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Unit 1: Studying Earth
Chapter 1: Planet Earth
1.1 Earth Planet of Life
A planet's characteristics are determined chiefly by its
Distance from Sun
The 4 inner planets are largely rock,
the 4 outer planets are gas giants.
The 9th "minor planet", Pluto, is composed largely of rock and ice.
Earth's density, composition and distance (3rd from the sun) make it, "the Goldilocks planet" (Just right):
the only planet with water in all 3 phases: liquid, solid (ice), and gas (water vapor). Liquid water (H2O) is essential to life.
Earth's water stores heat during warm periods, releasing it during cold ones, maintaining a more stable surface temperature than other planets.
Air also stores heat, without this "Greenhouse Effect" our average surface temperature of 14 °C (57 °F)
would be about -18 °C (–0.4 °F).
Mnemonics: a useful study technique
Make up kooky sentences to help recall hard stuff like the order of planets:
My Very Excellent Mom Just Sent Us Nine Pizzas (MVEMJSUNP):
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto
Or, the sequence of taxonomic categories:
King Philip Came On Fast Going Ships (KPCOFGS):
Kingdom, Phylum, Class, Order, Family, Genus, Species
Or, to understand centigrade (°C) temperatures:
"30 is hot, 20 is pleasing, 10 is cold, and 0 is freezing."
(In °F that's: 86, 68, 50, and 32)
FYI, here's how to convert between the 2 systems:
[°F] = [°C] × 9⁄5 + 32 [°C] = ([°F] − 32) × 5⁄9
9/5= 1.8 5/9 = 0.55
29.7 (°C (rounds to 30°))
Back to Chapter 1:
Things that wrap the globe are "...spheres":
Lithosphere: Earth's land — rocks and minerals (nonliving).
Hydrosphere: Earth's water (nonliving).
Atmosphere: Earth's air (nonliving).
Biosphere: All parts of Earth that support and contain life.
If Earth was an apple the biosphere would be thin as the apple's skin, only 20 kilometers (12.4 miles). 1K = 0.6M
Few organisms can withstand the low pressure, lack of oxygen, and cold of high mountains, or the high pressure, darkness, and little food of the ocean's depths.
Ecology: Studies interactions of Earth's living and non-living things.
Ecologists study Earth, home of living things.
Ecosystems: All the factors that are "biotic" (living) and "abiotic" (non-living energy, air, water, & land) in an environment.
Biodiversity: The variety of life in an ecosystem (Bio = life)
Evolution: All life shares a common ancestor over an almost unimaginably vast span of time (Earth is thought to be 4.5 billion years old, with evidence of organic material dating back over 3.5 billion years). Because those individuals best matched to changing environmental conditions are most likely to reproduce, their characteristics shape the population of their place and time.
Electromagnetic spectrum: radiates outward in waves, from Sun, Earth's primary energy source, and from Earth's heated core.
All except the color wavelengths are invisible (from longer to shorter: ROYGBIV:
red, orange, yellow, green, blue, indigo, violet).
Earth's heat primarily is in the (invisible) infrared portion of the electromagnetic spectrum and is emitted to space.
Skin tanning is caused by (invisible) ultraviolet rays from the sun (leads to skin cancer, also can be used to sterilize - kill - bacteria)
High UV index = risky, use high SPF sun block.
Stratospheric ozone protects from deadly UV rays, was being destroyed by human-made "CFCs" (ChloroFluoroCarbons)
once-used as aerosol propellants in spray cans and as refrigerants in air conditioners. Now banned — the great environmental success story of the 1980s!
Chap 1:2 Rock Cycle:
Igneous rock forms when melted rock (magma) cools.
Granite cooled beneath Earth's surface.
Basalt cooled as it rolled out of volcanoes.
Pumice was lava ejected from volcanoes that cooled while
still up in the air (it has so many air spaces it floats).
Sedimentary rock: sediments (tiny rock pieces)
produced by weathering (that breaks rock)
and erosion (that moves the pieces).
Sediments are deposited, pressed and cemented in layers.
Cementing occurs as evaporating water
leaves dissolved minerals behind.
These minerals bind sediments together by
filling the spaces between the pieces.
This is the kind of rock in which fossils may be found.
Limestone (from calcium carbonate shells of ancient sea organisms),
Shale (from mud),
Puddingstone is a conglomerate of cobbles (round stones) trapped in mud.
Metamorphic rock formed from any kind of rock subjected to intense heat and pressure
(though not enough to cause melting).
Marble metamorphosed from limestone.
Slate metamorphosed from shale.
Gneiss (say "nice") is coarse-grained and banded.
Shiny scaly metamorphs are schists.
Fine-grained metamorphs such as slate split (cleave) along parallel layers.
In large exposures, metamorphic rocks may show folds from the
tectonic forces that molded them deep within the earth.
In general, rocks with cemented grains, sometimes in layers, are sedimentary, they may have fossils.
Metamorphic rocks often have bands, are harder than most sedimentary rocks.
Igneous rocks are crystaline without bands or layers.
Any of the 3 kinds of rock can become any of the other kinds.
Nice to know (not on test):
good soil: 25% air, 25% water, 45% rock,
5% decomposing organic material (AKA "humus")
and decomposers* ('It's alive')!
*microscopic fungi and bacteria
Water (H2O) covers over 71% of our planet.
97% is salty (on average 300/00 (parts per thousand))
or 30 grams (g) per liter (L). ~75% sodium chloride (NaCl)
table salt, (remainder: other minerals, including 3% calcium chloride (CaCl2) from which corals, snails, clams, and many
(though not all) shell-forming organisms make their shells).
Less than 3% of the hydrosphere is fresh water. 2% of all fresh water is frozen in polar ice caps and mountain glaciers, now melting because of global warming.
Usable fresh water, available for consumption makes up only 1% in the form of liquid surface water (streams, ponds) and groundwater (aquifer: spaces between rock that hold a water layer).
Deep drilling and high pressure (from mass of rock & water above) brings water up artesian wells.
Many populations (including Stoughton's) have been using the water in their aquifers faster than it can be deposited.
This is called overdraft.
Air: 78% nitrogen, 21% oxygen.
Water vapor, other gases, and dust particles
make up the remaining 1%.
including less than 0.04% carbon dioxide (CO2) from which plants make (photosynthesize) food, adding oxygen to
the atmosphere. CO2 molecules have a vibration frequency (rate) that absorbs the infrared (heat) energy waves that
Earth radiates into space. That's the "greenhouse effect" without which Earth would be a "snowball planet" too cold for life. 200 years of burning "fossil fuels", the deep-buried solar energy collected over millions of years by ancient plants (now carbonized as coal from swamps, oil from ocean plankton) increases the greenhouse effect, making global warming the foremost environmental issue of our time.
Where auroras "Northern Lights" form
Stratosphere (includes ozone layer that
protects us from the Sun's deadly UV radiation)
Troposphere (where weather and life are found)
Earth's atmosphere has 4 layers, know at least the 1st 2 as especially important:
Troposphere, closest to Earth's surface, where weather and life occur. Climate is weather (chiefly temperature and precipitation) averaged over time.
Stratosphere, next highest in altitude, includes ozone (03) molecules (containing 3 oxygen atoms vs. the 2 oxygen atoms of the O2 molecules we can breathe). Although tropospheric (lower altitude) ozone is a dangerous pollutant causing breathing and other health problems, the stratospheric ozone layer is essential to life, protecting all living things from the sun's cancer-causing ultraviolet (UV) radiation.
A major environmental success of the 1980s was the banning of chemicals called chlorofluorocarbons (CFCs) found to be destroying stratospheric ozone, especially over the South polar region (cold accelerates the reaction).
Stopping CFCs will allow the "ozone hole" to eventually repair itself.
Mesophere, Coldest layer, is above the Stratosphere.
Thermosphere (note the "Th" — do not confuse with Troposphere) the Atmosphere's outermost layer.
There, solar energy ionizes gases (knocks off electrons, giving molecules net positive or negative electric charges.
Ions, recombining with "free electrons", give off light, causing auroras (shifting curtains of light that sometimes
cover the polar sky).
For Midyear and Final Exams be sure to know Troposphere and Stratosphere.
Biosphere: All parts of Earth that support and contain life.
If Earth was an apple the biosphere would be thin as the apple's skin, only 20 kilometers (12.4 miles).
From ocean floor to mountain top. Most organisms live between 500m below sea level to 6km above.
Few organisms can withstand the low pressure, lack of oxygen, and cold of high mountains or the high pressure, darkness, and little food of the ocean's depths.
Energy enters biosphere as sunlight, flows through organisms and their environments, eventually flowing out of biosphere as heat (infrared radiation) and is lost to space.
Environmental interaction works both ways: beaver dams change streams into a ponds.
Rainforests create 50% of their own weather. Factory smoke changes the atmosphere.
In class, please Copy Fig.1.1 p.13: How organisms interact w/ each "sphere", list the ways for air, water, ground:
Chapter 2: Nature of Science
Environment: Everything that surrounds an organism (a living thing).
Science: Observation-based way to explain repeatable natural phenomena
Observations lead to hypotheses: possible explanations based on evidence.
If hypotheses have any explanatory power, experiments can be designed that should have predictable, repeatable results.
If not, hypotheses must be changed.
Variable: Any factor affecting experimental outcomes.
Control Group: has all factors present when the original observations were made.
Experimental Group: is the same EXCEPT for 1 thing varied (added or excluded).
The Independent variable affects the dependent variables.
Graphic Representations: pie charts, line and bar graphs.
Biotic Factors: All living parts of an environment.
Abiotic Factors: All nonliving parts of an environment.
Chapter 3: Change in the Biosphere
Deep Time: Since Earth's beggining 4.5 or 4.6 billion years ago, change has been one of its characteristics, but, in a comparatively brief ~100,000 years of human existence, we have caused unusually rapid & far-reaching change. (BTW that's the time span you need to keep in mind because it's in our book but that's just our species, Homo sapiens, another species, H. erectus, dates back nearly 2 million years.)
