Bio 20:Unit 1A Chapters 1 and 2 The Biosphere and energy flow.
Chapter 1: The Biosphere as a Closed System Nelson Pages 6-16
A. The Biosphere • The narrow zone around the earth where life exists. • Biosphere consists of 3 components: • Lithosphere, Hydrosphere and Atmosphere. • Biotic = living organisms (life forms). • Abiotic = nonliving component (geological and physical factors).
Ecological studies investigate a specific environment by looking at the following: • Organism (the individual). • Population (group of individuals). • Community (1 or more populations). • Ecosystem (community and abiotic factors interact).
1. The atmosphere • Composed of 3 regions: • Troposphere, Stratosphere and Mesosphere. • 2 outer regions of atmosphere: Ionosphere and Magnetosphere. • Composed of gases: • 78% Nitrogen, 21% Oxygen, 0.03% Carbon Dioxide and 1% Argon/other gases.
Biological levels of organization: TASK: Write down the definitions for each of the bolded terms
Smallest living part of an organism Groups of cells with similar function Groups of tissues with similar function Groups of organ systems that make up the organism Group of organisms of same species, living in same area, during same time Groups of organs with similar function A community and its physical and chemical environment Large area and its organisms Group of different species living in same area Narrow zone around Earth with life
2. Biodiversity • Biodiversity = # of species in an ecosystem. • James E. Lovelock: • Gaia hypothesis = earth is like 1 living organism. • Dynamic equilibrium = continuous changes with environments constantly adapting. • What happens when the biodiversity of an ecosystem decreases? • Give 1 example (page 9 in text). • What effects were there? Why?
b. Unbalanced equilibrium • A change in any organism level of the ecosystem has extreme consequences. • The species that is most sensitive to changes in an ecosystem is an indicator species. • Amphibians are especially vulnerable. Why? • See page 12 and 13.
Example: bald eagle as indicator species • Killed by: • 1.) Settlers and farmers • Threat to livestock • 2.) Toxic chemical wastes produced by industries entered food chain • Egg shells became very thin
b) Equilibrium Unbalanced • At risk species • Classified depending on degree of risk • a.) Endangered • Species is close to extinction in all parts of the country or in a large location • b.) Extirpated • Species no longer exists in one part of the country but can be found in others
b) Equilibrium Unbalanced • c.) Threatened • Species that is likely to become endangered if factors that make it vulnerable are not reversed • d.) Special concern • Species at risk due to low or declining numbers at the fringe of its range or in a restricted area
Biosphere 2 Biosphere 1 = Earth Biosphere 2 = Artificial biosphere created in Arizona - one of the largest living laboratories in the world An airtight greenhouse that covers 3.15 acres and 7.2 million cubic feet volume Includes a rainforest, a million gallon salt water ocean, a coastal fog desert and 4 other wilderness ecosystems The Texas investment company that owns Biosphere 2 north of Tucson, Arizona is selling the place. Billionaire Ed Bass dropped $200 million in the 1980s to build Biosphere 2 as a prototype "space colony." The experiment suffered major scientific and managerial problems and was eventually opened to the public as a tourist attraction. 13
What is the value of wolves? • The decline of the wolf: • Thousands of wolves died after they ate poisoned bison carcasses that had been laid out as bait. • 1880-90’s: ranchers killed wolves; in Canada anyone bringing in a wolf skin was paid by the government. • Montana = 80 000 wolves were destroyed between 1883-1918. • Wolves decline allowed coyotes to increase. Coyotes eat smaller prey (voles, mice, squirrels, eggs of ground birds); these prey decreased in number. • Wolves left remains of prey; without these remains, scavengers like the magpies, ravens and vultures. • Elk population exploded with no predators; stripping the land of plants. Disease spread rapidly and the population started to decline.
Return of the wolf • 1987- plan to import wolves from Canada to Yellowstone. • 35 wolves have been transplanted since 1996; ranchers were opposed to this. • Signs of change: • Elk move from open fields to treed areas. • Vegetation is recovering. • Small predators (kit fox) are increasing population. • 5 cows and 53 sheep killed by wolves in Idaho; ranchers were compensated for losses.
Positions • Frontier view: • “to feed ourselves and the hungry world, we must open up, clear and claim wilderness areas for ranching and other forms of agriculture. Wolves endanger the effort. They kill cattle and sheep. They must be removed wherever they interfere with farming and ranching and they should not be reintroduced once they have been extirpated”. • Stewardship view: • “humans are the most intelligent animals on the planet. It is our duty to take care of other species and preserve our world. Once we recognize that we have damaged the ecosystem, we must try to repair the damage using whatever resources are available to us. Wolves must be preserved in all ecosystems where they are now found, and reintroduced to ecosystems where they once lived”. • Ownership view: • Canadians do not own wild animals or plants just because they live in Canada. We have no right to move them around wherever we fell like it. It may have been a mistake to kill the wolves of Yellowstone, but we have no right to take the wolves and move them to a place they haven’t been before. It is better to let the ecosystem in the park find a new balance.”
