APES

Ecosystem

A community of living organisms interacting with their nonliving environment through which energy flows and matter cycles

Abiotic factors

Nonliving physical and chemical components of an environment such as temperature, sunlight, water, and soil pH

Biotic factors

All living organisms in an environment including producers, consumers, and decomposers

Gross Primary Productivity (GPP)

The total amount of energy fixed by photosynthesis in an ecosystem per unit time

Net Primary Productivity (NPP)

The energy remaining after producers use some GPP for their own respiration; energy available to consumers

10% Rule

Only about 10% of energy transfers to the next trophic level; the remaining 90% is lost as heat

Food web

A diagram showing the complex network of feeding relationships among organisms in an ecosystem

Keystone species

A species that has a disproportionately large effect on its ecosystem relative to its abundance

Trophic cascade

A series of changes in population sizes at different trophic levels caused by the addition or removal of a top predator

Biogeochemical cycle

The movement of chemical elements through living organisms and the physical environment

Carbon cycle

The biogeochemical cycle by which carbon is exchanged among the atmosphere, oceans, soil, and living organisms

Nitrogen fixation

The conversion of atmospheric nitrogen gas into ammonia or nitrates usable by plants, performed by certain bacteria

Nitrification

The conversion of ammonium into nitrites and then nitrates by nitrifying bacteria in soil

Denitrification

The conversion of nitrates back into nitrogen gas by anaerobic bacteria, returning nitrogen to the atmosphere

Eutrophication

The process by which excess nutrients cause algal blooms, leading to oxygen depletion and dead zones in water bodies

Phosphorus cycle

The biogeochemical cycle of phosphorus through rocks, soil, water, and living organisms with no atmospheric reservoir

Hydrologic cycle

The continuous movement of water through evaporation, condensation, precipitation, infiltration, and runoff

Transpiration

The release of water vapor from plant leaves into the atmosphere

Infiltration

The process by which water soaks into the soil and recharges groundwater

Aquifer

An underground layer of permeable rock or sediment that stores groundwater

Terrestrial biome

A large region characterized by a specific climate and dominated by particular plant and animal communities

Tropical rainforest

A biome with high rainfall, high biodiversity, warm temperatures year

Temperate deciduous forest

A biome with moderate rainfall, four distinct seasons, fertile soils, and trees that shed leaves seasonally

Boreal forest (Taiga)

A biome dominated by coniferous trees, characterized by long cold winters and acidic soils

Tundra

A treeless biome with permafrost, very low biodiversity, and an extremely short growing season

Desert

A biome receiving less than 25 cm of rainfall per year with extreme temperatures and drought

Chaparral

A biome with hot dry summers and mild wet winters dominated by fire

Estuary

A partially enclosed coastal area where freshwater from rivers mixes with saltwater, forming a highly productive ecosystem

Wetland

An ecosystem where the soil is saturated with water, providing habitat, flood control, and water filtration services

Coral reef

A marine ecosystem built by coral polyps and their symbiotic algae, representing the most biodiverse marine habitat

Biodiversity

The variety of life on Earth including genetic, species, and ecosystem diversity

Species richness

The total number of different species present in a given area

Genetic diversity

The variety of genes and alleles within a species, critical for adaptation and resilience

Ecosystem services

The benefits that humans receive from functioning ecosystems including provisioning, regulating, cultural, and supporting services

Primary succession

Ecological succession beginning on bare substrate with no soil, such as after a volcanic eruption or glacial retreat

Secondary succession

Ecological succession occurring in an area where a community previously existed but was disturbed, with soil still present

Pioneer species

The first organisms to colonize a disturbed or barren area, often hardy nitrogen

Climax community

The stable, self

Intermediate Disturbance Hypothesis

The concept that ecosystems with moderate levels of disturbance maintain the highest biodiversity

Island biogeography

The study of how species richness on islands is determined by immigration rates and extinction rates relative to island size and distance from mainland

Ecological tolerance

The range of abiotic conditions within which a species can survive and reproduce

Limiting factor

An abiotic or biotic factor that restricts the growth, distribution, or abundance of a population

K

selected species

r

selected species

Carrying capacity (K)

The maximum population size an environment can sustainably support given available resources

Exponential growth

Population growth at a constant rate producing a J

Logistic growth

Population growth that slows as the population approaches carrying capacity, producing an S

Survivorship curve

A graph showing the proportion of individuals surviving to each age in a population; three types exist

Density

dependent factor

Density

independent factor

Age structure diagram

A graph showing the distribution of a population among age groups, used to predict future growth trends

Demographic transition model

A model describing how birth and death rates change as a country industrializes through four stages

Total Fertility Rate (TFR)

The average number of children a woman will have during her lifetime; replacement level is approximately 2.1

