Ecology: Interactions Among Organisms and Their Environment

Ecology Chapters 47-49 Ecology: Interactions Among Organisms and Their Environment I. Interactions: 6th characteristic of life A. Ecology (GK home): the study of our home, the earth 1. Study of interactions of organisms with the environment and with one another B. Levels of interactions and organization 1. Organisms 2. Populations 3. Communities 4. Ecosystems C. Abiotic vs Biotic D. Niche

II. Unifying concepts in population ecology A. Population growth 1. J-shaped curve (exponential growth) a. occurs when resources for growth and reproduction are unlimited b. Result: a species approaches maximum rate of growth 2. S-shaped curve (logistic growth) a. Growth levels off at the carrying capacity of the environment b. Result: numbers of individuals within a population are in balance with limiting factors (= "balance of nature" concept) 3. Factors limiting or regulation population growth a. Density-dependent factors i. Growth-limiting (mortality) factors increase in effect on population as number of individuals increase in the population ii. Examples: competition for food, disease, predation, parasitism b. Density-independent factors i. Growth-limiting (mortality) factors that do mot vary in effect on population as number of individuals increase in the population ii. Examples: sever changes in temperature, wave action of intertidal zone, freezing ice storms, hurricanes, volcanic eruptions

B. Unifying concepts in Ecosystem Ecology 1. Ecosystems defined 2. Energy flow through ecosystems a. First law of thermodynamics b. Second law of thermodynamics c. Pyramid of energy flow (10% rule)

3. Relationships- Symbiosis a. Commensalism b. Mutualism c. Parasitism Energy Flow Chart To summarize: In the flow of energy and inorganic nutrients through the ecosystem, a few generalizations can be made:

1. The ultimate source of energy (for most ecosystems) is the sun

2. The ultimate fate of energy in ecosystems is for it to be lost as heat.

3. Energy and nutrients are passed from organism to organism through the food chain as one organism eats another.

4. Decomposers remove the last energy from the remains of organisms.

5. Inorganic nutrients are cycled, energy is not. Inorganic nutrients include amino acids, iron, phosphorous, and calcium for example.

3. Energy dynamics of living systems a. Autotrophs and heterotrophs b. Food chains A food chain is the path of food from a given final consumer back to a producer. For instance, a typical food chain in a field ecosystem might be: grass ---> grasshopper --> mouse ---> snake ---> hawk Organisms can be either producers or consumers in terms of energy flow through an ecosystem. consumer trophic level food source Herbivores primary plants

Carnivores secondary or higher animals

Omnivores all levels plants & animals

Detritivores ------detritus

A trophic level refers to the organisms position in the food chain. Autotrophs are at the base. Organisms that eat autotrophs are called herbivores or primary consumers. An organism that eats herbivores is a carnivore and a secondary consumer. c. Food webs

4. Cycling of matter a. Water cycle

b. Carbon cycle c. Nitrogen Cycle

d. The Oxygen Cycle: Photosynthesis and respiration

5. Ecosystem change a. Primary succession b. Secondary succession c. Climax Community Ecoregion Chart Nonliving Components Ecoregion and Descriptors Possible Organisms Grasslands Escarpment (cliff-like), buttes, Grass, mice, grasshoppers, soil, fire, wind prairie dogs,bull snake, red-tailed hawk, etc. Rainforest Humidity, heavy rainfall, soil, Fig tree, periwinkle, howler equatorial, nutrient pool, little monkey, toucan, beetle, tree frog, temperature variation jaguar, etc. Coniferous forest (cone Granite rock formations, rocky Pine tree, pine beetle, mosquito, bearing evergreens) soil, wind, snow, high deer, black bear, mountain lion, elevation etc. Deciduous forest (leaf Moderate rainfall, fertile soil, Oak tree, maple tree, squirrel, bearing) low elevation, temperature cicada, white-tailed deer, black variation bear, etc. Ocean Salt, coral reef, rock, sand, Plankton, coral, fish, whale, waves, wave action, wind shark, etc. Estuary, tide pool Mixing of salt and fresh water, Seligrase, reedgrass, clams, tides, nutrient-rich soil, high crayfish, fish, heron,l seagull, humidity starfish, seals, hermit crabs, etc. Arctic Glacier, high latitude, Forget-me-nots, musk ox, permafrost, low temperature, caribou, seal, wolf, polar bear, short growing season, wind etc Fresh water streams Water, rocks, gravel Algae, mayfly, dragonfly, fish, bald eagle, etc. Desert Low rainfall, intense sunlight, Cactus, gila monster, kangaroo, daily extreme variations in peccaries, road runner, coyote, temperature, sandy soil etc. Riparian (streamside) High water table, moderate Willow, cottonwood, birch, temperatures, banks rabbits, moose, raccoons, owls, etc. Wetlands Water high humidity, water- Cattails, redwind blackbirds, logged soil, nutrient-rich soil ducks, northern harrier, etc.

