Biology: Ecology

Population

A group of individuals that belong to the same species and live in the same area

Community

All the different populations that live together in an area

Ecosystem

A biological community of interacting organisms and their physical environment.

Biosphere

Consists of all life on Earth and all parts of the Earth in which life exists, including land, water, and the atmosphere

Biotic Factor

Any living part of the environment with which an organism might interact

Abiotic Factor

Physical, or nonliving, factor that shapes an ecosystem

Weather

The condition of Earth's atmosphere at a particular time and place

Climate

The average weather conditions in an area over a long period of time

Biome

A group of ecosystems that share similar climates and typical organisms

Ecological Succession

The predictable replacement of one group of species by another group of species over time

Climax Community

A stable, mature community that undergoes little or no change in species over time

Pioneer Species

First species to populate an area during succession

Primary Ecological Succession Step 1:

Lichens break down rock and decompose to form soil so that plants can take root and grow

Primary Ecological Succession Step 2:

Grasses and herbs grow in newly formed soil

Primary Ecological Succession Step 3:

Shrubs and bushes take root

Primary Ecological Succession Step 4:

Young trees and fast-growing pines start to grow

Primary Ecological Succession Step 5:

Oak trees mature resulting in a climax community

Secondary Ecological Succession Step 1:

Fire or other natural disaster

Secondary Ecological Succession Step 2: (pioneer stage)

Pioneer species like grasses and herbs grow in the soil

Secondary Ecological Succession Step 3: (intermediate stage)

Pines, shrubs and young oaks grow

Secondary Ecological Succession Step 4: (climax stage)

Becomes a climax community again, with mature oaks

Benefits of Natural Wildfires

-used to help seeds germinate (if the need intense heat)

-produces nutrients to fertilize the soil for new growth

-thin the forests so that future fires are not as intense

-can kill non-native species and prevent them from becoming invasive

Producer

An organism that can make its own food

Consumer

An organism that obtains energy by feeding on other organisms

Herbivore

A consumer that eats only plants

Carnivore

A consumer that eats only animals

Trophic Level

Each step in a food chain or food web

Niche

An organism's particular role in an ecosystem

Decomposers

Organisms that break down wastes and dead organisms and return raw materials to the environment

Food Chain

A series of steps in which organisms transfer energy by eating and being eaten

Food Web

A community of organisms where there are several interrelated food chains

Energy Transfer Across Trophic Levels

Each level retains 10% of the energy from the previous level

Symbiosis

A close relationship between two species that benefits at least one of the species

Mutualism

A relationship between two species in which both species benefit

Commensalism

A relationship between two organisms in which one organism benefits and the other is unaffected

Parasitism

A relationship between two organisms of different species where one benefits and the other is harmed

Water Cycle

Evaporation

The sun changes liquid water into gas, moving into the atmosphere

Transpiration

Evaporation of water from the leaves of a plant

Evapotranspiration

The evaporation of water from soil plus the transpiration of water from plants

Condensation

The change of state from a gas to a liquid, water vapor in the atmosphere is cooled into clouds

Precipitation

Any form of water that falls from clouds and reaches Earth's surface

Infiltration

Flow of water from the land surface into the subsurface

Stormwater Runoff

Water from precipitation that flows over the surface of the land

Groundwater Flow

Water that is flowing beneath earths surface

Plant Uptake

The process by which water is taken from the soil by a plant's roots and is used to help the plant grow

Carbon Cycle

The organic circulation of carbon from the atmosphere into organisms and back again

Cellular Respiration

Releases CO2 into air

Photosynthesis

Absorbs CO2 into plants

Root Respiration

When plants absorb carbon from the soil

Decomposition

Breaks down organic matter and releases CO2 back into atmosphere

Nitrogen Cycle

The transfer of nitrogen from the atmosphere to the soil, to living organisms, and back to the atmosphere

Phosphorus Cycle

The movement of phosphorus atoms from rocks through the biosphere and hydrosphere and back to rocks

Point Source pollution

Pollutants discharged from a single identifiable location

Non point source pollution

Water pollution that does not have a specific point of origin

Eutrophication

A process by which nutrients, particularly phosphorus and nitrogen, become highly concentrated in a body of water, leading to increased growth of organisms such as algae or cyanobacteria, killing other organisms and potentially leading to anoxic water

Anoxic Water

Water without oxygen

Population Growth Equation

(births + immigration) - (deaths + emigration)

Carrying Capacity

Largest number of individuals of a population that a environment can support

Logistic Growth

Growth pattern in which a population's growth rate slows or stops following a period of exponential growth

Limiting Factor

Any biotic or abiotic factor that restricts the existence, numbers, reproduction, or distribution of organisms

Density Dependent Limiting Factor

Limiting factor that depends on population size

Density Independent Limiting Factor

Limiting factor that affects all populations in similar ways, regardless of population size

Predator-Prey Relationship

mechanism of population control in which a population is regulated by predation

Trophic Cascade

A series of changes in the population sizes of organisms at different trophic levels in a food chain, occurring when predators at high trophic levels indirectly promote populations of organisms at low trophic levels by keeping species at intermediate trophic levels in check

Invasive Species

A species, often introduced by humans, that takes hold outside its native range, often without natural predators