Lithospheric Change: Plate Tectonics
Tectonic plates: Liquid rock (magma) emerging from below Earth's surface cools to form the hard igneous rock, basalt. spreading ocean floors. The collision between China and the plate on which India and Pakistan are located pushes up the Himalaya Mountains.
Plate Tectonics: Theory unifying the geosciences.
(geo = Earth from Gaia, Greek Earth Mother goddess).
The lithosphere consists of several large moving pieces, or plates, whose boundaries are marked by mountains, earthquakes & volcanoes (where magma emerging, cools into rock). The pressure and frictional heat of tectonic forces cause rock to change (metamorphose) At subduction boundaries, gravity pulls plates back down into the mantle where rock liquifies into magma, completing the rock cycle. Most plates either converge (move together) or diverge (spread apart). At transform boundaries, plates stick, build tension until an abrupt shift (earthquakes where Juan de Fuca and N. American plates meet at California's San Andreas Fault). At convergent subduction boundaries, denser ocean plates dive under less-dense continental plates pushing up mountains. (Nazca plate sinks under South American plate forming the Andes.) At divergent boundaries, molten rock (hot liquid magma) rising from Earth's mantle, spreads and hardens, pushing the African plate away from the South American plate and widening the Atlantic.
Sideview of India crashing into China: http://animations.geol.ucsb.edu/animations/quicktime/IndiaAsiaCollision_fast.mov
I want to learn everything I can (and more than I need to know) about geological forces (plate tectonics, rock cycle, erosion, weathering, ice ages, etc.):
Weathering: Breaks rock by gravity, wind, water, and temperature change (causing repeated expansion (swelling) and contraction (shrinking) that weakens material). The smallest broken rock pieces are called sediments.
Erosion: Carrying away of the sediments by gravity, wind, and water. The erosion caused by flowing water forms the Grand Canyon.
Hydrospheric Change: Ice Ages
Earth's temperature drops if sun is blocked by smoke from major forest fires, volcanic eruptions or collision with large meteors. Ice caps and glaciers grow and sea levels drop (instead of replenishing oceans, precipitation freezes, building up on land). As ice melts, sea level rises. Our most recent ice age ended 10,000-12,000 years ago. Mile-thick ice slowly expanding from the poles pressed down and gouged out the land, caused major weathering and erosion, shaping the land as it took up vast quantities of rock from house-sized boulders (AKA glacial erratics) to the finest rock dust. Tall jagged mountains were worn to rounded nubs. Where melt rate equaled expansion, sand & stone left by the glacier formed Cape Cod. Farmers piled these stones in walls along the boundary lines of their fields. Huge ice chunks deeply buried by insulating dirt, eventually melted, forming round "kettle ponds."
Vicious cycles reinforce Earth's warming and cooling periods: Ice reflects solar heat, the more ice, the colder Earth gets. Dark water absorbs solar heat, the more ice melts, the more dark ocean is exposed and warmed,
making ice melt faster (albedo: reflectivity).
Like Cape Cod and Boston Harbor, our Blue Hills were shaped by the movement of glaciers The advance of glaciers is associated with an overall cooling of Earth's climate. Their retreat is linked to global warming trends. At present rates, Glacier National Park will soon become "The Park that used to be known as Glacier" and the arctic will be ice-free each summer, probably resulting in the extinction of Polar Bears.
Illecillewaet Glacier (Great Glacier) on the Canadian side of Glacier National Park, has retreated over 2000 meters since the photo
on the left was taken circa 1898. <www.nichols.edu/.../glacier/glacier_retreat.htm>
El Nino: Because warm water holds less oxygen than cold water (ever notice the bubbles escaping from a soda after you take it from the refrigerator?) the increased water temperatures associated with El Nino cause fish to die at Christmastime in S. America.
El Nino: Christmastime current of warm, nutrient-poor water flowing southward along the S. American coast, in some years lasting months. New England gets a mild winter, California floods, fish leave S. American waters, fishermen go hungry. (Heat excites molecules driving dissolved oxygen out of water, making it harder for fish to breathe. Similar to carbonated beverages giving off bubbles after being taken from the refrigerator.) Satellite images show that El Nino results from an expanding warm water zone shifting from the western Pacific known as the Southern Oscillation (pendulums swing or oscillate). Increasing frequency and duration of El Nino events seem linked to Global Warming.
Note: As of late summer 2010, we are reported (Boston Globe, 9/10/10) as having entered an El Nina, that portion of the cycle characterized by colder than average waters off the S. American coast. The report suggests an increased hurricane season:
"La Nina is marked by a cooling of the tropical Pacific Ocean and was reported to be developing a month ago. It strengthened throughout August and appears likely to last at least through early next year, NOAA’s Climate Prediction Service said.
“La Nina can contribute to increased Atlantic hurricane activity by decreasing the vertical wind shear over the Caribbean Sea and tropical Atlantic Ocean,’’ the center noted.
Wind shear is a sharp difference in wind speed at different levels in the atmosphere. A strong wind shear reduces hurricanes by breaking up their ability to rise into the air, while less shear means they can climb and strengthen."
Atmospheric Change: Global Warming
Volcanoes formed Earth's early atmosphere of water vapor (H2O), Carbon Dioxide (CO2), nitrogen and sulfur. Photosynthesizers used solar energy to create food from H2O and CO2 releasing the 1st oxygen.
The gases cycle through organisms (living or dead) and back into the Atmosphere. Forming a warming blanket or greenhouse effect. Burning releases stored carbon leading to Global Warming. Volcanic eruptions continue, as ever, to affect climate.
Until photosynthesizing organisms appeared, oxygen was unlikely to have been part of Earth's atmosphere. Coal and petroleum are the fossilized remains of the ancient photosynthisizers that replaced Earth's once-carbon-dioxide-based atmosphere with one remarkably high in the oxygen most present-day organisms require for survival. By burning these fossil fuels, humans are returning carbon dioxide to Earth's atmosphere — the very gas that contributes most to the greenhouse effect.
3.2: Needs of Organisms
Even organisms that can live without oxygen must have water to survive, making that the most important requirement for all living things. Nutrients are also required for survival. They (a) provide energy, (b) build tissues and (c) aid biochemical reactions.
In addition to food and water, Animals need territory to provide them with shelter.
Some plant seeds live through cold winters but do not sprout until spring. In winter these seeds are dormant.
Hibernation is a special form of dormancy in mammals characterized by (a) slow breathing, (b) low body temperature, and a (c) slow heart rate. It is surprisingly rare among New England mammals, it includes bears, bats, and a small number of rodents, not including squirrels.
Only the members of a given species can produce fertile offspring.
Nutrients: Substances an organism requires from food.
Territory: Living space claimed by an animal or group of animals.
Dormancy: An adaptive slowing of life processes for temporary periods when needs cannot be met but life continues.
A seed is alive, but dormant, so are deciduous trees like, Oaks and Maples, in winter, when light is reduced and the water they need is frozen, unavailable.
Hibernation: A sleep-like form of dormancy found in some mammals, allows survival when food is seasonally unavailable. Energy requirements drop as body temperature lowers, breathing and heart rate slow.
Species: Group of organisms similar enough that they can breed producing fertile offspring.
Habitat: The specific environment in which a particular species lives.
Geographic Range: The TOTAL area that contains habitats in which a species can live (geographical range may include some areas within that range that are not suitable habitat for a species and habitat destruction can reduce a
species' geographical range).
Population: All members of a species living in same area.
Community: All the different populations living and interacting in an area. Communities HAVE populations.
Several different species populations live IN community. Example: zebras, elephants, and giraffes.
Ecosystem: All the biotic and abiotic factors interacting in an area.
A population of giraffes
A community of populations including
trees, grasses, elephants, zebras,
An ecosystem that includes the biotic community
well as the abiotic factors of land, air and water
The biodiversity of an ecosystem is measured by the number of species it contains. All organisms obtain food, shelter, and other resources from their habitat. The mass extinction of species today most often results from habitat destruction caused by attempting to meet the needs of our growing human population. This puts us in direct competition with the biosphere
that makes life possible in the first place. Since good planets are hard to find, we must to learn to take
the best possible care of this one.
Unit 2: Ecological Interactions
Evolution is supported by these key concepts:
Species: able to produce fertile offspring
Speciation: the forming of new species increases biodiversity over time.
Natural selection: advantages favoring individual survival -->favor reproduction --> shaping population as traits increase/decrease based on who gets to reproduce.
Fossils: evidence form/structure change over time measured by the sediment layer found in. Structure means body parts. Form means the shape of those parts as well as the body’s shape overall
Comparative anatomy: measures differences (variations) among species of shared common ancestry.
Molecular clock: the rate of change can be timed by the predictably regular, random genetic mutation or "drift" observable in DNA sequences among species of shared common ancestry. Newer species are expected to show fewer of these mutations, older species to have accumulated more of them.
Chapter 4 Matter and Energy in the Ecosystem
4.1 Roles of Living Things
Producers use abiotic factors (water, air, minerals) to make food. Plants, algae and cyanobacteria
photosynthesize using solar energy, extremophiles are bacteria that use energy stored in inorganic molecules at hot springs or thermal vents on the ocean floor. Examples are anerobes (primitive bacteria for whom oxygen is a deadly poison) giving off hydrogen sulfide (the smell of rotten eggs) as a waste product.
(Know that in science "organic" means carbon-based).
Consumers cannot make their own food. Include animals, fungi, protists (simple eukaryotes) and bacteria (prokaryotes).
Herbivores are plant eaters and are primary consumers.
Carnivores eat other consumers.
Carnivores that eat plant eaters are secondary consumers. Carnivores that eat meat eaters are tertiary consumers.
Omnivores eat both plants and other consumers (meat). Depending on what they eat they can act as primary, secondary or tertiary consumers.
Scavengers usually do not eat living prey. Like omnivores, scavengers can act as primary, secondary or tertiary consumers.
