ABIOTIC

Parts of an ecosystem that are not made up of biological organisms. Air, soil, rocks, weather, water, nutrients, and molecules are all considered abiotic. They are not, and have never been, alive.

ALGAE

A type of plant that does not flower and has no real roots, stems, or leaves. Often refers to microscopic, single-celled marine plants, but also includes certain types of seaweed like giant kelp that can grow to lengths of 50 meters.

APEX PREDATOR

An animal on the very top of the food web, which has no predators. Many think that human beings are the top apex predator of the world.

ARCHAEA

A single-celled organisms with no cell nucleolus and a slightly different structure than bacteria. Can be found in human intestines and marshes but also in extreme conditions like super-acidic water and hot underground vents.

ATOM

The smallest unit of matter. Different types of atoms come together to make molecules. Atoms of the same kind come together to create elements. Everything in the known universe is made up of atoms.

BACTERIA

A type of single-celled microscopic organism found everywhere. They are instrumental in the breakdown of decomposing organisms and the cycling of nutrients through our ecosystem, and we depend on them to live. They can be harmful, causing disease, but also useful, in making cheeses, wine, and medicine!

BIG BANG

A theory of how the universe began. Many scientists theorize that billions of years ago there was nothing but an infinitely small and dense point called a singularity. This exploded, creating all of the atoms and matter in the universe.

BIODIVERSITY

When many different types of animal and plant species live in a particular ecosystem or habitat. Biodiversity is essential to the overall health and resilience of an ecosystem. Only through biodiversity can ecosystems adapt to change.

BIODIVERSITY HOTSPOT

An ecosystem or region with a significantly high amount of biodiversity that is also currently under threat of being destroyed. By identifying these regions, ecologists hope to intervene to protect them before it is too late.

BIOME

Areas on Earth that have similar climates, plants, and animals. Biomes are defined by their average precipitation rates and temperature. For example, very cold, dry areas are considered tundras, while very hot, wet places are considered tropical rainforests.

BIOTIC

The parts of an ecosystem that are made from living or formerly living organisms. Plants, animals, and bacteria—alive or dead—are all biotic. For example, a rotting log is considered biotic, and so is a chair made from dead wood.

CARBON FOOTPRINT

The amount of carbon dioxide and other fossil fuels created by the actions of a particular person or group of people. You can calculate your own carbon footprint by adding up the total amount of fuel used to heat your home, produce the food you eat, drive, fly, and so on.

CARBON SINK

A natural part of our environment that absorbs and stores massive amounts of carbon from the atmosphere. Large forests and parts of the ocean are considered carbon sinks.

CELL

Cells are the smallest unit of living organisms. They can form an entire single-celled organism or can be components of the tissue that makes up plants and animals.

CLIMATE

The regular, prevailing weather and temperature conditions of an area over a long period of time. Climate is not the same as weather. Weather refers to what happens at a specific time, or from one day to the next, while climate refers to the average temperature and weather conditions through the seasons.

CLIMATE CHANGE

Specifically refers to the rapid increase in global temperatures the earth has been experiencing, starting in the nineteenth century to now. It is the result of an increase of carbon dioxide and other greenhouse gases in the atmosphere from the burning of fossil fuels.

COMMUNITY

All of the living or biotic parts of an ecosystem and how those animals, plants, fungi, and bacteria interact with each other.

DEFORESTATION

The removal of a large number of trees or even entire forests in order to use the land for other purposes. Often forests are cleared for farmland or urban development.

DESERTIFICATION

The process wherein previously fertile land becomes a desert, a biome with little to no precipitation and not many plants. Forests and grasslands can turn into deserts through a combination of drought, unsustainable farming, and deforestation. Usually results in “soil death.”

DEVELOPMENT

The process of people building up areas like cities, towns, or agricultural centers and the infrastructure that supports them, like roads, dams, plumbing, and electrical transmission lines.

ECOTONE

The space between major ecosystems where they blend together; for example, the area where the edge of a forest meets a grassland. Ecotones have their own characteristics and are important for specific animal activity and protecting core ecosystems.

ELEMENT

A substance made up of only one type of atom.

ENDANGERED SPECIES

A species of animal or plant that is in danger of going extinct.

EROSION

The process of wind, water, or other natural forces breaking down something over a period of time. For example, the ocean waves hitting the shore can erode the coastal rock over time.

EVOLUTION

The process by which new species are created through mutations in their genes at birth. Mutations can be beneficial, neutral, or negative, but they must be passed down to the next generation to create a change in the species. Over a long period of time these mutations can add up—for example, enabling humans to walk upright. This explains why we are so different from our ancient ancestors.

EXTINCTION

Event when an entire species dies out and no longer exists. The dodo bird was hunted to extinction in 1662; more recently, the West African black rhinoceros was declared extinct in 2011. Today, many animals are endangered—at risk of extinction—due to climate change, illegal hunting, and habitat loss.

