APES Q2 Vocab

A horizon

The topsoil layer where minerals and organic matter mix; contains many roots and organisms.

Abiotic

Nonliving components of an ecosystem, such as sunlight, water, temperature, soil, and minerals.

Adaptation

An inherited trait that improves an organism’s ability to survive and reproduce in its environment.

Albedo effect

The effect of a surface’s reflectivity on how much incoming solar radiation it reflects; high albedo reflects more sunlight and low albedo absorbs more.

Asthenosphere

The soft, slowly flowing layer of the upper mantle beneath the lithosphere that allows tectonic plates to move.

Atmosphere

The layer of gases surrounding Earth, held in place by gravity.

B horizon

The subsoil layer where minerals such as iron, aluminum, and clay accumulate from upper soil layers.

Biogeography

The study of the geographic distribution of organisms and ecosystems across space and through time.

Biological Oxygen Demand (BOD)

The amount of dissolved oxygen microorganisms require to decompose organic matter in water; high BOD can indicate pollution and reduce oxygen available to aquatic organisms.

Biotic

The living or once-living components of an ecosystem, including organisms and organic matter.

C horizon

The soil layer consisting mainly of partially weathered parent material with little organic matter.

Carnivore

An organism that obtains energy primarily by eating other animals.

Cation Exchange Capacity (CEC)

The ability of soil to hold and exchange positively charged ions, such as calcium, potassium, and magnesium; higher CEC generally improves nutrient retention.

Climax community

A relatively stable community that develops at the later stages of ecological succession under prevailing environmental conditions.

Constant(s) (science)

Factors kept the same throughout an experiment so that results can be compared fairly.

Control group

The group in an experiment that does not receive the experimental treatment and serves as a baseline for comparison.

Controlled experiment

An experiment in which variables are carefully managed so the effect of the independent variable on the dependent variable can be measured.

Convergent plate boundary

A boundary where tectonic plates move toward one another, potentially forming mountains, volcanoes, trenches, and earthquakes.

Coriolis Effect

The apparent deflection of moving air and water caused by Earth's rotation; movement is deflected right in the Northern Hemisphere and left in the Southern Hemisphere.

Cultural Ecosystem Service

An intangible benefit people receive from ecosystems, such as recreation, tourism, spiritual value, education, and aesthetic enjoyment.

Decomposer

An organism, such as a fungus or bacterium, that breaks down dead organisms and waste, recycling nutrients into the environment.

Dependent variable

The variable measured in an experiment to determine how it responds to changes in the independent variable.

Directional Selection

A type of natural selection that favors one extreme form of a trait, shifting the population's trait distribution toward that extreme.

Disruptive Selection

A type of natural selection that favors both extreme forms of a trait over intermediate forms.

Dissolved Oxygen (DO)

The amount of oxygen gas dissolved in water and available for aquatic organisms to use for respiration.

Divergent plate boundary

A boundary where tectonic plates move apart, allowing magma to rise and form new crust, commonly at mid-ocean ridges and rift valleys.

Downwelling

The downward movement of surface water into deeper ocean layers, transporting oxygen and surface water into the deep ocean.

E horizon

A soil horizon where water leaches minerals, clay, and other materials out of the layer, leaving it relatively depleted and often light-colored.

El Nino Southern Oscillations (ENSO)

A recurring climate pattern involving changes in tropical Pacific Ocean temperatures and atmospheric pressure; includes El Niño and La Niña and affects global weather.

Early Successional Species

Species that establish relatively early during succession, often growing quickly and tolerating disturbed conditions.

Ecological Tolerance

The range of environmental conditions, such as temperature, pH, and salinity, within which an organism can survive, grow, and reproduce.

Ecosystem Services

The benefits humans obtain from ecosystems, including provisioning, regulating, cultural, and supporting services.

Eutrophication

The enrichment of water with nutrients, especially nitrogen and phosphorus, causing excessive algal growth; decomposition of the algae can lower dissolved oxygen and cause dead zones.

Experimental Groups

The groups in an experiment that receive the treatment or different levels of the independent variable.

Floodplain

A flat area beside a river that is periodically flooded and receives nutrient-rich sediment.

Generalist species

A species with a broad ecological niche that can use many resources and tolerate a wide range of environmental conditions.

Heterotroph

An organism that obtains energy and carbon by consuming other organisms or organic matter rather than producing its own food.

Hypothesis

A testable, proposed explanation for an observation or scientific question.

Indicator species

A species whose presence, absence, abundance, or condition provides information about environmental quality or ecosystem health.

Independent variable

The variable deliberately changed by a researcher to determine its effect on the dependent variable.

Late Successional Species

Species that become established during later stages of succession, often competing effectively in more stable, developed communities.

Leaching

The process by which water dissolves and carries nutrients, minerals, or pollutants downward through soil.

