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The usual abbreviation for *year (from the Latin annus, meaning year).

*Fens, sometimes called ‘string bogs’, of circumpolar distribution, found in Fennoscandia (see Baltic Shield) and *boreal...

The process by which an organism is fitted to its environment as a consequence of the characters it inherits, which have been filtered by ...

Of a plant organ, facing away from the axis or main stem (e.g. the lower surface of leaves). Compare adaxial...

The development of living organisms from non-living matter, as in the supposed origin of life on Earth, or in the concept of spontaneous generation which was once held to account for the origin of life but which modern understanding of evolutionary processes (...

Non-living; devoid of life. Compare biotic.

1 Removal of snow and ice by melting and by direct alteration from the solid to the gaseous phase (sublimation). The rate of loss is controlled chiefly by air temperature, wind velocity, ...

The erosive (see erosion) action that occurs when rock particles of varying sizes are dragged over or hurled against a surface. Some common agents of abrasion are the ...

The rejection of plant organs (e.g. of leaves in autumn). This occurs at an abscission zone, where hydrolytic (see...

The age of a geologic phenomenon measured in present Earth years, rather than its age relative to other geologic phenomena (...

The reporting of *pollen data from sediments, expressed in terms of the absolute numbers of pollen grains (for each species, genus, or family) per unit of area of surface and, where deposition rates are known, per unit of time. In certain circumstances this approach gives clearer information than does the traditional way of expressing pollen data as ...

The uptake of substances, usually nutrients, water, or light, by cells or tissues.

A graph that shows the percentage of each wavelength of light absorbed by a pigment (e.g. chlorophyll, which absorbs mainly in the red and blue parts of the spectrum)....

The artificial removal of water from a well, reservoir, or river.

Applied to the deepest part of the ocean, at depths between about 3000 m and 6000 m (see ocean divisions...

Fish that live in the deepest part of the ocean, below about 2000 m. Many abyssal species have prominent snouts; a tapering, rat-tailed body consisting of flabby, watery tissue; and a lightweight skeleton....

The part of the *pelagic zone of the ocean that overlies the *abyssal plain. It extends from a depth of between 2000 m and 4000 m to about 6000 m. The temperature is about 4°C and the pressure 20–60 MPa. ...

An extensive, level area of the *abyssal zone, lying between the edge of a *continental rise and a mid-oceanic ...

A phylum of bilaterally symmetrical, worm-like organisms most of which do not have an excretory system; all lack a gut. A retractable proboscis is present, covered with the recurved spines that give the animals their common name. All acanthocephalans are endoparasitic (...

A pesticide used to kill mites and ticks (subclass Acari).