Wednesday, March 7, 2007


I got inspired and have been experimenting with the prepartion of cartograms[1]. The data used is biodiversity-related and includes the degree of threat and rarity of species extracted from the IUCN Red Data list of threatened species, with the link to the site here.

Unfortunately, I did not have the latest data prepared as GIS layers, so this is for the year 2000. This will be the sort of exercise you might be expected to do in your eco/geo-informatics programme: getting the latest biodiversity data from the IUCN Red Data list, prepare the data as a GIS layer and present it as cartograms. You will be expected to discuss your results and to post your article on the Weblog for general discussion, complete with a reference list.

Continents of the World

The cartograms have scaled each country's size to the value of the variable (e.g. number of threatened fish species). Further the maps are thematically shaded with red indicating the highest value of threatened or endangered status going through orange, yellow, light green to dark green which represents the lowest values.

Number of plant extinctions

Percentage of threatened plants in the flora

Number of rare plant species

Total number of plant species

Number of threatened invertebrate species

Number of threatened fish species

Number of threatened amphibian species

Number of threatened reptile species

Number of threatened bird species

Number of threatened mammal species

As you can see South Africa is a Biodiverse region that has high risks of extinction, especially for plant species.

[1]Gastner, MT and Newman, MEJ 2004. Diffusion-based method for producing density-equalizing maps. Proc. Natl. Acad. Sci. USA 101, 7499-7504.


  • Hi, that's very nice! As I'm creating maps on ARCGIS, I'm wondering if there's a script I could use to create this cartograms (and not having to implement the stuff by myself)

    Best regards


    By Blogger Stephan, at March 20, 2007 at 5:33 PM  

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