- adaptive behavior - In behavioral ecology, this is any behavior which contributes to an individual's reproductive success and is thus subject to the forces of natural selection.
- Adaptive management - a systematic process for continually improving management policies and practices by learning from the outcomes of operational programs
- adoption - when an organism permanently assumes the role of parent towards a juvenile individual which is not its offspring.
- aerobic metabolism - the process of cellular respiration that occur in the presence of oxygen
- age structure - the distribution of various age groups in a population (typically that of a country or region of the world), which normally forms the shape of a pyramid.
- agroecology - the science of applying ecological concepts and principles to the design, development, and management of agricultural environments
- agroecosystem - an assembly of mutually interacting organisms and their environment in which materials related to crop production are interchanged in a largely cyclical manner
- allee effect - a biology-related concept that is characterized by the relationship between the size of the population and the growth rate of the species.
- altruistic behavior - behavior in which the subject shows less of a concern for their own well being and more for the welfare of others or offspring.
- anaerobic metabolism - the fermentation of organic compounds in which air is not breathed in. Contrary to aerobic respiration which needs oxygen to be carried out.
- Animal behavior - studied in ethology & zoology. the desire to understand animals and their use of communication, emotions, sex, and other behaviors.
- Applied ecology - the practice of employing ecological principles and understanding to solve real world problems (includes agroecology and conservation biology)
- area effect (island biodiversity) - the hypothesis that larger islands can support more species than smaller islands
- atmosphere - earth's atmosphere is composed of gases and water that are retained by earth's gravity and help the earthretain heat and reflect UV radiation.
- autecology - Also known as population ecology. It is a major sub-field of ecology that deals with the dynamics of species populations and how these populations interact with the environment.
- autopoïesis - An organized self-contained system whose parts and systems integrate seamlessly in a relationship of form and function.
- autotroph - an organism who makes its own food from inorganic material
- bark- the tough coverin
- Behavioral ecology - studies the ecological and evolutionary basis for animal behavior, focusing largely at the level of the individual
- biodegradable - capable of decaying through the action of living organisms
- biodiversity - diversity among and within plant and animal species in an environment
- Biogeochemistry - effect of biota on global chemistry, and the cycles of matter and energy that transport the Earth's chemical components in time and space
- biogeochemical cycle - the pathway through which a chemical, element, or molecule moves through the atmosphere,hydrosphere, lithosphere, and biosphere.
- Biogeography - the study of the geographic distributions of species
- bioinvader - non-native species
- biomass - the sum of all living living organisms in an area.
- biomass pyramid - also called an ecological pyramid, it is a graph that illustrates the productivity in a trophic level
- biome - The total complex of biotic communities occupying and characterizing a particular area or zone
- biosphere - the sphere of life; all living matter of the planet occupied by life
- biogeographic realm - is the largest scale of the Earth's surface based on the distribution patterns of plants and animals.
- biogeography - the study of the distribution of organisms, past and present, and of diverse processes that underlie their distribution patterns
- biological magnification - the increase in concentration of a substance
- biota - the total collection of organisms of a geographic region or a time period.
- biotic potential - under ideal conditions, the maximum rate of increase of a population in a given area
- boreal forest - forest areas of the northern North Temperate Zone, mostly made of coniferous trees, also known as taiga.
- cambium - produces secondary phloem and secondary xylem which gives rise to wood in plants
- community structure - a series of close knit groups that share common characteristics, they form a spider web pattern because of the natural divisions in the structure of the community
- camouflage - used to deceive or disguise from surroundings
- carbon cycle - is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.
- carrying capacity - the maximum number of individuals an environment's resources can support, including the food and water available for the environment
- Charismatic megafauna - a species of large animal species with widespread popular appeal that environmental activists use to achieve conservation goals well beyond just those species. Examples include the Giant Panda, the Bengal Tiger, and the Blue Whale. See also: Flagship species
- Chaparral - a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico. It is shaped by a Mediterranean climate (mild, wet winters and hot dry summers) and wildfire, featuring summer-drought tolerant plants with hard sclerophyllous evergreen leaves, as contrasted with the associated soft-leaved, drought deciduous, scrub community of Coastal sage scrub, found below the chaparral biome.
- Chemical ecology - which deals with the ecological role of biological chemicals used in a wide range of areas including defense against predators and attraction of mates
- climate - The long term average weather pattern in a particular place.
