ECOLOGY AND ECOSYSTEMS UNIT

WHAT IS ECOLOGY?

1. Ecology comes from the GREEK Words OIKOS (HOUSE OR PLACE WHERE ONE LIVES) and LOGOS (STUDY OF).

2. Ecology then means the Study of the “House” in which We Live.

3. Ecology can be defined more specifically as the Study of the Interactions between Organisms and the Nonliving Components of their Environment.

4. The Earth includes a tremendous variety of living things. Each organism Depends in some way on other living and nonliving things in its Environment.

5. Ecology involves collecting information about organisms and their environment, looking for patterns, and seeking to explain these patterns.

LEVELS OF ORGANIZATION

1. The surface of the Earth as a whole is an Ecosystem.  We call the Surface of the Earth the BIOSPHERE.

2. The Biosphere is the surface of the Earth (AIR, WATER, and LAND) Where Living Things Exist.

4. The Biosphere is composed of smaller units called ECOSYSTEMS. An Ecosystem includes all the Organisms and the Nonliving Environment found in a particular place.

3. Ecosystems can be as large or as small as we decide.  Any area you decide to Study can be considered an Ecosystem.

4. For example you may choose to study your back yard, Hackberry Flats, Fort Sill range or the Wild Life Refuge. Any of these would be considered an Ecosystem.

5.  A Population includes all the members of the Same Species that Live in one place at one time.

6. Populations are individual species, all the interacting Organisms (All The Different Populations) that live in a particular area make up a COMMUNITY. The Physical Location of a Community is called the HABITAT.

7. The simplest Level of Organization in Ecology is that of the ORGANISM.

8. The Diversity of an Ecosystem is a measure of the number of different species there, and how common each species is.

9. Ecosystems are very Complex.  They can contain hundreds or even thousands of interacting species.

THE NICHE

1. Each Organism or Species in the Community has a ROLE or PROFESSION in that Community and in Ecology this is the Organisms NICHE.

2. A species’ Niche is its way of life, or the role the species plays in its Environment.

3. The Niche includes the range of conditions that the species can tolerate, the methods by which it obtains needed resources, the number of offspring it has, its time of reproduction and all its other interaction with its environment.

4. The FUNDAMENTAL NICHE is the Range of Conditions that a species can Potentially Tolerate and the Range of Resources it can Potentially Use.

5. The REALIZED NICHE of a species is the Range of Resources It Actually Uses.

6. GENERALIST are species with Broad Niches; they can tolerate a range of conditions and use a variety of resources. Species that have narrow Niches, such as the Koala, are called SPECIALIST.

BIOTIC AND ABIOTIC FACTORS

1. An Ecosystem possesses both LIVING COMPONENTS OR BIOTIC FACTORS and NONLIVING OR ABIOTIC FACTORS.

2. The Nonliving Factors, called Abiotic Factors, are Physical and Chemical Characteristics of the environment. They include Solar Energy (Amount of Sun Light), Oxygen, CO2, Water, Temperature, Humidity, pH, and availability of Nitrogen.

3. The Living Components of the environment are called Biotic Factors. They include all the Living Things that affect an organism. Biotic Components are often categorized as Producers, Consumers, and Decomposer.

FLOW OF ENERGY IN ECOSYSTEMS

1. The MOST Important Factor Determining HOW MANY and WHAT KIND of Organisms that can live in an Ecosystem is the amount of ENERGY Available.

2. The amount of energy an Ecosystem receives and the amount that is transferred from organism to organism has an important effect on the Ecosystem’s structure.

3. All Organisms need Energy to carry out essential functions, such as growth, movement, maintenance and repair, and reproduction.

4. Energy in an Ecosystem FLOWS from the SUN to Autotrophs (Producers) then to Organisms that Eat the Autotrophs, then to Organisms that feed on other Organisms (Consumers).

5. The Primary Source of Energy for an Ecosystem is the SUN.

6. Producers are Autotrophic Organisms (Autotrophs) with the capability of carrying out Photosynthesis, and making food for themselves and storing some for other Organisms to consume.  Examples are plants, some bacteria, and algae.

7. All Other Organisms in Ecosystem are Consumers or Heterotrophs that eat the Producers or other Organisms.

8. Heterotrophs or Consumers can be broken into different groups depending on what they EAT:

    A. Decomposers – Consumers who feed on Remains of Dead Plants and Animals.

    B. Herbivores – Eat Producers or Plant Eaters.

    C. Carnivores – Eat other Consumers. Meat Eaters.

    D. Omnivores – Eat Both Producers and Consumers. Plant and Meat Eaters (US).

    E. Detritivores – Feed on the “Garbage” of an Ecosystem.

9. In an Ecosystem these Producers and Consumers are placed in Trophic Levels (Feeding Levels).

10. A Trophic Level is a group of organisms whose feeding source is the same number of steps from the Sun.

    A. Producers (Autotrophs) are the First Trophic Level.

    B.  Herbivores are the Second Trophic Level.

    C.  Carnivores are the Third, Forth and Fifth Trophic Levels.

11. Most Animals (Carnivores) feed at more than one Trophic Level.

12. Energy Flows through an Ecosystem in a Complex Network of Feeding relationships called a FOOD WEB. 

13. A FOOD CHAIN indicates who eats whom in an Ecosystem.  A Food Web may contain several Food Chains.

14. Energy is Lost or Used as it Flows through the Trophic Levels of an Ecosystem.

15.  Producers (Plants) absorb Energy from the Sun, but only about ½ of the Energy capture from the Sun becomes part of the Plants Body.  The other ½ is used for Living and Growing or Lost as HEAT.

