Political Science 2137 Lecture Notes - Lecture 2: Chlorophyll, Inedia, Boron

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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
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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
--cellular respiration
--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
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
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9. Food chains
--survival depends on chains which extract nutrients and energy: corn--cow--person--
--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
--life also requires: energy, oxygen, carbon and water (the biggies)
10. Soil...the nutrient loop
--overhead on soil--
--our dependence on soil for life is clear: plants get their key nutrients from soil: we get
ours directly or indirectly from plants
--decomposers complete the nutrient loop
--soil: a delicate system subject to a wide variety of insults:
erosion, misuse of fertilizers and pesticides, acid rain, fire
--altered soil chemistry may destroy is biota thereby compromising its capacity to nurture
--"Civilization can survive the exhaustion of oil reserves but not the continuing
wholesale loss of topsoil."
11. Conclusion
--into this complicated natural machinery we have been:
1. introducing in substantial qualities artificial compounds which don't fit into the
life cycle (eg. CFCs); and which
2. may overwhelm (along with natural compounds produced by us) the ability of the life
cycle to continuously restore life.
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