- climate change - change in weather conditions such as cloud cover wind speed, temperature, rainfall or humidity in a specific region.
- cohert - an individual in a population that is of the same species
- climax community - a biological community of plants and animals that has reached a constant state occurring when the species is best adapted to average conditions in that area
- climax-pattern model - a community is adapted to many environmental factors that vary in their influence over a region
- conservation biology - scientific study of the earth’s biodiversity and aimed at protecting habitats and species from extinction.
- Coast Redwood-(Sequoia sempervirens) the sole living species of the genus Sequoia in the cypress family Cupressaceae. It is an evergreen, long-lived, monoecious tree living 1,200–1,800 years or more. It is one of the tallest living trees on Earth, reaching up to 379 feet (115.5 m) in height (without the roots) and up to 26 feet (7.9 m) in diameter at breast height.
- conservation ecology - which studies how to reduce the risk of species extinction
- commensalism - A symbiotic relationship between two organisms of different species in which one attains some benefits while the other is unaffected
- communication display - a pattern of behavior that is a social signal, sending others a message through different displays of movement, and voice
- communication signal - instinctive and learned behaviors by which animals send and receive to each other in information laden cues, encoded in stimuli.
- community - a group of various organisms living in the same environment
- community assembly theory - explains how environmentally similar sites have different species or similar species because of the resources they need or "niche requirements"
- Community ecology (or synecology) - studies the interactions between species within an ecological community
- consumer - an organism, usually an animal, that feeds on plants or other animals.
- contiguous region - touching along the side or boundary
- competition - when organisms from the same or different species compete against each other for food, better living conditions, better reproductive success, or any limited resource where the most fit or most adapted individual comes out on top and thus survives and reproduces
- competitive exclusion principle - states that two species can not both exist if they are competing for exactly the same resource. Therefore there is always one with a small advantage that will cause the other species in most cases to become extinct.
- composite signal - a signal used in order to communicate which has information within more than a single cue.
- coniferous forest - is a land biome, or large section of land
- cooperation - is the process of working or acting together, intentionally or not. It encompasses working in harmony, side by side, while also involving something as complex as the inner workings of a human being or even the social patterns of a nation.
- courtship display - Ritual social behavior between possible mates
- Coast Live Oak (Quercus agrifolia)- evergreen oak, native to the California Floristic Province
- cross section -It is the face you get when you make one slice through an object.
- deciduous broadleaf forest - a forest in a more mild climate with dry seasons, where the tree's foliage changes with the varying seasons.
- Decomposition - process by which tissues of dead organisms break down to more simplistic forms of mater and organic material, freeing up the limited space in the biome
- dendrochronology- a technique for determining the age of a tree by counting tree rings.
- density-dependent control - any factors that affect individuals of a population and that vary with population density.
- Desert ecology - The sum of the interactions between both biotic and abiotic factors of the desert biomes. including the interactions of plant, animal, and bacterial populations in a desert community.
- Desert ecoregion - major desert ecosystem defined by distinctive geography and receiving uniform solar radiation and moisture.
- desert - a landscape that receives less than 10 inches of rain per year
- desertification - a process by which areas become desertlike wastelands with low biodiversity
- Demographics - the characteristics of human populations for purposes of social studies.
- demographic transition model - a model, which represents a shift from high to low birth rates and death rates as part of the economic development of a country
- denitrification - The breakdown of nitrates by anaerobic bacteria into other forms. Generally soil.
- density independent factor - A factor that affects the size of a population regardless of the population density.
- detrital food web - a food web depicting energy flow from photoautotrophs through detrivores and decomposers
- detritivore - heterotrophs which consume decomposing bits of organic matter, such as leaf litter.
- decomposer - organisms that breakdown substances into simpler substances
- distance effect (island biogeography) - the uniques assemblage of life form and species on an island
- dry woodland - a type of biome that forms when rainfall is averaging around 40 to 100 centimeters, and also has many tall trees
- dominance hierarchy - organization of individuals into groups with a social structure.
- Dominance species - a species which characterizes and predominates an ecological community as measured byprimary productivity or biomass.
- doubling time - the amount of time it a population takes to double its size.
- Early wood - The part of an annual ring of wood characterized by large, thin-walled cells formed during the first part of the growing season.
- ecology - The study of interactions between organisms and their environment
- ecological communities - is defined as a group of actually or potentially interacting species living in the same
- ecological literacy - is the ability to understand the natural systems that make life on earth possible
- ecological selection - ecological processes that operate on a species' inherited traits without reference to mating or secondary sex characteristic.
