o_19ko2dt161ng2j4e1tgnoqv1s45a.pdf

J. GREGSON, R. DE KOK, J. MOAT & S. BACHMAN (2007)
coordinates (georeferencing) suitable for analysis by GIS. Although the data originates from
different eras and is of varying accuracy, the accuracy of herbarium specimen records can be
weighted, to take into account imprecise locality data from older specimens. A series of inhouse
tools have been developed to aid georeferencing of Kew’s herbarium specimens including
converting co-ordinates from different projections e.g. UTM and taking bearings from a known
locality e.g. ‘20 miles north of Gaborone’.
The software used by the GIS unit includes all ESRI products (previously ArcView and now
ArcGIS 9) and ERDAS primarily for remote sensing work. The Digital Chart of the World
can be used as a standard base map for plotting species point distribution maps. Additional
maps (called layers) can then be added and queries between the map layers are possible.
Standard GIS techniques and algorithms have been used in a variety of ways and are continually
being developed for novel applications.
A simple example (Fig. 1) shows a point distribution map combined with a map of geological
substrate. A histogram can be quickly plotted showing how the distribution of different species
varies with geological substrate. By combining point distribution maps with other types of
map, histograms can be produced to show the range of substrates, vegetation types or altitudes
which a particular species prefers – this information can be used in conservation planning,
Fig. 1. Analysis of distribution in relation to geological substrate.
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