Lithosphere

The rigid outer layer of Earth, consisting of the crust and the uppermost solid mantle; divided into tectonic plates.

K-selected species

Species that generally produce few offspring, mature later, provide substantial parental care, and tend to live near carrying capacity.

Keystone species

A species whose effect on ecosystem structure and biodiversity is disproportionately large relative to its abundance.

Mantle Convection Cell

A circulating movement of mantle material caused by heat differences, with warmer material rising and cooler material sinking; helps drive plate tectonics.

Mesopause

The boundary between the mesosphere and thermosphere; the coldest region of Earth's atmosphere.

Mesosphere

The atmospheric layer above the stratosphere and below the thermosphere, where most meteors burn up.

O horizon

The uppermost soil horizon consisting primarily of organic material, such as leaf litter and decomposing organisms.

Oligotrophic

Describes a body of water with low nutrient concentrations, low algal productivity, and generally high dissolved oxygen.

Permeability

The ability of a material, such as soil or rock, to allow water to pass through connected pores or cracks.

Physical weathering

The breakdown of rock into smaller pieces without changing its chemical composition.

Porosity

The percentage or proportion of a material's total volume that consists of pore spaces, which may hold air or water.

Pioneer species

The first species to colonize a barren or disturbed area and begin the process of ecological succession.

Primary consumer

An organism that feeds directly on producers, such as plants or algae; usually an herbivore.

Primary productivity

The rate at which producers convert solar or chemical energy into organic matter through photosynthesis or chemosynthesis.

Primary succession

Ecological succession that begins on a surface without developed soil, such as newly exposed rock after a lava flow or glacier retreat.

Provisioning ecosystem service

A material good obtained from ecosystems, such as food, fresh water, timber, fuel, and medicinal resources.

Pycnocline

A layer of water in which density increases rapidly with depth, limiting vertical mixing between surface and deeper water.

r-selected species

Species that generally reproduce rapidly, produce many offspring, mature early, and provide little parental care; often thrive in disturbed or unpredictable environments.

Rain Shadow Effect

A dry region on the leeward side of a mountain formed when moist air rises, cools, and releases precipitation on the windward side, then descends and warms.

Regulating Ecosystem Service

A benefit from ecosystems that regulate environmental processes, such as climate regulation, water purification, flood control, and pollination.

Respiration

The cellular process by which organisms break down organic molecules to release usable energy; aerobic respiration consumes oxygen and releases carbon dioxide and water.

Riparian zones

Areas of land alongside rivers, streams, and other waterways that support vegetation and help filter runoff, stabilize banks, and provide wildlife habitat.

Secondary succession

Ecological succession that occurs after a disturbance in an area where soil remains, such as after a wildfire or abandoned farmland.

Soil Horizon

A distinct horizontal layer of soil with characteristic physical, chemical, and biological properties.

Soil Profile

A vertical section of soil showing its sequence of horizons from the surface downward into the parent material.

Soil Texture

The relative proportions of sand, silt, and clay particles in soil, which influence water retention, drainage, and other soil properties.

Soil Triangle

A triangular diagram used to classify soil texture based on the percentages of sand, silt, and clay.

Specialist species

A species with a narrow ecological niche that depends on specific resources or environmental conditions.

Species Diversity

A measure of biodiversity that considers both the number of species present and their relative abundances.

Species Evenness

A measure of how evenly individuals are distributed among the species in a community.

Species Richness

The number of different species present in a community or ecosystem.

Stabilizing Selection

A type of natural selection that favors intermediate trait values and selects against both extremes.

Stratopause

The boundary between the stratosphere and mesosphere.

Stratosphere

The atmospheric layer above the troposphere and below the mesosphere; contains the ozone layer, which absorbs much of the Sun's ultraviolet radiation.

Subduction Zone

A region where one tectonic plate sinks beneath another into the mantle, often producing trenches, earthquakes, and volcanic activity.

Supporting Ecosystem Service

A fundamental ecological process that enables other ecosystem services, such as nutrient cycling, soil formation, and primary production.

Sustainability

The ability to meet present needs without compromising the ability of future generations to meet their own needs.

Thermosphere

The atmospheric layer above the mesosphere where temperatures rise substantially with altitude and many auroras occur.

Threatened species

A species likely to become endangered in the foreseeable future throughout all or a significant portion of its range.

Transform fault

A plate boundary where two tectonic plates slide horizontally past one another, commonly producing earthquakes without creating or destroying much crust.

Tropopause

The boundary between the troposphere and stratosphere, marking a change in atmospheric temperature patterns.

Troposphere

The lowest atmospheric layer, where most weather occurs and where temperature generally decreases with increasing altitude.

Upwelling

The upward movement of cold, nutrient-rich deep ocean water toward the surface, supporting high levels of marine productivity.