- ecological productivity
- Ecological succession - a focus on the understanding that directs vegetation change
- ecophagy - the consuming of an ecosystem
- Ecophysiology - which studies the interaction of physiological traits with the abiotic environment
- ecopoiesis - fabrication of a sustainable ecosystem on a currently lifeless, sterile planet
- ecoregion - a region defined by its geography and ecology
- ecosynthesis - the use of introduced species to fill niches in a disrupted environment with the aim of increasing the speed of ecological restoration.
- ecosystem - the total of interacting organisms (biocoenosis) and non-living things (biotope) in a specific environment
- Ecosystem ecology - which studies how flows of energy and matter interact with biotic elements of ecosystems
- Ecosystem function
- ecosystem modeling - The use of mathematics, computer programs and models to understand and predict ecosystem behaviour
- Ecosystem services - resources and processes that are supplied in a natural ecosystem that benefits organisms.
- ecotone - a transition area between two adjacent but different landscape patches
- ecotoxicology - looks at the ecological role of toxic chemicals (often pollutants, but also naturally occurring compounds)
- El Niño - a band of anomalously warm ocean water temperatures that occasionally develops off the western coast of South America and can cause climatic changes across the Pacific Ocean
- ecozone - an area that has characteristics of natural origin such as climate, terrain, vegetation, etc. It is also the largest division of the Earth's surface filled with living organisms.
- endangered species - a species that contains numbers so low that it risks becoming extinct
- energy pyramid - a graphical representation designed to show the biomass or biomass productivity at each trophic level in a given ecosystem
- environmental restoration - repairing damages to an area caused by humans, natural disasters or industry.
- ethology - the study of animal behavior as behavioral ecology, a branch of zoology.
- eutrophication - an increase in chemical nutrients in the ecosystem. It may occur on land or in water. This increase of chemicals usually causes an increase or decrease of plant growth.
- evaporation - is the slow vaporization of water from either the soil or surface water.
- evolutionary ecology - (or ecoevolution) the evolutionary changes in the context of the populations and communities in which the organisms exist
- exotic species - introduced species not native or endemic to a habitat
- extinction - when organisms completely die off and there are no more of that organism left.
- exponential growth - is the growth of a population that is consistent
- emigration - leaving ones native region to go to another
- estuary - a body of water on the coast attached to the ocean and rivers or streams that often give it a black color as a result of silt and sediment.
- fall overturn - the mixing (or "turning over") of water that takes place in autumn that reoxygenates the water.
- fire ecology - which looks at the role of fire in the environment of plants and animals and its effect on ecological communities
- fixed action pattern - is a behavior that is independent when changes in the environment occur
- flagship species - is a species chosen to represent an environmental cause, such as an ecosystem in need of conservation.
- food chain - a group of organisms interrelated by the fact that each member of the group feeds upon the one below it.
- food web - a set of interconnected food chains by which energy and materials circulate within an ecosystem
- forest ecology
- foundation species - is a species of dominant primary producer in an ecosystem both in terms of abundance and influence.
- founder effect - the accumulation of random genetic changes in an isolated population
- functional ecology - the study of the roles, or functions, that certain species (or groups thereof) play in an ecosystem
- Genetic bottleneck - is an evolutionary event in which a significant percentage of a population or species is killed or otherwise prevented from reproducing.
- geographic dispersal - when an organism moves into another region to join another community.
- Global ecology - examines ecological phenomena at the largest possible scale, addressing macroecological questions
- global ecophagy - the consuming of an ecosystem.
- global warming - the warming of the Earth's average temperature of near-surface air and oceans
- grassland - and where grass or grasslike vegetation grows as the dominant form of plant life
- greenhouse effect - warming that results when solar radiation is trapped by the atmosphere, which is caused by gases that allow sunshine to pass through but absorb heat that is radiated back from the warmed surface of the earth
- grey pine - Digger pine (Pinus sabiniana), also called bull pine or gray pine, has limited commercial use today, but it once was important to California Indians, who used its seeds and parts of cones, bark, and buds as food supplements, and its twigs, needles, cones, and resin in basket and drum construction.
- habitat - Specific ecological or environmental areas that are inhabited by specific plants and animal species.
