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EC: Niche and Nutrient Cycling Lesson

There's No Place Like My Niche!

Where is your home? What is your job? What do you eat? All animals, not just humans, have a role they play in the environment. This is called their niche. 

Niche Notes

There are two types of niches that exist:

  1. The fundamental niche is the range of conditions that a species can potentially tolerate and the range of resources it can potentially use.
  2. The realized niche of a species is the range of resources it actually uses. It is the result of competition for resources or other interactions with organisms in the ecosystem.

Follow the presentation below to learn more about the niche. 

Energy Flow - It's a One-Way Street

Energy flows in one direction in the ecosystem. It cannot be recycled.

Matter, on the other hand, can be recycled. Nearly all living things are composed of four elements: carbon, hydrogen, oxygen, and nitrogen. This cycling of elements and chemical compounds among organisms and their environment in the biosphere is what allows life to continue on Earth.

There are three major nutrient cycles ecologists study:

  1. Water Cycle
  2. Carbon Cycle
  3. Nitrogen Cycle

Each of these cycles is best represented by a visual model, or diagram, that represents how that nutrient moves through living things and their environment. The cycles show close ties among all the pieces of the ecosystem and allow ecologists to make predictions about the impact of events. For example, if trees are lost due to a hurricane, there might be less transpiration. This could affect rainfall in the ecosystem.

Water Cycle

The water cycle is the movement of water between different reservoirs (earth, atmosphere, ground). Recall that cells are about 70-90% water; water is essential to life because most of life's processes (in the cell) occur in an aqueous environment. The availability of water within an ecosystem will determine how diverse and productive that ecosystem is.

Study the model below of the water cycle. Hover over each number to learn about major processes in the water cycle. You will be responsible for understanding each and how they cooperate to complete the water cycle.

The Water Cycle, description of diagram below

See description of diagram Links to an external site.

Hydrologic Cycle

 

Carbon Cycle

Recall that photosynthesis and cellular respiration form the basis of the carbon cycle. Carbon is found in all of the major macromolecules (carbohydrates, nucleic acids, proteins, and lipids) which are necessary for all living systems.

The Earth's atmosphere contains carbon in the form of carbon dioxide (CO2). There are five major reservoirs of carbon:

  1. the atmosphere
  2. the terrestrial biosphere
  3. oceans
  4. ocean sediments and
  5. the earth's interior.

See description of diagram Links to an external site.

Nitrogen Cycle

All organisms need nitrogen, an important nutrient, to make proteins and nucleic acids.

See description of diagram Links to an external site.

The major reservoir for nitrogen is in the atmosphere (80%) as N2 gas. Most living things cannot use this nitrogen gas directly. Fortunately, there are bacteria that can transform nitrogen gas into a form that is useable.

Nitrogen-fixing bacteria (Cyanobacteria and Rhizobium) play a key role in the nitrogen cycle.

Challenge and Before You Go

Practice Time! Use the knowledge you learned from the lesson to complete the practice activities below.

Before You Go - You Need To Know

The following key points are from the explore section of the lesson. You must know the following information before moving to the next lesson. This is just a summary of the key points.

  1. What is the difference between habitat and niche?
    • A habitat is where the organism lives, such as the forest. A niche is a role the organism plays in the environment (where it lives, what it eats, what eats it, when is it active, etc).
  2. Is energy recycled?
    • No
  3. What are the three major nutrients that are cycled?
    • Water, carbon, and nitrogen
  4. What is nitrogen fixation?
    • When bacteria change nitrogen gas into a form of nitrogen that organisms can use
  5. Where is most of the Earth's water located?
    • Oceans contain 96.5% of the water supply.
  6. Can you name the top three locations?
    • Oceans (96.5%), Glaciers/ice caps (1.7%), Groundwater (1/6%)

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