Vocabulary abiotic biotic carrying capacity community density-dependent factor ecology ecosystem exponential growth intertidal zone limiting factors logistic growth mortality parasitism predation biological magnification omnivore detritivores (decomposers) niche food chain succession primary consumers (herbivores) producers secondary consumers (carnivores)

Study Questions 1. What is the biosphere? Is it the same as the ecosphere?

2. What portion of the atmosphere, hydrosphere, and lithosphere permit life to exist? Why is life, as science knows it, only in a certain area?

3. Define population, community, and ecosystem ecology and clearly understand how they are distinguished from one another yet integrated. Give two examples of each.

4. Distinguish between exponential (J-shaped) growth and logistic (S-shaped) growth. What is the major difference between these two types of growth? Why does the human species appear to be characterized by the J-shaped curve?

5. What is carrying capacity?

6. What are the differences in regulation of population growth by density-dependent factors vs. density-independent factors?

7. Define succession. What factors lead to succession?

8. Define trophic level. Give examples of each of the following: producer, consumer, decomposer, detritivore.

9. In ecosystems, why do we refer to the concept that energy flows through the system but that chemicals (water, nitrogen, oxygen, carbon dioxide, etc.) cycle?

10. What are some of the consequences of the biological magnification of DDT, dioxan, or other highly toxic unnatural chemicals?

11. Why is it important that the "balance of nature" be maintained in natural ecosystems? Scientific Explanation: What is an ecosystem? The biosphere is the part of the Earth that contains all the living things on the planet. Each ecosystem that we study is a part of the biosphere. A system is a group of things that interact with one another. The organisms that make up the living part of an ecosystem are called biotic factors. An organism depends on other biotic factors for food, shelter, protection, and reproduction. Nonliving things that we find in an ecosystem are called abiotic factors. Abiotic factors have an effect on the type and number of organisms living in an ecosystem. Some abiotic factors include soil, water, temperature, and sunlight.

Pyramids

The concept of biomass is important. It is a general principle that the further removed a trophic level is from its source (detritus or producer), the less biomass it will contain (biomass here would refer to the combined weight of all the organisms in the trophic level). This reduction in biomass occurs for several reasons:

1. not everything in the lower levels gets eaten

2. not everything that is eaten is digested

3. energy is always being lost as heat

Biological Magnification

Biological magnification is the tendency of pollutants to become concentrated in successive trophic levels. Often, this is to the detriment of the organisms in which these materials concentrate, since the pollutants are often toxic. The "best" example of biomagnification comes from DDT. This long-lived pesticide (insecticide) has improved human health in many countries by killing insects such as mosquitoes that spread disease. On the other hand, DDT is effective in part because it does not break down in the environment. It is picked up by organisms in the environment and incorporated into fat. Even here, it does no real damage in many organisms (including humans). In others, however, DDT is deadly or may have more insidious, long-term effects. In birds, for instance, DDT interferes with the deposition of calcium in the shells of the bird's eggs. The eggs laid are very soft and easily broken; birds so afflicted are rarely able to raise young and this causes a decline in their numbers. This was so apparent in the early 1960's that it led the scientist Rachel Carson to postulate a "silent spring" without the sound of bird calls. Her book "Silent Spring" led to the banning of DDT, the search for pesticides that would not biomagnify, and the birth of the "modern" environmental movement in the 1960's. Birds such as the bald eagle have made comebacks in response to the banning of DDT in the US. Ironically, many of the pesticides which replaced DDT are more dangerous to humans, and, without DDT, disease (primarily in the tropics) claims more human lives. Carnivore 2

