Ecology and Biogeochemical Cycles: Key Concepts for Students

Ecology

The study of the interactions of organisms with other organisms and the physical environment.

Habitat

Place where an organism lives.

Population

All the individuals of a species within a particular space.

Community

Various populations of multiple species interacting with each other.

Ecosystem

Community interacting with the environment.

Abiotic Components

The nonliving components of an ecosystem, including atmosphere, water, and soil.

Biotic Components

Living things in an ecosystem that can be categorized according to their food source.

Autotrophs

Also called producers; organisms that require only energy and inorganic nutrients to generate food necessary for the ecosystem.

Photoautotrophs

Land plants and algae that use light energy to produce organic nutrients.

Chemoautotrophs

Some bacteria that obtain energy from chemical processes.

Heterotrophs

Also known as consumers; organisms that make energy from the food they eat.

Herbivore

Organisms that primarily consume plants.

Carnivore

Organisms that primarily consume other animals.

Omnivore

Organisms that consume both plants and animals.

Insectivore

Organisms that primarily consume insects.

Decomposers

Organisms that break down dead organic material.

Detritus feeders

Organisms that consume detritus, or decomposing organic matter.

Predation

An interaction in which one species, the predator, kills and eats the other, the prey.

Cryptic Coloration

Camouflage that makes prey difficult to spot.

Aposematic Coloration

Bright warning coloration exhibited by animals with effective chemical defenses.

Batesian Mimicry

A palatable or harmless species mimics an unpalatable or harmful model.

Müllerian Mimicry

Two or more unpalatable species resemble each other.

Herbivory

An interaction in which an herbivore eats parts of a plant or alga.

Symbiosis

A relationship where two or more species live in direct and intimate contact with one another.

Parasitism

An interaction where one organism, the parasite, derives nourishment from another organism, its host, which is harmed in the process.

Endoparasites

Parasites that live within the body of their host.

Ectoparasites

Parasites that live on the external surface of a host.

Mutualism

An interspecific interaction that benefits both species.

Commensalism

An interaction where one species benefits and the other is neither harmed nor helped.

Facilitation

An interaction in which one species has positive effects on another species without direct and intimate contact.

Biogeochemical Cycles

Pathways by which chemicals circulate through ecosystems involving both living (biotic) and nonliving (abiotic) components.

Reservoir

A source of chemicals normally unavailable to producers.

Exchange Pool

A source from which organisms generally have the ability to take chemicals.

Water Cycle

The water (hydrologic) cycle is characterized by evaporation, precipitation, and runoff from the surface to lakes, rivers, and oceans.

Primary Reservoir of Water Cycle

The primary reservoir of the water cycle is the ocean, although freshwater reserves may be located in aquifers.

Carbon Cycle Reservoirs

The reservoirs of the carbon cycle are organic matter (forests and dead organisms for fossil fuels), limestone (calcium carbonate shells), and the ocean.

Carbon Cycle Exchange Pool

The exchange pool of the carbon cycle is the atmosphere.

Photosynthesis in Carbon Cycle

Photosynthesis removes carbon dioxide from the atmosphere.

Respiration and Combustion in Carbon Cycle

Respiration and combustion add carbon dioxide to the atmosphere.

Imbalances in Carbon Cycle

Imbalances in the cycling of greenhouse gases, such as carbon dioxide, can lead to global warming and climate change.

Nitrogen Cycle Reservoir

The reservoir of the nitrogen cycle is the atmosphere.

Nitrification

Nitrogen gas must be converted to a form usable by plants (nitrates), and this conversion is called nitrification.

Nitrogen-Fixing Bacteria

Nitrogen-fixing bacteria perform nitrogen fixation in root nodules, converting nitrogen gas to ammonium.

Nitrifying Bacteria

Nitrifying bacteria convert ammonium to nitrate.

Denitrification

Some bacteria convert nitrate back to nitrogen gas through denitrification.

Imbalances in Nitrogen Cycle

Imbalances in the nitrogen cycle can cause acid deposition and acid rain.

Phosphorus Cycle Reservoir

The reservoir of the phosphorus cycle is ocean sediments.

Phosphate Availability

Phosphate in ocean sediments becomes available through geologic upheaval, which exposes sedimentary rocks to weathering.

Weathering in Phosphorus Cycle

Weathering slowly makes phosphate available to the biotic community.

Limiting Nutrient

Phosphate is a limiting nutrient in ecosystems.

Imbalances in Phosphorus Cycle

Imbalances in the phosphorus cycle may lead to cultural eutrophication.