AgricultureFeeding a growing population • Human nutritional needs: • 2000-2500 calories/day, less is undernourishment (famines are acute incidents of undernourishment catalyzed by war or environmental devastation) • In US, avg. is 3500 calories/day = overnutrition* 1/3 Obese • Malnourishment (pg. 285-287)– shortage of adequate vitamins/minerals: • Kwashiorkor – lack of protein = swollen abdomen • Marasmus – lack of protein/calories = skeletal thinness/wrinkled skin • Anemia – lack of Iron = low energy/fatigue • Ariboflavinosis – Vit. B2 deficiency (one of the most common in the US) = skin problems, sore mouth • Goiter/Hyperthyroidism – iodine deficiency • Rickets – Vit D deficiency (not enough Calcium) • Vit. A deficiency = poor vision • Scurvy – Vic. C deficiency = loose teeth/black and blue skin
Types of agriculture– two types: • Industrialized – uses large amounts of fossil fuel energy, water, fertilizers, pesticides to produce large quantity of a single crop (monoculture), 25% of all cropland (mostly developed countries) – Types of include: • Plantation agriculture – in tropical developing countries, growing cash crops (bananas, coffee, soybeans, etc.) on monoculture plantations for sale in developed countries • Traditional agriculture, practiced by 44% of world, in developing countries, provides 20% of world’s food supply – two types: • Traditional subsistence – crops for family farm survival (uses human labor/animals) • Traditional intensive – increase # of humans/animals/fertilizer = higher yield, farmer can feed family and sell for income.
Green Revolution– uses 8% of oil output • Since 1950, caused increase in global food production from increased yields/unit area of cropland (called first green revolution) – Three steps: • Developing/planting monoculture, selectively-bred, high-yield varieties of key crops: rice, wheat, corn. • Large amount of fertilizer, pesticides, water to produce high yields • Increase # of crops grown/year on land w/multiple cropping (2-3 crops a year on same land) • Since 1967, second green revolution b/c of fast growing dwarf varieties of rice/wheat = greater yield. • Genetic engineering and crop production
Deforestation – taking out the natural (water-absorbing) trees/vegetation to make way for timber, fuel, livestock grazing, farming – causes nutrients to leach from topsoil, erosion of topsoil, runoff causing flooding, guillies / landslides.
Irrigation – 57% of irrigation water doesn’t get to crops, most water is used for agriculture – types include. • Drip-irrigation (efficiency = 90-95%) (Best) – above/below ground pipes/tubes deliver water to individual plant roots • Center-pivot (eff. = 80-90%) – water pumped from underground, sprayed from mobile circling sprinklers • Gravity flow (eff = 60-80%) (Worse) – water fills ditches in crop field, much is lost **this can also be called flood-irrigation
Sustainability • Agriculture • organic fertilizers • high-yield polyculture plants • biological pest control • integrated pest management • efficient irrigation • soil conservation
Controlling pests • Types of pesticides • Insecticides • Chlorinated hydrocarbons (DDT) – high persistence (HP), biologically magnified (BM) • Botanicals (from plants - Rotenone, pyrethrum, camphor), LP, not BM • Microbotanicals (bacteria, fungi, protozoa), LP, not BM • Herbicides • Fungicides ………etc……..… • First generation – natural pesticides (though certainly toxic, like metals/arsenic) • Second generation – DDT and man-made chemicals (*we don’t know true effects because we have not studied these significantly)
The LD50 is the dose that kills half (50%) of the animals tested (LD = "lethal dose"). • A threshold is the exposure level or dose of an agent above which toxicity or adverse health effects can occur, and below which toxicity or adverse health effects are unlikely. • For example, taking aspirin is therapeutic and not dangerous up to a contain dose, but above that dose it can cause nausea, brain damage, bleeding, and, eventually, death.
Costs and benefits of pesticides use • Benefits: • save human lives – from malaria (mosquitoes), bubonic plague (rat fleas), typhus (body lice/fleas), sleeping sickness (tsetse fly) • increase food supplies/lower cost – losses from pests would be worse without pesticides • increase profits for farmers • work faster/better than alternatives • when used properly/risks are less than benefits • Risks: • **BIGGEST PROBLEM: Accelerate development of genetic resistance to pesticides – insects can develop immunity w/in 5-10 years through directional natural selection • Broad-spectrum insecticides also kill natural predators/parasites which help control pest populations • Pesticides don’t stay put – 2% gets to crops during aerial spraying (go into air, surface water, groundwater, food, etc.) • Some harm wildlife (wiped out 20% of honeybee colonies, kill 67m birds and 6-14m fish/year) • Can threaten human health – 3m in developing countries are poisoned by them each year.
Integrated pest management – important for pollution prevention (could drop pesticide risks by 75%), crops are evaluated as part of a ecological system; controlled by: cultivation, biological, chemical methods: Goal is to reduce crop damage to an acceptable level: • Relevant laws • FIFRA (1947) – Federal Insecticide, Fungicide, and Rodenticide Act – requires EPA approval for use of all commercial pesticides • EPA sets tolerance level specifying amount of toxic pesticide that can remain on crops that people eat • Banned: most chlorinated hydrocarbons, several carbamates/organophosphates.