Detritivores eat detritus: decomposing organic matter. Worms and many other organisms living in soil or near the bottom of aquatic ecosystems are detritivores. Scavengers and detritivores start the process of returning dead bodies to the environment.
Decomposers are bacteria and fungi that recycle nutrients from organisms back into the environment. Without decomposers, the producers (such as plants and algae) would quickly run out of nutrients. Decomposers complete the cycle of matter in ecosystems.
4.2 Trophic Levels:
Producers are the 1st and largest trophic level because they make their own food they are known as autotrophs (means "self-feeding").
Consumers form the 2nd and higher levels. Because they gain their energy by eating other organisms we call them heterotrophs (means "feeding-on others"). Primary consumers (plant eaters) form the 2nd trophic level, secondary consumers form the 3rd trophic level and tertiary or higher order consumers form the 4th and higher trophic level(s). The 3 types that may feed at all but the 1st level are omnivores, scavengers, and decomposers. Each level depends on the level below.
Be careful: tricky test questions may ask you to know the difference between trophic levels 1-4 (starting with producers at level 1) and consumer levels 1-4 (starting with herbivores at 1°). Draw the triangle:
5 Quartenary (4°) Consumers
4 Tertiary (3°) Consumers
3 Secondary (2°) Consumers
2 Primary (1°) Consumers
Note that higher levels (than quartenary) are possible but rare.
Because energy transfer decreases by at least 90% with each upward step (herbivores gain 10% or less of the plants' energy, etc.), few ecosystems exceed 4 trophic levels, producer biomass (mass of living organisms) is vastly greater than primary consumer (herbivore) biomass and top-level carnivores tend to have low population densities and require large territories. Some interesting exceptions include marine (ocean) ecosystems, and the omnivorous human being who, in most parts of the world is primarily herbivorous and relies on technology to maintain a high population density rivaled (among large mammals) only by the krill-eating seals of Antarctica.
4.3 Ecosystem Structure AKA Food Webs:
The important thing in reading food webs is that arrows point from energy sources (food) -> to who gets that energy (consumers). Google Images "Food Webs" and try to figure out which organisms are herbivores (1° primary consumers) directly receiving their energy from producers. Look at consumer levels: How many steps are there between the top-level carnivore-of-carnivores and the herbivores? Remember to check all possible arrow pathways. If there were 3 consumer levels the carnivore would be a tertiary (3°) consumer. If there were 4 levels then the carnivore would be a quaternary (4°) consumer: 1 producer -> 2 herbivore -> 3 carnivore -> 4 carnivore -> 5 carnivore. Which organisms are autotrophs (producers)? Which are heterotrophs (consumers)? Are the decomposers (bacteria and fungi) represented? Many are invisible, they feed at all levels, and are sometimes not shown or shown bracketing all other organisms.
The difference between food chains and food webs is that food chains show 1 series of transfers between trophic levels while food webs show a network of chains with multiple feeding choices (several organisms may depend on the same food source, or one organism may have several organisms to choose from).
Which provides greater chances for survival (flexibility, ecosystem stability) in the event that a food source is removed from the ecosystem, food chain or food web?
Food web questions often ask how the rise or fall of one species will effect the populations of other species that it competes with, feeds on or that depend on it for their food. Many scientists think that high biodiversity equates with ecosystem stability.
Interesting points to ponder: Polar (Arctic/Antarctic) and temperate zone ecosystems tend to have low biodiversity (fewer species) but each species may have large populations (many individuals). Tropical ecosystems (rain forests, coral reefs) tend to have high biodiversity (many species) but intense competition results in these species having small populations (fewer individuals of each species). The near-extinction of Antarctic whales caused by 20th century whaling led to booming populations of krill-eating squid, fish, penguins and seals (p58, Fig.4.6). But will our new krill fishery lead to the crash of fish, squid, penguin and seal populations? How may that effect the region's tertiary (3°), or even quaternary (4°) level consumers such as the toothed whales (orcas, sperm whales)?
Biological magnification is the increasing concentration of fat-soluable pollutants in organisms at higher trophic levels in a food web (water-soluable pollutants tend to be excreted as urine). The rapid reproduction rate and short life spans of organisms low on the food web make them more resiliant (able to adapt) to pollutants and pesticides. Their populations rapidly shift in favor of individuals able to reproduce in spite of the poisons. The traits of those who die before reproducing are removed from the population. In spite of spraying we will never get rid of mosquitos. In spite of antibiotics, we will never eliminate bacteria. During relatively long lifetimes, large top-level carnivores such as tuna, swordfish, whales and humans tend to accummulate the poisons ingested by each individual organism they eat and pass these poisons on to our offspring. This is why I never saw hawks or eagles during my childhood. It took laws and many years before enough of the pesticides were eliminated from our environment for raptor populations to recover. This is yet another environmental success story that has resulted from people trying hard to make the world a better place than we found it. The harder we try the smarter we get.
4.3 Ecological Pyramids
Chemistry of Life
We will spend at least 1 week on this material (which is not in our text) before continuing with 4.4 below.
Chapter 4.4 Cycles
Recognize that CHNOPS refers to 6 elements most commonly found in organisms (P refers to Phosphorous, S to Sulfur). 96% of your body is made from just 4 of these:
Carbon, in the form of CO2, makes up less than 0.04% of Earth's atmosphere but Carbon makes up 18.5% of human body weight. In science, the term "organic" means carbon-based. Other elements readily bond with Carbon, making it the element most essential to life.
Hydrogen, primarily found in Earth's atmosphere as part of H2O (water), makes up 9.5% of your body. Nitrogen, as N2, makes up 78% of Earth's atmosphere but this form is not easily combined with other elements because N2 is triple bonded together. Nitrogen makes up 3.5% of the human body in the form of proteins, and, as the nucleic acids RNA and DNA.
Oxygen makes up the majority (65%) of your body and 21% of Earth's atmosphere. It is the product of photosynthesis and is used in respiration to release the energy chemically stored in foods.
The Water Cycle purifies Earth's water through evaporation. Transpiration is evaporation from the leaves of plants, the mechanism that draws water up from the roots. As water vapor (an invisible gas) rises, the temperature and pressure of the surrounding atmosphere decrease until the vapor condenses (forms microscopic droplets we perceive as clouds). Water returns to Earth as precipitation.
The main thing to keep in mind about the carbon cycle is the role of the photosynthesizers. that convert CO2 into sugars such as glucose: C6H12O6 (carbohydrates).
Key terms to be sure of for water cycle include transpiration (evaporation of the invisible gas, water vapor, from plants' leaves) condensation, the formation of tiny droplets by changes in temperature and/or pressure, and precipitation, when droplets' size grows to the point where gravity causes their fall.
The nitrogen cycle is complex but you'll be OK if you keep in mind the key word legumes, plants that host the nitrogen-fixing bacteria that make nitrogen compounds available to all other organisms. (These nitrogen compounds are essential for building proteins and nucleic acids (DNA, RNA) and the bacteria that fix atmospheric nitrogen live in legumes' roots). Legumes include beans, clover and alfalfa. Farmers can plant legumes in crop rotation to reduce their dependence on synthetic nitrogen-based fertilizers. Excess fertilizer (nutrient) runoff pollutes water leading to reduced oxygen levels (eutrophication).
Chapter 5: Ecosystem Interactions
5.1 Habitats and Niches
The location of an organism within its ecosystem is called its habitat. The role of an organism (what it does) within its ecosystem is called its niche. While, in theory, an organism might be able to have a large, or, fundamental niche, the actual role of an organism in the environment (its realized niche) is usually reduced by competition with other species. The disappearance of one population due to the direct competition with another species for resources is called competitive exclusion. As a rule, no 2 species may occupy an identical niche at the same time and place.
5.2 Evolution and Adaptation
A species fits into its niche because of evolution, change in a population's characteristics over time. Charles Darwin theorized that evolution occurred through the process of natural selection powered by random individual variation. Individuals having favorable ("adaptive") traits are likely to dominate the population, while unfavorable traits are likely to die off. Divergent evolution causes populations to be adapted to specific niches, reducing competition with other species. Each species uses a different part of its ecosystem. Highly specialized species depend on specific food and habitat such as the the bamboo-eating panda bear and the Eucalyptus-eating Koala. Generalist species usually are less vulnerable to niche-eliminating habitat change and include humans, cockroaches and mice able to survive by changing their behaviors to fit new conditions.
Though similar ecosystems may be widely separated by time or space, similar environmental pressures select for similar adaptations in different organisms. When different organisms that occupy similar niches share similar adaptations this is called convergent evolution. Examples include birds and bats (both have wings) as well as top-level marine carnivores such as ichthyosaurs (extinct ancient marine reptiles), sharks, and dolphins.
Other species are an important part of an organism's environment. When two species interact so closely that they are adapted to each other, the interaction is called co-evolution. Examples include animals that help to either pollinate or spread the seeds of the plants on which they feed.
A non-native organism that is introduced into an existing ecosystem is known as an alien species. Humans, accidentally or on purpose, are the leading cause of species introductions. Invasive alien species are those that outcompete native species by taking advantage of the resources of their new ecosystem and the absence of factors (such as predators, climate and disease) that limited their population growth in their old ecosystem.
offspring than can survive. Darwin recognized that this
leads to competition for resources favoring selection
of those most favorably adapted to env. conditions.
Population growth curves in which each generation is a
multiple of the previous generation are examples of
exponential growth. If limits such as predation, disease
or food supply are no longer an issue, population grows
exponentially because more are born than can usually
survive to ensure survival by a few. This has been the recent
situation for the human species. At what point is this imbalance
between births and deaths no longer sustainable?
Do we reduce the number of births or does the number of deaths catastrophically increase?
In these questions, our species has more choice than any living beings that have ever previously existed.
food, living space and other factors limit population growth
leading to S-shaped curves: early growth is exponential but
eventually births equal deaths, and growth reaches zero at
the ecosystem's carrying capacity for a species, the
maximum number surviving to reproduce.
