|Describes the taxon of a feature.|
|Used on these elements|
|Status: in use|
|Tools for this tag|
Used in association with natural=wood natural=tree barrier=hedge or landuse=forest or natural=scrub natural=wetland natural=heath or possibly independently taxon=* to indicate the biological to which the tree, or plant belongs.
The use of taxon prevents the proliferation of various tags to describe biological components of mapped objects (e.g., name:biological=* genus=* species=*) which will inevitably lead to inaccuracy (e.g., species=Oak) unless all mappers are competent botanists. It is also semantically equivalent to the taxotagging scheme of the Encyclopaedia of Life, which uses tags such as taxonomy:taxon_level.
It is intended to be used more loosely than a biological purist would expect (e.g., Robinia sp. pink-flowered cultivar). This is because it might not be possible to accurately identify plants depending on knowledge, access, time-of-the-year or other factors. Places with interesting an exotic trees might not even be readily identifiable by an expert, but often the broad taxonomic position can be assessed rapidly. In major plant collections one might wish to identify signficant cultivars or varieties. For instance, in Nottingham Arboretum there is a cut-leaved Alder (Alnus glutinosa) which has been designated a 'Champion Tree'. Simply assigning species would tell us nothing about the intrinsic interest of this tree.
For the moment no usages of taxon are forseen for animals or fungi.
|Major Oak||This is a good example of a significant tree which is a local monument and a tourist attraction with a specific name. Taxon can be namespaced to provide vernacular names, widely used codes (BSBI reference), additional taxonomic data (e.g., genus).|
|Pink-flowered Robinia cultivar|
|Typical London Plane||A good example of a hybrid taxon where the current biological name may change, but where there is a national nomenclature standard. In this case the standard nomenclature has been preferred. Species renaming could become a significant issue.|
|Street trees in Girona||One example of one of the trees imported from the Girona city GIS.|
|Street & Park trees in Vienna||One of many examples of cultivar names used in a tree import from Vienna. This demonstrates how taxon & species tagging can be used to provide both precision & convenience by using separate tags for the cultivar and species names.
Cultivar names in the taxon are probably best shown as "cv. 'Pallida'" rather than just as the cultivar name, for instance the ivy taxons Hedera helix hibernica (a subspecies) is not the same as Hedera helix cv. 'Hibernica' (see On-line Plant Atlas [ dead link ]).
|A beech hedge||Example of multiple species within hedge|
|Wooded area tagged with multiple species||Example of an area with taxon tagging|
Choice of taxon name
It may seem absurd, but many common tree species have a range of widely used formal taxonomic names. Examples include:
- London Plane (de: Ahornblättrige Platane; es: Plantano de Pase ; fr: Platane a feuilles d'érable), this is named as Platanus x acerifolia on , but the standard name used in Britain and Ireland is Platanus x hispanica.
- Horse Chestnut (de: Rosscastanie; es: Castaño de Indias; fr: Marronnier d'Inde).
- Silver Birch (de: Birke; es: Abedul común; fr: Bouleau verruqueux). The standard name used throughout Northern Europe is Betula pendula, but the nomen dubium Betula alba has been used recently in the standard floras for the Iberian Peninusla (Flora Iberica, and provincial floras).
As many taxonomic names are in a state of flux because of revisions based on molecular phylogeny, and botanists in different countries often have slightly different concepts of particular taxa, it is recommended to use the name current in the standard flora for a region. Many of these lists are available on-line, for instance the Botanical Society of the British Isles taxonomic list. Particular problems arise when these standard lists are revised as recently happened on the publication of the 3rd edition of Stace's Flora or Britain and Ireland. If in doubt be conservative in choice of taxonomic names (often this means not using wikipedia, as articles are frequently updated to reflect recent research which may not become accepted).
For well-known species such as trees the common vernacular names are often very stable and highly conserved. It is therefore good practice to also add a taxon tag name-spaced with a two character ISO-language code.
In general use of the full taxonomic name; i.e., including author(s) and date, is not needed.
An alternative to using taxon=* is to use tags for each taxonomic category: the most widely used ones are:
In practice these are much more widely used synonyms for (the rarely used, or unused) taxon:genus=* & taxon:species=*. As tagging of trees has developed it has been found that the two styles of tagging biological nomenclature are not mutually exclusive and can be used successfully together. Use of genus=* with either species=* or taxon=* makes resolution of the some of the nomenclatural difficulties mentioned above rather easier to resolve.
Recording vegetation cover values
If tagging an area, way or node there may be reasons to record the cover=* value of different species within an area. Presented below is a method for recording plant cover within a given area; e.g., a wood or wetland.
Percentage cover is usually recorded by using aor measuring out a specific area and then estimating by eye the coverage of different species within that area. Note: Remember that percentage cover can add up to over 100% because there are multiple layers/canopies within a habitat.
Estimating species frequency
- DAFOR standing for dominant, abundant, frequent, occasional, rare is a quick way of measuring coverage or frequency of a plant taxon=* within a given area. The dafor=* tag may require measuring an area or use of a quadrat but is generally a rough estimation of plant coverage. For instance dafor:Ganzia rigens=Dominant or dafor:Fagus sylvatica=Occasional.
Recording number of individual plants
Record the number of plants using the plant_count=* within a node, way or area.