Welcome to Ariadne's Forest Glossary
Glossary: E is for ... ecology, exogen, and extinct
by Ariadne Unst
Glossary of E...
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- earthquake (n.)
- Sudden motion or shaking in the Earth.
Caused by the quick release in
seismic waves of slowly accumulated energy. Often occurs along faults,
tectonic plate boundaries, or the mid-oceanic ridges.
- ecological diversity (n.)
- The variety of unique biological communities on the Earth.
- ecological niche (n.)
- A "place" occupied by a particular species and providing
all resources (shelter, temperature, food, water, etc.) that a species needs to survive.
The physical, chemical, and biological conditions
required by a species to survive, grow, and reproduce.
- ecologist (n.)
- A scientist that studies the relationships and interactions among organisms and
- ecology (n.)
- Scientific study of the relationships among organisms, and between
organism the living and non-living aspects of their environments. Study of the
interactions that determine distribution and abundance of organisms. First use
by E.H. Haeckel (1869) in German, from oikos (Greek for home) and
logos (Greek or discourse). For an introduction to ecology, see
- ecosystem (n.)
- The basic unit in ecology.
Includes both the organisms and the non-living environment.
The entire complex of organisms and factors of environment in an
ecological unit in a defined space.
An ecosystem consists of both organic and inorganic components,
and includes soil, plants, animals, climate, and physical geoography.
A sustainable natural
its living organisms, and the
ways these organisms interact (especially through energy and nutrient flow)
with the physical space and with each other.
Populations are tied to the amount of energy captured by primary producers in an ecosystem.
- ecotone (n.)
- An zone of contention for dominance between different plant communities. A
transition area, narrow or broad, between contiguous communities.
- ecotype (n.)
- A subspecies or variety adapted to a specific environment or set of conditions.
- edaphic factors (n.)
- The elements of that environment that determine, in combination, the
nature of soils. Such factors include the alkalinity of the soil, the degree
of moisture, and the degree of sunlight. From the Greek edaphos for
- endangered species (n.)
- A species that is in danger of
extinction because it is so low in number or its habitat is disappearing too quickly.
The time till a species goes
can be extimated from its birth and death rates.
Given those rates, the smaller the population,
the more likely is extinction to arrive sooner.
This is because of random fluctuations in births and deaths, and because
births and deaths have to be whole numbers.
- endemic (adj.)
- Native and restricted to a given area, which can be quite local or quite
far-ranging (a region, state, country, or continent).
- endocarp (n.)
- The innermost layer of a pericarp; e.g., a cherry stone.
- endogen (n.)
- A monocotyledonous
plant that increases with time by the growth of new tissue within. Compare
with an exogen.
- endosperm (n.)
- A nutritive substances or tissue in seed plants within the embryo sac.
- entire (adj.)
- A type of leaf margin that is continuous and smooth.
- entrainment (n.)
- The process of particle lifting by an agent of erosion.
- entropy (n.)
- The measure of the disorder (randomness) of matter
and energy in a system.
- environment (n.)
- Abiotic and biotic factors that influence:
- (1) the life of an organism.
- (2) the function of some nonliving natural system.
- enzyme (n.)
- A type of protein that can facilitate and
regulate chemical reactions in cells.
- ephemeral (n.)
- DTransitory; lasting for a short time;
describing a plant or flower that blooms for only a short time.
- epicotyl (n.)
- The portion of the young stem of a plant seedling that is above the cotyledons.
- epigynous (adj.)
- Having floral organs (stamens, petals, and sepals) near the summit of the ovary.
- epiphyte (n.)
- An organism that grows on another plant but is not parasitic on it.
A type of vegetation that gets physical support from the
branches of other plants.
- epiphytic (adj.)
- Without soil roots; obtaining nutrients from air, rainwater,
and organic debris.
- equilibrium theory of
island biogeography (n.)
- The number of species on an island balances immigration (controlled by
regional processes) against extinction (controlled by local processes).
- The greater the separation of an island from others, the fewer the species
that inhabit it.
- Defined in 1967 by R.H.MacArthur and E.O.Wilson.
- environmental lapse rate (ELR) (n.)
- The rate of air temperature change with altitude.
The average ELR in the troposphere is an air temperature
decrease of 6.5 degrees Celsius per kilometer rise in elevation.
- erosion (n.)
- Removal of weathered sediment or rock by
the wind, water, or ice.
- eukaryote (n.)
- Organism whose cells have a membrane-bound nucleus
and where many specialized structures are located within their cell
boundary. Genetic material is organized in such organisms into
chromosomes residing in the nucleus.
- evergreen (adj.)
- Has green leaves year-round. The old leaves remain green until the new
foliage develops. Contrast with deciduous.
- evolution (n.)
- The series of changes (such as mutation or natural selection) through
which any organism acquires the characteristics that differentiate it from
another organism. See also phylogeny.
- excurrent branching (n.)
- Tree growth in which the main axis continues to the top of the tree from
which smaller, lateral branches arise. Example: conifers.
- exocarp (n.)
- The outermost layer of a pericarp; also called the epicarp.
- exogen (n.)
- A dicotyledonous
plant that increases with time by the addition of successive concentric rings
inside the previous growth and beneath the bark. Compare with an endogen.
- exfoliating (adj.)
- Peeling off in thin layers, like an onion skin.
- exotic (adj.)
- A plant that does not grow naturally in your area (or region, state,
country, or continent).
- exponential growth (n.)
- Growth where the change in size or quantity (per unit of time)
is some fraction of the previous size or quantity;
specifically it dependends on population size.
- extant (adj.)
- Types or species that are currently living. Not extinct.
- exotic (adj.)
- Not native; introduced from elsewhere.
- extinct (adj.)
- Describes a type or species that is no longer living.
The likelihood that a species is in danger of
extinction can be calculated for
- ecology (n.)
- From evolve, from the Latin evolvere (to roll out).
For an introduction to evolution, see
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