unit 3 web

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Information about unit 3 web

Published on January 17, 2008

Author: Saverio

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ENVIRONMENTAL SCIENCE 101:  ENVIRONMENTAL SCIENCE 101 LIVING RESOURCES: UNIT 3 Environmental Policy:  Environmental Policy Environmental policy: Official rules and regulations about the environment that are adopted, implemented and enforced by a government agency as well as General public opinion about environmental issues. The best environmental policies incorporate economic, ecological and social/cultural considerations: since self-interest policy is to power as rational choice is to cost-benefit approaches. The following sequence reflects the history of environmental policy and law in the US: A hands-off attitude toward industry and private property; Direct litigation and regulation; Collaborative and pragmatic approaches Environmental Policy Cont’d:  Environmental Policy Cont’d Policy Cycle: Process by which problems are identified and acted upon in the public arena. Depending on the problem, either the public or the government normally identifies the problem in the policy cycle. After a problem is identified, the next step is to set an agenda followed by proposal development. Before enacting a law or rule in the policy cycle is to build support for the problem. Building support for the problem is characterized by media campaigns, public education and lobbying After policy is implemented, the next step in the policy cycle is to evaluate results. After the results are evaluated, the next step in the policy cycle is to suggest changes. In carrying out the policy cycle, Public Interest Groups use intensive media campaigns or even stage a protest Environmental Policy Cont’d:  Environmental Policy Cont’d The National Environmental Policy Act (NEPA) was the first congressional recognition of the need for a national policy for a clean environment. It was signed by President Nixon in 1970 The most powerful component of the National Environmental Policy Act (NEPA) has been the distribution of authority for environmental policy among different federal agencies For example EPA is responsible for regulating air and water pollution while the Department of Agriculture administers the national forests and Soil Conservation Service NEPA also require an Environmental Impact Statement (EIS) for any federal project that has major new pollution emissions, major building projects, possible health threats to people and potentially harmful effects on areas of cultural, scientific, or historical importance. Environmental Policy Cont’d:  Environmental Policy Cont’d Bill is a piece of legislation introduced in Congress and intended to become law After an original idea is turned into a bill, it needs to be sponsored by a legislator. After a bill is introduced in the House and Senate, it is referred to a committee. Right before a bill can be debated on the floor in the House and Senate it must have been to the full committee and marked up. If the president vetoes a bill, It can still become law if 2/3 of the House and Senate vote to override the veto. FOOD: Food Needs:  FOOD: Food Needs Human body requires a continuous supply of energy (food) The energy needs of an average person is 2500 calories per day Chronically receiving less than 90% of your caloric need is termed as UNDERNOURISHED Receiving less than 80% of your caloric need is called SERIOUS UNDERNOURISHED How does undernourishment occurs? when the food supply is low when individuals have no means of obtaining food Unemployment, and other economic or political factors can make a country not being able to produce enough food for her citizens or an individual not being able to afford to buy food FOOD: Food Needs cont’d:  FOOD: Food Needs cont’d Problems associated with undernourishment are: Reduced quality of life (weakened), low work output (part of vicious cycle of poverty and hunger) Possibility of Starving to death Undernourishment is a serious problem of developing countries Undernourished children are: Stunted in both mental and physical development and are vulnerable to disease 25% of children (13 million per year) in developing countries die of diseases related to undernourishment In contrast, a major health problem in developed nations is OVERWEIGHT 50% of US citizens are considered to be overweight FOOD: Food Needs cont’d:  FOOD: Food Needs cont’d The leading cause of death of in developed nations is CARDIOVASCULAR disease, which is related to excess fat in the diet In addition to caloric needs, the human body requires certain nutrients, such as proteins (amino acids), vitamins, and minerals Deficiency of certain nutrients are said to be MALNOURISHED One may take sufficient calories and yet still be malnourished Millions of death per year result directly or indirectly from malnutrition Deficiency in Protein and energy lead to Stunted growth, impaired lives, Kwashiorkor (Ghana; displaced child) and marasmus (Greek; waste away) Deficiency in IRON (mineral) leads to ANEMIA Deficiency in IODINE (mineral) leads to GOITER Deficiency in VITAMIN A leads to Blindness MAJOR FOOD SOURCES:  MAJOR FOOD SOURCES Humans depend heavily on 3 crops for food WHEAT, RICE and CORN They