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Earth’s Major Biomes. Ecosystems. Ecology= “study of one’s house” eco = Greek for "house", ology = Greek for "study of” “Study of organisms in relation to the environment” (American Ecological Association). Biosphere = Intersection of:. Atmosphere Hydrosphere Lithosphere Pedosphere
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Earth’s Major Biomes Ecosystems
Ecology= “study of one’s house” • eco = Greek for "house", • ology = Greek for "study of” • “Study of organisms in relation to the environment” (American Ecological Association)
Biosphere = Intersection of: • Atmosphere • Hydrosphere • Lithosphere • Pedosphere • Together = • Ecosphere
Living inhabitants of earth: • an estimated 5 to 100 million. About 2.55 million have been scientifically named and described so far, including: • 250,000 flowering plant species • 800,000 lower plant species • (1.05 million plant species altogether) • 45,000 vertebrate animal species • 950,000 insect species • (1.5 million animal species altogether) • About 10,000 new species are identified each year, mostly insects.
Processes which sustain ecosystems: • A) energy flows • B) stable biotic structure • C) nutrient cycling
Energy flows: • Energy is the capacity to do work • Forms of energy all trace back to radiant energy from the sun • Radiant energy from sun is converted to • 1) heat • 2) chemical energy (stored in chemical bonds of molecules) • 3) mechanical energy • 4) electrical energy
Thermodynamics: Study of energy and its changes • 1st Law of Thermodynamics: Energy cannot be created or destroyed, but can be transformed from one form to another • Example: Photosynthesis • 6CO2 + 12H20 + radiant energy from sun C6H12O6 (glucose or sugars) + 6H20 + 6O2 • Plants use green pigment (chlorophyll) to absorb radiant energy and convert radiant energy into chemical energy • Notice: CO2 is essential for all life on earth and the process of photosynthesis gives off the O2 that all animals need to breath.
2nd Law of Thermodynamics (the law of entropy) • As energy is transformed from one state to another, some is changed to heat energy which is dissipated and given off to the environment • Example: In the process of cell respiration, chemical energy stored in food molecules (glucose) is released within cells of plants and animals. Now food molecules are broken down and mechanical energy is produced. • In the process of energy transformation, some is lost. • C6H12O6 (glucose) + 6O2 + 6H20 • 6CO2 + 12H20 + mechanical energy • and heat
Oh My God! Let’s tax those CARBON EMISSIONS from the respiration of plants and animals and people! Call out the EPA!
Question: • How is it possible that in 2007 the U.S. Supreme Court voted 5-4 that CO2 is an “air pollutant” that could be regulated by the Environmental Protection Agency? Didn’t these people go to high school and college?
A Carbon Tax? • Carbon is the basis of all life on earth • And yet, U.N.’s “Greenhouse Development Rights Framework (GDR) (2007, Bali) plan proposes a “consumption luxury tax” to be levied on everyone on the planet who makes over $9,000/year. Americans would pay about $780 per year, or $212 billion in “climate reparations” to poorer countries with the Plan. • Reason magazine’s Rob Bailey ran the numbers: the total “climate reparation” from rich to poor countries = $600 billion/year. • The Obama energy bill of 2009 is far more expensive. It squeaked by the house but has not passed the Senate.
Example 2 of 2nd law: • In the conversion of stored energy in coal to electricity that occurs in a coal-fired power plant, 2/3 of original energy in coal is lost to waste heat. • Carbon is also oxidized to form CO2. • (But the real pollutants are from impurities in the coal, including mercury and sulfur dioxide, which can form sulfuric acid, a component of acid rain.)
Conundrum: • Living organisms have a high degree of organization and complexity. • Thus, the evolution of life to more complex forms seems to refute the 2nd law. • Life can only become more complex if it consumes high amounts of energy. • This is true also for industrialized societies such as ours- which get 85% of their energy from fossil fuels (ancient sunlight).