Carnivore 1

Herbivore

Autotrophs

=DDT Biological Magnification of DDT among trophic levels.

carrying capacity # of indivi- normal duals 25% death

time time

J-Curve(exponential growth) S-Curve (J-curves become S-curves when a population encounters one or more limiting factors)

* The human population doubles every 40-50 yrs.

Earth: A Human Concern Ch 49 I. Environmental philosophies A. Consumption philosophy B. Accountability philosophy C. Ecological facts of life 1. Environmental resilience vs. gradual or catastrophic change 2. Calculating real costs 3. Keystone species exist in all ecosystems 4. What goes up must come down--somewhere 5. Everything is connected 6. Man is a part of, not apart from, the biosphere D. Case studies 1. The ecological and moral consequence of human poverty 2. man-induced, rapid extinction of the earth's biota 3. Industrial development at the expense of humans, other animals and plants a. acid deposition (see chart at end of notes) b. plant stress c. biological magnification d. disease, human health impairment, mortality

II. The dilemma of human population growth A. Patterns over time B. Current patterns C. Factors influencing growth patterns 1. Agriculture 2. The industrial revolution 3. Improved sanitation and disease control 4. Improved nutrition 5. Improved educational opportunities D. Predicting growth potential of human populations using age distribution patterns E. Population growth, resource consumption and environmental degradation E. Case study 1. The People's Republic of China- population F. Pollution 1. Acid Rain a. Fossil fuel/industry

b. NO2, SO2 gasses become acidic c. United States and Germany- acid rain of the Black Forest 2. Ozone Depletion

CFC’s – Cl reacting with O3 3. Smog PM10 precipitating smog 4. Global Warming a. Fossil fuels

b. CO2 gasses accumulate and trap heat in the atmosphere c. Called the greenhouse effect Vocabulary poverty: pollution: catastrophic change: PM10: biodiversity: primary pollutant: age distributions: secondary pollutant: consumtion philosophy: biological magnification: environmental resilience: real costs: Keystone species: "gradual" factors: acid deposition:

SO2: oxides of nitrogen: fossil fuels: ozone: chloroflourocarbons: Cl: greenhouse effect: global warming:

Study Questions 1- Several of the compounds or particles we call pollutants are produced by plants and animals naturally. Why are they listed as pollutants if they are "natural" products?

2- How do you suppose that "indoor" pollution differs from "outdoor" pollution?

3- How can "heat" become a pollution?

4- What is your exact feeling about the environmental concerns of the earth? Are there any real concerns or problems that cannot be solved by science and technological breakthroughs? How about specifically here in NV?

5- Is there really a dilemma related to human population growth? Explain.

6- Can we afford to wait for this uncontrolled experiment to run its course?

7- What can you do? Do you want to do anything about pollution?-- decreasing biodiversity?-- poverty? Vermont Washington Maine Minnesota Montana North Dakota

Oregon Wisconsin New York Idaho South Dakota Michigan

Wyoming Pennsylvania Iowa Nebraska Ohio Nevada Illinois Indiana West Utah Colorado Virginia Virginia Kansas California Missouri Kentucky North Carolina Tennessee South Arizona Oklahoma Arkansas New Mexico Carolina

Mississippi Georgia Alabama Texas Florida Louisiana

* Moderate to high acidity Very high acidity Areas sensitive to acid (pH 4.5-5.0) (pH 4.2-4.4)