16.  At each Trophic Level, the Energy stored in an organism is about 1/10 that of the Level Below it.  (10%).

17.  Because Energy diminishes at each successive Trophic Level, Few Ecosystems can contain more than 4 or 5 Trophic Levels.

18. Organisms at Higher Trophic Levels, Large Carnivores, tend to be Fewer in number than those at Lower Trophic Levels, Producers.

NUTRIENT CYCLES WITHIN ECOSYSTEMS

1. Energy Flows through an Ecosystem and Nutrients Cycle in an Ecosystem.

2. In an Ecosystem the Three Primary Nutrient Cycles:
    A. The Water Cycle
    B. The Carbon Cycle
    C. The Nitrogen Cycle

THE WATER CYCLE

1. To a large degree, availability of Water determines the Diversity of Organisms in an Ecosystem. Water is crucial to Life. Cells contain 70 percent to 90 percent water, and water provides the Aqueous environment in which most of Life’s reactions occur.

2. The Availability of WATER is one of the Key Factors that regulate the Productivity of Terrestrial (Land) Ecosystems.

3. Bodies of Water such as Lakes, Rivers, Streams, and the Oceans contain a substantial percentage of the Earth’s Water. The atmosphere also contains Water – in the form of Water Vapor, some water is found below ground known as Ground Water.

4.  The Movement of Water between these different reservoirs is known as the Water Cycle.

5. The Water Cycle Usually Consists of the following steps:

    A. EVAPORATION from lakes, rivers, and oceans.  OR/AND

    B. TRANSPIRATION from plants and trees.

    C. CONDENSATION – Cloud Formation

    D. PRECIPITATION – Rain, Snow, Sleet, Hail.

    E. RUN OFF, or RETURNED back into the Cycle.

THE CARBON CYCLE

1. Together, Photosynthesis and Cellular Respiration Form the Basis of the Carbon Cycle.

2. The Earth’s atmosphere contains Carbon in the form of Carbon Dioxide (CO2).

2. During Photosynthesis, Plants and other Autotrophs use CO2 along with Water and Solar Energy, to Build Organic Molecules (Carbohydrates), Thus storing the Carbon for themselves and other Organisms.

3. Both Autotrophs and Heterotrophs use Oxygen to break down Carbohydrates during Cellular Respiration.

4. Consumers obtain Energy-Rich molecules that contain Carbon by Eating Plants and Animals.

5. Carbon is return to the environment through decomposers and cellular respiration (breathing releases CO2 back to the atmosphere).

6. Large amounts of Carbon are tied up in Wood, only returning to the atmosphere when wood is burned.

THE NITROGEN CYCLE

1.  ALL Organisms need Nitrogen, an important nutrient, to make Proteins and Nucleic Acids.

2. Most Nitrogen is found in the Atmosphere (80%) as N2, and most living things cannot use it. ALL Organisms rely on the actions of Bacteria that are able to transform Nitrogen Gas into a Usable Form.

3. Nitrogen Fixing Bacteria (Cyanobacteria and Rhizobium) play a key role in the Nitrogen Cycle. They live in the soil and in the roots of some kinds of plants, such as beans, peas, clover, and alfalfa. These Bacteria have Enzymes that can break the atmospheric N2 bonds. Nitrogen Atoms are then free to bond with Hydrogen atoms to form Ammonia (NH3).

4. Conversion of Nitrogen Gas to Ammonia is called Nitrogen Fixation.

5. Ammonia can be absorbed by Plants from the Soil, and used to make Proteins, and enter the Food Web for Consumers.

7. Consumers obtain Nitrogen from Eating the Plants and Animals they eat.

8. Decomposers return the Nitrogen back to the soil from the remains of dead plants and animals.  Nitrogen is also return from animal and plant waste by decomposers (dung, urine, leaves and bark). This process is known as AMMONIFICATION.

9. Through Ammonification, Nitrogen that would be lost, is recycled back into the Ecosystem.

10. Nitrogen is returned to the Atmosphere through DENITRIFICATION. Denitrification occurs when Anaerobic Bacteria (Chemoautotrophs) break down Nitrates and release Nitrogen Gas back into the Atmosphere.

11.  Plants can absorb nitrates and ammonia from the soil, but Animals (Including Ourselves) CANNOT.

12. Animals, including ourselves, obtain Nitrogen in the Same Way we Obtain Energy – By Eating Plants and Other Organisms and then digesting the Proteins and Nucleic Acids.

13.  Autotrophs (Plants) are therefore DEPENDENT on Nitrogen Fixing Bacteria, and All other Organisms including YOU Are DEPENDENT ON THEM!

KINDS OF ECOSYSTEMS

1. The THREE Types of Ecosystems are:

    A. TERRESTRIAL ECOSYSTEMS (LAND MASSES)

    B. FRESH WATER ECOSYSTEMS

    C. OCEAN ECOSYSTEMS

2. The Terrestrial Ecosystems are divided into 7 wide areas of land called BIOMES.  Biomes are very large terrestrial ecosystems that contain a number of smaller but related ecosystems within them.

3. A certain biome may exist in more than one location on Earth, but similar biomes have similar climates, and tend to have inhabitants with similar adaptations.

4. Biomes are distinguished by the presence of Characteristic Plants and Animals, but they are commonly identified by their Dominant Plant Life.

5. The SEVEN LAND BIOMES ARE:

    1. Tropical Rain Forrest
    2. Savannas
    3. Deserts
    4. Grasslands
    5. Deciduous Forrest
    6. Coniferous Forrest or Taiga or Evergreen Forest
    7. Tundra