- Getting Around
- About FOSS4G
An innovative web services based GIS architecture for global biogeographic analyses of species distributions
Jeffery Cavner, Natural History Museum, University of Kansas
Spatial patterns and properties of species richness in natural communities are of keen interest to biogeographers and conservation biologists as they describe key features of the location and distribution of the earth's biological diversity. Patterns of species richness are determined by constituent species range sizes, spatial locations of those ranges, species associations, co-occurrence and species interactions. Analysis of these phenomena at biogeographical scales, i.e. continental to global extents, presents computational and visualization challenges.
The creation of species presence/absence matrices is one approach for linking range size and richness patterns. The presence/absence matrix is a gridded data format, where columns represent species and rows represent geographic sites or localities. Each matrix element is coded for the presence (1) or absence (0) of each of hundreds or thousands of species.
The presence/absence matrix allows for the interlinking of two concepts: the dispersion field, and the diversity field. The diversity field is the species diversity of all sites in which a particular species occurs. A dispersion field is the set of geographic ranges of all the species occurring in a given site. It has been demonstrated that species diversity of sites and the mean range size of species has a symmetrical relationship with the range size of species and the mean species diversity within those ranges.
Null models are used with presence/absence matrices to test hypotheses requiring that large matrices be randomized while maintaining the total value of each row and column constant. By treating these matrices as Boolean grids, we developed highly-optimized swap algorithms to achieve this in a software suite of WPS web services which utilize QGIS as a client.
Two different types of range diversity plots map the relationships between the mean proportional species diversity against the proportional range size of a species; and the relationship between the mean proportional range size and the proportional species diversity. These two different ‘views’ of the data can then be linked for display to phylogenetic trees in the case of the species specific plot and geographic space in the case of the locality specific plot.
By combining the computational power of high-performance servers exposed as web services with a thick client for GIS data visualization we are bringing together advanced visualization techniques with optimized bio-statistical algorithms to advance vital investigations in global biodiversity research and conservation.