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Download The Effects of Agriculture on Wildlife and the Environment
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The Effects of Agriculture on Wildlife By Sarah Langan Pesticides • Include insecticides and herbicides • Routinely applied by farmers to increase crop yields • Ariel spraying • Ground spraying • Granules • Wildlife is exposed to pesticides by • Breathing them in • Ingesting them through contaminated food and water • Absorbing them through their skin or feathers Insecticides • Eliminate crop pests by attacking their central nervous systems • Direct affects on wildlife include • • • • Sickness Behavioral changes Diminished reproductive abilities Death DDT • Persists in the environment, insoluble in water, and accumulates in runoff • Fat solubility permits bioaccumulation • Effects bald eagle, osprey, peregrine falcon, and other birds • Causes the shells of the birds’ eggs to become so thin that they are crushed when the parents try to incubate them • Banned in the United States in 1973 • Banned worldwide in 2006, except in African countries where it is used to kill mosquito vectors of malaria Diazinon • Negative impacts on birds • Decreases the number of eggs laid • Decreases survival rates of eggs and hatchlings • Increases embryonic deformities • One granule can kill five house sparrows • Banned from use on farms and golf courses in 1988 • Still widely used as home pest control • 2001 estimates show that six million pounds are applied annually Herbicides • Most commonly used pesticides on farms • Direct effects • Paraquat: causes abnormal embryonic bird growth and reduces rates of hatching in waterfowl eggs • Indirect effects • Destroys habitat and food sources Solutions - Pesticides • Ground application • Use most effective pesticide that is least detrimental to wildlife • Microbial insecticides • Bacteria, viruses, and fungi that selectively attack a single species or group of target insects • Do not harm mammals, birds, or fish • Crop pest parasites and predators • Leave some areas untreated • Drainages, bottomlands • Field borders, fencerows, ditch banks • Cover granules completely with soil • Develop more pest resistant crops Run off • Chemicals from pesticides and nutrients from fertilizers build up in the soil • Soil erosion deposits nutrients into aquatic ecosystems • Sedimentation • Build up of suspended soil particles • Direct affects • Suppresses plant development • Limits sight-feeding fishes’ ability to find food • Clogs fishes’ gills and limits oxygen intake • Smothers eggs and larvae Eutrophication • Excess nitrogen and phosphorous create low oxygen conditions in aquatic ecosystems • Increases plant and animal biomass but decreases diversity and changes the dominant biota • Algal blooms • Block sunlight from reaching aquatic plants • Destroys habitat for fish and depletes food for waterfowl • Dead blooms sink to the bottom and are consumed by bacteria • Bacteria use large amounts of dissolved oxygen when multiplying Dead Zones • Aquatic areas of unlimited algae growth and <2 ppm of dissolved oxygen • Gulf of Mexico • 6000 – 7000 square miles • Caused primarily by runoff from the Mississippi River Valley • Gulf of California • Yaqui Valley irrigations are followed by large blooms of red and brown tides • 19 – 223 square miles • Causes paralytic shellfish disease Solutions – Runoff • Use fewer fertilizers • Decrease the rate of application • Animal waste control or conversion into fuel for electricity and heating • Limit the amounts of nutrients, organic matter, and harmful chemicals in waste from manufacturing facilities Deforestation • Primary cause is agriculture • Destroys habitat and food sources • Increases competition for limited resources • Increases risk of extinction • Endemic species • Populations that cannot adapt Solutions – Deforestation • Stop clear-cutting • Replace trees that are cut down • Governmental regulations Species that Benefit from Farming • Traditional farming practices in developing countries create grassland habitats for threatened birds Organic Farming • No chemical pesticides • Hedgerows and ditches provide habitat for natural predators • No artificial fertilizers • Strictly manure • • • • Antibiotics only given to livestock as needed Crop rotation Mixed farming Spring sowing Pros and Cons • Known to increase biodiversity on the farm • 2010 University of Leeds study: 12.4% increase • 2012 University of Oxford study: 30% increase • Lower crop yields • 2010 University of Leeds study: 55% decrease • 2012 McGill University and University of Minnesota study: 25% decrease overall, 13% decrease with improved management techniques • Cereal crops have worst yield decrease • Legumes, soybeans, and fruits yield almost as much as conventional farming Shade-grown coffee • Introduced by the Smithsonian Migratory Bird Center in 1996 • Coffee grows in the shade of native trees maintained by the farmer Pros and Cons • Creates suitable habitat for many avian species • Natural pest control by birds, bats, and predatory insects • Higher soil quality than sun-grown coffee • Lower yield than sungrown coffee • Farmers profit from fruit, firewood, medicinal herbs, building materials, and ecotourism Questions?
