Ecology - Chapter 1

Definition: A biological community, it's environment, and all of the parts in it

Example: Rainforests, lakes, and grasslands are all examples of ecosystems.

• The prefix eco- is from the ancient Greek word for home, because ecosystems are the natural homes of organisms in them
• Ecosystems must be sustainable for survival of organisms
• All ecosystems have biotic (living) and abiotic (non-living) parts
• Ecosystems can be large and small
• Many organisms depend on multiple ecosystems to survive (example: migratory birds)

Definition: An ecosystem that can constantly support many different organisms by itself

Example: A lake with a healthy amount of different organisms (fish, plants, etc.) and enough resources to support them all (light, clean water, etc.).

• The word sustain has two meanings to endure (to continue in the same state) and to support
• All organisms require sustainable ecosystems for survival
• The more sustainable an ecosystem is the more chance for organisms to survive and thrive

Definition: All of the parts of an ecosystem that are living, and the interactions among these parts

Example: Anything in an ecosystem that lives is a biotic part of that ecosystem. Trees, grasshoppers, mushrooms, and bacteria are all examples of biotic parts.

• Biotic Characteristics also include all of the interactions among the living things in the ecosystem, such as symbiosis, predation and competition.
• Symbiosis: the interaction between two different species that have a close association (example: mushroom fairy rings)
• Predation: when an organism consumes another organism for food (example: a wolf eating a deer)
• Competition: when multiple organisms compete for the same resource(s) (example: bears and birds competing for salmon, their food source)

Definition: All of the parts of an ecosystem that are non-living; the abiotic parts of an ecosystem are needed by living organisms to live

Example: Water, oxygen, light, nutrients (see Nutrients for more details), and soil are all examples of abiotic characteristics.

• The lithosphere, hydrosphere, and atmosphere are all abiotic spheres. (see Lithosphere, Hydrosphere, Atmosphere and diagram below for more details)
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• The water cycle, carbon cycle, nitrogen cycle, and phosphorus cycle are all important abiotic cycles

Definition: the land of Earth's surface; all of the Earth's surface that isn't water

Example: As said in the definition, anything that is Earth's surface that isn't water. For example, hills, valleys, rocks, deserts, and mountains are all part of the lithosphere.

• The prefix litho- comes from the Greek word "lithos", meaning stone or rock
• The water cycle, the carbon cycle, the nitrogen cycle, and the phosphorus cycle all involve the lithosphere in some way.

Definition: all the water found on Earth's surface; all of the Earth's surface that isn't land


Example: As said in the definition, anything that is Earth's surface that isn't land. For example, oceans, ponds, seas, rivers, and lakes are all part of the hydrosphere.

• The prefix hydro- comes from the Greek word "hydro", meaning water
• The water cycle, the nitrogen cycle, and the phosphorus cycle all involve the hydrosphere in some way.

Definition: the gases above the Earth's surface; air

Example: Earth's atmosphere contains various gases, including oxygen, nitrogen, and carbon dioxide.

• The prefix atmos- comes from the Greek word "atmos", meaning vapour
• The water cycle, the carbon cycle, the nitrogen cycle all involve the hydrosphere in some way.

Definition: All the places on Earth occupied by living organisms

Example: The Earth's ecosystems are part of the biosphere, because organisms live in ecosystems.

• The prefix bio- comes from the Greek word "bios", meaning life
• Unlike the lithosphere, hydrosphere, and atmosphere, which are all abiotic spheres, the biosphere is a biotic sphere

Definition: chemicals needed for organisms to survive that cycle through ecosystems

Example: Water, carbon, nitrogen, and phosphorus are all examples of nutrients.

• Nutrients are one of the abiotic characteristics of an ecosystem
• Nutrients are reused, due to multiple nutrient cycles (example: the carbon cycle, as seen below)
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• When an excessive amount of nutrients is added to an aquatic ecosystem, eutrophication occurs (see Eutrophication for more details)

Definition: a process that occurs when an excessive amount of nutrients are added to an aquatic ecosystem, causing excessive growth of plants

Example: If excess phosphorus leaked into a lake, algae would grow at an increased rate. Because there is more algae than usual, less light reaches other plants. This causes these plants to die. When the algae dies, the oxygen levels of the ecosystem will decrease to the point that the other organisms in the lake die too.

• Phosphorus is the main nutrient that causes eutrophication
• Eutrophication is often caused by humans
• Fertilizers containing phosphorus from nearby farmlands often run-off into lakes
• See diagram below for more details
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Definition: A process that converts energy from the Sun into useable chemical energy

Example: Organisms that contain chlorophyll use carbon dioxide, water, and light in the process of photosynthesis. These organisms depend on photosynthesis to generate glucose (their source of energy) and oxygen.

