Where does richness collide?

The number of different species found in a defined community or area: it is the simplest measure of biodiversity, a plain count that treats a rare species and a common one alike. Whittaker's 1972 Evolution and measurement of species diversity set richness apart from fuller diversity measures, which also weight how evenly individuals are spread across the species present, so a place can be rich in species yet dominated by a few. The referent here is a tally of kinds of living thing in a habitat, and it has nothing to do with a medium's capacity to carry information or with excess fuel in a burning mixture.[1]

Unit

One instance is a species count for a defined area or community

Recovery means

Not applicable

Measured by

Counted directly as the number of species recorded in samples, often adjusted for sampling effort by rarefaction or estimators

The capacity of a communication medium to carry information and reduce ambiguity, ranked by how well it conveys multiple cues, supports quick back-and-forth, uses natural language, and feels personal. In Daft and Lengel's 1986 media richness theory, set out in Organizational information requirements, media richness and structural design, a face-to-face conversation is richer than a phone call, which is richer than a written memo, and managers are expected to match a rich medium to an ambiguous task. The referent is a property of a channel of human communication, judged by the cues it carries, not a count of species in a habitat or the fuel content of a combustible mixture.[2]

Unit

One instance is a medium placed on an ordering from rich to lean

Recovery means

Not applicable

Measured by

Assessed by rating media on cue variety, feedback speed, language, and personal focus, and by how well richness matches task ambiguity

How far the fuel-to-air ratio of a combustible mixture exceeds the exact ratio at which all the fuel and all the oxygen would be consumed together. As Heywood's 1988 Internal combustion engine fundamentals describes, a rich mixture holds more fuel than that balanced point and leaves some fuel unburned, while a lean mixture holds excess air, and the departure is captured by the equivalence ratio, which is greater than one for a rich mixture. The referent is the proportion of fuel in a gas mixture about to burn, measured as a ratio, and it shares nothing with a tally of species or the carrying power of a communication channel.[3]

Unit

One instance is a mixture's equivalence ratio, a dimensionless number above or below one

Recovery means

Not applicable

Measured by

Determined from the measured fuel and air flows as an equivalence ratio, or inferred from exhaust gas composition by a lambda sensor