Academic Decathlon Science Section : Ecology : Vocabulary

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A horizon

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the topsoil; this layer of soil is primarily made up of weathered parent material, but is relatively rich in organic materials due to leaching from the O horizon above it.

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Abiotic

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of or pertaining to the physical environment

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Abundance

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the number if individuals of a species in a given area, or the relative amount of species in a particular ecosystem'

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Age structure

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the proportion of the population in each age class

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Allele

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one of two or more different possible forms of the same gene, resulting in genetic variability within a population

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Ambient energy hypothesis

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says that where there is more energy, there will be greater biodiversity

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Amensalism

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a relationship between organisms of two different species in which one is unaffected and the other is negatively impacted by the association

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Antibiosis

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a relationship between organisms of two different species in which one is negatively impacted by a substance produced by the other; a specific type of amensalism

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Autotrophic organisms

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organisms that produce their own nutritional organic compounds

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B horizon

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sometimes called the subsoil; contains limited organic matter and often has accumulated mineral particles due to leaching from the topsoil

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Basal species

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species that do not feed upon any other species but are eating by other species

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Benthic Zone

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the ecological zone at the bottom of a body of water

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Biodiversity

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the variation of life

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Biodiversity hotspots

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places of high biodiversity that have been greatly threatened by human activity

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Biogeochemical cycles

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Cycles of nutrient movement through ecosystem components

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Bioluminescence

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the biochemical emission of visible light by organisms

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Biomass

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the amount of organic material that can be found at a given area at any given time

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Biosphere

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the highest level of biological organization encompassing all of the world's ecosystems

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Biotic

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of or having to do with life or living organisms, particularly in their ecologic relationships

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C horizon

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the soil layer that lies beneath the subsoil and is comprised of unconsolidated materials; there is low biological activity in this layer, and it retains many characteristics of the parent material

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Carrying capacity

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the maximum population size of a species that a given ecosystem can support

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Chemical weathering

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the breakdown of rock materials by water, oxygen, and acids

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chemosynthesis

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the process by which microbes create energy by converting carbon molecules and nutrients into organic matter in the absence of sunlight

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climate

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the longterm average weather pattern for an area, which places constraints on the life that can successfully endure, grow, and reproduce

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climax community

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the theoretical stable endpoint in the successional trajectory that experiences very little ongoing change until disturbance rebalance resets the successional clock

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commensalism

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a relationship between two organisms of diferent species in which one organism benefits from the association and the other is neither benefitted nor harmed

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community

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two or more interacting populations of plants and animals of different species in the same area

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community ecology

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the study of the interactions within and among ecological communities

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conservation biology

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the study of the decline of biological populations and the critical ecosystems in which they occur

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continental climates

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climates characterized by large seasonal and daily variation in termperature

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deciduous

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describes a type of woody vegetation that loses its leaves in the fall, allowing much more light to penetrate the canopy than in the summer months

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decomposition

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the breakdown of complex organic compounds into simpler ones, which add nutrient materials to the soil

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density-dependent factors

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factors that impact growth, death, and birth rates differentially depending on the inital size of the population for a given area

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density-independent factors

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factors that impact birth and death rates proportionally with population size, regardless of how many individuals were initially present

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disturbance

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a discrete event in time that disrupts ecosystem, community, or population structure and changes the physical environment

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ecological niche

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a set of optimal environmental conditions that are most conducive to the successful photosynthesis, growth, survival, and reproduction of a species, and that defines the way that a species fits into an ecological community or ecosystem

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ecology

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the scientific study of the relationships between organisms and their environment

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ecosystem

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a community of organisms and the physical environment they live in

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ecosystem diversity

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the diversity of ecological communities that are found within a fixed area

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ecosystem ecology

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the study of the way climate alters the distributionof biotic communities, the rates at which nutrients and water enter a community, and the way that soils and precipitation patterns alter the relationships between plant communities and other organisms

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ecosystem process

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the ways that energy and materials are transferred from one pool to another

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ectoparasites

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parasitic species that live on the surface of their host

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endogenous

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originating inside the ecosystem