Rule of 70

A formula for estimating doubling time: doubling time equals 70 divided by the annual growth rate percentage

IPAT model

A formula showing that environmental Impact equals Population times Affluence times Technology

Ecological footprint

The total land and resources required to support one person's consumption and absorb their waste

Plate tectonics

The theory that Earth's lithosphere is divided into moving plates whose interactions create geological features

Soil horizon

A distinct layer of soil with characteristic properties; horizons from top to bottom are O, A, E, B, C, and R

Humus

Decomposed organic matter in soil that improves structure, water retention, and nutrient availability

Cation Exchange Capacity (CEC)

A measure of soil's ability to hold positively charged nutrient ions; higher in clay and humus

Soil erosion

The removal of topsoil by water or wind, often accelerated by agricultural practices and deforestation

Salinization

The accumulation of salts in soil due to evaporation of irrigation water, reducing agricultural productivity

Desertification

The process by which fertile land becomes desert through overgrazing, deforestation, or poor irrigation practices

Albedo

The reflectivity of a surface; high albedo surfaces like ice reflect more solar radiation than low albedo surfaces like ocean

Coriolis effect

The deflection of wind and water currents to the right in the Northern Hemisphere and left in the Southern Hemisphere due to Earth's rotation

Thermohaline circulation

The global ocean conveyor belt driven by differences in water temperature and salinity

Upwelling

The rising of cold, nutrient

Rain shadow effect

The phenomenon where the leeward side of a mountain receives little precipitation because moisture is lost on the windward side

El Niño

A periodic warming of Pacific Ocean surface waters that disrupts global weather patterns including drought and flooding

Green Revolution

The mid

Monoculture

The agricultural practice of growing a single crop over a large area, increasing efficiency but reducing resilience

Crop rotation

The practice of alternating different crops in the same field each season to reduce pests and restore soil nutrients

Cover crops

Plants grown between main crop seasons to prevent erosion, suppress weeds, and fix nitrogen

No

till farming

Integrated Pest Management (IPM)

A pest control strategy combining biological, cultural, and chemical methods to minimize pesticide use

Bioaccumulation

The buildup of a toxic substance in the tissues of a single organism over its lifetime

Biomagnification

The increasing concentration of a toxic substance at successive trophic levels in a food chain

Maximum Sustainable Yield (MSY)

The largest catch that can be taken from a fishery without reducing the population's ability to recover

Bycatch

The unintentional capture of non

Aquaculture

The farming of aquatic organisms such as fish and shellfish in controlled environments

Mountaintop removal

A surface mining method that removes mountain peaks to expose coal seams, filling adjacent valleys with waste rock

Acid mine drainage

Sulfuric acid produced when water reacts with sulfur

Urban heat island effect

The phenomenon where cities are significantly warmer than surrounding rural areas due to dark surfaces, lack of vegetation, and waste heat

Urban sprawl

The uncontrolled expansion of urban areas into surrounding land, reducing farmland and natural habitat

Photovoltaic cell

A device that converts sunlight directly into electricity using the photovoltaic effect in semiconductor materials

Cogeneration

A process that simultaneously produces electricity and useful heat from the same energy source, greatly increasing efficiency

EROI

Energy Return on Investment; the ratio of energy obtained from a source to the energy required to obtain it

Hydraulic fracturing (fracking)

A drilling technique that injects high

Photochemical smog

A brownish haze formed when sunlight reacts with nitrogen oxides and volatile organic compounds to produce ground

Temperature inversion

An atmospheric condition where a layer of warm air traps cooler air and pollutants near the surface, worsening air quality

Primary pollutant

A pollutant emitted directly into the atmosphere from a source, such as carbon monoxide or sulfur dioxide

Secondary pollutant

A pollutant formed in the atmosphere through chemical reactions between primary pollutants, such as ozone or acid rain

Acid deposition

The falling of sulfuric and nitric acids from the atmosphere as rain, snow, or dry particles, damaging ecosystems and structures

Ozone layer

The region of the stratosphere containing concentrated ozone that absorbs harmful ultraviolet radiation

Chlorofluorocarbons (CFCs)

Synthetic compounds formerly used in refrigerants and aerosols that break down stratospheric ozone when exposed to UV radiation

Montreal Protocol

The 1987 international treaty that phased out the production of ozone

Point source pollution

Pollution that comes from a single, identifiable source such as a factory discharge pipe

Nonpoint source pollution

Pollution that originates from multiple diffuse sources such as agricultural runoff or urban stormwater

Hypoxic zone

An area of water with dissolved oxygen levels too low to support most aquatic life, caused by decomposition following eutrophication

Thermal pollution

The degradation of water quality caused by discharging heated water from industrial or power plant cooling systems