Lecture 5 Ecosystem Services- Ecology of FoodQuestions:Agricultural PracticesTraditional (Swidden) AgricultureIndustrialized agricultureSustainable yieldTradeoff between sustainability and productivitySlide 8Pesticides videoPowerPoint PresentationFisheries managementSlide 12Slide 13Slide 14Slide 15DDT (dichlorodiphenyltrichloroethane)Slide 17Slide 18Rachel Carson videoSlide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31problems with pesticidesSlide 33More problems with pesticidesHow to maximize effects of pesticides and minimize environmental impacts?Slide 36Slide 37Why use chemicals when there are natural methods?Biological control & the Allee effectIntegrated Pest ManagementThe ecology of eatingSlide 42Sustainable agricultural practices:Slide 44Slide 45Lecture 5Ecosystem Services- Ecology of Food•ECOL 1000: Ecological Basis of Environmental Issues•University of Georgia•Spring 2015Questions:•What are some differences globally in the production of food?•How do we manage resources for sustainable food production?•What are issues associated with agricultural pest control, and what are potential solutions?Agricultural Practices•With ~ 30,000 edible plants, 15 plant & 8 animal species provide 90% of food•35% land used for food production•Traditional: human labor and draft animals used to produce food for the family–Shifting cultivation in tropical forests–Nomadic livestock herding•Industrialized: large inputs of energy (fossil fuels, fertilizers, irrigation, and pesticides)–Primarily in developed countriesTraditional (Swidden) AgricultureTropical trees are cut down and burned in order to clear land for plantingTwo purposes:-Remove debris…land cleared for planting-Ash is high in minerals which promotes plant growthSustainable agricultural practice?Industrialized agriculture•Large expanses of land•Most if not all organic matter removed•Tilling exposes the soil to wind and water erosion•Lost nutrient cycling; Large quantities of chemical fertilizers must be added to maintain productivity•Monoculture is susceptible to pests and plant diseasesSustainable yieldIn order to ensure a similar yield at each harvest, there must be sufficient time between harvests for the resource to recover to pre-harvest levelsSustainable resource: is the resource is renewable (need to know rates…)Tradeoff between sustainability and productivityTotal crop yield using industrial methods is > 3.5 times traditional methodsBut, look at the ratio of energy output to energy input-Much higher for traditional methods than industrial-Energy input > 17 times as much in industrialized country!Tradeoff between sustainability and productivityPesticides videoPatterns of risk for nitrate (fertilizers) contamination-High concentrations of nitrate linked to birth defects, cancer, and blue baby syndrome (low oxygen)-Presence of other contaminantsFisheries managementIn the absence of fishing, the population will grow to carrying capacityMaximum sustainable yield: The maximum rate at which individuals can be harvested from a population without reducing population size long-term; recruitment balances harvestingRequires understanding of population dynamicsPacific sardine: exploitation shifted age structure to younger classes~50% of fish come from natural populationsOverexploitation of fisheriesGeorges Bank (off New England)Cod dominated the fisheryBecause of overfishing in the early 80s, they were replaced by skates and dogfish sharksPopulation explosion of locustsManaging agricultural pests~40% of all agriculture consumed by pests & diseaseErgot fungusWeevilsDevelopment of chemical pesticides mid 20th century, including DDT, to control mosquito-borne illnesses, like malariaConstruction of the Panama CanalIf DDT worked on mosquitos, why not use it on all insect pests?DDT (dichlorodiphenyltrichloroethane)•Enthusiastically used to control outdoor & indoor insect pests•Aerial spraying, sprayed on swimming pools, sprayed on agricultural fields•Long-lived compound; not easily broken down•Does not easily break down in body, attaches to and retained in body fats•Passes up the food chain…BioaccumulationBioaccumulation: The process by which toxins are stored in the tissue of living things, and increase in concentration when passed through the food chainRachel Carson videoRachel Carson (1907 – 1964) was a marine biologist and conservationist whose writings are credited with advancing the global environmental movement. She began her career as a biologist in the U.S. Bureau of Fisheries, and became a full-time nature writer in the 1950sCarson documented environmental impacts of the indiscriminate spraying of DDT in the US.She was critical of using large amounts of chemicals into our environment without fully understanding their effects on the world and human health. She suggested that DDT andother pesticides may cause cancer and that their agricultural use was a threat to wildlife, particularly birds, because it reduced the thickness of eggshells.Biocides&MisinformationIn 1962 Silent Spring by Rachel Carson was publishedHer efforts resulted in public outcry, which eventually led to DDT being banned for agricultural use in the US in 1972, and subsequently banned for agricultural use worldwide under the Stockholm Convention. Carson’s work in large part coincided with other events during the early stages of the environmental movement.DDT’s limited use in disease vector control continues to this day and remains controversial.Bald Eagles videoAlong with the passage of the Endangered Species Act, the US ban on DDT is viewed as a major factor in the comeback of the bald eagle and the peregrine falcon from near-extinction in the United StatesBreeding PairsBreeding PairsDateDate625625196019604174171965196538538519701970DDT BannedDDT Banned1972197279179119751975865865198019801,5701,570198519853,7473,747199019905,876 5,876 1995199510,373 10,373 2000200016,678 16,678 20052005BaldEagles(Lower 48) BaldEagles(Lower 48)The boll weevil moved from Mexico to the U.S. and spread rapidly throughout the Cotton Belt. Since, it has cost US cotton producers over $15 billion - from yield losses and costs to control the insect pest.In the first half of the 20th Century, boll weevils routinely killed half of the cotton crop from Texas to Georgia.Following World War II the development DDT enabled U.S. farmers again to grow cotton as an economic crop. DDT was