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endoparasites

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parasitic species that live inside their host organism and feed on the host organism or rob the host of nutrients or other resources

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environmental studies

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a field of study that examines human impacts on physical, biological, and chemical process

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estuary

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the ecosystem where the river meets the ocean

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evapotranspiration

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the sum of the water lost from evaporation plus transpiration

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evenness

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the percentage that the individuals of each species contribute to the total number of organisms of species present

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evolution

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directional change in populations over time

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evolutionary speed hypothesis

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says that there are more species in some areas because speciation happens faster in these areas or hsa been happening longer

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exogenous

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originating outside of the ecosystem

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exploitation competition

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occurs when one species utilizes more of a limiting resource or uses a limiting resource more effectively than another species

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facultative mutualism

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a type of mutualistic relationship where the organisms both benefit from being together, but is not required for survival

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first law of thermodynamics

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states that energy cannot be created nor destroyed

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first order streams

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the smallest and highest elevation streams

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food web

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an interwoven set of relationships between two trophic levels within an ecosystem

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fundamental niche

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niche based on environmental factors

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gap phase dynamics

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small scale successional dynamics that occur between larger disturbance events, allowing increased light to enter the ecosystem and serving to diversify the community

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genetic diversity

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variation in alleles present in a population that results in individual differences in appearance, function, and behavior

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genetic drift

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change in the genetic composition of a population due to chance or random events rather than by natural selection, resulting in changes in allele frequencies over time

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genotype

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the genetic makeup of a particular organism

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geographic area hypothesis

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states that large areas have more diversity than smaller land areas

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greenhouse gases

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atmospheric gases that absorb and radiate the earth's radiation

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gross primary productivity (GPP)

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the total rate of photosynthesis or the total energy obtained by autotrophs

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herbivore

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an organism that consumes living plants or algae

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heterotrophs

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organisms that consume plant or animal material for maintenance and growth

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horizon

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each layer within the soil profile

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hydrologic cycle

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the process by which water travels from the air to the Earth and back to the atmosphere

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hypothesis

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an educated guess based on prior experience and knowledge about what is driving an observation; it is phrased in such a way that it is scientifically testable

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interference competition

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occurs when one species actively attempts to exclude another species

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intermediate disturbance hypothesis

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says that in the absence of disturbance, a few most competitive species becomes dominant; when there are small periodic disturbances, biological diversity is greater

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intermediate species

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a species that is both a food source for others as well as a consumer of other species

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interspecific interaction

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biotic interactions between members of different species

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intraspecific interaction

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biotic interactions between members of the same species

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keystone species

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species that fill roles that are critically important important to the functioning of the community

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kinetic energy

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.5mv^2 (energy of an object in motion)

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landscape ecology

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a field of ecology that examines large scale spatial patterns and their relationship to ecological funtioning

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litter

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the fresh, undecomposed organic matter on the soil surface

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mangroves

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coastal ecosystems inhabited by salr tolerant trees and shrubs

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maritime climates

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climates characterized by high humidity with little daily or seasonal fluctuations in temperature

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marsh

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an ecosystem type that is formed when upland sediment is carried downriver and accumulates near ocean shorelines; dominated by grasses, rushes, and forbs that are rooted underwater

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mechanical weathering

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the physical breakdown of parent material by processes such as freeze/thaw and wet/dry cycles that cause parent material to expand and contrast, slowly breaking the rock into smaller pieces over time and increasing the surface area

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metapopulation

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interacting groups of populations of the same species that are dispersed among patchy habitats but have occasional migration and interaction

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mineralization

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the process where bonds between carbon molecules and inorganic nutrients are broken, making them available for uptake by plant roots

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mutualism

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a relationship between members of two species in which both members benefit from association

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natural selection

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the process by which individuals with better adapted heritable characteristics tend to survive and reproduce more successfully than other individuals

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Net primary productivity

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the rate of energy stored after accounting for the energy expended

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Niche

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a set of optimal environmental conditions that are most conducive to the successful photosynthesis, growth, survival, and reproduction of a species and that define the way that the species fits into an ecological community or ecosystem

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nitrogen fixation

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the assimilation of nitrogen into organic compounds

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O horizon

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the surface layer of soil, consisting of organic material that accumulates from decomposing plant materials

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Obligatory mutualism

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a type of mutualistic relationship whereby one species cannot survive without the other species

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orographic or rain shadow effect

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a moving air mass picks up moisture as it travels over a body of water. As the air mass moves up a mountain range, it cools and condenses, releasing much of its moisture as rain or snow. The drier air mass then warms as it travels down the inland side of the mountain range.