- habitat connectivity - Allowing for the conservation or maintenance of continuous or connected habitats, so as to preserve movements and exchanges associated with the habitat.
- habitat corridors - a strip of land that helps with the movement of a species between disconnected areas of their naturalhabitat.
- habitat fragmentation - a process of environmental change that involves the discontinuations, or fragmenting, of a species' natural habitat.
- hardwood- the wood from a broadleaved tree (such as oak, ash, or beech) as distinguished from that of conifers.
- homeostasis - the property of a system that regulates the internal environment and maintains a constant and stable condition. ex: endothermic animals maintain a constant body temperature.
- host - an organism that has another organism on or in itself
- human ecology - a field of study that deals with relationships between humans and their societies; their natural, social, and created environments.
- hydrologic cycle - the cycle or process of evaporation and condensation of water, and its distribution across the earth driven by solar energy
- hydrosphere - the water vapor in the Earth's atmosphere
- hydrothermal vent - an underwater steaming fissure that has unique ecosystems.
- ion exchange - A reversible chemical reaction when ions with the same charge can be switched. This can be used in purification of a substance.
- illegitimate receiver - An organism that is not intended to receive another organism's signal, but intercepts it anyway, to the fitness detriment of either the signaler or a legitimate receiver of the signal.
- illegitimate signaler - a predatory species will mimic signals to lure in their prey
- immigration - The one-way inward movement of individuals or into another population or population area.
- imprinting - a time-dependent form of learning triggered by exposure to sign stimuli
- Incense cedar - a species of conifer native to western North America.
- indicator species - is any biological species that defines a trait or characteristic of the environment. The presence and/or abundance of organisms of these species are typically used to indicate the health and an ecosystem
- instinctive behavior - occurs when an animal has a particular internal state while it is in the presence of an external stimulation called a releaser
- Intermediate Disturbance Hypothesis - a theory that tries to predict how a species diversity will change with changing levels of disturbance
- interspecific competition - this occurs when different species try to use the same resources in an environment
- Intertidal zone - Area exposed to the air during low tide.
- invasive species - a non-native species whose introduction to an area is likely to cause economic or environmental harm or harm to human health
- jungle - A large, undeveloped, humid forest that is home to many wild plants and animals.
- K-selected species - the species that is a group of strong competitors in a crowded environment and have fewer but stronger offspring.
- keystone species - keystone species is a species that has a disproportionate effect on its environment relative to its abundance. Such species affect many other organisms in an ecosystem and help to determine the types and numbers of various others species in a community.
- La Nina - when the ocean surface cools
- lake - a body of liquid on the surface of the Earth; it is considered a lake when it is not part of an ocean, is inland, and is fed by a river
- Landscape ecology - studies the interactions between discrete elements of a landscape
- learned behavior - a type of action or reflex that you learn
- Lek - type of animal territory in which males of a certain species gather to demonstrate their prowess before or during mating season
- limiting factor - any essential resource that is in short supply in an environment
- logistic curve - an S shaped curve that usually represents population growth.
- Lotka–Volterra equation - an ecological predator-prey model
- macroecology - the study of large scale ecological phenomena
- mangrove wetland - mangroves are most often defined as trees or shubs found in sub tropic climates. where plants "assemblage or mangal" and provide habitat for many marine organisms
- marine ecology - and aquatic ecology, where the dominant environmental milieu is water
- marine snow - tiny particles, including dead organic matter from the upper layers of the ocean, sinking deep into the ocean
- mark and recapture - used to estimate populations and find survival rates, movement and growth.
- Mediterranean ecoregion - characterized by its dry summers and rainy winters
- Medullary Rays - Refers to radial sheets or ribbons extending vertically through the tree across and perpendicular to the growth rings. Also called pith rays or wood rays.
- Mesopredator release hypothesis - hypothesis that states as top predators dwindle in an ecosystem an increase in the populations of mesopredators occur
- metabolic theory of ecology - theory that explains the relationship between an organism's body mass and metabolic rate
- microbial ecology - the ecology of micro-organisms
- micro-climate - an area influenced by either natural or manmade features that change the climatic conditions from the normal regional climate
- microecology - the study of small scale ecological phenomena
- migration - the movement of organisms from one place to another
- mimicry - imitative behavior. animal species resembling one another.