Producers are autotrophs(Greek; auto = self, troph = nourishment, so self-nourishing). • Autotrophs get their energy from the sun via photosynthesis. Plants are the most important producers on land, and algae and certain types of bacteria are the most important producers in aquatic areas.
Consumers are heterotrophs(Greek for “different nourishers”). • These are animals which eat plants and other animals as sources of food energy and body-building material. • a)primary consumerseat producers (plants). These are herbivores(plant eaters, such as cattle, deer, giraffs, etc.)
b)secondary consumers eat primary consumers and are the carnivores, such as lions, tigers, etc.
c) Tertiary Consumers- omnivores eat both primary and secondary consumers. These include bears, humans, pigs.
Detrivores and Decomposers • Detritivores or detritus feedersfeed off of dead organic matter, detritus, or decomposed animal and plant material. • Examples include earthworms, vultures, termites, ants, millipedes, soil insects • Decomposers (saprotrophs – Greek sapro means “rotten”, troph means “nourishment”) microbial heterotrophs, which break down organic material and use the decomposition products to feed themselves with energy. In the process, they often release simple molecules like CO2 and salts that can be used by producers. Examples include bacteria and fungi. These are extremely important for converting dead organic matter into humus for the soil, breaking down of dead wood, etc.
Trophic levels • Each level is called a trophic level (trophic= feeding). • However, because most organisms feed on several kinds of food, food chains are less common than food webs, which are a complex of interconnected food chains in an ecosystem. • Each ecosystem has about 3 or 4 trophic levels.
2nd law in action: • whereas a primary consumer like a rabbit might need a fairly small range for foraging (about 15 acres), a secondary consumer like a tiger needs a much larger home range (almost 100 square miles)
Carbon Cycle: • Carbon exists in gaseous, liquid and solid forms and occurs in five main reservoirs: • Reservoirbillion metric tons 1) Atmosphere- as CO2 (380 ppm766 Or (0.038%) of atmospheric gases 2) Ocean - as CO2, CaCO3, and HCO3. 39,000 (about 50 times more CO2 in the oceans than atmosphere). 3) vegetation, animals, soils, peat, etc. 2,100 4) fossil fuels (oil, coal, natural gas) 4,000 5) carbonate rocks as CaCO3 (about 100X more)80,000
Photosynthesis: Plants remove CO2 from the atmosphere and form glucose (sugars). • 6CO2 + 12H20 --> C6H12O6 + 6O2 + 6H2O • Again, sugars are used in cell respirationof living things: • C6H12O6 + 6O2 + 6H20 --> 6CO2 + 12H20 + energy for biological work
More CO2 in the atmosphere means more biomass! • Many greenhouses increase levels of CO2 to 2 to 4 times normal levels (700 to 1400 ppm) • This results in faster growth rates, longer growing seasons, larger plant size and larger yields of crops (by 20 to 50%) • Increased CO2 means agricultural crops need less water and adapt better to drought and pollution.
Fossil Fuels are, in effect, ancient sunlight, and are non-renewable • Combustion of wood, peat, and fossil fuels causes oxidation of solid carbon to form gaseous CO2 • About 210 billion metric tons of CO2 are added to atmosphere each year from all sources; human activities add about 7 billion metric tons, or about 3% of the total. Other sources (97%) are oceans, vegetation, soils, and volcanoes.
96.9% of all greenhouse gases in atmosphere are water vapor, whereas CO2 makes up less than 2%. • 66 to 86% of the total greenhouse effect is due to water vapor and clouds, and only 9 to 27% is due to CO2. Humans are responsible for less than 3% of CO2 emissions, and less than 1% of total greenhouse effect.
