Dots on maps

[Bob Mesibov]

Hope this doesn't sound like an advertisement, but I too move locality
records in and out of ArcView GIS and find it an exceptionally
convenient tool for displaying and analysing locality data. I map
terrestrial invertebrates, mainly millipedes. Almost all the localities
are UTM grid squares 100m on a side. Older, less accurate records have
been upgraded by interviewing collectors or studying field notes, and
vague old records have been arbitrarily assigned a likely spot for
mapping purposes. Because the total number of records isn't large (less
than 100 000), I manage them in spreadsheets, one per taxon.

For mapping and other purposes the whole spreadsheet is loaded into
ArcView as point localities (SW corner of 100m grid square) with an
associated table of label and other data. Once in ArcView, the spatial
data becomes queriable and reportable in many different ways, which is
the joy of GIS. I was interested to read of Ken Walker's 'jar of
jellybean' maps with different collecting periods shown as different
colours. This kind of analysis can be done in seconds with ArcView.

I distrust environmental modelling and its predicted ranges, but I use
vegetation and other environmental GIS layers with my locality data to
eyeball obvious patterns, and to select likely places for further field
work. More recently I've been studying how results using grid maps
(presence/lack of record in grid squares) vary with grid scale, and how
ideas like 'area of endemism' and 'congruent distributions' might be
objectively defined. Work like this would take years with paper maps;
with a PC-based GIS it takes minutes.

To return to John Grehan's message requesting systematists to publish
distribution maps along with their list of sites, can I add an ask? It
would be very much easier for us biogeographers, hunting useful scraps
of spatial information, if published lists of localities (usually under
'Other Material Examined') were in table form, ideally with a lat/long
or UTM column, instead of a long, run-on paragraph.

Bob Mesibov
--
Dr Robert Mesibov
Honorary Research Associate
Queen Victoria Museum and Art Gallery
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
(03) 6437 1195; international 61 3 6437 1195