• Carbon dioxide, water, light energy, and chlorophyll are needed for photosynthesis, and are converted to become glucose and oxygen (see diagram below)
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• Glucose is a carbohydrate, which is made from carbon, oxygen, and hydrogen. Plants get carbon and oxygen from carbon dioxide, and hydrogen from water.
• Plants get water mostly through their roots, and carbon dioxide through pores in their leaves called stomata
• The more chlorophyll-containing organisms there are in an area, the more oxygen is generated
• In aquatic ecosystems, photosynthesis is mostly performed by phytoplankton

Definition: A group of organisms that gain the energy the same way; organisms that share the same trophic level also share the same place on a food chain

Example: A tree (a primary producer, making it an organism on the first trophic) gains it's energy from the Sun's energy. A grasshopper (a primary consumer, thus putting it in the second trophic level) consumes a few leaves off the tree, gaining some energy from the tree. A bluebird, an organism on the third trophic level, consumes the grasshopper, gaining some of the grasshopper's energy.

• Plants are primary producers, and make their own food. (see Photosynthesis for more details)
• All animals (including humans) are consumers, because they consume other organisms to gain energy
• Consumers that only eat animals are called carnivores
• Consumers that only eat plants are called herbivores
• Consumers that eat both animals and plants are called omnivores
• Food chains, like the one below, can be used to represent trophic levels
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• There are less organisms at higher trophic levels because of trophic efficiency (see Trophic efficiency for more details)

Definition: The mass of all living organisms in a group or area

Example: The grass biomass of an ecosystem refers to the mass of all the grass in an ecosystem.

• The energy stored in biomass moves through trophic levels (see Trophic levels)
• The energy stored in biomass decreases at each trophic level (see Trophic efficiency for more details)

Definition: A way to measure the amount of energy/biomass that moves from one trophic level to the next

Example: A grasshopper consumes a few leaves off a tree, gaining a certain amount of energy from the tree. A bluebird eats the grasshopper, gaining a certain amount of energy from the grasshopper.

• Trophic efficiency is usually only around 10 percent. This means that if an organism were to consume another organism, that organism would only gain 10% of the other organism's energy (see diagram below)
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• There are multiple reasons trophic efficiency is often so inefficient; because organisms may not consume all of the organism they are consuming, because organisms may not digest everything eaten, and because the previous organism has already used that energy for life functions.

Definition: A process where materials are ingested by an organism at a faster rate than they can get rid of them

Example: A fish consumes multiple plankton containing PCBs. The fish cannot get rid of the PCBs inside it at a faster rate than it is being ingested.

• Biomagnification, a process related to bioaccumulation, is the increase of concentration of a toxin from one trophic level to the next (see Biomagnification and diagram below for more details)
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• Bioaccumulation often negatively affect aquatic ecosystems; water contamination from DDTs and PCBs can have deadly consequences

Definition: A process involving the increase of concentration of a toxin from one trophic level to the next

Example: A fish consumes multiple plankton containing PCBs. That fish now has a high concentration of PCBs inside it. A larger fish consumes that fish and and multiple other fish that are also contaminated with PCBs. That larger fish has an even higher concentration of PCBs.

• Biomagnification can severely damage food chains in aquatic ecosystems
• Biomagnification affects organisms at a higher trophic levels more, because the concentration of toxins increases at each trophic level

Definition: A process that extracts energy from organic matter, under aerobic conditions (with oxygen)

Example: A plant uses oxygen to extract carbon dioxide, water, and energy out of glucose.

• Cellular respiration uses oxygen and glucose to produce carbon dioxide, water, and energy
• Fermentation is a similar process that occurs under anaerobic conditions (without oxygen) (see Fermentation for more details)

Definition: A process that extracts energy from biomass, under anaerobic conditions (without oxygen)

Example: Bacteria in a landfill with little oxygen extract some energy from glucose molecules found in waste.

• Not all energy from the glucose is extracted. The energy not extracted by the bacteria is converted into methane gas.
• Methane gas is a fuel that can be burned to generate electricity.

Definition: Gases in the atmosphere increase the atmosphere's temperature by preventing heat from leaving

Example: Methane gas, carbon dioxide, and water vapor are examples of greenhouse gases.

• Without greenhouse gases, the Earth's average temperature would be less than 0 degrees C.
• Greenhouse gases are responsible for the greenhouse effect.

Definition: the increasing of Earth's temperature as a result of greenhouse gases trapping heat in the atmosphere

Example: Carbon dioxide traps heat in the Earth's atmosphere.

• Global warming is caused by the greenhouse effect (see diagram below)
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• Because of the increase of fossil fuels being burned, the concentration of carbon dioxide in the atmosphere has greatly increased
• Because of the high concentration of carbon dioxide in the atmosphere and the greenhouse effect, global warming has increased

Definition: precipitation that is more acidic than usual, that is caused by atmospheric gases reacting with water

Example: Nitrogen oxide and sulfur dioxide from burning fossil fuels mix with water in the atmosphere to create nitric acid and sulfuric acid, which eventually comes down as acid precipitation.

• Pure water has a pH level of 7.0, while normal rainwater has a pH level of 5.6
• Rainwater affected by pollution can have a pH level as low as 4.2
• Acid precipitation can dissolve calcium, an important nutrient for forests
• Acid precipitation can increase aluminum, which hurts trees
• Acid precipitation can lower the pH level of the water in an aquatic ecosystem, harming organisms in the water
• See diagram below for more details
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