Author: Lee Belbin, August 2019
The Tools | Tabulation function in the Spatial Portal can be considered to generate areas, however while these “areas” can be defined and quantified, they are not yet able to be added to the Spatial Portal map.
Cross tabulations are the equivalent to scatter plots (Tools | Scatterplot – single/multiple) for contextual layers instead of environmental layers. The scatterplot uses variables that have a continuous value at a location (e.g., temperature) while the tabulations use layers with class values (e.g., State/Territory). Each class of a contextual layer can be represented by a mapped area, as for example “ACT” from the layer called “Australian States and Territories”.
When two contextual layers are overlayed or intersected, other areas are defined. For example, if you chose Add to Map | Layer and selected “ASGS States and Territories” and “CAPAD 2014 terrestrial classes”, you can examine spatially how various reserve types are distributed across the States and Territories of Australia.
Note, however, that not all combinations of classes exist, for example, there are no “Conservation reserves” in the ACT or “Wilderness zones” in Victoria.
Such combinations are not always obvious on the map. Where there are intersections, as for example “National Parks” in Victoria, an area must be defined, and from Figure 1, the area in total is 2596.6 square kilometres. Figure 1 only shows the first 16 rows of this cross-tabulation and the option chosen was area in square kilometres. Alternative tabulations for each cell in the table are the number of species (species richness) and number of occurrence records.
Each of the cells in the table with positive entries represents an area on the map. Currently, these ‘cell-areas’ are not able to be mapped individually, but we will enable this in the future.
Figure 1. Cross-tabulation of States/Territories and CAPAD 2014 classes showing the first 18 reserve types