Comprehensive Ecology Study Guide: Climate Dynamics, Population Properties, and Growth Models

Climate change

A long-term change in climate patterns, including average temperature, precipitation, and their variability.Weather

Weather

Short-term atmospheric conditions at a particular place and time. A cold day alone does not establish a climate trend.

Climate

The long-term statistical patterns of weather in a region or across Earth.

Holocene

The geological epoch beginning about 11,700 years ago, emphasized in the slides for its relatively stable climate compared with major glacial transitions.

Milankovitch cycles

ong-term changes in Earth's orbit and orientation that alter the seasonal and geographic distribution of incoming sunlight.

Eccentricity

Variation in the shape of Earth's orbit. An important cycle operates over roughly 100,000 years.

Obliquity

The angle of Earth's axial tilt. Its variation has a cycle of roughly 41,000 years.

Precession

The wobble in the orientation of Earth's rotational axis, with a characteristic cycle around 20,000-23,000 years.

Greenhouse gas

An atmospheric gas that absorbs and emits infrared radiation. Slide examples: water vapor, carbon dioxide, and methane.

Greenhouse effect

Warming associated with greenhouse gases absorbing and re-emitting outgoing infrared radiation, including toward Earth's surface.

Earth's energy balance

The relationship between solar energy absorbed by Earth and energy emitted to space. A persistent imbalance changes temperature.

Infrared radiation

Longer-wavelength electromagnetic radiation emitted by Earth and absorbed by greenhouse gases.

Albedo

The fraction of incoming sunlight a surface reflects. Snow and ice have high albedo; dark ocean has low albedo.

Carbon dioxide (CO2)

A greenhouse gas released by respiration, decomposition, and combustion, and removed by photosynthesis and other carbon-uptake processes.

Methane (CH4)

A greenhouse gas that can be released during oxygen-poor decomposition and from fossil-fuel systems. Thawing permafrost can contribute methane emissions.

Carbon cycle

The movement of carbon among the atmosphere, organisms, soils, oceans, sediments, and geological deposits.

Carbon reservoir

A part of Earth that stores carbon, such as a forest, ocean, soil, or fossil-fuel deposit.

Carbon sink

A system that absorbs more carbon than it releases over a specified period.

Carbon source

A system or process that releases more carbon than it absorbs over a specified period.

Fossil fuels

Carbon-rich geological fuels, including coal, oil, and natural gas. Burning them transfers stored carbon to the atmosphere.

Combustion

Burning: a chemical reaction that releases energy and can convert carbon in fuels or biomass into atmospheric CO2.

Deforestation

Removal of forest cover. It can release stored carbon and reduce future carbon uptake by vegetation.

Keeling curve

The record of atmospheric CO2 measurements begun by Charles David Keeling at Mauna Loa in 1958, showing seasonal oscillations and a long-term increase.

Seasonal CO2 oscillation

The annual rise and fall in atmospheric CO2 caused largely by seasonal changes in photosynthesis, respiration, and decomposition.

Parts per million (ppm)

A concentration unit meaning parts of a substance per million parts of a mixture. The CO2 graphs use ppm.

Ice core

A cylinder of ice containing evidence of past conditions. Trapped air bubbles preserve samples of earlier atmospheric gases.

Climate proxy

An indirect record used to reconstruct past climate, such as tree rings, coral growth, or ice-core measurements.

Positive feedback

A response that amplifies an initial change. Example: warming melts ice, lowering albedo and causing additional warming.

Negative feedback

A response that counteracts an initial change. It reduces the initial disturbance rather than amplifying it.

Ice-albedo feedback

A positive feedback in which melting reflective ice exposes darker surfaces, increases solar absorption, and promotes more warming.

Tipping point

A threshold beyond which feedbacks can drive a major system shift that may be difficult to reverse.

Climate projection

An estimate of future climate based on specified assumptions or scenarios. It is conditional on those assumptions.

Per capita emissions

Emissions divided by the number of people, often expressed as tons per person per year. Different from a country's total emissions.

Ocean stratification

Layering of ocean water by density that can limit vertical mixing and transfer of heat or carbon into deeper water.

Photosynthesis

The process by which plants, algae, and some microbes use light energy to fix carbon into organic compounds. It removes CO2 from the environment.

Respiration

A process that releases usable energy from organic compounds. Aerobic respiration produces CO2 and water.

C3 plant

A plant whose first stable product of carbon fixation has three carbons. C3 plants often show a stronger direct photosynthetic response to extra CO2 than C4 plants.

C4 plant

A plant that initially fixes carbon into a four-carbon compound and concentrates CO2 near the Calvin cycle, often reducing the direct benefit of extra atmospheric CO2.

Stomata

Adjustable pores on plant surfaces that allow gas exchange and water-vapor loss.

Transpiration

Loss of water vapor from a plant, mainly through its stomata.

Water-use efficiency

Carbon gain relative to water lost. Partial stomatal closure under elevated CO2 can increase it.

FACE experiment

Free-Air CO2 Enrichment: an outdoor experiment that raises CO2 around vegetation to study responses under relatively natural conditions.

Net primary productivity (NPP)

The rate at which producers accumulate organic matter after subtracting their own respiration from gross photosynthetic production.

Nutrient limitation

A situation in which insufficient nutrients constrain growth, so increasing CO2 alone may not increase productivity.

