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Lecture 2

lecture 2 principles of ecology: our ecological footprint

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Political Science
Political Science 2137
Ross Gibbons

PS 2235 - Politics of The Environment Lecture #2: Principles of Ecology: Our Ecological Footprint Summary of previous lecture: --politics, the policy agenda and political efficacy --from hunter-gatherers to urban dwellers: the Three Great Transitions --environment, ecology, ecosystem and sustainable development --population growth as a demand on the environment --neoconservatism (PC and Liberals) and the lack of environmental policy --Easter Island: civilization and quality of life depends on a sustainable relationship with the environment 1. Introduction --our resources are finite; our political will is low; yet it is clear that environmental problems must be solved even if solutions require widespread social, economic, political change --in Western philosophy (including religion and political theory) we often place human beings and human societies above and beyond nature (aka the environment) which allows us to exploit and use non-human species as if our existence was not connected to theirs 2. Our Ecological Footprint --the land and water area that would be required to support a defined human population and material standard indefinitely --humanity's continuing dependence on nature...what must be done to support a humane existence for all in the future 3. Principles of Ecology and Ecosystems --1. plants and animals have evolved the ability to deal with the physical conditions to which they are normally exposed, (evolutionary adaptation) --2. many, if not most, individual plants and animals can change their tolerances to physical factors if exposed to gradually changing conditions, (acclimation) --3. there are limits to evolutionary adaptation and acclimation (constraints placed on all organisms by their chemical makeup) --human beings are embedded in and supported by natural ecosystems yet human beings and human systems are rapidly destroying these ecosystems...understanding ecosystems is tantamount to understanding our place in the scheme of things--saving them is saving ourselves 4. LIMITS TO SURVIVAL (why and how we survive) --each of us operates within limits of survival --name some (in various environments) --if it is too cold, hot, dry or wet...death!!! --life in any species is an ongoing multitude of interactions between all organisms and their physical environment --eg. energy is captured from the sun, water flows through land, all plants and animals exchange gases with the atmosphere --conditions vary/change but often change is slow enough to enable adaptation...adaptation is a key process and a form of self-regulation which returns and renews life...this renewal we call the life cycle 5. Key elements/processes in the LIFE CYCLE --photosynthesis --cellular respiration --transpiration --decomposition --the food chain (use overhead) 6. Photosynthesis --plants are able with the help of sunlight to combine carbon dioxide (CO2) and water (H20), both of which have a low energy content into high energy carbohydrates such as sugar, starch and cellulose --light energy is absorbed by green pigments called chlorophyll; oxygen is a by-product of the production of carbohydrates...both plants and animals are able to use the new energy...animals eat plants, or each other, or both...and so energy is passed down the chain 7. Cellular respiration: controlled oxidation...the slow burning of carbohydrates --harnessed by special chemical compounds --results: cells divide; leaves grow; reproduction takes place; muscles flex; everything else happens 8. Photosynthesis: has completely changed the earth's atmosphere--why do visitors to the Moon keep their hats on?--oxygen gradually accumulated over time (more than a billion years) --oxygen is used to produce ozone; ozone enabled us to evolve out of the water --cellular respiration is (roughly) the reverse of photosynthesis --plants (and the rest of us) can't live by photosynthesis alone (breatharians!!!) --the water loss through leaf pores by evaporation is called transpiration or the 'water cost' of photosynthesis...there is enormous movement of water from soil to air by plants: a single corn plant moves about 60 gallons of water in a lifetime 9. Food chains --survival depends on chains which extract nutrients and energy: corn--cow--person-- mosquito--frog--snake--hawk--maggots --the necessities of life include nutrients --nutrients necessary for life include: 1. large amounts of nitrogen, potassium and phosphorus; 2. moderate amounts of calcium, magnesium, sulphur, iron; 3. trace amounts of copper, zinc, boron --sulphur is a key element in all protein; iron is a key element in hemoglobins --plants get their key nutrients from the soil: soil has decomposers (bacteria, fungi, soil insects, worms)...they digest the wastes/dead bodies of other organisms; break down organic molecules and return them to soil of water...the food chain continues -
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