Ecosystem

What is an Ecosystem?

An ecosystem includes:

  • All the living things in a given area –

    • Organisms such as plants & animals interacting with each other and their…

    • Nonliving environments such as the weather, Earth, Sun, soil, climate, and atmosphere.

In an ecosystem, each organism has its own niche or role to play.

Biotic & Abiotic Factors

Biotic Factors

  • Living things in an ecosystem that compete with one another for food.

  • Examples:

    • Fungi, bacteria, plants, archaea, animals, protists, and more.

Abiotic Factors

  • Nonliving things in an ecosystem.

  • Examples:

    • Air, salinity, soil, temperature, light, water, minerals, pH, humidity, and more.

FOOD = STORED CHEMICAL ENERGY

Food Chains & Food Webs

How organisms get food is how energy moves through an ecosystem. This flow of energy is called the food chain.


A food web is an interconnected set of food chains because organisms can eat more than one thing! It is the flow of energy through MULTIPLE PATHWAYS.


  • Plants

    • Plants transform the sun’s energy into food/energy/sugar for itself

    • Plants are producers/autotrophs, meaning they produce their own food.


Autotrophs

  • AKA producers.

  • They produce their own food and store their energy from sunlight through photosynthesis.

Heterotrophs

  • AKA consumers

  • An organism that eats other plants or animals for energy or nutrients.

Interdependence

  • Heterotrophs are dependent on autotrophs for food.

    • Directly: by eating a plant

    • Indirectly: by eating an animal which gained its energy from eating a plant.

  • Autotrophs are dependent on heterotrophs.

    • Specifically, decomposers to return energy to the soil.

Producers

  • Producers are organisms that get their energy directly from the Sun. Their cells are able to turn sunlight into food through a process called PHOTOSYNTHESIS.

  • In photosynthesis, producers combine carbon dioxide, water and sunlight to produce oxygen & sugar.

  • THAT SUGAR IS THEIR FOOD!

  • Other organisms get energy by eating producers/plants.

    • Think of when you eat lettuce or another vegetable. You are eating a producer! The lettuce plant converts sunlight into food that your body uses as energy.

  • Without producers, life on Earth could not exist.

*** The formula for Photosynthesis:

  • Photosynthesis takes solar energy and transforms it into stored chemical energy in the form of glucose/sugar.

    • Energy is never created or destroyed. It only changes form.

  • The formula for photosynthesis is the process that plants undergo to transform the Sun’s energy into glucose.

  • Plant sugars are stored chemical energy in the stems, leaves, roots, and fruit of the plant.

    • Sugars = food = energy

  • Plants are living.

  • They use nonliving components such as sunlight, water, and carbon dioxide to produce nonliving food and oxygen.

  • It must interact with its ecosystem to live.

Food Web

  • A food web is a group of overlapping food chains with different pathways to show the flow of energy in an ecosystem. The energy starts with the sun.

The Ecosystem is a Living System!!

  • The ecosystem includes interaction between biotic and abiotic parts.

  • Energy is transported and transformed through the system.

  • Energy moves in only one direction through the levels of an ecosystem.

  • Energy is passed from lower to higher trophic levels in an ecosystem. As food energy flows through an ecosystem, some of it is released into the environment as thermal energy. This is commonly called heat.

  • The rest of the energy is used by the organism for life processes.

Trophic Levels

  • Each tier in the pyramid is called a trophic level.

  • Energy starts at the bottom and flows upward.

  • The greatest amount of energy is at the bottom of the trophic level.

  • The least amount of energy is at the top of the trophic level.

  • This is why it takes many producers to support a small number of top level consumers.

  • So, since producers have the most energy in a food chain or web, the give an organism more energy than a primary consumer or secondary consumer would.


ENERGY IS LOST AT EACH TROPHIC LEVEL!

  • Up to 90% of energy is used up at each trophic level by organisms for life processes such as metabolism, heating, reproduction, etc.

  • Approximately only 10% is available for the next level.

2 Big Ideas

  1. The direction of the arrow in a food web shows the direction of the flow of energy.

  2. A food web always starts with a producer getting energy from the sun. Producers/plants serve as the energy bridge from the sun to all other organisms.

10% Rule in Food Chains

  • The 10% rule in a food chain is a law that explains that each trophic level transfers 10% of its energy to the level above them in the food chain. The other 90% of their energy is lost as heat or used for growth and reproduction.

  • What about the other 90%? They are used for life processes!

Matter & Energy in Ecosystems

** Consumers

  • Unlike producers, consumers do not produce their own energy-rich food.

  • A consumer is an organism that can’t make its own food and gets energy by eating other organisms.

