In compliance with the directions for requesting changes to the Darwin Core (DwC) vocabulary, we hereby submit to the TDWG Technical Architecture Group a proposal for five new terms to express information on sample-based data.
Sample-based data is a type of data available from thousands of environmental, ecological, and natural resource investigations. These can be one-off studies or monitoring programmes. Such data are usually quantitative, calibrated, and follow certain protocols so that changes and trends of populations can be detected. This is in contrast to opportunistic observation and collection data which today form a significant proportion of openly accessible biodiversity data. Sample-based data are often not shared because the underlying protocols have been hard to encode in a standardised way. For further background information and examples, please consult the sample data primer document [1].
We cannot emphasise enough that our intention here is not to establish how data should be captured or modelled but rather demonstrate one way data can be exposed to maximize discoverability and reuse. In particular, GBIF, in association with EU BON [2] project partners, is exploring how the IPT and Darwin Core Archives can enable the flow of sample based data in support of GEO BON Essential Biodiversity Variables (EBVs) [3].
While DwC already provides many terms that are relevant for describing sample-based data, based on several inputs (GBIF organised workshop on sample data, May 2013 ; previous discussions on the TDWG mailing list; discussions on the EU BON mailing list), we have identified a need for five new terms. These are:
sampleSize
https://github.com/tdwg/dwc/issues/10 https://github.com/tdwg/dwc/issues/10
#Justification
Required for sharing organism abundance data from controlled sampling and monitoring surveys (i.e., sampling events). For an introduction to the sampling proposal please see http://links.gbif.org/ipt-sample-data-primer http://links.gbif.org/ipt-sample-data-primer.
#Definition
A numeric value for the time duration, length, area or volume involved in the sampling event.
#Comment
The terms sampleSize and sampleSizeUnit are required to be used as a pair. The value of sampleSize is a number. Example: 5 for the value part of 5m.
#Term group
Event
sampleSizeUnit
https://github.com/tdwg/dwc/issues/11 https://github.com/tdwg/dwc/issues/11
#Justification
Required for sharing organism abundance data from controlled sampling and monitoring surveys (i.e., sampling events). For an introduction to the sampling proposal please see http://links.gbif.org/ipt-sample-data-primer http://links.gbif.org/ipt-sample-data-primer.
#Definition
The unit of measurement used in the sampling event.
#Comment
The terms sampleSize and sampleSizeUnit are required to be used as a pair, e.g., 5 metre. Example values of sampleSizeUnit include minute, hour, day, metre, square metre, cubic metre. Recommended best practice is to use a controlled vocabulary such as the Ontology of Units of Measure http://www.wurvoc.org/vocabularies/om-1.8/ http://www.wurvoc.org/vocabularies/om-1.8/ of SI units, derived units or other non-SI units accepted for use within the SI (e.g. minute, hour, day, litre). Example: metre for the unit part of 5m.
#Term group
Event
quantity
https://github.com/tdwg/dwc/issues/12 https://github.com/tdwg/dwc/issues/12
#Justification
Required for sharing organism abundance data from controlled sampling and monitoring surveys (i.e. sampling events). For an introduction to the sampling proposal please see http://links.gbif.org/ipt-sample-data-primer http://links.gbif.org/ipt-sample-data-primer.
#Definition
The quantity, per sampling event, given as a number or enumeration value for the quantityType.
#Comment
The terms quantity and quantityType are required to be used as a pair. The value of quantity is a number or enumeration. Examples: 12.5, r
#Term group
Occurrence
quantityType
https://github.com/tdwg/dwc/issues/13 https://github.com/tdwg/dwc/issues/13
#Justification
Required for sharing organism abundance data from controlled sampling and monitoring surveys (i.e., sampling events). For an introduction to the sampling proposal please see http://links.gbif.org/ipt-sample-data-primer http://links.gbif.org/ipt-sample-data-primer.
#Definition
The entity to which the number or enumeration reported in quantity refers.
#Comment
The terms quantity and quantityType are required to be used as a pair, e.g., 14 individuals. The value of quantityType (i.e., the entity being measured) is expected to be drawn from a small controlled vocabulary. Examples: Individuals, % Biomass, % Biovolume, % species, % coverage, BraunBlanquetScale, DominScale.
#Term group
Occurrence
parentEventID
https://github.com/tdwg/dwc/issues/9 https://github.com/tdwg/dwc/issues/9
#Justification
Allows arbitrary linking of sub sampling events, e.g., for nested sampling plots. This was demanded by several people during the discussion of the TDWG sample based data session. For an introduction to the sampling proposal please see http://links.gbif.org/ipt-sample-data-primer http://links.gbif.org/ipt-sample-data-primer.
#Definition
An event identifier for the super event which is composed of one or more sub-sampling events.
#Comment
The value must refer to an existing eventID. If the identifier is local it must exist within the given dataset. Example: A1 identifying the main Whittaker Plot in nested samples, each with their own eventID (e.g., A1:1, A1:2).
#Term group
Event
None of the existing DwC terms is sufficient for any of the proposed terms although two are somewhat related: sampleEffort ("The amount of effort expended during an Event") and individualCount ("The number of individuals represented present at the time of the Occurrence"). Neither are adequate sampleEffort just provides a free text statement so is hard to parse in comparison to sampleSize and sampleSizeUnit and individualCount refers exclusively to individuals and not percentages or entities like biomass, biovolume, etc.
[1] http://links.gbif.org/ipt-sample-data-primer http://links.gbif.org/ipt-sample-data-primer
[2] http://eubon.eu/ http://eubon.eu
[3] http://www.earthobservations.org/documents/cop/bi_geobon/ebvs/201301_ebv_pa per_pereira_et_al.pdf http://www.earthobservations.org/documents/cop/bi_geobon/ebvs/201301_ebv_pap er_pereira_et_al.pdf
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Éamonn Ó Tuama, Markus Döring, GBIF Secretariat