are called whole grains and provide adequate amount of CARBOHYDRATES PROTEINS, and FAT but lack certain Amino acids, vitamins, and minerals Hence the need to supplement our diet with fruits and vegetables Meat, diary products and fish can also supply some of these nutrients as well as being additional sources of protein Consumption of meat and diary products is higher in developed countries than developing countries 80 % of the milk and meat in the world are consumed by North America, Europe and Japan Another sources of protein in FISH; Japanese eats a lot of fish Fish may be consumed directly or indirectly by eating livestock that have been fed fish products FOOD PRODUCION:  FOOD PRODUCION The largest amount of cropland in the world is in the USA (twice as much as China and India) China and India are second and third respectively Based on projections of population growth, cropland production per capita will decline all over the world except Europe, where population is declining Regions with low cropland area per capita do not only have limited supply of food but also experience occasional famines Famines can result from: Bad weather, natural disasters, wars, political unrest that disrupt agricultural activities Political and Economic conditions in a country can also influence the effect of famines on the populace FOOD PRODUCION CONT’D:  FOOD PRODUCION CONT’D Grain production increase dramatically between 1950 and 1990 (2.1% per year compared to population growth rate of 1.8% per year) due to: the development of improved varieties of crop plants Increased fertilization and irrigation Better control of diseases, pests and weeds However, since 1990 average worldwide food production has been leveling off and it is now increasing at a rate of only 1.1% per year less than the current population growth rate of 1.4% The recent food production plateau is due in large part of the fact that developed nations have already achieved most of the gains in yields obtainable from fertilization, irrigation and pesticide use Food Production: Future Prospects:  Food Production: Future Prospects Cereal crops production increased between 1965 and 1995 due in large part to the development of improved crop varieties These varieties have genes that provide higher yield and better resistance to drought, infection, and pests New genes must be found (in the wild) for a continuous genetic improvement of crops Most of the world’s food comes from 16 widely grown crops One third of the worldwide grain production is used to feed livestock Due to the second law of thermodynamics, only a small portion of the energy in the grain is captured by the livestock and hence available for human There will be more food if human feed directly on the grain rather than giving it to livestock Fish farming also called “Blue Revolution” has the potential to contribute to human food needs. Food Production: Future Prospects cont’d:  Food Production: Future Prospects cont’d Currently enough grain is grown in the world to feed every person on earth On the contrary, 750 million people are undernourished or malnourished and that 15 to 20 million people, mostly children die each year as a direct result of malnutrition Distribution problems rather than production is to be blamed US spends billions of dollars each year on storing grain and subsidizing farmers not to grow crops Food aid is one option to get food to people but ideally a country should be able to buy food by selling something that they produce However many small nations rely on one commodity to provide income, for example Cuba relies on the sale of sugar cane, hence when sugar cane fail her economy gets into trouble and there is no money to import food Some countries has to sell the food they grow (CASH CROPS; cocoa in Ghana), meanwhile the wages earned by those who grow the crops are inadequate for them to buy sufficient food AGRICULTURE: Soil:  AGRICULTURE: Soil SOIL: A complex mixture of weathered mineral materials from rocks, partially decomposed organic molecules and a host of living organisms All plants either natural or agricultural ecosystem depend on the soil in which they grow Soil is the medium through which plants obtain oxygen for their roots and water and minerals for the entire plant Soil particle size affects the water and oxygen availability for plants-: larger-sized particles create more air space than smaller-sized particles and smaller-sized particles hold more water than larger-sized particles There are 3 important classes of soil particles size: SAND, SILT and CLAY No one soil size is best for plants but a mixture provides the best conditions AGRICULTURE: Land Degradation :  AGRICULTURE: Land Degradation 10% of the earth’s land is currently used for agriculture Expanding cropland will result the loss of natural habitats and grazing lands Poor soil, sloping topography and poor climatic conditions make much of the land not being used marginal land (not ideal for crop production) AGRICULTURE: Land Degradation cont’d:  AGRICULTURE: Land Degradation cont’d Causes of Soil degradation Worldwide Agriculture has been responsible for the degradation of land - It reduces and in extreme cases, eliminates the ability to grow crops Cropland is also lost by converting it to nonagricultural