[tdwg-content] Abundance

Peter Hovenkamp peter.hovenkamp at naturalis.nl
Mon Sep 30 10:02:56 CEST 2013

Just a thought from a comparative outsider:

The various terms to describe abundance, frequency, occurrence etc etc.
appear to be so different for different taxonomic groups and different
purposes: Flocks of geese, bulks of timber, kilo's of fish,
ramets/genets/cover for creeping plants, abundance as numbers of stems > 10
cm dbh for others, etc etc.

Are not attempts to capture this in a single vocabulary as doomed as
attempts to do develop a single ontology to capture all
characters/character states across all taxa?

Peter Hovenkamp

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On Sun, Sep 29, 2013 at 1:54 AM, Robert Stevenson
<Robert.Stevenson at umb.edu>wrote:

> Some thoughts about usage of some of the terms under discussion and the
> ultimate goals
> I often use the term "abundance" as a refinement of the term "occurrence".
> I say  "Species X occurs or does not occur at Location L.  This kind of
> statement is refined with a statement such as "Females are rare in March"
> or "Juveniles are common or very abundant in July".  The details of the
> life stage, timing and numbers of individuals or groups are more specific
> but still categorical.
> I think of such statements as being derived from "expert opinion" or being
> summary statements based on enumerations from a series of samples taken
> during several field trips. I think these kinds of generalities are useful
> for policy making.
> In terms of data, the simplest category is "presence only" data. Some
> times this is referred to as occurrence data - some number of individuals
> are seen at a particular time and location. Many museum records fall into
> this category as there is no other information associated with the
> specimen.  Such records are equivalent to an incidental sighting by a field
> ecologist.
> Today many biodiversity data are collect following a particular protocol.
> Here sampling effort is known.  A specific number of individuals seen in a
> "given area" and during a known time interval. From this information one
> can compute population densities.
> As several others have commented, the results are dependent on the
> particular protocols and it can be difficult to reconcile data from two
> different protocols.  How are data from pitfall traps equivalent to data
> from baits.....? This is an important challenge because we know that
> usually one and often two protocols are insufficient to characterize the
> presence of all members of a taxon
> If I am not mistaken, the goal is to establish terms that will let humans
> efficiently prepare data and write programs so that machines can reason
> with the data. If so, the key challenges seem to be
> 1) Distinguishing presence-only data from data collected using known
> protocols
> 2) Finding ways to reconcile data from different protocols
> Rob Stevenson
> Rob Stevenson
> Biology Department
> UMass Boston
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