Environmental Science & Ecology

Environment

Everything around an organism, including living and nonliving things.

Environmental science

The study of how the natural world works and how humans affect it.

Ecosystem

A community of living organisms and the nonliving environment they interact with.

Biotic

The living parts of an environment, such as plants, animals, fungi, and bacteria.

Abiotic

The nonliving parts of an environment, such as water, temperature, sunlight, soil, and rocks.

Environmentalism

A social movement focused on protecting the environment and solving environmental problems.

Environmental studies

The study of environmental issues using science plus subjects like economics, politics, and ethics.

Sustainability

Using resources in a way that meets our needs without preventing future generations from meeting theirs.

Scientific method

A process used to investigate questions by making observations, testing ideas, and analyzing evidence.

Hypothesis

A testable explanation or prediction about something you observe.

Variable

Anything that can change in an experiment.

Independent variable

The variable that the researcher changes on purpose.

Dependent variable

The variable that is measured to see how it is affected by the independent variable.

Null hypothesis

The idea that there is no significant relationship or effect between the variables being tested.

Control group

A group that does not receive the experimental treatment, used for comparison.

Natural experiment

An experiment where researchers study a situation created by nature or outside events rather than controlling it themselves.

Replication

Repeating an experiment or having multiple samples to make results more reliable.

Sample size

The number of individuals or observations included in a study.

Accuracy

How close a measurement is to the true or accepted value.

Precision

How close repeated measurements are to each other.

Uncertainty

The amount of doubt or possible error in a measurement.

Theory

A well-supported explanation of how something works, backed by a large amount of evidence.

1st law of thermodynamics

Energy cannot be created or destroyed; it can only be transferred or changed into another form.

2nd law of thermodynamics

Every energy transfer increases entropy (disorder), so some energy becomes less useful, usually as heat.

Community ecology

The study of how different species interact with each other in a community.

Symbiosis

A close, long-term relationship between two different species.

Biosphere

All parts of Earth where life exists, including land, water, and the atmosphere.

Competition

When organisms try to use the same limited resource, such as food, water, or space.

Competitive exclusion principle

Two species cannot occupy the exact same niche indefinitely; one will eventually outcompete the other.

Resource partitioning

When competing species use different parts of a resource or use it at different times, reducing competition.

Predation

When one organism kills and eats another organism.

Parasitoid

An organism, usually an insect, whose young live inside or on a host and eventually kill the host.

Parasitism

A relationship where one organism benefits while the host is harmed, but usually not immediately killed.

Pathogen

An organism or agent that causes disease.

Herbivory

When an animal eats plants or algae.

Mutualism

A relationship where both species benefit.

Photosynthesis

The process plants, algae, and some bacteria use to turn sunlight, water, and CO2 into chemical energy (sugar) and oxygen.

Commensalism

A relationship where one species benefits and the other is not significantly affected.

Native species

A species that naturally occurs in a particular area without being introduced by humans.

Exotic species

A species that is not native to an area and has been introduced there, often by humans.

Alien species

Another term for a species that is not native to an area.

Invasive species

A non-native species that spreads quickly and causes harm to the environment, economy, or human health.

Mutualism interaction effect

+ / + -> both benefit

Commensalism interaction effect

+ / 0 -> one benefits, other unaffected

Parasitism interaction effect

+ / - -> parasite benefits, host harmed

Predation interaction effect

+ / - -> predator benefits, prey killed

Competition interaction effect

- / - -> both are negatively affected by competing for resources

Biome

A large region with a specific climate and characteristic plants and animals.

Terrestrial biome

A biome found primarily on land.

Aquatic biome

A biome found in water, such as freshwater or marine environments.

Habitat

The specific place where an organism lives and gets what it needs to survive.

Tundra

A very cold, dry biome with few trees, low-growing plants, and permanently or seasonally frozen soil.

Permafrost

Soil or rock that stays frozen for at least two consecutive years.

Taiga

A cold biome dominated by coniferous trees such as pine and spruce.

Boreal forest

Another name for the taiga, found mainly in northern regions.

Temperate rainforest

A cool, wet forest with very high rainfall and large trees.

Temperate seasonal forest

A forest with warm summers, cold winters, and trees that lose their leaves each year.

Shrubland

An area dominated by shrubs and small woody plants, usually with relatively dry conditions.

Woodland

An area with more trees than shrubland but fewer trees than a forest, allowing more sunlight to reach the ground.

Chaparral

A dry temperate shrubland with hot, dry summers and mild, wet winters; common around the Mediterranean climate.

Temperate grassland

A biome dominated by grasses, with moderate rainfall and often hot summers and cold winters.

Cold desert

A very dry desert with cold temperatures, often found at high elevations or high latitudes.

Tropical rainforest

A hot, wet biome with very high rainfall, dense vegetation, and extremely high biodiversity.

Savanna

A tropical grassland with scattered trees and distinct wet and dry seasons.

Tropical seasonal forest

A warm forest with a wet and dry season; many trees lose their leaves during the dry season.

Hot desert

A very dry biome with high temperatures, little rainfall, and organisms adapted to conserve water.

Freshwater biomes

Aquatic ecosystems with low salt levels, including lakes, rivers, streams, and wetlands.

Streams

Small, flowing bodies of freshwater.

Rivers

Large, flowing bodies of water that usually eventually flow into a lake, ocean, or another river.

Lakes

Large bodies of standing freshwater surrounded by land.

Ponds

Smaller bodies of standing freshwater, usually shallow enough for sunlight to reach much of the bottom.

Littoral zone

The shallow area along the edge of a lake or pond where sunlight reaches the bottom and plants can grow.

Limnetic zone

The open, sunlit surface water of a lake or pond, away from the shore.

Phytoplankton

Tiny, plant-like organisms that float in water and perform photosynthesis.

Zooplankton

Tiny animal-like organisms that drift in water and often eat phytoplankton.

Profundal zone

The deep area of a lake where little or no sunlight reaches.

Benthic zone

The bottom of an aquatic ecosystem, including the sediment and organisms living there.

Oligotrophic

A lake with low nutrients, clear water, and relatively little algae; usually has lots of oxygen.

Mesotrophic

A lake with a moderate amount of nutrients and biological productivity.

Eutrophic

A lake with high nutrients and lots of algae and plant growth, which can lead to low oxygen.

Freshwater wetlands

Areas where land is covered or saturated with freshwater for at least part of the year. They help filter water, reduce flooding, and provide habitat.

Estuaries

Places where freshwater from rivers mixes with saltwater from the ocean. They are highly productive ecosystems.

Salt marshes

Coastal wetlands dominated by salt-tolerant grasses and other plants, usually found in areas with tidal water.

Mangrove swamps

Tropical/subtropical coastal wetlands dominated by salt-tolerant mangrove trees with specialized roots.

Intertidal zones

Coastal areas between the high-tide and low-tide marks, which are regularly exposed to air and covered by water.

Coral reefs

Diverse marine ecosystems built mainly by coral animals, usually found in warm, shallow, clear water.

Coral bleaching

When stressed corals lose their symbiotic algae, causing them to turn white and potentially die.

Open ocean

The large area of ocean away from the coast and seafloor; it makes up most of Earth's marine environment.

Photic zone

The upper layer of water where enough sunlight reaches for photosynthesis.

Aphotic zone

The deeper layer of water where little or no sunlight reaches, so photosynthesis cannot occur.