Margaret Hillman (2007): • “When the chips are down I think democracy is a less important goal than is the protection of the planet from the death of life, the end of life on it. (Carbon rationing) has got to be imposed on people whether they like it or not.” • From “A Plan to Save the Planet, But is Anyone Willing to Pay the Price?,” Local Transport Today
David Bellamy, Botany Professor, Great Britain’s best-known environmentalist: • “What a load of poppy-cock! Global warming- at least the modern nightmare version- is a myth. • (CO2) is in fact, the most important airborne fertilizer in the world, and without it there would be no green plants at all. Even a doubling of CO2 in the atmosphere would produce a rise in plant productivity. Call me a biased old plant lover, but that doesn’t sound like much of a killer gas to me. Hooray for global warming is what I say, and so do a lot of my fellow scientists. • It would be terrible if billions or trillions of dollars were wasted “on a problem that doesn’t exist- money that could be used in umpteen better ways: fighting world hunger, providing clean water, developing alternative energy sources, improving our environment, creating jobs.”
Nitrogen Cycle: nitrogen also occurs in gas, liquid and solid forms • Critical for soils and for life itself because nitrogen is an essential part of proteins, enzymes, hormones and nucleic acids, which store genetic information about an organism's traits. • Nitrogen (N2) makes up about 78% of earth's atmosphere. This gas is inert, highly stable and unusable.
Five steps in the process of nitrification: • 1) Nitrogen fixation mostly occurs by bacteria in soil. N2 is converted to ammonia (NH3). Rhizobium is the most important nitrogen-fixing bacteria and lives on nodules on the roots of plants like beans or peas. • 2) In the process of nitrification, ammonia (NH3) is converted to nitrite (NO2) then to nitrate (NO3) by other types of soil bacteria called nitrifying bacteria. • 3) In the process of assimilation, plant roots absorb NO3 and/or ammonia (NH3) and incorporate the nitrogen of the molecules into plant proteins and nucleic acids. When animals eat the plants, they are able to convert these to animal compounds. • 4) Ammonification, When living things produce N-containing waste products like urea (in urine) and uric acid, the N is released as NH3- ammonia. This process again is accomplished by bacteria. • 5) Denitrification. Nitrate (NO3) is reduced to gaseous N again by bacteria which are aneorobic, i.e., can live in areas without free oxygen.
Nitrogen fertilizer adds valuable nitrate and ammonia to soils and is used by humans to increase agricultural productivity. • Nitrate can leach through soils and contaminate groundwater. This is especially hazardous for infants and is a serious pollutant in agricultural areas in the Midwest. • Overuse of commercial fertilizers can cause a buildup of nitrate and ammonia in nearby waters, where it stimulates growth of algae in the process of eutrophication. • When dead algae decompose, free oxygen in water is consumed. • When the dissolved oxygen (DO) in the water falls below a critical level, other aquatic organisms, like fish, can no longer breathe and so they die off.
Net primary productivity • Amount of biomass produced from photosynthesis in excess of the amount broken down by a plant's cell respiration. • This relates to the amount of photosynthesis in a given time. • The most productive ecosystems in terms of biomass are continental shelves and tropical rainforests. • Tropical forests cover only about 7% of earth's land surface but include over half of world's species.
Law of Limiting Factors • Limiting factors are the variables which tend to restrict the niche of an organism. Different species have different tolerance levels for environmental extremes like heat, cold, etc. • If any factor lies outside the organisms range of tolerance the organism can't live there. So for each factor (temperature, pH, etc.), an organism will have:
Law of Limiting Factors • optimum range- point of maximum growth • range of tolerance- range of max. to min. for each factor • limits of tolerance- death occurs when factor reaches this level • zone of stress- between optimum range and limit of tolerance. • Any factor which exceeds an organism's limits of tolerance can remove the organism
law of the minimum • The 19th Century agricultural chemist Von Liebig postulated that the growth of each organism is limited by whatever essential factor is in shortest supply or is present in harmful excess. • Von Liebig did his work on the effects of chemical nutrients on plant growth. • Other limiting factors can include competition from other species, acid rain, drought, temperature changes, etc.
Biomes = major ecosystems comprised of distinct assemblages of plants and animals