Population growth is limited by density-dependent limiting factors
such as predation, parasitism, disease, and competition for food,
water and living space as well as by density- independent limiting
factors such as climate, human disturbance and such natural disasters
as earthquakes and floods that affect populations regardless of size.
Study the diagram (p.82) and know the difference between the
density-dependent and density-independent limiting factors:
- populations controlled by density independent limiting factors follow boom and bust cycles.
factors that are favorable, such as seasonal
temperature and rainfall, dieing-off when the
season passes to return at the same time next year.
Advances in technologies such as agriculture, energy development,
electronics, transportation, finance, and medicine have allowed
humans a recent period of exponential population growth in which
our species has covered the Earth while many other organisms
have declined. As resources become fully utilized we face the
challenge of deciding whether our impact on the biosphere will be
limited voluntarily, through education and careful planning, or as the
result of such disastrous changes to the planetary systems we depend
on that our way of life can no longer be supported.
Chapter 6 Ecosystem Balance
6.1 Ecosystem Relationships
Predator-prey relationships seldom result in extinctions. The hunter and the hunted control each other's populations. Keystone predators promote niche diversity in their habitat by preventing their prey from outcompeting other organisms. When prey populations rise predator populations also rise (preventing their prey's starvation from over-grazing), and when hunting causes the fall of prey populations the predators' populations also fall. Other Symbioses (close, co-evolved relationships between organisms) include parasitism, in which one organism feeds on the tissues or body fluids of another, injuring and possibly killing the host organism, commensalism, which benefits one species and neither helps or harms the other and mutualism in which both species benefit.
6.2 Ecological Succession
Primary succession is the sequence of communities forming in an originally lifeless habitat. Lichens (an example of a symbiotic relationship between
an algae and a fungus) are the classic "pioneer organism", usually first to grow on rock, able to make soil by secreting acids that cause rocks to weather.
Secondary succession is the sequence of communities where a disturbance eliminates most organisms except the soil, usually due to fires, storms, and human activity.
- Increasing nutrient demands
- Longer life cycles
- Photosynthetic competition (shades out the lower plants) and
- deeper root systems able to capture a greater share of the ecosystem's water resource
Aquatic succession is the sequence of communities forming in a pond as aquatic plants decompose adding nutrient-rich sediments until eventually pond becomes marsh, marsh becomes meadow and meadow becomes forest.
[Volcanic] island succession depends on rare colonizations by mainland organisms. Geographical isolation offers many empty niches to those species able to find mates. Limited gene pool and inbreeding all promote speciation from a common ancestor. In this way, the offspring of a few ancestors can rapidly evolve into new species, each uniquely adapted to a specific role. The classic example, Darwin's finches, are birds similar to the mainland finches of South America but, adapted to the varying physical conditions and food resources of several different niches on the Galapagos Islands. Some developed heavier bills for crushing hard seeds, others developed longer bills for taking insects from holes. One type even acquired the behavior of breaking off cactus spines to use as a tool for extracting insect larvae from holes in plants. As environmental conditions change some traits increase the probability of individuals surviving to reproduce. Those traits increasingly characterize the population while other less-favored traits decrease. As a result of the differential survival rates, new species form with behavioral and physical characteristics best suited to the local environment (and different from related species best suited for conditions of other environments). This is known as the evolution of species by means of natural selection. For example, in periods of drought-induced food scarcity, competition for niches intensifies. The ability to crack harder seeds or catch more difficult-to-reach insects makes the difference between life and death for a bird. On average, this leads to smaller populations specialized for heavier bills among birds that eat seeds and nuts and longer probing bills for birds that eat insects. When environmental conditions improve ("the living is easy"), a wider variety of foods become abundantly available and "regression to the mean" (a more-generalized bird) may become the norm as populations (and genetic diversity) increase.
As you compare these birds, what beak variations do you see? How do you think this relates to each bird's environmental conditions?
6.3 Ecosystem Stability
How easily is an ecosystem affected by a disturbance? Can it return to its original state? How quickly does it reach some sort of adaptive equilibrium? Biotic and abiotic factors, energy and nutrient flow, and community structure all play a part. Like falling dominoes, changes in one part may have unforeseen consequences to the whole. Chaos theory explores this sensitivity to small changes and the idea that initial states are crucial to later developments. Biodiversity and greater food web connections may increase resilience (the ability to bounce back from a hit). Species and whole ecosystems may evolve then die but new species and ecosystems can evolve to replace them. The growth of human populations is widely believed to be causing the greatest mass extinction since the dinosaurs. The main problems are habitat destruction, introduced invasive alien species, damage to water resources, and, emission of the greenhouse gases that cause global warming. The concern: How will our disruption of the biosphere affect its ability to support human life?
Unit 3: Biomes
6.4 Intro to Terrestrial Biomes
Biome: a major ecosystem type with distinctive temperature, rainfall, and organisms.
Biomes are characteristically graphed by precipitation and temperature (and see text, p100):
Image source: http://www.globalchange.umich.edu/globalchange2/current/2007/Labs/Unit%203b2007.htm
I highly recommend playing with the on-line climographs at http://www.uwmc.uwc.edu/geography/100/koppen_web/koppen_map.htm
To learn more, the map originates from http://www.uwmc.uwc.edu/geography/100/climlab.htm
An on-line college biome unit is available at http://www.runet.edu/~swoodwar/CLASSES/GEOG235/biomes/intro.html
Note that these courses use the "Koppen" climate classification system codes:
BWh and BWk: Desert
Dfc, Dfd, and Dwd: Northern Coniferous (aka Boreal, Taiga) Forest
Dfa, Cfa, and--in Europe, Cfb: Deciduous Forest
Af and Am: Rain Forest
All categories are theoretical constructs devised by people with different viewpoints.
This explains the differences between biome maps from various sources.
Note too, that as climate and other human and natural impacts alter the biosphere,
these regions can be expected to shift as they always have for as long as life has existed.
BTW: if you want to do conversions yourself the formulas are:
[in] =[cm]/2.54 [cm] =[in]*2.54
[°F] = [°C] × 1.8 + 32 [°C] = ([°F] − 32) × 5⁄9To understand centigrade (°C) temperatures remember:
"30 is hot, 20 is pleasing, 10 is cold, and 0 is freezing."
(in °F that's: 86, 68, 50, and 32)
Quiz yourself by printing the following table and folding over either the left, center or right columns.
Comparing to the triangle graph, what ranges do the following numbers approximate?
Climate = weather averaged over time
Coniferous = having seed cones ( pines, cedars, firs, spruces, hemlocks, redwoods are all conifers)
Deciduous = dropping leaves (oaks, maples, birches, beech, chestnuts, elms are all deciduous trees)
Evergreen = keeping leaves/needles (tropical species include mahogany, ebony, cypress, balsa, teak)
Grasslands = fire-adapted plants re-grow from roots
Pavement = hard layer (high runoff and evaporation rate)
Permafrost = always frozen (a narrow "active layer" thaws during a brief growing season of long days)
Savanna = grassland with some trees, annual brief intense rainy season followed by long dry season
Steppe = (say "Step") Semi-arid grassland
Shrubland = affected by cool ocean currents, fire-adapted plants (seeds may require fire exposure to germinate, shrubs and herbs may have fragrant, flammable oils, evergreen leathery leaves). California and the Mediterranean countries have this type of climate.
Chapter 7: Deserts and Tundra
Deserts: 30% of Earth's land, 1% Earth's biomass
Tundra: 10% of Earth's land
How deserts and tundra form:
Deserts located chiefly between 23° and 30°, tundra at 60° because:
1. warm, moist air rises outward from equatorial oceans, forming tropical rain forests on land
2. dried and cooled the air now descends (making desert) at the Tropics of Cancer (23°N) and Capricorn (23°S) evaporating any moisture from those lands
3. (leaving the desert behind, the warm, humid air rises) temperate zones receive this moisture as precipitation,
4. dry air descends, forming tundra at 60°.
Deserts also formed by Desertification: An area the size of the state of the state of Maine is turned into desert every year by people overgrazing livestock on semiarid (sort of dry) grasslands next to deserts:
overgrazing livestock depletes vegetation and compacts soil ("pavement" decreases soil's ability to absorb precipitation, increases evaporation, runoff, and erosion) = desert
Low precipitation so
" water movement thru soil (aka leaching)
" organic matter in soil (too dry, too little biomass for decomposers)
High elevations and latitudes form cool deserts (Gobi in Mongolia is freezing).
" water runoff because of hard pavement that is exposed by wind erosion of the loose, mineral-rich, upper layer (sand storms, hills called "sand dunes"),
Dry (air) = extreme temperature swings day (hot) vs. night (cold). Why: moisture moderates temperatures, no moisture, nothing to slow temperature changes.
Low precipitation. Permafrost (lower layer always frozen) vs "active layer" (that thaws during summer).
Biotic Characteristics (adaptations can be behavioral and/or physical)
Plants: Cacti leaves are spines, minimize evaporative surface area (H2O loss) and protect from animals. Succulent "juicy" tissues store H2O. Plants either have spreading shallow root systems or deep "tap roots" that punch through pavement tapping aquifer
Many desert animals are nocturnal (night active), spend days underground to avoid heat. Insects and reptiles have scaly body coverings that hold in H2O and protect.
Low, shallow-rooted plants rapidly grow and set seed during brief summer.
Many ponds (breed mosquitoes).
Many animals migrate includes ground-nesting birds that find berries, insects, and few predators during breeding season.
Caribou (reindeer) migrate to avoid overgrazing.
Chapter 8: Grasslands
Grasslands, 3 main types, 2 of them temperate (having seasonal temperature variation):
Steppe: semiarid (not as dry as desert) annual precipitation: desert < 25cm, steppe > 25cm.
high evaporation rate, windy, extreme temperature variations (-5°-30°C)
Prairie: 50cm annual precipitation (hot dry summers, rainy season, sometimes floods)
Savanna: tropical/subtropical (temperature stays warm year-around), marked by alternating
dry and rainy seasons (a long, hot 9 month drought and a short, intense period of up to 125cm precipitation).
