Ecology and Ecosystems Lecture Review

A set of vocabulary flashcards covering key ecological principles, population dynamics, ecosystem interactions, nutrient cycles, biomes, and human impacts on the environment based on the lecture notes.

Ecology

The study of interactions of living organisms with one another and with their environment.

Biotic Factors

Living or once-living components of an ecosystem, such as wolves, amoebas, bacteria, and rotting logs.

Abiotic Factors

Non-living physical and chemical factors in an ecosystem, such as temperature, sunlight, precipitation levels, and pollution.

Producer (Autotroph)

An organism that produces organic sugars using visible light or inorganic chemicals as an energy source.

Consumer (Heterotroph)

An organism that relies on consuming other organisms for energy.

Herbivore

A consumer that exclusively feeds on plants, such as buffalo, horses, rabbits, cows, and elephants.

Omnivore

A consumer that feeds on both plants and animals, such as pigs, rats, foxes, bears, cockroaches, and humans.

Carnivore

A consumer that feeds on other animals, such as tigers, dogs, and Tyrannosaurus rex.

Decomposer

An organism, such as bacteria or fungi, that feeds on and breaks down other dead organisms.

Scavenger (Detritivore)

An organism, such as certain insects, vultures, crows, or shrimp, that consumes carrion.

Biomass

A measure of the total dry mass of organisms in a given area.

Nitrogen Fixation

The process by which soil, root, or ocean bacteria form ammonia ($NH_3$) using atmospheric nitrogen gas ($N_2$).

Ammonification

The process by which decomposers break down dead organisms and return nitrogen to the environment as ammonium ($NH_4^+$).

Denitrification

The process in which bacteria use nitrate ($NO_3^-$) for oxygen ($O_2$) and release nitrogen gas ($N_2$) back into the atmosphere as waste.

Sedimentation

The process in which phosphorus ending up in deep water is compressed into rock, which later resurfaces through weathering.

Keystone Species

A species, such as the sea otter, that is critical to an ecosystem because it affects the survival of many other species, with an impact much larger than its biomass suggests.

Symbiosis

An ecological relationship between organisms of two different species that live together in direct and intimate contact.

Mutualism

A symbiotic interaction in which both organisms gain a benefit.

Commensalism

A symbiotic interaction where one organism gains a benefit while the other is unaffected.

Parasitism

A symbiotic relationship where one organism (the parasite) lives in or on another organism (the host), feeding off its matter or food and causing it harm.

Amensalism

An interaction where one species is harmed while the other species suffers no effect ($0$), such as the chemical secretion of a black walnut tree.

Lag Time

The period of time between peaks and troughs in the population graphs of predator and prey groups.

Intraspecific Competition

Competition occurring between individuals of the same species.

Interspecific Competition

Competition occurring between individuals of different species.

Niche

The unique position occupied by a species, including its habitat and its role within an ecosystem.

Fundamental Niche

The entire range of conditions where a species can survive.

Realized Niche

The actual niche that a species occupies when competing with other organisms.

Resource Partitioning

The division of a limiting resource among species by using different slices or locations to reduce competition.

Competitive Exclusion

The exclusion of one species by another due to competition, driving the less adapted species to another niche or to extinction.

Growth Rate

The rate of population change calculated as $\text{Births} - \text{Deaths} + \text{Immigration} - \text{Emigration}$.

Population Density

The measure of population in a specific area, calculated as $\text{population} / \text{area of land}$.

Exponential Growth

An unlimited rate of population growth characterized by a J-shaped curve that occurs when birth rate exceeds death rate.

Logistic Growth

Population growth that slows and stabilizes as it approaches carrying capacity, characterized by an S-shaped curve.

Carrying Capacity ($K$)

The largest population size that an environment can support.

Density-Dependent Limiting Factors

Environmental factors that limit population growth specifically at high population densities, such as competition, predation, disease, crowding, and stress.

Density-Independent Limiting Factors

Environmental factors that limit population growth regardless of density, such as weather, natural disasters, and human activities.

Succession

The sequence of community changes either following a disturbance or within a previously uninhabited region over time.

Primary Succession

The establishment of a community in a previously uninhabited location, starting with soil formation from rock weathering.

Pioneer Species

The first species to populate an area during primary succession, such as moss and lichens.

Secondary Succession

The re-growth of remaining species in a community following a disturbance such as a fire or clear-cutting.

Biome

A major regional ecosystem characterized by specific climate patterns and biological communities.

Estuary

A highly productive aquatic ecosystem where rivers meet the ocean.

Renewable Resources

Natural resources that can be replaced at the same rate at which they are consumed, such as solar energy, wind, and fresh water.

Non-renewable Resources

Natural resources that form at a rate slower than they are consumed, such as coal, oil, minerals, and metals.

Greenhouse Effect

The warming of Earth's atmosphere when greenhouse gases such as $CO_2$, $H_2O_{(g)}$, and methane ($CH_4$) trap solar radiation.

Cultural Eutrophication

Rapid lake aging occurring over decades caused by human-induced nutrient runoff from sewage, industrial waste, and fertilizers.

Habitat Fragmentation

The division of a habitat by human developments or barriers, preventing an organism from accessing its full habitat.

Biomagnification

The process by which a pollutant increases in concentration as it moves up the food chain, affecting top consumers most severely.

Invasive Species

Non-native species introduced to an ecosystem by humans that become highly successful and disrupt local ecological relationships.

Indicator Species

An organism, such as an amphibian or top predator, whose status provides a sign of an ecosystem's overall health.