uses such as housing developments Soil degradation occurs not only on cropland but also on grazing land and land that has been deforested AGRICULTURE: Land Degradation cont’d:  AGRICULTURE: Land Degradation cont’d Mechanisms responsible for soil degradation Major cause is EROSION WIND WATER It removes topsoil and nutrients it contains resulting in loss of soil fertility It moves soil into waterways, damaging aquatic ecosystem Erosion removes 75 B tons of soil each year Minor cause of land degradation is the buildup of toxic chemicals or salts in the soil or chemical degradation AGRICULTURE: Land Degradation cont’d:  AGRICULTURE: Land Degradation cont’d In the US about 33% of the topsoil originally present at the time of European settlement has been lost Changes in farming practices reduce soil erosion for e.g. CONTOUR plowing and TERRACING can reduce erosion caused by rain runoff Cover crops planted immediately after harvesting can stabilize the soil Less plowing and cultivation reduce the amount of wind and water erosion AGRICULTURE: other problems:  AGRICULTURE: other problems Irrigation Irrigation of crops accounts for 70% of all human water use 15% of cropland is irrigated worldwide There are great benefits and problems associated with irrigation The biggest problem being the depletion of sources of water faster than they can be replenished Depriving roots of oxygen due to soil becoming waterlog Salinization resulting from evaporation of irrigation water from soil faces leaving behind mineral salts that creates salty soil affecting plants survival Fertilization Over fertilization can reduce plants yields AGRICULTURE: other problems cont’d:  AGRICULTURE: other problems cont’d Energy Use Farming is energy-intensive in industrialized countries Direct energy use: Gas used to run machinery Indirect energy use: Energy use in manufacturing fertilizers, pesticides, processing food and bringing food to the market Hence Sustainable Agriculture means - Agriculture should not degrade the environment, rely on non-renewable resources, should keep up with the needs of growing human population and should be profitable Pest Control: Pesticides:  Pest Control: Pesticides PEST is something or someone that annoys us. Biological Pests: Organisms that reduce the availability, quality or value of resources useful to humans 55% of the world’s potential food production is lost to pest: 35% in the field and 20% in storage One approach to tackling crop loss is to use pesticides: a chemical that kill pests (Herbicides, Insecticides and Fungicides) WHO has established that for every $1 worth of pesticides used $4 worth of crop is saved One of the first pesticides developed was DDT (1940s), had a low toxicity to humans but high to insects and was very stable It had a devastating effect on mosquito population saving a lot of people from dying from Malaria Pest Control: Pesticides cont’d:  Pest Control: Pesticides cont’d The problems associated with DDT was discovered in 1960, hence banned in the US (Silent spring) In 1950 small amount of pesticides was used in the US and crop loss to pest was 31% Currently, 64 times more pesticide is being used than in 1950 and crop loss to pest is 40% Why has there been little progress in pest control? RESISTANCE of pest to pesticides due to NATURAL SELECTION Pest Control: Pesticides cont’d:  Pest Control: Pesticides cont’d Pesticides use not only become ineffective in time, they may also be counter productive by killing NONPEST species (Wildlife), including Predators of pest species and Humans 20,000 people are estimated worldwide to die from pesticide poisoning each year Farm workers are especially at risk Consumers are also at risk due to residues of many pesticides that remain on the fruits and vegetables available in the markets. The above problems require alternatives for pesticides Pest Control: Alternatives:  Pest Control: Alternatives A number of alternatives exist FARMING PRACTICES CROP ROTATION BURNING CROP RESIDUE BIOLOGICAL CONTROL USING NATURAL ENEMIES Generalized insect predators like ladybugs and praying mantises Specialized parasite for a particular pest BLEEDING DISTRUPTION Interfering with mating attraction chemical Releasing sterile males to mate with females INTERGRATED PEST MANAGEMENT (IPM) Combination of biological control and pesticide use BIODIVERSITY: Species:  BIODIVERSITY: Species Biodiversity of an area is defined as the number of species living there, including genetic diversity within each species and the complexity of the ecological community of which species are a part What is a species? Biologically, individuals that can interbreed with each other (mate and produce fertile offspring). Members of the same species can interbreed whereas members of two different species cannot Much studies has been done on birds and mammals but not on bacteria, fungi and invertebrate (their number of species are still unknown) The earth’s biodiversity is concentrated in certain areas, mostly in the tropics BIODIVERSITY: Species cont’d:  BIODIVERSITY: Species cont’d Why should biodiversity be preserved? 