As a biology student just beginning with GIS, I wondere if someone could give me an idea of what tools to go about using to compare the range of 3 species that have trophic effects on one another.

I have 3 vector layers, of count data plotted as xy coordinates on a map of the UK, taken from latitude and longitude recorded data. The first is Water Vole distribution, the second European Rabbit, the third American Mink.

The aim of my assignment is to see whether their ranges coincide (Mink and rabbit supposedly do), or whether they occupy different areas (supposedly, vole and rabbit).

I am looking for a tool that will help with this, but as a GIS beginner, I have explored using point density tool to give me nice density maps in raster form. But am unsure how to get a quantitative output for analysis from this (key for my report).

I am looking to see if there is a correlation/link between rabbits and lynx, and if there is an inverse relationship between voles and lynx. I need a statistics tool that can give me outputs for this.


The analysis you are referring to is called Spatial Pattern Analysis. Your hypothesis regarding whether or not there is an interaction between species point counts can be tested with point pattern analysis. There are a wide selection of tools available to you. Many professional wildlife people use R for these analyses, which provide a rich set of tools (e.g. spatstat) to go about testing your hypothesis. However, the learning curve is steep. If you are interested, there is a tutorial on analysing spatial point patterns in 'R'. I would especially investigate using using a bivariate Ripley's K analysis. I had a similar question a while back similar to yours, although with trees (How to implement bivariate Ripley's K function in ArcGIS 10?). Keep in mind that ArcGIS does not have the capability to perform this bivariate analysis.

ArcGIS certainly does have the capacity to test point patterns. There is a free 1 hr ESRI training seminar called Introduction to Spatial Pattern Analysis that should help you get started. Additionally, ESRI has a huge resource section on spatial statistics.

Additional Resources:

An overview of the Spatial Statistics toolbox


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