Chapter 2 - Energy flow in the Biosphere – Nelson Pages 20-37
1. Matter and Energy Relationships • Matter and energy are essential components of the universe and living organisms. • Matter - everything that takes up space and has mass • Energy - the capacity to do work • the biosphere is composed of a variety of ecosystems • each ecosystem has a structure based on • a) energy flows • b) matter cycles
Remember this!!! Energy Flows, Matter Cycles!
a. Ecosystem Structure • An ecosystem = all the organisms living in a community and all the abiotic factors they interact with. • 1) Autotroph (producers) • organisms that: • get energy from sunlight or nonorganic energy sources. • convert inorganic compounds to organic forms. • are the basic trophic level in an ecosystem; supports all other organisms Trophic level = category of organisms defined by how they get energy.
Chemosynthesis: • Chemoautotrophs require only carbon dioxide, water and an energy source to make nutrients. • This energy is emitted from hydrothermal vents near the edges of Earth’s crustal plates. • Usually found in caves or deep oceans. • Many animals thrive in the extreme environment around hydrothermal vents. • Tube worms: survive on energy from bacteria.
Heterotroph (consumers): organisms that derive their energy by consuming other organisms. • a) Primary Consumers • - herbivores (eat only plants) • b) Secondary and Tertiary Consumers • - carnivores (eat other animals) • - omnivores (animals which eat both producers and consumers)
Decomposers • - organisms that derive their energy from dead organisms and waste products. • 1. Scavengers (eat tissues from dead organisms). • 2. Decomposers (feed on detritus). • Why is decomposition important?
2. Trophic Levels in Ecosystems • Trophic levels • the steps in the transfer of energy and matter within a community (feeding levels) • species in an ecosystem are divided into trophic levels on the basis of their main source of nutrition. • three main types of trophic levels are producers, consumers, and decomposers.
a) Food Chains Food chain movie • organization of trophic levels where energy flows from producer to primary and secondary consumers (and others if present) • Simple feeding sequence: who eats who? • Not representative of complex ecological relationships.
b) Food Webs • interconnected food chains within an ecosystem • highlight the complex, real-world interactions between species • makes connections from primary producers, through consumers, and back to decomposers Food Chain Movie
Most stable ecosystems have complex and well developed food webs the removal of one of its organisms may have little effect
Where abiotic factors limit the # of organisms, webs begin to look more like food chains • The lower the biodiversity, the simpler the food web, the more vulnerable each organism is to changes in the ecosystem
The behavior of energy is best explained by the Laws of Thermodynamics. Where do photosynthesis and cellular respiration fit in? What are they?
3. Laws of Thermodynamics: • a) First Law of Thermodynamics • Energy cannot be created or destroyed, only changed from one form to another • b) Second Law of Thermodynamics • With each successive energy transfer, less energy is available to do work. In biological systems, this “waste” energy is often heat.
Ecological Pyramids • Because of the loss of energy with trophic levels, there are two consequences for the ecosystem: • Because productivity is lower at higher trophic levels, there is less biomass. 2. Lower biomass at higher trophic levels, combined with large body size of top consumers, results in lower population. Densities.
results in a stepwise decrease in energy (pyramid). • there are 3 types of pyramids commonly used by ecologists.
Pyramid of numbers - # of organisms at each trophic level - each bar represents numbers relative to the pyramid base - pyramids are based on data from a given area eg: 1 km 2 tertiary consumer secondary consumer Primary consumer Producer
b) Pyramid of Energy - energy stored by each trophic level is given in calories or Joules. Energy per unit area per unit time (Kcal/m2/yr).
Pyramid of Biomass – stored energy is represented by biomass (dry weight) Biomass per unit area per unit time (g/m2/yr)
Energy is lost at each step in a food chain or web; the general estimate of this loss at each step is 90%, so only 10% of energy consumed is available to the next trophic level. This is known as the 10% rule.
Photosynthesis and Cellular Respiration • Photosynthesis equation: • CO2(g) + H2O (l) + energy C6H12O6 (glucose) + O2(g) • Cellular respiration equation: • C6H12O6 (glucose) + O2(g) CO2(g) + H2O (l) + energy (heat and ATP) • Chemosynthetic organisms: • Require CO2(g) + H2O (l) + energy • Energy required is H2S, NH3, Fe 3+ , S8
Human Use of Energy in Ecosystems (Page 33) Matter is continually entering ecosystems. What if some of the matter entering a food chain was harmful? How would it affect the ecosystem?
Hunting & Fishing • With introduction of horses into N. America, humans were able to increase hunting of animals, e.g., bison • Larger nets and an increase in boats have reduced marine fish e.g, cod, halibut, salmon
Monocultures • Biologists estimate 6 to 15 million different species of organisms • Humans rely on 700 different species of plants • Wheat, rice, cotton, barley, corn • Humans tend to use a focused amount of species; useful wild plants have been destroyed to grow food crops
Negative consequences to using monocultures • Plants become susceptible to pests and disease • Plants may lead humans to cures or medicines for diseases but are lost • Eventually, soils cannot support non – native species of plants • Barley and wheat are not suited for rich fertile soils found in tropics • Soils become deficient in their N and P minerals
Pesticides Have had largest impact on food webs Benefit society Reduce # of pests (weeds, molds, insects, birds, etc.) to crop production Reduce spread of disease (malaria, West Nile) Negative consequences to ecosystems: Eliminating an insect species on small island using DDT reduced spread of malaria, however, entire food web of island was affected Other insects disappeared - then lizards - then cats - increasing rat population – outbreak of disease = more problems!!!