Glossary

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T

Taiga
The coniferous forest that extends across much of North America and Eurasia bounded by tundra to the North and by steppe to the south.
Tannins
Complex astringent substances containing phenolic compounds found in plants and usually making the plant material less readily digested. Especially common in bark, unripe fruits and galls on woody plants.
Taxonomy
The study of the rules, principles and practice of classifying living organisms.
Tectonic plate
An area of the earth's crust which moves during geological time resulting in continental drift and other major changes in the topography of the surface of the globe.
Temperature coefficient
see Q10.
Temporal variation
Variability in conditions, such as temperature, on an hourly, daily or seasonal basis.
Terpenoids
Aromatic hydrocarbons formed by many plants and responsible for many of the plant scents.
Territoriality
The establishment by an animal or animals of an area from which other individuals are partially or totally excluded.
Tertiary
A geological era lasting from approximately 65 to 2 million years ago.
Thermoneutral zone
The range of environmental temperatures for an endotherm over which it has to exert the minimum metabolic effort in order to maintain a constant body temperature.
Thinning line
The line on a plot of log mean individual weight against log density along which self-thinning populations of a sufficiently high biomass tend to progress, and beyond which they cannot pass.
Third generation insecticides
Synthesized, usually organic insecticides, which are nevertheless produced with the aim of minimizing the impact on non-pest, non-target species.
Tiller
A branch formed at or near ground level by grasses and sedges.
Time-delay population model
A model of population growth in which the net reproductive rate of individuals currently is determined by the population size some time previously.
Tolerance (successional)
Where modification of the environment by early occupants has little or no effect on subsequent performance of late-successional species.
Topography
Representation of the physical structure of an environment.
Transfer efficiency
Efficiency with which energy is passed through various steps in the trophic structure of a community.
Transgenic
An organism containing a gene which has been artificially transferred from a member of another species.
Transient polymorphism
The occurrence of two (or more) forms of a species or of genes (alleles) within a population while one form is being replaced by another.
Transmission threshold
The basic reproductive rate of a parasite that is a necessary condition for a disease to spread.
Transpiration
The evaporation of water from a plant surface.
Triassic
A geological era lasting from approximately 250 to 213 million years ago.
Trichome
Single- or many-celled outgrowth from the epidermis of a plant. A plant hair.
Trophic level
Position in the food chain assessed by the number of energy-transfer steps to reach that level.
Trophic structure
The organization of a community described in terms of energy flow through its various trophic levels.
True predator
A predator which kills other organisms (their prey) more or less immediately after attacking them, killing several or many over the course of its lifetime.
Tundra
The biome that occurs around the Arctic circle, characterized by lichens, mosses, sedges and dwarf trees.
Turbulence
Fluid flow in which the motion at any point varies rapidly in direction and magnitude.
Turgor
The distention of living tissue due to internal pressures.

 
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