- molecular assembler
- molecular ecology - a field of evolutionary biology concerned with applying molecular population genetics, molecular phylogenetics, and genomics to traditional ecological questions. Essentially the same as ecological genetics
- molecular engineering - any means of creating molecules through the use of technology
- monsoon - air circulation patterns that influence the continents north or south of warm oceans
- mutualism - A biological interaction between individuals of two different species, where each individual derives a fitness benefit. It includes relationships which are mutualistic, parasitic or commensal.
- natural selection - happens over a long period of time and is defined as a certain trait and how species with this trait can or can not survive, and how it affects the reproduction of this good or bad trait. Therefore if a species carries a bad trait that lowers its survival rate its reproductive rate will lower as well.
- natural resource - naturally forming substances that are considered valuable in their natural or unrefined form
- negative feedback loop - feedback that reduces the output of a system. ex. when the temperature rises in a room, it turns off the thermostat so that the temperature remains stable
- neutralism - belief that changes in evolution are caused by random mutation rather than by natural selection.
- niche - a position or function of an organism in a community of related organisms.
- nitrification - the oxidation of ammonia with oxygen into nitrite
- nitrogen cycle - this is a continuous cycle by which nitrogen from the atmosphere and compounded nitrogen keeps getting exhanged through the soil into substances that can be taken up and used by green plants, what is left returns to the air as a result of denitrification.
- nitrogen fixation - conversion of nitrogen into nitrogen compounds (ex. nitrate and nitrite) that is carried out naturally by certain bacteria and algae.
- nutrient - provides nourishment and promotes growth.
- ocean - the large body of salt water which covers almost 75% of the earths surface.
- paleoecology - a science which seeks to understand the relationships between species in fossil assemblages
- parasite - an organism which survives with another through a symbiotic relationship with another organism—its host—which it does not usually kill directly but does negatively affect.
- parasitoid - An organism that is a parasite for most of its life and will usually kill its host
- permafrost - permanently frozen layer of terrain found beneath the arctic tundra
- per capita - a measurement indicating "per unit of population"
- pheromone - a chemical which is typically given off into the environment as a signal which causes a natural behavioral response in members of the same species
- phloem - the vascular tissue in plants that conducts sugars and other metabolic products downward from the leaves.
- phosphorus cycle - the biogeochemical cycle that describes the movement of phosphorus through the environment
- pioneer species - species that first inhabit an environment which was previously unoccupied
- pollination - a type of fertilization and reproduction where the transpoatation of pollen grains from plants to ovure- bearing organs. This takes place by either wind, water, or animal assistance
- pollinator decline - a tall slender pine tree, the most widespread connifer of western North America, planted for timber and as an ornimental
- Ponderosa Pine (pinus ponderosa) -
- population density - the number of individuals of a species living per unit of an area.
- political ecology - a theoretical lens focusing on how political and economic power effects ecology, as well as how ecology can also shape the political economy, by understanding and analyzing environmental influences on social activity.
- population ecology (or autecology) - deals with the dynamics of populations within species, and the interactions of these populations with environmental factors
- population pyramid - a graphic illustration which shows the age structure in apopulation (typically that of a country or region of the world), which normally forms the shape of a pyramid.
- population size - the number of individuals of a species in a particular geographic range.
- predation - the interaction among populations when one organism consumes another one.
- predator - an organism that lives by killing and consuming another living organism.
- prey - living organisms that predators feed on
- primary producer - an autotroph that obtains energy directly from the nonliving environment through photosynthesis or less commonly through chemosynthesis
- primary production - production of organic compounds from carbon through photosynthesis. This effects all life on Earth either directly or indirectly
- protocooperation - two species interact with each other beneficially
- population distribution - means the pattern of where people and animals live. Throughout the world distribution is uneven for example places which contain small amounts of people are considered sparsely populated whereas places which are densely populated contain many people.
- quadrat - 1. A piece of type metal used for filling spaces. 2. A quad a rectangular plot of land extensively studied for its ecology
- rain shadow - A dry area of land that is leeward of a mountain range that results in arid or semiarid conditions
- red fir (Ables magnifica) - western North American fir, native to the mountains of southwest Oregon and California
- reproductive base - includes all members of a population that are of reproductive and pre-reproductive ages.
- resource - a substance or object in the environment required by an organism for normal growth, maintenance, and reproduction.
