[tdwg-content] Abundance

Donald Hobern [GBIF] dhobern at gbif.org
Mon Sep 30 10:14:20 CEST 2013

We may also need other properties in parallel to enable full expression of all detail.  However I think that this might be achievable through careful planning of the “abundanceAsNumber” field and some kind of “abundanceUnit” field (which could be the anchor for much more semantic machinery) – associated fields on methodology and level of effort will also be important.


However the pure number will be useful as it stands.  Given this discussion, I think the main issue is that the name “abundance” may cause too much ambiguity and confusion.  I think we are really talking about something closer to “quantity”.





Donald Hobern - GBIF Director -  <mailto:dhobern at gbif.org> dhobern at gbif.org 

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GBIF Secretariat, Universitetsparken 15, DK-2100 Copenhagen Ø, Denmark

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From: tdwg-content-bounces at lists.tdwg.org [mailto:tdwg-content-bounces at lists.tdwg.org] On Behalf Of Peter Hovenkamp
Sent: Monday, September 30, 2013 10:03 AM
To: tdwg-content at lists.tdwg.org
Subject: Re: [tdwg-content] Abundance


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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