Grasslands maintained between deserts and forests in location and precipitation.
Desert-grassland boundary shifts with climate/precipitation changes.
Biotic Characteristics (adaptations can be behavioral and/or physical)
Grasses: world's most common flowering plant (includes bamboo, marsh reeds, rice, wheat and corn)
Well-adapted (biomass mostly below ground in roots) to survive grazing animals, drought and
natural fires that limit woody plants (competitors — mass mostly aboveground).
Fire promotes seed germination, converts dead plant matter to fertilizer.
Trees and shrubs, rare in grasslands, must be drought- and fire-resistant to survive.
Animals migrate, hibernate, burrow, to cope with seasonal climate extremes.
Steppe (say "step"): short grasses (leaves are fine "blades") minimize evaporation,
shallow-rooted "bunchgrass" clumps hold water in small grass-shaded area.
Biodiversity lower than other grasslands (water the density-dependent population limiting factor).
Considered by some to be a type of desert, also known in America as short-grass prairie,
located east of rain shadow-caused high deserts.
Prairie: sod-forming grasses (lawn-like root mats) hold moisture, resist erosion.
Soil organisms and burrowers create air spaces (aerate) soil so nutrients, water,
and oxygen reach grassroots more quickly. Wind-dispersed seeds.
Soils rich in decomposed organic matter = humus.
Animals include bison, deer, antelope, ferrets, fox, coyote, snakes, hawks, wolves,
grizzly bears, grasshoppers, mice, birds, prairie dogs, gophers, and other ground squirrels.
Large animals displaced by domesticated livestock (cattle, etc.). Biodiversity reduced by
human needs for food and space — grain crops have turned prairies into the
"breadbaskets of the world."
Savanna: tropical/subtropical grasslands ranging to scrublands, open woodland.
Plants: horizontal runners (stems) and rhizomes (roots) for rapid rainy season growth,
tufts/clumps resist uprooting, sharp leaves, thorns protect woody plants.
Animals: migrate, vertical feeding patterns (different species graze different parts
of plants) to minimize competition, overgrazing. Traditional human societies were nomadic.
Camouflage tends to lighter colors in dry biomes, darker in more humid biomes.
Environmental Issues: desertification ("dust bowl"), high natural biodiversity displaced by
human monoculture of a small number of commercially important plant and animal species,
habitat destruction disrupts migratory routes.
Chapter 9: Forests (Humid) Terrestrial Biomes
Humidity minimizes day/night temperature swings, precipitation higher, more regular throughout year than most other biomes (but dry tropical forest has wet/dry seasons)
Northern Coniferous Forest "Taiga", "Boreal Forest": Subarctic Asia, Europe, America.
Limiting factors: short growing season, long, cold, dry winter, annual avg. temp 0°C, annual avg. precipitation: 40-200cm. Decomposition slow, soils nutrient-poor, acidic, drainage poor (pools water).
Snow insulates, prevents permafrost, protects roots, small animals.
timber and to access minerals (Canadian tar sands bituminous petroleum, ~10% of our total
imported fuel, gold, copper..., all through massively polluting forms of resource extraction).
Northern Hemisphere (Europe, Asia, Eastern USA)
Limiting factors: 6-month growing season, wide seasonal temp. variation (-30°-30°C), precipitation: 50-300cm.
Decomposition of leaf litter in summer is rapid, thick humus is important invertebrate & fungi habitat, rich soil has optimal water holding capacity. Valued for furniture-making, Maple, Birch, Oak and Beech are well-known examples:
Tropical Rain Forest:
Equatorial, steady warmth (25°C) continuous growing season, high annual precipitation.(200-450cm) promotes growth of insects, bacteria, fungi.
Limiting factors: High moisture causes rapid decomposition & nutrient recycling, most nutrients exist in living organisms, leaving soils poor, little light penetrates canopy.
image of tropical rain forest soil.
Temperate rain forest (Northern Pacific Coast of USA and Canada, also New Zealand, Chile) has seasonal temperature changes (tall, ancient, coniferous evergreens):
Conifers: have seed cones (are gymnosperms, the most ancient tree form), leaves are evergreen resinous needles with waxy coatings (shed snow, conserve water, protect from animals). Some species are the most ancient large organisms, 1000s of years old.
Taiga biodiversity low, but populations high: contains 1/3rd of Earth's trees (mainly spruce, conifers found elsewhere include pine, fir, hemlock, cedar), forest floor has ferns, lichens, sphagnum moss
Deciduous trees: flower (are angiosperms, more recently evolved, have displaced gymnosperms from most niches) have fruiting bodies (nuts, acorns are "mast"), broad leaves maximize photosynthesis, leaves fall (to protect branches from breaking under weight of snow and ice and conserve water that is unavailable (frozen) in winter). Forests are divided into layers: Emergent trees rise above the canopy where most trees have their crowns. Understory has woody shrubs and saplings (young trees). Herbaceous stratum (forest floor) is home to shade tolerant herbs (small non-woody plants adapted to die back each winter and regrow in the spring).
Biodiversity moderate, 3 layers (strata): canopy (tree species include maple, oak, beech, ash, hickory, birch), understory (young trees, shrubs), herbaceous stratum (herbs and ferns die back in winter, annuals re-grow from seed, perennials from root).
Tropical dry forest deciduous trees drop leaves in dry season, re-leaf in rainy season.
Tropical rain forest trees: evergreen broad leaf have pointed "drip tip", coatings, (to resist rot). Spreading buttress roots (prevent tipping, take advantage of thin soils). Lianas (vines) climb trees to reach light with minimal biomass, epiphytes (orchids, bromeliads) grow without soil on trees, absorbing airborne nutrients/moisture.
Biodiversity high but populations low: 6% Earth's land area holds 50% Earth's biomass, up to 70% Earth's species, 4 layers: tallest trees are emergent (from) dense high (50-60m) canopy that captures 99% of light (includes cypress, balsa, teak, mahogany, ironwood). Other species must survive low light, limited nutrients of lower canopy and understory. Few plants can survive low light, poor soils of forest floor.
In all forest types, tree fall clearings provide opportunities for new growth but large-scale "clear cuts" disrupt ecosystem integrity.
Temperate forest species: cold-adapted, burrow, hibernate, migrate to meet food/reproductive needs
Taiga herbivores include: small seed-eating rodents & birds, large browsers: moose, elk, beaver, snowshoe hare; carnivores: ravens, owl, bear, wolf, lynx, wolverine
Deciduous forest species include: insects, amphibians, reptiles, rodents, & other small mammals, deer; carnivores: fox, wolves, birds of prey
Rain forest species: arboreal (tree-dwelling) with high biodiversity in vertical niches, complex relationships and specialist pollinators (insect, bat, bird), large ground herbivores include tapir, okapi, canopy species (sloth, monkey, parrot, toucan); carnivores: margay (& other cats), snake, eagle.
Migratory birds are common to all forests, an adaptation to overwhelm/minimize exposure to predators, optimize access to seasonally available food sources and breeding territories. Many birds are present in all forests year around, in cold biomes this depends on continuing access to high energy seed and berry foods. In cold biomes insect populations follow boom and bust cycles. Large herbivore wastes promote insect population growth supporting amphibians and reptiles (salamanders, toads, snakes).
Key Environmental Issues:
Deforestation, a form of habitat destruction resulting from human need for wood and living space. Conifers (softwood) for paper and lumber. Rain forests for fast-growing monoculture of oil palm, rubber tree, coffee, soy bean; ranching, petroleum and mineral extraction. European and Eastern N. American deciduous forest (hardwood) for farms, orchards, urban development, wood used for fuel, flooring and furniture. New and increasing threats: climate change, invasive alien species. Biodiversity loss increases vulnerability to disease, parasitism and pollution. Regeneration depends on in-migration or adaptation by new species to available niches, is slowed by loss of forest-dependent species and their relationships. Rain forest loss: 50% in past 50 years, from more than 10% to less than 6% of Earth's land surface area, a rate that continues accelerating.
I've created biome graphic organizers for this entire unit. Use the notes above to fill in the graphic organizers to help you study Grassands and Forests. The rest (Dry Biomes, Aquatic and Marine) I've already done for you.
Chapter 10: Aquatic (Freshwater) Biome
Usable freshwater, available for consumption makes up approximately 1% of the hydrosphere. Two main kinds:
A) Standing Water Ecosystems include shallow ponds and deep lakes, wetlands (grassy marshes, shrub and tree-filled swamps, acidic bogs with cranberries, carnivorous plants and sphagnum moss). Wetlands are highly vulnerable to habitat destruction by expanding human population. Wetlands are valuable as sponges absorbing floods, filters of pollutants and excess nutrients, and nursery habitat for wildlife.
B) Flowing Water Ecosystems have a downhill flow caused by gravity and include rills (p327), brooks, streams, creeks and rivers. They are vulnerable to stream diversion to meet human energy and water resource needs.
Estuary: (plural: estuaries) where river meets ocean (brackish=mix of fresh and salt water) saltiness (salinity) varies (and see Chap 11).
Salinity, depth, flow rate, dissolved oxygen are the determining factors for types of organisms in aquatic biomes.
Salinity: Aquatic biomes are divided into two main groups (fresh and salt) based on the amount of dissolved minerals in the water. The average salinity of fresh water is 0.5‰ (parts per thousand (ppt), not to be confused with parts per hundred, or %) , ocean salinity is ~30‰ (depending on freshwater input vs. evaporation -- so lower in estuaries, higher in tropics).
Depth determines amount of light (photic zone) the deeper the darker (aphotic zone). Underwater plants are ONLY found in the photic zone
Flow Rate: water, moving or still
Dissolved Oxygen: determined by temperature (warm or cool, liquid or frozen). Cold water holds more oxygen than warm water. Water freezes from the top down, is often still liquid under ice (because ice, less dense, floats).