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  • When an animal population in an ecosystem eat too many plants it throws off the balance of the ecosystem.

  • Another population might not get enough food.

  • Soil may erode because there are no roots to hold it in place.

  • Highways cutting through ecosystems can separate animals from their food.

  • And they can be deadly to cross.

  • Deforestation refers to the decrease in forest areas around the world that are lost for other uses such as farmlands, urbanization, or mining activities.

  • Greatly accelerated by humans since 1960, deforestation has been negatively affecting natural ecosystems, biodiversity, and the climate.

  • Farms are human-made. Go figure.

  • Farms cause changes in an ecosystem by decreasing plant populations and changing the soil.

  • When we clear land for farming, we often lose some soil

  • The plants originally on this land are gone, and what replaces them may be plants that aren’t as good as holding on to the soil and its nutrients.

  • So, the soil may not be as good.

  • An invasive species is sometimes introduced into an ecosystem

  • The invasive species can take up food, water, and space needed by an organism that was already there. This can be deadly.

  • Changes to an ecosystem occur when:

    • Invasive species are introduced (plant or animal)

    • When humans mine for minerals and fossil fuels.

      • Land & soil is disrupted

      • This affects the organisms in the area

    • When humans cut down forests

    • When humans introduce pesticides or fertilizers.

      • Pesticides kill organisms.

      • Fertilizers can make things grow out of balance.

  • Remember, think of a habitat as the special place in a community in which a plant or animal lives.

  • An ecosystem is a community of living and nonliving things that work together.

  • N ecosystem is basically the neighborhood where animal lives.

  • The habitat is the animal’s address in that neighborhood.

4 Main Cycles

Water Cycle

  • Water is matter that cycles because matter cannot be created nor destroyed.

  • Water moves continuously through ecosystems. It is recycled over and over.

  • This movement of water isc allied the water cycle and involves 3 main processes:

    • Evaporation

      • The process that changes liquid water into gaseous water (liquid vapor)

    • Condensation

      • The process of water vapor turning back into liquid water

    • Precipitation

      • Water released from clouds in the form of rain, freezing rain, sleet, snow, or hail.

      • This is the way that most atmospheric water returns to the Earth’s surface.

Oxygen Cycle

  • Oxygen is matter that cycles.

  • Like water, oxygen also cycles through the environment and is crucial for the survival of all organisms.

  • Plants release oxygen as a waste product of photosynthesis.

    • This is the primary source of oxygen in Earth’s atmosphere.

  • When consumers breathe, they take in oxygen. Then their blood carries the oxygen to all parts of their body. When they exhale, consumers release carbon dioxide. This contains oxygen.

  • Producers take in carbon dioxide. This cycles oxygen through the ecosystem.

  • Decomposition is another part of the oxygen cycle that contributes to the sustainability of ecosystems.

    • Decomposition is the breaking down of dead organisms and organic waste. When animals and plants die, they are broken down by a type of consumer called decomposers. Have you ever noticed fungi covering a decaying tree or log? These fungi are a type of decomposition. DECOMPOSERS NEED OXYGEN TO CARRY OUT DECOMPOSITION.

    • As organisms decay into the ground, oxygen, carbon dioxide, and water are returned to the soil and air. This continues the oxygen cycle.

Carbon Cycle

  • Carbon is matter that cycles.

  • Carbon is a fundamental building block for all living things.

  • All organisms contain carbon.

    • Some organisms get carbon from food. This includes humans.

    • Other organisms get carbon from the atmosphere or bodies of water. Plants are an example.

    • Like other types of matte,r carbon cycles through ecosystems. This continuous recycling of matter helps to keep the ecosystem sustainable.

  • Carbon in the soil.

    • LIke oxygen, carbon can enter the environment when organisms die and decompose, This returns carbon compounds to the osi And it releases carbon dioxide into the atmosphere for use by other organisms.

  • Carbon in the Air:

    • Carbon is found in the atmosphere as carbon dioxide. Plants and other products take in carbon dioxide and water during photosynthesis. They use it to produce energy-rich sugars. Theses sugars are a source of carbon and energy for organisms that eat producers. When sugar is broken down by cells and its energy is released, carbon dioxide is released as a by-product. This carbon dioxide enters the atmosphere. It is recycled and used again.

  • Due to both human and natural activities, the amount of carbon dioxide in the air has increased and continues to increase.

Nitrogen Cycle

  • Nitrogen is matter that cycles.

  • The element nitrogen is important, too. It is recycled in ecosystems between Earth & its atmosphere.

  • There is lots of nitrogen in the atmosphere, but it is in a form that plants and animals can’t use.

  • Decomposers break down nitrogen into a usable form!