- resource partitioning - when two or more species share, and compete for a resource in different ways in order for both species to coexist
- Restoration ecology - attempts to understand the ecological basis needed to restore impaired or damaged ecosystems
- R-selected species - A species selected for its superiority in variable or unpredictable environments
- run-off - the flow of water over land from rain, melting snow, or other sources
- savanna - A flat grassland with scattered trees in tropical or subtropical regions
- secondary succession - succession that occurs after the original population has been destroyed or disturbed, as with a forest fire
- selfish behavior - occurs when an individual, despite the impact it may have on the rest of the population, increases its own chances of reproducing
- selfish herd - how individuals in a group can act together without planned direction
- sexual selection - a trait that makes an individual more likely to find a mate than others. A microevolutionary process.
- Sierra Nevada Mountains - major mountain range of western North America, running along the eastern edge of the U.S. state of California.
- sign stimulus - Fixed action patterns such as mating dances.
- signal receiver - The individual who is responding to the communication signals sent by the signaler.
- signaler - a way to capture attention from a species
- social parasite - A group or individual that latches on to another group or individual to benefit itself. This type of process affects the original pattern of the group its feeding off.
- social behavior - behavior of an individual towards society and members of the same species as a whole.
- soil - the naturally occurring, unconsolidated or loose covering on the Earth's surface
- soil ecology - the ecology of the pedosphere
- song system - a series of discrete brain nuclei used to produce and learn certain songs of songbirds.
- source-sink dynamics - a theoretical model used by ecologists to describe how variation in habitat quality may affect thepopulation growth or decline of organisms
- southern pine forests - a forest consisting of a pine species that thrives in the sandy, dry, and nutrient-poor soil on the coastal plains of the south Atlantic and Gulf states.
- speciation - the evolutionary process where new biological species come about
- spring overturn - the mixing of lake waters through the melting of ice cover, the warming of surface waters, convection currents, and wind action occurring in spring
- sulfur cycle -
- summer wood- The part of the wood in a growth ring of a tree that is produced later in the growing season.
- stream - a flowing-water ecosystem that starts out as freshwater springs or seeps
- survivorship curve - a graph showing the number or proportion of individuals surviving at each age for a given species
- symbiosis - a non-predator prey interaction between individuals of different species.
- symbiosis - is a relationship between two or more individuals in a species mainly concerning food. (For example: if the species is competing for the same food, trying to avoid getting eaten or is attempted to eat the other.) There are five different types of symbolic relations that describe who benefits from the relation.
- tactile display - when a signlar touches the receiver in ritualized ways
- Taylor's law
- terrestrial ecology
- terrestrial ecoregion
- territory - an area that one or more individuals defend against competition.
- threat display - a signal used by any certain species in order to show that the user intends to attack
- Theoretical ecology - the development of ecological theory, usually with mathematical, statistical and/or computer modeling tools
- total fertility rate - the average number of children that a mother bears in a population during their years of reproduction.
- tree ring - each of a number of concentric rings in the cross section of a tree trunk, representing a single year's growth.
- trophic cascade
- trophic level - where an organism is on the food chain—what it eats, and what eats it
- tropical rain forest - a biome characterized by regular, heavy rainfall, with a humidity of 80 plus percent, and biodiversity
- tundra - a permanently frozen, treeless expanse between the icecap and treeline of Arctic regions
- umbrella species - species which are selected for making conservation related decisions, typically because protecting these species indirectly protects the many other species that make up the ecological community of its habitat.
- ultra Plankton - a large breed of sea plankton found in marine environments.
- upwelling - when the flow of water is in an upward direction created by atmospheric winds that blow over the ocean's surface away from the coastline and cause deeper, colder, water to rise to the top.
- Urban ecology - the study of ecosystems in urban areas
- warning coloration - a warning signal that prey uses to warn off predators
- water cycle - (a.k.a. hydrologic cycle) the nonstop movement of water on, above, and below Earth's surface. The water changes between liquid, vapor, and ice at different times during the cycle.
- water vapour - the gaseous state of water.
- watershed - the land where water from rain and show melts drains downhil into a body of water (i.e. a river, lake,reservoir, estuary, wetland, sea, or ocean).
- web of life - also known as the food chain, food network, or trophic social network. It describes the eating relationships between different specied in a certain ecosystem.
- wood grain - a texture seen in a cut surface of wood.
- Yellow rain - A powdery, poisonous, yellow substance reported as dropping from the air in southeast Asia and found to be the excrement of wild honeybees contaminated by a fungal toxin
- zero population growth - The population of a given area neither increases or decreases over a period of time.