Benthic: bottom of a body of water
Sediment deposition (gravity-caused settling and accumulation of particles from erosion and weathering).
Turbidity: the effect of suspended sediments reducing water clarity.
Plankton- drifters cannot swim against currents.
Phytoplankton (Phyto=plant) The most important producers in AQUATIC ecosystems, need to be able to stay in the light, with nutrients, the limiting factors.
Zooplankton (Zoo=animal) consumers, feed on phytoplankton or on other zooplankton.
Most marine animals breath oxygen dissolved in water. Marine mammals surface for air.
Detritus = tiny pieces of decomposing organic material, food web base eaten by Detritivores. Many benthic animals depend on this food source (p170).
Stream-dwelling organisms are adapted to flow rate.
Chapter 11: Marine (Saltwater) Biome
Oceanic Zone: Largest zone (90%. of ocean) from 200M (edge of continental shelf, the shallow border area surrounding major land masses) to 11,000M benthic zone (abyss).
Neritic Zone: "Near" Low tide mark to continental shelf edge includes estuaries (where rivers meet ocean). Neritic Zone more productive (has more photosynthesizers) than oceanic zone as benthic zone is photic. Tropical coral reefs have very high biodiversity, productivity, and biomass, but high species competition for niches and food results in low species populations (make this ecosystem highly vulnerable to habitat destruction). Over long periods of time, corals build vast calcium carbonate (limestone) structures called reefs. Corals are simple animals living in colonies in symbiotic mutualism with photosynthesizing algae called zooxanthellae that live within their tissue. These algae provide corals with carbohydrates in exchange for nutrients (the corals' wastes) and shelter. With most nutrients locked up in living organisms, like rain forest soils, rapid nutrient cycling makes reef waters nutrient-poor. "Seaweed" (algae) Kelp beds are a cold water counterpart to coral reefs in terms of high biodiversity.
Intertidal Zone: Area alternately exposed and submerged by tides, vulnerable to coastal development, important buffer zone, protects nearby lands from tsunamis & storms.
Estuaries (where fresh & salt water meet) slow the flow, filter sediments & pollutants. Rich in nutrients, detritus & light: base of food webs. River delta: triangular landform at river's mouth where slowing water results in deposition (settling) of sediments eroded from land. Sedimentation leads to subsidence (sinking) and compression into layers. A characteristic estuarine ecosystem is the temperate salt marsh (grassy) though low in biodiversity it has VERY high species populations, productivity & biomass (salt hay). High levels of detritus & nutrient flow from land make these waters nutrient-rich, important spawning ground (nursery) for many species. Most salt marshes have been filled to provide living space for the expanding human population. The tropical counterpart to a salt marsh is the mangrove swamp (woody, mangroves are salt adapted trees) these ecosystems are vulnerable to shrimp farming (aquaculture) & filling for living space.
Tides: gravitational relationship of ocean to the Earth/Moon unit cause coastal sea level rise and fall over a 12 hour 25 minute period as equal and opposite waves follow Moon's revolution around Earth (a smaller influence is alignment of Earth, Moon and Sun causing monthly "Spring" (extreme) and "Neap" (moderate) tidal variation). Tides at different points on Earth are influenced by a very large number of factors but tidal differences are smallest in open ocean and highest where ocean narrows between land masses. In Boston Harbor a 10-11 ft difference is typical.
Abiotic Characteristics (and see Chap 10 guide)
Light (photic) greatest at surface, but nutrients sink, limiting factor on photosynthesis
Dark (aphotic) the deeper the darker, less diversity in oceanic benthos (bottom). Food web depends on nutrient fall "marine snow" and on chemosynthesis (not described in text) by autotrophic bacteria feeding on chemicals from undersea volcanoes.
Currents — wind-driven, text fails to discuss temperature-driven "conveyer belts" (between equator & poles) controlling world climate & daily vertical plankton migration.
Salinity — varies with evaporation rate and freshwater inputs (tropics saltiest, glacial melt makes polar seas less saline, but cold water is more dense than warm water. Estuaries mix fresh + salt water, called brackish).
Most of Earth's living space is the ocean (97% of Earth's water, covering 71% of Earth's surface).
Plankton- drifters cannot swim against currents.
Phytoplankton (Phyto=plant), our planet's most important, ancient, and numerous producers, need to be able to stay in the light, and where there are nutrients (most productive in shallow, neritic, zone). Herbivorous zooplankton (zoo=animal) feed on phytoplankton. Carnivorous zooplankton and other marine animals feed on herbivorous zooplankton.
Most marine animals need & are able to get oxygen that is dissolved in water 8ppm (parts per million) is a high level of dissolved oxygen, marine mammals, reptiles, and birds, surface for air (atmosphere is 21% oxygen, 78% nitrogen).
Detritus = tiny pieces of decomposing organic material, food web base eaten by Detritivores. Many benthic animals depend on this food source.
Mid Year Review: Briefly Define Each Term
CHAP 1- Planet Earth
Lithosphere: Describe how each of the 3 rock types are formed:
What role do the amounts of an area's nonliving factors such as water, light, oxygen, and pressure play in determining its quantity and variety of living organisms?
CHAP 2- Methods of Science
Know the steps in designing a scientific experiment (Scientific Method):
CHAP 3- Change in the Biosphere
Know habitat requirements needed to support a population of organisms
Intro To Chemistry
Energy Levels (Orbitals)
CHAP 4- Matter and Energy in the Ecosystem
Be prepared to analyze consumer levels in a food web
Crop RotationNote that amino acids are an example of an organic molecule (containing carbon) that can only exist because Nitrogen-fixing bacteria (in soil and concentrated in legume root nodules) convert atmospheric Nitrogen into a form other organisms can use. These means that the Nitrogen cycle is particularly important in discussing amino acids and the proteins they form.
Note that in any discussion involving CO2 the Carbon cycle is likely to play a most important role.
CHAP 5- Interactions in the Ecosystem:
Be able to analyze effects of evolutionary pressures on species relationships
Density-dependent limiting factor (there are 6 of these and their limiting effects intensify as populations increase)
Density-independent limiting factor (there are 3 of these and they limit populations regardless of size)
Survival of the fittest
CHAP 6- Ecosystem Balance
Population change analysis (in community of producers, predators, prey, competitors)
Know how to ID biomes given precipitation and temperature based on the diagram on p100 (see copy below)
CHAP 7- Desert and Tundra
Explain similarities/differences between desert and tundra lithospheres for plant adaptations
CHAP 8- Grassland Biomes
Know what biotic and abiotic factors maintain a stable grassland ecosystem, preventing its succession to forest
Runner vs. Rhyzome
CHAP 9- Forest Biomes
Know typical species and general
characteristics of each type of forest (note examples below)
CHAP 10- Freshwater Biomes:
Wetlands: give at least 3 reasons for their environmental
Photic vs. Aphotic Zone
CHAP 11- The Marine Biome:
Explain characteristics of estuaries that make them economically important
Tip: use a key term in your browser (not site) search box to move to the part of this page you want.Unit 4: People in the Global Ecosystem
Chapter 12 People and Their Needs
Chapter 14 Feeding the World, Human Nutrition & Food Supply
Unit 5: Energy Resources
Note that petroleum refinery processes
such as the example shown above require high heat and pressure in an oxygen-free
environment (to prevent combustion). Click here for a link
to a detailed 10 minute video if you would like to know more about the refining
Running out, pollution and habitat destruction: problems with fossil fuel extractionfrom natural environments and use by our society
Biomass fuel: Fuels formed from remains of recently living plants (renewable resources using CO2 to grow so
a non-renewable metal element, heavier than lead, toxic as well as radioactive,
Water is important as a coolant -- a "loss of coolant accident" could lead to meltdown.
There are several reactor technologies. In some designs, the turbine water is made radioactive by contact with the fuel. In the design shown here, turbine water is kept separate from the fluid circulated in the reactor.
In breeder reactors, U-238 is converted to fissionable Pu-239 that can be used either as the fuel or to make nuclear weapons of mass destruction.
The containment structure is intended to prevent the release of radioactivity in the event of accident.
Since 9/11, it has been proposed that containments should be designed to resist a jetliner impact (this is not yet the case). Used nuclear fuel is stored in pools of cooling water at power plants all over the USA, awaiting final disposal as high level waste that will remain hazardous for 10,000 years. To date, the state of Nevada continues to resist the federal government's decision to site this waste repository at Yucca Mountain as described on p260 of our text.
On March 5, 2009, President Obaba's Energy Chief, Steven Chu, suspended funding for the Yucca Mountain Project.
solar heating uses building position and design, has no moving parts. In the
diagram above, note the barrel representing thermal mass that absorbs heat
during day, releasing it slowly after the sun sets. Note also the overhanging
roof that admits low winter sun but shields from the higher summer sun (recall
that seasonal temperature differences are caused by differences in daylength
and solar angle, the lower noontime angle of winter is more diffuse and less
direct than the more nearly perpendicular angle of noontime summer sun).
Remember, solar heating is different from using the sun to generate electricity, if you need help on the latter, let me know. The 2 main techniques are using solar heat to boil water, powering a steam turbine as in conventional power stations, except 'it's all done with mirrors', and, photovoltaics, aka "PV cells" (described above) that collect light on sheets formed from 2 layers of silicon semiconductor material.
Unit 6: Resources in the Biosphere
Subsurface mining: shafts, tunnels, and chambers are blasted and dug to reach
mineral deposits deep underground. These passages can collapse, trapping miners,
who also risk death from explosions of dust and natural gas. The chronic (routine,
long term) exposure to dust causes many miners to die from lung disease.
http://www.bemax.com.au/images/asx160206bmx3.jpg (Australian zircon mining)
Mining and the separation of desired minerals from their ores
result in tailings left in spoil piles, mountains of discarded
materials, often containing a concentration of toxic substances. Great
environmental damage results when these materials are blown by the wind or
leached by rainwater into the aquifer.
