IV. Land and Water Use: Pesticides
Pesticides and pests: includes herbicides, rodenticides, fungicides, nematocides, and insecticides; biocides kill many species; cotton has the highest rate of insecticide application; broad spectrum vs. narrow spectrum; Rachel Carson (1962) published Silent Spring, pointing out the adverse effects of DDT, DDT was banned in the US in 1972
Chemical groups of pesticides: inorganic pesticides (S, As, Cu, Pb, Hg) are toxic and environmentally persistent, natural organic pesticides (extracted from plants), fumigant chemicals (carbon tetrachloride, methyl bromide) are used to sterilize soil and decrease infestation in stored grains, chlorinated hydrocarbons (organochlorines like DDT, aldrin, dieldrine, chlordane) are nerve toxins, probable carcinogens and liked to fertility disorders and are either banned or heavily restricted (roundup is an organophosphate that is not a nerve toxin). Pesticide benefits: eradicated many insect vectors including mosquitoes (malaria, dengue, yellow fever), rat fleas (bubonic plague), typhus (lice and fleas), and tsetse flies (African sleeping sickness); increased food supply and decreased cost of producing food. Pesticide problems: often kill nontarget species, may kill helpful pest predators like ladybugs, spiders, and wasps, may kill insect pollinators like honeybees, creates genetically resistant insects (pest resurgence), pesticide treadmill, pesticides migrate through erosion, wind and water (the grasshopper effect), farm worker health problems. Pesticide legislation: regulated by EPA, FDA, and USDA; Federal Food, Durg, and Cosmetic Act (FFDCA, 1938) allows EPA to set tolerance levels for pesticide residues in food, Delaney clause added (1958) no cancer causing chemicals can be added to food; Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA, 1947) regulate sale and use of pesticides, now pesticides must be registered with EPA; Food Quality Protestion Act (1996) EPA can set pesticide tolerance levels taking into account effects on aggregate pesticide exposures (like effects on children); in 2001, 127 countries agreed to ban peristent organic pollutants (POPs) including aldin, chlordane, dieledrin, DDT, PCBs, dioxins, furans, etc. however the US continues to produce these chemicals, US crops may contain these chemicals since not all countries stopped using them and we import crops (circle of poison). Bhopal: Bhopal, India (1984) the Union Carbide plant, which produced Sevin, released many gases used to create the pesticide (plant was on the edge of a shantytown), but it is believed 15,000 died and over 800,000 suffered chronic diseases like lung disease, eye damage, immune dysfunction, nerve damage, cancer, birth defects, and impaired mental difficulty, Union Carbide paid India $470 million in compensation, but it was not distributed to the victims. Organic Agriculture: 100% organic: must be produced without hormones, synthetic fertilizers, pesticides, or antibiotics, it can not be genetically modified, Made with organic ingredients: must be 70% organic. Integrated pest management (IPM): uses low doses of nonpersistent, nonbiomagnified pesticide to reduce pest numbers, followed by a combination of these: increasing crop diversity (strip cropping, polyculture), crop rotation, shelterbelts, trap crops, biological control (insect predators, sterile males, pheromones, biopesticide-Bt)
Questions:
a. sterile male b. Bt spray c. ladybugs d. crop rotation e. trap crops
1. pest control method most effective on a Mediterranean fruit fly outbreak on citrus trees in Florida
2. biological control method preferred for combating aphids
3. cultural method effective for a variety of grain and legume crops when it is desired to sell all crops produced
4. pest control measure most effective on butterfly and moth larvae
5. Which of the following is the best reason to use organophosphates instead of organochlorines as a pesticide?
a. less persistent in the environment b. more toxic to humans in lower doses c. cost less to produce d. bioaccumulate and biomagnify e. affect the endocrine system instead of nervous system
6. Which of the following is not a drawback to using insecticides to control a pest outbreak?
a. insect predators are also killed b. natural pollinators may be killed c. it can protect the crop from damage caused by insect pests and improve land productivity d. create genetically resistant insects e. some birds may also be killed
7. Which of the following is an organochlorine pesticide?
a. DDT b. arsenic c. malathion d. Sevin e. Roundup
8. Which federal legislation requires companies to register their pesticides with the EPA?
a. FIFRA b. Delaney clause c. FFDCA d. Food Quality Protection Act
9. Insecticides cannot help prevent the transmission of which of the following diseases?
a. dengue b. malaria c. African sleeping sickness d. yellow fever e. tuberculosis