25 % of drugs and medicine are derived from plants and many more plants have medicinal properties but remain to be investigated Some plants are potential sources of food but are yet to be domesticated Humans derive much pleasure from nature activities, including wildlife An ecosystem, with full complement of species, functions well and provides such benefits as stability of climate and a sink for carbon dioxide Apart from benefit to humans, species have the right to exist BIODIVERSITY: Extinction:  BIODIVERSITY: Extinction 99% of all species that have ever lived are now extinct 75-90% of species have been destroyed due to mass extinctions Current extinction rate due to human activity is at 20,000 species per year Some species are recovering naturally but prevention of extinction is the key to maintain earth’s biodiversity The most important cause of current extinction is the alteration or destruction of habitat caused by human activities Some species have become extinct or close to extinction due to overhunting The northern cod is an example of species that is near extinction resulting in the collapsed of the cod industry The do do bird and passenger pigeon have gone extinction due to overhunting BIODIVERSITY: Extinction cont’d:  BIODIVERSITY: Extinction cont’d Some species are recovering form near extinction due to overhunting. They include whooping crane and a number of whale species In addition to hunting animals for food, many species are hunted for body parts, such as the ivory tusks of Elephants. There is also an enormous market in live exotic animals When a habitat is destroyed or fragmented, it means fewer places for individuals to live Consequently, populations become smaller and more vulnerable to being wiped out by harsh weather or food shortage BIODIVERSITY: Extinction cont’d:  BIODIVERSITY: Extinction cont’d Introduction of new species either intentionally or accidentally can also caused species extinction For example the introduction of a plant called KUDZU (grows by climbing and spreading its vine) to Southern US to stabilized soil after road construction kill a lot of plant by covering and blocking them from SUNLIGHT Kudzu is now considered as pest in the US Introduction of (non-native) species also called ALIENS or EXOTIC often undergo population explosion since in most cases their natural enemies are not found in their new location In most cases they outcompete many native species and force them into extinction BIODIVERSITY: Endangered species:  BIODIVERSITY: Endangered species Endangered Species are those that are not yet become extinct but are on the verge of extinction National and international Laws have been established to prevent endangered species from becoming extinct In 1973, US passed the Endangered Species Act Species MOST AT RISK are categorized as endangered, while those at LOWER RISK are categorized as THREATENED or VUNERABLE Currently there are about 1500 species on the endangered and threatened list BIODIVERSITY:Endangered species cont’d:  BIODIVERSITY:Endangered species cont’d A recovery plan is prepared for endangered species and certain activities such as construction or development are prohibited in areas where they live. So far only SIX species, including BALD EAGLE, have responded well enough to recovery measures to be removed from the list ZOO and CAPTIVE BREEDING play a role in preserving species They serve to educate the public and excite interest in preserving endangered species Captive breeding program can rescue a species from brink of extinction as was done for the PEREGRINE FALCON but whether such programs can successfully return viable population to the wild remains to be seen Land Use: Forest and Rangelands:  Land Use: Forest and Rangelands 11% of the earth’s land is crop land This percentage is attributed to human population growth demand Range and Forest lands which are natural resources are being lost to cropland Loosing Range and Forest land to cropland is Unsustainable activity Hence the need to preserve these natural resources to create a sustainable world Land Use: Forest and Rangelands cont’d:  Land Use: Forest and Rangelands cont’d Forest products are used for : Fuel, Construction and Paper The greatest use of wood is as FUEL More than half of the population of the world use wood as their primary fuel for heating and cooking The high demand for wood for fuel has significantly reduced Forestland Forests do not only provide wood but are also resources They reduce erosion, protect water quality, moderate climates and provide habitat for wildlife Forest removal rates accelerated about 10,000 years ago when agriculture began Since then about 16% of forestland has been cleared for cropland, pastures and settlements Land Use: Forest and Rangelands cont’d:  Land Use: Forest and Rangelands cont’d Tropical forests Tropical forests occupy about 10% of the earth’s land but contain at least 50% of all the world’s species Tropical rain forest are being cleared for cattle ranches, cropland, plantations and lumber Some places like Haiti, the Philippines, and Madagascar have lost more than 80% of the original forest. Between 1940 to 1983 Costa Rica lost 75% of the forested land mostly to banana plantations The primary way of clearing forestland for agriculture and livestock is through SLASH and BURN Due to loss of soil fertility farmers abandoned old lands and established new ones causing increasing the rate of forestlands losses