Three conservation tactics include:
Soil and Climate
Asia is particularly famous for its terraced rice farming technology that dates back thousands of years and allows dense human populations in regions where agricultural land is at a premium. Originally a wetland grass, rice needs to be planted 'wet' but harvested 'dry' giving rise to the complex water management system seen in the photo below.
Hazardous Wastes are solid, liquid, or gaseous wastes that are potentially harmful to humans and the environment, even in low concentrations. Include:
Reactive wastes, such as the metal sodium, are so unstable that they will explode
if mixed with other substances.
Corrosive wastes, like battery acid and lye (drain cleaner), eat through clothing, skin,
metal and other materials
Ignitable wastes, such as cleaning fluid and other petrochemicals, can burst into flames
at relatively low temperatures.
Toxic wastes, such as arsenic, are poisonous to people and cause health problems
such as birth defects and cancer.
Radioactive wastes, like uranium, burn skin, destroy cells and cause genetic mutation.
Some take short halflives to decay, others remain dangerously radioactive for
thousands of years, many are also toxic. They include mining wastes, protective clothing
and equipment used in power plants, nuclear medicine and research.
Medical wastes, such as syringes, old medicines, body fluids and other medical equipment
that may be toxic, sharp, or carry infectious diseases.
Note that Hazardous home wastes (cleaners, medicines, pesticides) should be disposed of during your DPW's "hazardous waste day" events (never dumped down the drain or discarded as ordinary garbage) these are being replaced by less dangerous products wherever possible.
Controlling Pollution on Land
Volume Reduction: 1/4 of all landfilled wastes are disposable items that should be replaced
by repairable, reusable or recycleable products (examples include cloth shopping bags
instead of paper or plastic, cloth handkerchiefs instead of tissues, recycled paper,
plastic and metals, machines fixed instead of discarded).
Biodegradable substances decompose easily and enrich the soil. They include natural items
such as grass clippings and other plant material that are most easily returned to the
environment for recycling by placing them in a compost pile. The result is humus
(decomposed plant material) useful for gardening.
Hazardous Waste Disposal
Waste exchange: one company's waste is another's valuable material.
Deep well injection: pumps wastes into layers of porous rock through lined pipes,
below layers of nonporous rock that protect drinking water supplies
(for journal credit, research "carbon sequestration").
Secure chemical landfills: located in nonporous bedrock, capped by clay to keep out water.
Controlled incineration: burns wastes at high temperatures up to approx. 1600°C
Chemical and biological treatment plants: use chemical or biological reactions that neutralize hazardous wastes so that they are no longer hazardous to dispose of.
Example: mixing acids with bases to neutralize pH.
Radioactive waste disposal: High-level wastes are currently stored in water-filled
steel containers encased in concrete. These containers are not expected to last
for the 100s to 1000s of years that the wastes remain dangerous. Low-level wastes are either stored for decay to harmless levels and then discarded like other solid wastes or
buried in secure chemical landfills.
"Superfund" is legislation designed to identify and clean up hazardous areas,
officially called CERCLA (Comprehensive Environmental Response, Compensation
and Liability Act of 1980):
- Makes polluters pay
- Sets a National Priorities List (NPL) of most serious threats
- Takes emergency action (spills/accidental releases)
- Researches reduction, treatment, disposal
- More funding is needed to reduce hazardous waste production, prevent pollution
(new processes to reduce environmental releases, substitute nontoxic for
toxic solvents, exchange (reuse) and recycle toxics to reduce costs, eliminate cleanups)
- Environmental justice: the fight for laws against exploiting poor communities/nations as dumping grounds.
Chapter 20 Water Resources
20.1 Uses for Water.
The USA drains 1 trillion L (liters) of water per day, 75% is surface water (lakes, rivers), 25% is groundwater:
- Residential: 9%, 300 liters/daily (72 gallons) per American
- Industry: 44%, a declining number (for several decades, low transportation cost -- "cheap" oil -- has allowed manufacturers to follow cheap labor overseas)
- Agriculture: 47%, mostly for crop irrigation, (also for raising and processing livestock).
- More than 50% of the water used in flood irrigation is lost to evaporation, leaving behind mineral salts that kill plants.
- furrow irrigation sends water through ditches between rows (furrows) of plants
- overhead sprinkler systems, often center pivots circling wellheads, are common but high winds can blow away the water.
20.2 Water Resources.
Note the parallels between water purification and waste water treatment. That is because, for much of the world, drinking water comes from the same river in which it and its neighbor's wastes are disposed of: one community's effluent becomes another community's water resource. We are fortunate in that our water supply originates from a combination of protected watersheds located in our town and in an undeveloped area in the western part of our state.
Water Pollutants and Sources
Some Pathogenic Microorganisms to Know (They Kill Millions Each Year):
Bacteria -->Cholera, Typhoid Fever, Dysentery (via infected human wastes)
Worm-->Schistosomiasis (via water snail --> “ “ “ )
damages liver, bladder, intestines
Protozoan-->Malaria (via mosquitoes-->breed in water )
fever, liver damage, kills 2 million yearly
Heavy Metals: metallic elements having high mass numbers (Mercury, Lead, Cadmium, Nickel, Chromium) Damage brain, liver, kidneys.
Photo by Eugene Smith
In 1950s, town of Minamata, Japan, Mercury discharge by plastics factory-->Biological Magnification-->Fish-->8000 suffered paralysis/brain damage, 100s died.
In 19th Century Europe, Mercury-->fur-->felt-->hats-->”Mad Hatters”
Worst Oil Spill: 1991 Gulf War
Worst US Oil Spill: 1989
“Exxon Valdez”-->43,000Metric Tons-->Prince William Sound, Alaska
At this time in our nation's history, our major source of water
pollution is agriculture including animal wastes, fertilizers, pesticides and
soil in runoff.
Chapter 22 Air & Noise Pollution
Please don't give in to despair ("pollution is awful, we're all going to die").
Know that air quality is MUCH better than when I was a child.
Many air pollution problems and questions (acid rain, leaded gas, the ozone hole,
'is smoking dangerous?') have already been solved or are in the middle of being solved
(cleaner fuels, higher emission standards, energy conservation and alternative energy).
We have more, smarter, richer people with vastly better science and technology than ever before in human history.
Air pollutants include particulates (tiny pieces - ash, metal, dust) and gases (usually oxides of combustion).
Photo-chemical smog is triggered by sunlight reacting with oxides (photo = light).
Indoors, the deadliest air pollutant is smoking, which causes emphysema, a disease in which tiny air sacs in the lungs break down, and lung cancer (cancer = out-of-control cell growth).
Another health problem is Carbon Monoxide (CO) poisoning that prevents oxygen from binding to blood hemoglobin. (hemoglobin is the protein in red blood cells that carries the oxygen from your lungs to all parts of your body). Like CO2, CO is a product of combustion, the oxidation of carbon aka "burning."
Air pollution damages crops and pollutes water and soil, entering our food chain. Air pollution has global as well as local effects.
Acid precipitation is rain or snow with a very low pH, mainly caused by oxides from coal-burning power plants combining with water in the air.
pH is a measure of the power of hydrogen ions (H+) dissolved in a solution:
The more H+, the more acid (sour), the lower the pH number.
the less H+, the more base (bitter), the higher the pH number.
Both extreme acids and extreme bases are highly corrosive. The pH scale is logarithmic (each number is ten times stronger or weaker than the previous number). The top pH is 14. Distilled water is neutral (7 pH). Acids, like vinegar, have a pH lower than 7. Bases, like ammonia, have pH higher than 7. Normal rain or snow is slightly acidic (5.6 pH) because it forms a weak carbolic acid by combining with Carbon Dioxide (CO2) in the atmosphere.
Ozone depletion results from breakdown of ozone (O3) molecules in the atmosphere by the Chlorine (Cl) and Flourine (F) in compounds known as CFCs. Recall that stratospheric ozone protects from UV rays, but tropospheric ozone is a corrosive pollutant that can cause serious breathing problems, making ozone: "good up high, bad nearby."
The Greenhouse Effect refers to atmospheric gases that help slow Earth's heat loss to outer space. Global warming is the increase in greenhouse gases, chiefly Carbon Dioxide (CO2) from burning organic fuels. Since the industrial revolution, ice core data reveals an atmospheric CO2 increase from 280 to 380PPM = 36% (our text, using old data, says 20%, let's go with what we now know, and say over 30%). Global warming accelerates the water cycle: dry places becoming drier, wet places wetter, ice melt and expansion of heated ocean water cause rising sea levels. As habitats change, species migrate, evolve, or go extinct. Our task:
"To manage the avoidable and to avoid the unmanageable"
-- Thomas Freidman, 2008.
Some air pollutants are removed by natural processes such as precipitation and biological activity. Air pollutants can be reduced by controlling automobile and industrial emissions. Fear of economic hardship has made air pollution control a tough sell. People want a clean environment but are we willing to pay the price?
Noise, measured in decibels (dB), can also be a pollutant. Loud or persistent noise above 80dB can cause hearing loss, stress & other health problems. The federal government limits allowable noise levels.
Acid Precipitation figure from our text representing the 14 point pH scale:
Ozone Depletion figures from our text representing Chlorine (Cl) breakdown of ozone (O3) and an increase in the thinning of stratospheric ozone over the Southern hemisphere from 1979-92:
Global Warming figures from our text representing increased CO2 concentrations in Earth's atmosphere and the decreased radiation to space of infrared (heat) energy from Earth's surface caused by greenhouse gases absorbing this energy, heating the atmosphere:
It is essential to separate Global Warming from Ozone Depletion.
Ozone Depletion is a solved problem that was being caused by CFCs (chlorofluorocarbons). CFCs began to be banned in the USA in 1978 and in other countries since then. Ozone Depletion will (over a long period of time) eventually stop through natural processes.