FERTILE

A quality of soil that is capable of producing vegetation. It is rich in the nutrients plants need and has no toxic substances that prevent plants from growing.

FOOD WEB

The mapping of the flow of energy through an ecosystem: who eats what, and who gets energy from whom.

GREENHOUSE GASES

Gases like carbon dioxide, water vapor methane, ozone, and fluorocarbons, which absorb heat and solar radiation. Greenhouse gases occur naturally and are also a byproduct of burning fossil fuels like coal and petroleum. The rapid release of these greenhouse gases caused by human activity has accelerated global warming resulting in climate change.

HABITAT

The natural home of a living organism.

INVASIVE SPECIES

A nonnative plant, animal, bacteria, or fungus that is introduced into a new ecosystem, often to the ecosystem’s detriment. Invasive species usually harm an ecosystem by outcompeting other species for resources like food, sunlight, and space.

KEYSTONE SPECIES

A plant, animal, bacteria, or fungus that an entire ecosystem depends on. If a keystone species is removed from an ecosystem, the whole community could collapse.

LIVING FOSSIL

An animal or plant species that has been around for a very, very long time. Close relatives of the species are usually all extinct.

MATTER

Matter is made up of atoms and molecules and comprises everything around us. Matter cannot be created or destroyed, only rearranged. Matter cycles through ecosystems through many processes like eating and decomposing.

MOLECULE

Atoms come together to form molecules. For example, carbon and oxygen are both atoms. One carbon and two oxygen molecules come together to create carbon dioxide (CO2).

NICHE

How a certain plant, animal, or other living thing fits into its ecosystem. What is the organism’s behavior? What job does it do? What resources does it need for survival? These special roles define its niche.

NUTRIENTS

Vitamins, minerals, and other substances necessary to support life. Carbohydrates, fats, proteins, carbon, and water are just some of the many nutrients humans need to survive.

NUTRIENT CYCLE

The movement of organic and inorganic matter through an ecosystem to be used by living things. Nutrients are necessary for living things to grow and repair their bodies. These nutrients return to the soil and air through life processes like breathing, pooping, and eventual decomposition after death. The carbon cycle and the phosphorus cycle are two examples of nutrient cycles.

ORGANISM

An individual living thing. A plant, animal, single-celled life form, even you—all are organisms.

PHOTOSYNTHESIS

The process whereby plants turn sunlight into food. Sunlight energy combines with carbon dioxide and water to form a sugar called glucose (food!). The excess “waste” from this process is oxygen, which plants release into the atmosphere.

PHYTOPLANKTON

Microscopic plants found in water; the basis of almost all marine ecosystems.

POLLUTION

When a harmful substance is put in the wrong place and/or in the wrong quantity and has a harmful effect on the environment.

POPULATION

A group of a certain species that live in the same place. People count the population to know how many animals, plants, or people occupy an area. For example, there is a population of about 54,453 people living in Timbuktu, Mali.

PRECIPITATION

Water vapor that has condensed to fall to earth as rain or snow. When talking about whether a region is wet or dry, we are describing how much precipitation, or rainfall, the place gets.

PRIMARY CONSUMERS

Animals that get their energy directly from feeding on plants. They are usually the second trophic level in a food web.

PRODUCERS

Plants that get their energy (and “food”) directly from the sun. They are the first trophic level in a food web.

RESERVOIR

A deposit of stored resources. A frozen glacier or lake is a reservoir for water. Underground rock sediment is a reservoir for phosphorus. The atmosphere is a reservoir for oxygen.

SOIL DEATH

Soil that has been depleted of nutrients. This happens when land is overused and nutrients are removed from the soil faster than nature can replenish them. It is usually associated with overgrazing or depleting the soil with one kind of crop.

SPECIES EVENNESS

A measure of how biodiverse and how equal in population species are at each trophic level. It is key to understanding the health of an ecosystem, the ratio between living things competing for the same resources, and the ratio between predator and prey.

SUCCESSION

The process of change that happens in an ecosystem over time. Biodiverse ecosystems can adapt to changes that happen to the land.

SUSTAINABLE

Term for use of the earth’s resources without destroying or depleting them. Sustainable use allows our natural resources to replenish themselves for the next generation.

TROPHIC LEVELS

The hierarchy of how energy flows through an ecosystem, starting with plants (producers) and ending with the apex predator. Shows who eats whom and who is eaten by whom. The number of levels can change depending on the ecosystem.

WEATHER

The state of the atmosphere at a specific time. It could be sunny, cloudy, rainy, dry, or other states. Weather is informed by the climate. While climate refers to averages over long periods of time, weather can change from day to day, hour to hour, or even minute to minute in some places!

ZOOPLANKTON

Tiny microscopic animals found in water. Usually they are the secondary consumers in a marine food chain and eat phytoplankton.