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Ecology and Food CENV 110 Topics • Ecology: what is it? • The difference between ecology and the environment • Elements of ecology • The balance of nature • Food webs: currencies, biomass, energy • Succession • Ecology and Food Youtube video • Ecology - Rules for Living on Earth: Crash Course Biology #40 What is ecology? • It is a process – • The study of the interaction of living organisms with one another and their environment • Ecology is a scientific discipline • Environmental studies is broader – includes hydrology, soils, energy, climate etc. • Environmentalism is a form of activism, seeking to change politics, laws and institutions Related disciplines • Evolution, genetics, physiology, behavior, biogeography, natural history, conservation biology Key questions ecologists ask • What determines the distribution and abundance of species and biodiversity? • The movement of mass and energy through living systems – food webs etc. • Succession of ecosystems • The processes of interaction between species and their environments Ecological concepts • Habitat: the biotic and physical environment • Niche: the specific habitats and biotic requirements of a species • Population: a self sustaining group of individuals from the same species • Community: the combination of species that interact in the same place • Ecosystem: the biotic community and the physical environment • Biome: a distinct group of plants, animals and physical environments that are characterized by the dominant plant forms. For example the boreal forest, the continental shelf • Biosphere: the part of the earth and its atmosphere that are capable of supporting life – the oceans, soil, rivers, lakes, terrestrial habitats and the lower atmosphere Specialties • • • • • Population Ecology: Community Ecology: Evolutionary Ecology Physiological Ecology Behavioral Ecology: Food webs Key concepts: Energy flow • 80-90% of energy is lost as it flows from one trophic level to another, through metabolism of the consumers. Thus the pyramid of energy will narrow rapidly as you move to higher trophic levels. • Top predators will always be rare compared to their prey, which will be rare compared to the food the prey consume. Key concepts biomass • The pyramid of biomass is also unpredictable, since some species at low trophic levels, such as phytoplankton, turn over very rapidly, very high birth and predation rates. • Other long lived low energy species may have high biomass but low energy flow. Food production and food webs • Agriculture has so much impact on ecosystems because we take away the primary producers, thus removing the base of the food web Succession • The sequence of changes to a community following disturbance or colonization that leads to a long term stable community Old Field Succession Receding glaciers Mt. St. Helens Agriculture and succession • Rebuilding ecosystems after agriculture primarily involves letting the process of succession take place • The time it takes to restore the original community depends greatly on the kind of ecosystem – In east coast forests it may be less than 100 years – In west coast rain forest it could be 500+ years Theories of the climax community • Original theory was that there was a single community, the climax, that was resistant to invasion • Later it was recognized that the nature of the climax will differ based on local physical conditions: there is no single climax community • Growing evidence that there may be different climax communities, perhaps due to chance, and that they are not necessarily resistant to invasion Views of ecological stability and the balance of nature • • • • Balance of Nature Randomness: nature as a joker Spatial patterns Multiple Stable states Ecology and food production • Applied ecology: pest control • Applied ecology: fish and wildlife harvesting • Landscape ecology: transformation of ecosystems Pest control • Chemical control is simply blasting crops with pesticides • Biological control is looking at the ecology of the pest Biological control • • • • Introduction of diseases Introduction of predators or parasites Sterile males Integrated pest management – Uses both biological control and other techniques such as chemicals Failures of biological control • Mongoose in Hawaii – Introduced to kill rats, had terrible effect on native birds. Not planned with ecology in mind • Cane toads in Australia – Introduced to control sugar cane beetles – did not control beetles but became major pest eating lots of other things and poisoning animals that eat the toads Key points • Ecology is different from environmental studies and environmentalism. • It seeks to understand the interaction between individuals and their environment • There are a number of central concepts in ecology that are relevant to food production and understanding the impact of food production. Study questions • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Distinguish between ecology, environmental studies and environmentalism. Ecology is a scientific discipline Environmental studies is a broader scientific discipline – includes hydrology, soils, energy, climate etc. Environmentalism is a form of activism, seeking to change politics, laws and institutions What are some of the key questions ecologists ask of nature? What determines the distribution and abundance of species and biodiversity? How does mass and energy move through living systems How do communities change in response to disturbance The processes of interaction between species and their environments What is the biosphere? the part of the earth and its atmosphere that are capable of supporting life – the oceans, soil, rivers, lakes, terrestrial habitats and the lower atmosphere What is a food web? It is a description of the way that mass and energy flow between species in an ecosystem. What is the difference between an autotroph and a heterotrophy? An autotroph produces energy from natural abiotic sources, primarily sunlight. A heterotrophy gets its energy from other individuals through feeding. Why are top predators usually rare? Because energy is lost at each trophic level as you move up the food chain. So by the time you get to the top predators there is much less energy available and smaller populations can be supported. What does the “top” mean in top predator? It refers to the predators being of high trophic level and sitting “on top” of the food chain or the trophic pyramid. Give an example of how there might be few individual autotrophs but many individuals that feed on it. You might have a few large trees in an ecosystem, or you could have many small insects or other herbivores feeding on an individual plant. How does most agriculture affect the food web? It eliminates the plant community and replaces it with species that produce food products. Thus often totally changing the species in the food web. Agriculture also removes much of the primary production for human consumption, leaving less production for higher trophic levels. What species are the first to colonize in the sequence of plant succession that follows a disturbance? Usually they are annual plants with highly dispersive seeds that can land on the disturbed ground. What is “old field succession?” It is the sequence of plant communities that follow the abandonment of a farm field. What is a climax community? The theoretically stable community that is the end product of succession. How does biological control differ from integrated pest management? Biological control refers to using biological agents rather than chemical agents to control pests. Integrated pest management uses a range of tools that may include both biological control and chemicals.