Forb

A non-grass herbaceous flowering plant. The prairie example contrasts grasses with forbs.

Permafrost

Ground that remains at or below 0 degrees C for at least two consecutive years. Thawing can expose stored organic carbon to decomposition.

Methane hydrate

Methane trapped within cage-like structures of water ice, forming a potentially large methane store.

Ice sheet

A very large mass of land-based glacial ice. Loss of land ice to the ocean raises sea level.

Ice shelf

A floating extension of land ice. Its loss can indirectly raise sea level by allowing grounded ice to flow faster into the ocean.

Ocean acidification

A decrease in ocean pH caused mainly by uptake of atmospheric CO2. It does not require seawater pH to fall below 7.

pH

A logarithmic measure related to hydrogen-ion concentration. More hydrogen ions means lower pH.

Carbonic acid (H2CO3)

A weak acid formed when CO2 reacts with water. Its dissociation contributes hydrogen ions to seawater.

Bicarbonate ion (HCO3-)

A weak acid formed when CO2 reacts with water. Its dissociation contributes hydrogen ions to seawater.

Carbonate ion (CO3^2-)

An ion used with calcium to build calcium carbonate shells and skeletons. Acidification reduces its availability.

Calcium carbonate (CaCO3)

The mineral material in many shells and coral skeletons, formed from calcium and carbonate ions.

Calcification

The formation of calcium carbonate structures, such as shells or coral skeletons.

Coral bleaching

The paling or whitening of coral after loss of its symbiotic algae, often under heat stress. Bleached coral is not necessarily dead.

Zooxanthellae

Photosynthetic symbiotic algae living in coral tissues. They provide energy and contribute to coral color.

Mast

Fruits and seeds produced by woody plants that provide food for animals. Acorns from oaks are a slide example.

Biodiversity

The variety of life, including variation within species, among species, and among ecosystems.

Species composition

The identities and relative representation of species in a community. It can change as ranges shift.

Vector

An organism that transmits a pathogen between hosts. A mosquito is a vector; the parasite or virus it carries is the pathogen.

Malaria

A disease caused by Plasmodium protozoan parasites and transmitted by infected female Anopheles mosquitoes.

Dengue and yellow fever

Viral diseases transmitted by infected Aedes mosquitoes. Unlike malaria, they are caused by viruses rather than protozoan parasites.

Population

Individuals of the same species occupying a defined area, with potential for interbreeding.

Unitary organism

An organism that develops as a relatively distinct individual from one zygote, such as a bird or mammal.

Modular organism

An organism that grows by producing repeated units or modules, common in plants.

Zygote

A fertilized cell formed by fusion of gametes. It begins a new genetic individual.

Genet

The complete genetic individual arising from one zygote, including its asexually produced modules.

Ortet

The original individual from which a clone originates.

Ramet

A module or clonal unit produced asexually from a genet. Ramets may stay connected or become separate.

Clone

Genetically matching asexual descendants, apart from mutations. Many aspen stems can belong to one clone.

Spatial distribution

The arrangement or locations of individuals in space.

Geographic range

The area encompassing the locations occupied by a species. Not every place inside it must be occupied.

Fundamental niche

The environmental conditions and resources under which a species could persist in the absence of limiting interactions with other species.

Geographic barrier

A physical feature that restricts movement and colonization, such as a mountain range or ocean.

Environmental heterogeneity

Variation in environmental conditions or resources across space or time.

Local population / subpopulation

Individuals of a species occupying one local habitat patch within a larger population system.

Metapopulation

A collection of local populations connected by dispersal, with possible local extinction and recolonization.

Abundance (N)

The total number of individuals in a defined population.

Population density

The number of individuals per unit area or volume. Density = abundance / area or volume.

Crude density

The number of individuals per unit of total area, including unsuitable portions of that area.

Ecological density

The number of individuals per unit of available living space or suitable habitat.

Random distribution

A spatial pattern in which an individual's position is independent of other individuals' positions.

Uniform distribution

A pattern of relatively even spacing, often caused by territoriality, competition, or other negative interactions.

Clumped distribution

A pattern in which individuals occur in groups or patches, often due to patchy resources, social behavior, or clonal growth.

Quadrat

A sampling unit of known area used to estimate abundance or density, especially for sessile organisms.

Sessile organism

An organism fixed in place rather than freely moving from location to location.

Mark-recapture

A population-estimation method involving capture, marking, release, and a later sample to identify recaptured individuals.

Lincoln-Petersen estimator

An estimate of population size: N = M × n / r. M = initially marked; n = second sample; r = marked recaptures.

Equal catchability

The assumption that individuals have comparable probabilities of capture. Strong trap-shy or trap-happy behavior can violate it.

Index of abundance

An indirect indicator of population abundance, such as tracks, scat, or bird calls. It is not necessarily an exact count.

Age structure

The proportion of individuals in different age classes in a population.

Age pyramid

A graph showing population numbers or percentages by age class, often with males and females on opposite sides.

Prereproductive class

Individuals that have not yet reached reproductive age.

Reproductive class

Individuals currently within the ages at which reproduction occurs.

Postreproductive class

Individuals beyond their reproductive ages.

Recruitment

The addition of individuals to a population or specified life stage, such as seedlings establishing in a forest.

Increment borer

A tool that removes a narrow core of wood to examine tree rings without cutting down the tree.

Pith

The central region of a stem, associated with its earliest growth.