Forestry Old Forest- 100 + years old. New Forest Even Aged- tree farms Uneven Aged- Natural Forest Deforestation- removal of trees * Slash and Burn Fragmentation- disruption of habitat Person
Tree Harvesting • SELECTIVE CUTTING- best for the environment • SHELTER WOOD CUTTING • SEED TREE CUTTING • * CLEAR CUTTING- most devastating • STRIP CUTTING
Sustainable land-use strategies • Forests • Grow timber on long rotations (100-200 years) • Selective cutting of individual trees, strip cutting (NOT clear cutting) • Minimize fragmentation of remaining forests • Reduce road-building in remaining forests • Use logging/road-building that minimizes soil erosion.
Forest Fires • Ground Fires- • Chaparral (California) • * rainy season followed by drought. • Crown Fires- * Benefits- Return nutrients, rid of pest & disease
National forests– forests cover 30% of US land, provide habitats for 80% of wildlife, supply 2/3 of water runoff; there are 156 national forests, good b/c: • Economic: $4B worth of oil/minerals, 3M cattle graze on it, 19% of US forest area • Ecological: habitat for 200+ endangered species, habitat for $4-7B pollinators, provides clean drinking water for 60m people • Recreational: hunting, fishing, camping
Public and federal lands • Management– best way to preserve biodiversity – more than 17,000 areas (10% of world) is protected – conservationists want to protect 20% - would need funding by national governments and cooperative ventures with businesses • (** #1 reason for extinction is habitat destruction) • Wilderness areas– provide mostly undisturbed habitats for wild plants/animals, provide a natural lab to discover how nature works…preserves biodiversity, protect them as centers of evolution • National parks – National Park System established in 1912, has 55 national parks (most in the west) – most are too small to sustain large species, many suffer from invasion from non-native species – pollution is the biggest problem • Wildlife refuges– Teddy Roosevelt established first Wildlife Refuge in 1903, now 524. Visited to hike, hunt, fish. 75% are wetlands and protect migratory birds, protect 20%+ endangered species (have helped many recover). • Wetlands - important for biodiversity, Federal Wetlands Law: requires a permit to fill or deposit material in a wetland (cut wetland loss by 80%); goal is zero net loss (does allow for mitigation banking. • Estuaries- rivers meet the sea- important breeding grounds.
Rangelands • Overgrazing– too many animals graze on grassland for too long and exceed the carrying capacity of the grassland (mostly caused by excessive feeding of livestock animals; leads to: • Lower NPP (net primary productivity) of grasslands • Erosion of grassland by wind/water • Compaction of soil (decreases water holding capacity) • Invasion of grassland by shrubs • MAJOR cause of Desertification!!
Urban land development • Planned development three models: • Concentric circle model – sprawl develops outwards from a central business district; example: NYC • Sector model – pie-shaped wedges of commercial/industrial/housing districts • Multiple-nuclei model – many independent cities very close together; example: LA, California
Suburban sprawl– growth of low-density development on the edges of cities (encourages the dependence on cars); leads to loss of cropland/forest/wetlands, pollution of drinking water/air, greenhouse gas emissions, etc.
Urbanization– number of people living in cities w/greater than 2500 people: • Advantages: populations live longer/lower infant mortality, better access to medical care/family planning/education, recycling is more feasible, helps preserve wildlife habitats (occupy 2% of earth’s land) • Disadvantages: not self-sustaining, consumes 75% of earth’s resources, lack trees, produce little of their own food, can have water supply problems Urban Blight- run down urban areas- “projects”
Transportation infrastructure • Canals and channels– artificial waterways used for travel, shipping, or irrigation, often narrows or straightens natural streams, can increase flow of water increasing erosion and flooding, reducing habitats for wildlife • Ecosystem impacts of roads – cutting down forests for roads can lead to erosion, and runoff • Mass transit • Advantages: More energy efficient than cars, produce less air pollution than most cars, require less land than roads and parking areas for cars, cause fewer injuries/year, reduce car congestion in cities • Disadvantages: expensive to build/maintain, cost efficient only in densely populated areas, can cause noise
Land conservation options • Preservation– set aside land for protection – John Muir was an early leader of the preservationist movement he also founded the Sierra Club • Remediation – (repair) similar to decontamination - removal or neutralization of chemical substances from a site to prevent any adverse effects. • Mitigation– means “trade off” – mitigation banking is when destruction of existing wetland/land is allowed as long as an equal area of the same type of wetland/land is created or restored (not always successful – but better than nothing) • Restoration– trying to restore a degraded habitat or ecosystem to a condition as close as possible to the pre-degraded state
Mining • Surface mining safer than sub-surface • Open-pit mining: machines dig holes and remove ores • Dredging: chain buckets/draglines scrape underwater mineral deposits • Area strip-mining – strip away overburden and remove minerals (used on flat surface) • Mountain top removal • Sub-surface mining– dangerous, removes deep deposits, disturbs less land/produces less waste material. * Shaft, Tunnel, Slope • Room and pillar – machine out all but a pillar to hold up mine roof • Longwall mining – steel props support mine roof
Relevant laws and treaties • General Mining Law of 1872 – allows mining companies to take minerals from public land without paying royalties • Surface Mining Control and Reclamation Act (SMCRA), 1977 – regulates the environmental effects of coal mining (sets standards)
World Wide FISHERIES • 1 billion people depend on fish as their main source of food. • 1 million employed in fishery industry. • 125 million ton harvested annually - 75 % consumed as food.
Blue RevolutionOverfishingBycatch Magnuson Fishery Conservation and Management Act. (1976) Sanctuaries- Dry Tortugas
Aquaculture Trawler fishing Fish farming in cage Spotter airplane Purse-seine fishing Sonar Drift-net fishing Float Buoy Long line fishing lines with hooks Deep sea aquaculture cage Fish caught by gills Fig. 10-17, p. 216