Ecosystems

Ecosystems

A complex system which examines the relationships between a community, and the relationships with these organisms have with non-living components of the same environment

• Healthy ecosystems can help clean our water, purify our air, maintain soil, regulate climate, recycle nutrients and provide us with food

• A larger ecosystem (e.g. rainforests), can also contain smaller ecosystems within

Energy flow:

• All organisms in an ecosystem require energy. The source of almost all the energy can be traced back to the sun

• The sun’s radiant energy1 provides us with invisible energy (e.g. UV rays) and visible/light energy

• Almost 70%of the sun’s energy is absorbed by the Earth and converted into thermal energy2, the other 30%is reflected by the clouds or Earth’s surface and a very miniscule amount is absorbed by plants

There are different “spheres” that make up the earth. Atmosphere, lithosphere, hydrosphere and biosphere. Air, earth (as in soil), water and habitats respectfully.

*Look in “Keywords” below to see more in depth definitions.

Keywords:

Atmosphere — the layer of gasses extending upwards from the surface of the Earth

• It is essential to our survival as it regulates the temperature of the Earth and blocks UV rays

Lithosphere — the rocky outer shell of Earth that makes up the Earth’s soil and landscape

Hydrosphere — all the water on, above or below the Earth’s surface

Biosphere — where living organisms can be found in the above three spheres

Species — a group of similar organisms that can reproduce and whose offspring can reproduce

Population — all members of the same species that can be found in the same area

Biotic factors — living components in an ecosystem 

Abiotic factors — non living “ ”

Carrying capacity — the maximum population size of a biological species that can be sustained by that specific environment

1Radiant energy — the energy that travels through empty space

2Thermal energy — the energy that helps warm up the atmosphere, water and essentially Earth itself

Relationships

The different relationships and/or interactions between different organisms with each other and their environment

• All living things need energy to survive, and they need extra energy to grow and reproduce

• They use whatever abilities they have to get energy they need to survive and thrive

• Energy of the sun flows into biotic components of the ecosystem through the process of photosynthesis

• Producers are responsible for the process where the energy from the sunlight and abiotic components(nutrients) are combined to produce sugar (and oxygen is a byproduct of this), this process is more commonly known as photosynthesis

• The producers use sugar to survive just as other organisms do, and the extra sugar is stored as starch or is used to grow and reproduce

To help keep a balance in ecosystems, there are things called food webs and food chains (that make up the food web).

Levels of the food chain (top to bottom):

There are two main roles, consumers3 and producers. The consumers are also split up into different levels.

Tertiary consumers (L4)

• An organism that consumes secondary consumers

• Carnivores

• Examples: pumas, wolves, eagles

Secondary consumers (L3)

• An organism that consumes the primary consumers

• Carnivores

• Examples: snakes, spiders, seals

Primary consumers (L2)

• An organism that consumes the producers

• Herbivores

• Examples: rabbits, grasshoppers, deer

Producers (L1)

• Any organism that can produce food for itself 

• Goes through a process called photosynthesis4

• Is the bottom of the food chain and is consumed by primary consumers

• Examples: grass, trees

*Note: an organism’s role in the food chain can change if they are an omnivore. They can be any of the three consumers depending on the order in which the food chain is described, but they generally occupy the third trophic level (tertiary consumers).

Examples: bears, birds, raccoons

Only a fraction of the energy is passed up each level. Only around 10%.

L1 to L2 (10% of 1,000), L2 to L3 (10% of 100), L3 to L4 (10% of 10)

Reasons why only 10% gets passed on:

• Organisms don’t eat every part of their prey

• May not have absorbed (e.g. when it gets pooped out)/wasted

• Some parts gets used up for respiration

Since the food chain/web is very dependent on each of its levels, if a species's population grows/declines/completely dies out, the species that are connected to the affected one’s population will also waver. Through time, the food chain will adapt and become balanced once again.

Keywords:

3Consumers — organisms that cannot make their own energy, and therefore, must consume other organisms and must undergo cellular respiration to obtain energy

Indicator species — a species whose status provides information on the overall condition of the ecosystem and of other species in that ecosystem

• They reflect the quality and changes in environmental conditions as well as aspects of community composition

4Photosynthesis — the process by which the producers produce their own food

• Equation: Carbon dioxide + Water (with the help of light energy) = Sugar + Oxygen

• The sugar produced can be stored, used for carbohydrates, or converted to starch for long term storage

Cellular Respiration — “ ” plants use up the stored/produced sugar. It is a complementary reaction to the previous process

• Equation: Sugar + Oxygen = Carbon dioxide + Water + Energy

Biomasses — mass of living organisms

• The total biomass of each trophic level decreases as you go up

Ecologists — a person who studies how different living things obtain their food and the relationships that organisms have between each other as a result of this primal need for energy

Niche — the sort of role or job that a species plays in the very complex set of interactions that exist in an ecosystem

• Also defined as the way in which an organism interacts with other species as well as with their environment

Symbiotic relationships — a relationship between two different species (and is split into several different categories of relationships)

• Mutualism = benefit to both organisms

• Commensalism = one organism benefits while the other is neither benefited nor harmed

• Parasitism = one organism benefits and the other is harmed

• Competition = both organisms are harmed

Carbon Cycle

The cycle in which carbon goes through (much like the water cycle)

Cycle steps:

1. Burning of fossil fuels (boats, factories, etc.)

2. CO2 in atmosphere

3. Photosynthesis (to help plants grow/reproduce)

4. Food chain (where animals eat the plants)

5. Animal dies/decaying organisms

6. Turns into fossils and fossil fuels

*Note: this is a simplified version of the cycle as it branches out to different scenarios and not strictly the ones stated above. The one listed happens to be the most common.

• Carbon is an important element, because it is the basic building block of all living things

• It is recycled in the cycle through photosynthesis and respiration

• There are two types of carbon. Inorganic (the ocean or the Earth’s crust), and organic (such as bodies of living things and fossil fuels

• When living organism die, their carbon molecules are returned to the soil by decomposers and are released to the air as carbon dioxide

Carbon is used in…

• Photosynthesis & Respiration

• In animal shells

• Getting energy (e.g. fossil fuels)

Keywords:

Nitrogen fixation — when atmospheric nitrogen is converted into unstable nitrogen

Denitrification — when nitrogen is put back into the air