10. Which of the following applications requires the least amount of pesticide for maintenance?
a. algaecidies to a pond exposed to cow feedlot wastes b. herbicides to a no-tillage field c. pesticides to a golf course d. insecticide inside a home to control pests e. insecticides to a field of cotton
IV. Land and Water Use: Forests and Grasslands
Land Use: 33%: cities, arid areas, wetlands, 29%: forest and woodlands, 27% range and pasture, 11% cropland. Forests: old growth forests: little to no human intervention (coastal redwoods can live thousands of years and be 300 ft tall, Southern Pine can live 300-400 yrs), largest remaining are boreal forests of Russia and Canada and tropical forests of Brazil and Oceania. Secondary forests: have been cut and allowed to regenerate (eastern US forest). Utilitarian forest use: harvest lumber, wood pulp to make paper, logging occurs in carefully managed forests for sustainable yield, fuel wood and top make charcoal in developing countries, tropical hardwoods are harvested unsustainably from virgin forests, can be clear cut for rangeland. Ecological role of forests: habitat for a huge number of species, cooler microclimate, involved in carbon and nitrogen cycles, from a watershed, carbon sink, decrease erosion and runoff. Forest management: maintaining a forest for sustainable harvests, forest regeneration, even-aged management, monocultures degrade habitat, increase pests, disease and erosion, uneven aged management permits natural regeneration, more animal diversity, fewer diseases and pests, and less erosion. Tropical forests: vanishing at an alarming rate (tropical rain and dry forests), highest rates of deforestation are in Amazon and Congo river basins, deforestation is due to: agriculture, logging, charcoal formation, grazing, oil and gas exploration, mining and smelting, and hydroelectric dams, “slash and burn” agriculture, debt for nature swap. Temperate forests: issues includecutting old growth forests, and methods of tree harvest: clear-cutting, coppicing (leaving stumps of a tree to regenerate forest- oak, maple, and ash), seed tree cutting, selective cutting (preferred environmental method), roads for log transport (increase erosion, sediment, and debris in surface water, cause habitat destruction and fragmentation). Forest regulations: Forest management act (1897): created national forests, Multiple Use Sustained Yield Act (1960): requires National forests be managed for multiple uses, resulting in sustainable yield of products and services, US Forestry Service manages most US forests. Fire: burns off the duff, returns nutrients to the soil, prevents large canopy fires, and important to many ecosystems, since 1972 the policy is to let fires burn as long as they do not severely impact areas, Bush’s “Healthy Forests Initiative” legalized salvage logging. Sustainable forestry: purchase sustainably produced products (Home Depot, Staples). Grasslands: support migratory herds of grazers, used for agriculture and rangeland, dense grasses decrease erosion, overgrazing leads to erosion and soil compaction, desertification, 90% of US grain crop is used for livestock. US rangeland: 60% privately owned, management includes controlling the stocking rate, continuous grazing vs. rotational grazing, raise several species together.
Questions:
1. large proportion of remaining old growth boreal forests
2. has lost the greatest amount of forested land compared to its original forests
3. less than 0.1 % of the original forest remaining
4. harvested for its tropical hardwoods resulting in tremendous loss of biodiversity
5. harvested by people needing firewood or charcoal
6. Problems associated with monoculture of trees include all of the following except
a. increased pests in monoculture pine forests b. decreased biodiversity on tree farms c. increased disease causing fungi in monoculture fruit trees d. a monoculture plantation could interfere with the water cycle e. increased sunlight helps promote growth of conifers in monoculture
7. Which of the following best represents an ecological benefit of forests?
a. create a beautiful view for humans b. can be used for hunting, fishing, and camping c. provide wood pulp for paper d. play an integral role in the water cycle e. provide lumber for building homes
8. Which method of timber harvest is preferable for southern yellow pines, such as loblolly, longleaf, and slash pines, typically used for pulpwood to make paper?
a. shelterwood cutting b. clear-cutting c. selective cutting d. coppicing e. seed tree harvesting
9. Which of the following is a consequence of overgrazing?
a. abundant riparian vegetation b. increased sod and topsoil c. desertification of marginal lands d. decreased erosion e. decreased soil compaction
10. All of the following can be harvested sustainably from forests except
a. nuts b. minerals c. rubber d. fruits e. syrup
11. All of the following are causes of deforestation of tropical forests except
a. acid deposition b. logging c. mining d. agriculture e. grazing
12. For which of the following reasons would the USFS order a prescribed burn?
a. remove snags b. rid an area of pest species c. remove nutrients from the forest d. clear the forest for agriculture e. help reduce erosion
13. Which of the following would be a good rangeland management practice in areas subject to a dry season?
I. Rotational grazing II. Deferred grazing III. Grazing multiple species
a. I only b. II only c. III only d. I and III e. II and III
14. Which of the following best describes how US forests are currently managed by the USFS?
a. primarily for timber harvest b. timber harvest and grazing c. timber, habitat, and recreation d. preserved for aesthetic value e. preserved as species habitat and recreation
15. All of the following are reasons why federal rangelands are in poor condition in the United States except
a. large numbers of bison present on federal land b. overstocking animals on rangeland c. low subsidized grazing fees d. lack of enforcement of stocking rates e. limited funds for range improvement