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Overkill

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ongoing fishing, hunting, or gathering beyond a rate from which a species can rebound

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parasite

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an organism that consumes the tissues of the host organism or robs it of its food or other resources

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parent material

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the rock or mineral substrate that underlies the soil profile

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pathogen

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an organism that causes disease in a host species

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pelagic zone

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the open ocean

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permafrost

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a permanently frozen subsurface soil layer

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predator

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an organism that kills and eats another organism

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prey

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an organism that is killed and eaten by a predator

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phenotype

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the physical manifestation of an organism's genetic makeup

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photosynthesis

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the conversion of sunlight into carbon compounds, which drives the production of energy for use by primary producers

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pioneer species

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the first species to establish after a disturbance

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pools

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1) deep, slow moving stretches of streams with fine sediment

2) the amount of material or energy in an ecosystem

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population

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a group of individuals of the same species that live in a particular area and interact with one another

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population dynamics

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ways in which organisms of the same species interact with each other in the same geographic area

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populatoin ecology

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the study of populations of organisms, which often seeks to find answers to questions about how and why the locations and numbers of populations change over time

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population size

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the number of individuals in the population

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potential energy

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stored energy that is available for performing work

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predation

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an interspecific relationship by which one species, a predator, kills and eats another organism, its prey

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predator-prey cycles

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regularly spaced intervals of increases and decreases in the population sizes of the predator and prey

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primary productivity

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the rate that sunlight is converted by autotrophic organisms via photosynthesis into organic materials

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production

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the rate of generation of biomass in an ecosystem

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productivity hypothesis

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says that greater production should result in greater biological diversity

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range

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the geographical area in which a particular species can be found

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realized niche

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a niche based on environmental factors and the presence of other species

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resilience

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an ecosystem's resistance to change

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respiration

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the process by which organisms take up oxygen (O2) and produce carbon dioxide (CO2)

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Riffles

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fast moving portions of a stream that are flowing over coarse substrate

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Riparian

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the narrow ecosystem that parallels streams, rivers, and other water channels

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rocky intertidal area

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the rocky zone occupying the area between high and low tide

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salinity

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a measure of the dissolved salt content in water

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savannas

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a grassland ecosystem occurring in tropical and subtropical ecosystems with trees and shrubs intermixed with a dense grass understory

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scientific method

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the process by which scientific inquiry takes place, including the following defined steps: ask a question, state a measurable hypothesis , conduct an experiment, analyze the results, and make a conclusion; based on these conclusions, a hypothesis is then either rejected or not

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second law of thermodynamics

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energy disperses from being localized to spread out unless it is prevented from doing so

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secondary production

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generation of biomass of heterotrophic organisms

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soil profile

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vertical layering in the soil collumn

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soil texture

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the relative proportions of different sized sediment grains

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speciation

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the formation of new and distinct species by evolution

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species diversity

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a measure of the variability and variety of living organisms in an ecosystem

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species richness

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the number of different species occurring in the defined geographic area

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stability

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ability of an ecosystem to recover after a disturbance

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stress

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an environmental condition that constrains physiological processes, lowering an organism's rate of growth, survival, or reproduction

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succession

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the directional change in species composition, structure, and resource availability of an area over time that is driven by biotic activity and interactions as well as changes in the physical environment and the dominating species

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succulent

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plants such as catci that have thick, heavy foliage for water storage

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surface runoff

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overland flow of excess water

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symbiont

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organism that lives in associatoin with another organism

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theory

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formed to collectively explian the results of a larger number of experimental observations

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top predator

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eats other species but is not a food source for any other species

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upwelling

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periods when deep, cold nutrient rich ocean waters are driven to the surface to replace the warmer, nutrient poor surface waters