Land Use: Forest and Rangelands cont’d:  Land Use: Forest and Rangelands cont’d Tropical forests are also use for timber by selectively cutting high-value tress This is not as destructive as clear-cutting but damage is done due to ACCESS ROAD construction, damaged caused by falling trees and also the dragging of the fallen trees These three factors result in forests fragmentation and the loss of their animal species To prevent further losses of Tropical forest, countries that own them should adopt new strategies like Ecotourism and Permitting drug companies to explore forest for new medicines Wealthy nations should provide incentives to poor nations that own tropical forest, example DEBT-FOR-NATURE SWAP Land Use: Forest and Rangelands cont’d:  Land Use: Forest and Rangelands cont’d Temperate forests Temperate forests are also used for timber rather than being cleared for agriculture Replanting of temperate forest return the land to a forested state but does not bring it back to the original forest since it lacks BIODIVERSITY In this country there is virtually no VIRGIN forest (never cut) However, the same total acres of forest at present is them same prior to European settlement This is due to natural reforestation (secondary forest) of lands that were used and replanting of logged areas Land Use: Forest and Rangelands cont’d:  Land Use: Forest and Rangelands cont’d Temperate forests in North America are harvested by: CLEAR CUTTING; more damaging (leads to soil erosion, and removes habitat for wildlife) STRIP CUTTING; (narrow corridors) less damaging SELECTIVE REMOVAL (high-value trees) less damaging Fire is a natural part of many forest ecosystems Managing forest resources often involves dealing with fire For many years total fire prevention was practiced leading to large buildup of dead wood which fueled many forest fires In 1988 75% of Yellowstone National Park was burned due to this Recently the positive and natural aspects of forest fire have been recognized leading to periodic prescribed burns/ or allowing naturally-occurring fires to run their course Land Use: Forest and Rangelands cont’d:  Land Use: Forest and Rangelands cont’d Rangelands (grazing lands) Grazing lands (rangelands) are too dry for raising crops Animals graze on these lands and convert plant material into meat for humans In addition to their role in livestock production, rangelands are important reservoirs of biodiversity In this country (US) more threatened species exist in rangelands than in other biome OVERGRAZING is the greatest single threat to rangelands Grazing animals eliminate palatable species leaving behind unpalatable species (often thorny or prickly) Grazing also removes cover plant exposing soil to erosion leading to a cycle of increasing degradation called DESERTIFICATION (permanent damaged) 15 % of livestock feed comes from rangeland, the remaining 85% comes from corn Preserving Nature:  Preserving Nature Parks and Nature Preserves For humans parks and preserves serve as places of: RECREATION; INSPIRATION; EDUCTION For animals they serve as SANTUARIES Yellowstone National park was the first to be established in the US (1872) It was originally established to provide public access to its hot springs and geysers but now it has become an important nature preserves In conjunction with neighboring parks and national forestland it support herds of buffalo and large predators such as grizzly bear and the recently introduced WOLF Preserving Nature cont’d:  Preserving Nature cont’d Preserves size is very important in determining how successful the species within its borders will be For example smaller Islands have smaller populations and are more prone to extinction, since many species have a minimum viable populations size below which the population will decline and cannot recover 4% of the earth’s land has been set aside as parks or preserves 43% of these protected areas are in the Tundra and Desert biomes since these areas (tundra and desert) are not in high demand for human use Almost part of each different biomes of the world has been set aside and protected but GRASSLANDS and AQUATIC SYSTEMS are under represented Preserving Nature cont’d:  Preserving Nature cont’d The regions with the greatest percentage of their land in protected status are North and Central America (10 %) compare to the former Soviet Union with just 3% In the US land are set aside for different purpose WILDERNESS AREAS (10%): little human activity is allowed PARKS: more human activity is allowed WILDLIFE REFUGE: hunting activities are allowed Preserving Nature cont’d:  Preserving Nature cont’d Wetlands Wetlands are generally defined as areas covered by shallow water at least some of the year They are important resources for Wildlife About two thirds of all endangered species in the US spend some of their life in wetlands Wetlands are also important in purifying the water moves through them They also serves as SPONGES that soak up excess rainfall The severity of flooding often increases when wetlands are destroyed In US many wetlands have been drained to create farmland and in some states 90% have disappeared In the lower 48 states of the US less than 50% of the original wetlands still remain

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