Global Warming (aka climate change) is the major environmental problem of our time. Global Warming and our recognition of its effects have significantly increased since the 1990s when the information in our text was gathered. Global Warming is caused by burning fossil fuels, currently our society's main power source, and a valuable nonrenewable resource required for many purposes besides just burning it up for fuel. We need to stop burning fossil fuels and develop our many existing energy alternatives.
It is not helpful that people with a vested interest in "business as usual" have succeeded in confusing many people about whether or not Global Warming is "real" and our action required. Many different sources of information collected by 1000s of scientists dating back to the 19th century all point to the inescapable conclusion that in spite of particular weather events, the overall trend is hotter, in some places wetter, in others dryer, in some places windier, in others less windy. The most rapid changes are occurring in the polar regions. For the first time in human history, merchant ships now cross the Arctic Ocean. In the temperate zone the changes are also notable: New England's mean annual temperature is 4.3°F (2.4°C) warmer than it was 150 years ago.
Ignoring Global Warming is likely to cause planetary habitat destruction with wars and mass extinctions from competition among nations and species fleeing floods, droughts, wildfires, and sea level rise. While climate change and accompanying shifts in environmental conditions have always occurred, the present changes, instigated 200 years ago by our industrial revolution (and still incomplete for that majority of humanity that lives in the still-developing nations) are happening more rapidly than ecosystems can adjust to. The result will be different ecosystems (No, this does not mean 'the world is going to end and we're all going to die'. It does mean that you'd better get the best education you can and plan on a process of lifelong learning as you continue adapting to change as it occurs).
Managing Global Warming will require major economic and social adaptations. One incentive for paying attention to this issue is that there will be many financial opportunities for those who enter the careers that will assist humanity in surviving (and hopefully prospering) through this dramatic transition.
Unit 7 Managing Human Impact
Chapter 23 Habitat Destruction
As of May 6, 2010, if BP's ~25002mile Gulf oil spill had spread out over our state, it would have covered an area the size of all of Eastern Massachusetts including the Cape. Depending on source, the leak, 5000 feet below the ocean surface, was been flowing at a rate somewhere between 200,000 and 2 million gallons per day since March 20th (image from <http://paulrademacher.com/oilspill/>):
Update: 5.12.10: BP inserted a hose it has succeeded in taking up only a small fraction of the gushing oil.
Update 5.30.10: Much of the heavy crude has remained below the surface, perhaps because of the effects of the highly toxic chemical dispersants (surfactants) being used near the sea floor (as well as at the surface) to break up the oil. The EPA has demanded that BP stop using these chemicals. The federal government has revised its estimates of the spill's severity saying it was up to 4 times worse than BP had reported, significantly worse than the previous record-holder, the nearly 12 million gallons spilled by the Exxon Valdez in 1989. Last week, BP poured 30,000 tons of "mud" on the spill site in what they referred to as a "top kill" in combination with a "junk shot": attempting to block the flowing oil with bits of knotted rope, golf balls and other debris intended to stop up the pipe. None of this worked. The oil entered the "loop current" having the potential to round Florida and reach Cuba and the Eastern Seaboard.
The 4.20.10 accident was revealed to have been caused by a series of mishaps, equipment failures and poor management decisions: A back up electronic control pod on the blowout preventer was shown to have been unreliable and to have had a faulty battery. The rubber gasket that was the only means of shutting off the well's flow was severely damaged during a safety test. BP management overruled their contractor's recommendation and removed "mud", a man-made drilling fluid critical for holding back the well's flow, before 3 cement plugs were in place. The procedure for sealing off the well continued in spite of the unanticipated appearance of "mud" being expelled by gas pressure in the borehole. A fascinating eyewitness account was aired on the CBS program "60 Minutes" and discussed in class.
In class, students asked about the current status of the shrinking Aral Sea. Here is a picture from April 5, 2010:
Disturbing the part of an ecosystem an organism is adapted to and needs to survive.is called habitat destruction. This is the main cause of extinction (the disappearance of one or more populations of a species from all or part of its geographic range). Extinction is a loss to the biodiversity of an ecosystem. Many things can lead to habitat destruction. For example, non-native species introduced to an area by humans (AKA "alien species" may out-compete native species for resources. When habitats are destroyed, specialized species are more likely than generalized species to become extinct. A specialized species (such as the panda) usually disappears with the loss of its food source. A generalized species (such as the raccoon) may be able to find another habitat where it can meet its needs. People are doing things to preserve biodiversity such as maintaining areas of wilderness, places that remain relatively undisturbed by human actions. Some people are establishing "gene banks", secure places (a bit like Noah's Ark) where seeds, plants or other genetic material are stored to prevent extinction. A gene is a stretch of DNA containing the information that shapes one of the proteins of an organism.
More than 99% of every species that has ever lived has gone extinct. Relatively short periods of time in which many species go extinct are called mass extinctions. With entire ecosystems disappearing, we are in the midst of a mass extinction that seems unique for being the 1st such event caused by a single species (us). It is thought that nearly all the major animal groups were formed during the Cambrian Explosion, an adaptive radiation, or period of rapid evolution, about 530 million years ago, during which it took only a few million years to fill vacant niches. More recently, the Cretaceous Extinction, 65 million years ago, wiped out the non-avian dinosaurs, marking the onset of the Cenozoic period, the age of mammals. About half of all US forests and more than half of all wetlands have been destroyed. This makes it hard for us to tell developing nations to protect rain forests and mangrove swamps.
The text (written in the 1990s) predicts the loss of the "Aral Sea", once the world's 4th largest lake, by 2010 because its 2 main river sources were diverted for irrigation. Go on-line, did this prediction prove accurate? Explain.
Chapter 24 Sustainable Future
The guiding strategy for conservation is to reduce resource use by increasing use efficiency and decreasing demand. One conservation tactic is Source reduction, reducing resource use by lowering amount of a resource needed to satisfy demand. Another tactic, familiar to everyone, is recycling, reducing resource use by collecting usable waste materials and using them to produce new items.
Because the burning of nonrenewable fossil fuels is a major obstacle to achieving a sustainable future, important ways that we can conserve energy at home are to use less hot water and, when shopping for major appliances, we should look for those that are labeled as having a high energy rating ("Energy Star") because they use less energy to maintain their operating temperature. Examples include freezers, stoves, water heaters, refrigerators, dish washers, clothes washers, and dryers.
An important conservation strategy for conserving endangered species is the establishment of wildlife preserves, areas of land or water set aside for the protection of the ecosystem in that area. To fulfill its function, a wildlife preserve must contain all components of an ecosystem. One drawback of preserves is that they are seldom large enough to contain everything that a genetically viable population needs to survive. Habitat "fragmentation" may lead to small natural areas connected by narrow corridors. Such areas support much lower levels of biodiversity than a large unbroken areas of wilderness.
Chapter 25 Environmental Protection
Environmental issues often have an economic component: the law of supply and demand (that prices are set by how much sellers want to sell and buyers want to buy) can be illustrated with a supply-demand curve: price varies with what the market will bear. BTW this kind of "curve" can look straight. The prices we pay for nonrenewable resources such as gasoline reflect perceptions of scarcity as well as risk assessments of "how dangerous it is" to use or obtain a particular technology based on past experience, experiment, and cause/effect models.
Here is a supply-demand curve:
Note that as quantity of the resource supply increases, the Demand line and price per unit go down.
Here is a risk assessment matrix:
Cost/benefit analyses are one way of determining "is it worth it?", weighing the good and bad of an activity against its costs, both now and later. Policies are a government, company, or other organization's decision on how to deal with an issue. Policies include a plan of action, with rules backed by incentives (rewards), and penalties (punishments). Policy decisions are based on risk assessment: and cost/benefit analysis. Some people argue that cost/benefit analyses have failed in the past because:
a: How do you put a price on things we all want or need:
beautiful habitats lush with biodiversity, clean air, pure water?
b: when everyone shares different levels of responsibility for damage to the environment,how do we charge for the costs?
c: different interest groups assign different values to items on a list of costs and benefits resulting in different policy decisions.
Too often, factors needed for healthy environmental conditions have been "externalized": unfairly excluded from consideration in the discussion because no economic cost or benefit was assigned.
Here is an example of a cost/benefit analysis:
Final Exam Review: The exam primarily focuses on Units 5-7.
The following key ideas from Unit 4 are also included:
Ethics are societies' statements of moral values (right vs. wrong). A "sustainable development" ethic seeks to meet global human needs without limiting the ability of future generations to meet their needs. This means re-engineering society so humans can last indefinitely into the future by not using up Earth's limited food, water, living space, and energy resources.
It may once have seemed that human's could continue to expand into unexplored frontiers, areas previously untouched by humans and rich in resources that were ripe for our exploitation. This old-school "frontier" ethic is now characterized by our text as being 'out-of-touch' with reality because it continues to selfishly assume that
- Earth's resources are unlimited, and meant soley for human consumption,
- people are separate from nature (not subject to natural laws), and,
- human success is measured by 'control' over natural world.
These notions fail to reflect what we are learning about how Earth actually functions and the growing human population's impact on natural systems we depend on for our survival. You should be able to give several examples that demonstrate the shortcomings of the frontier ethic given the state of our world today.
- Renewable resources are those that regenerate quickly (return to initial levels within a human lifespan).
- Nonrenewable resources either do not regenerate or have regeneration times vastly longer than a human lifespan. For example, soils, a product of the weathering of rock particles over vast spans of time and the breakdown of organic materials by soil organisms (worms and other small invertebrates, as well as decomposer bacteria and fungi). In both cases, agricultural practices are depleting a resource we depend on for our food supply and promoting the desertification of our planet. Monoculture (huge fields growing just 1 crop) take the nutrients out of the soil, leaving farmers dependent on agricultural chemicals that kill soil organisms, preventing the important work they do in restoring soil fertility. Tilling, the turning and loosening of soil to grow the crop, has the unfortunate side-effect of promoting erosion by wind and water.
Good luck on exams. Have a great summer!************************************************************************************************************************