Maxent

Maxent is a program to model species geographic distribution based on maximising entropy.

Description

Maxent is a tool that uses a maximum-entropy approach for species habitat modeling.  This software takes as input a set of layers or environmental variables (such as elevation, precipitation, etc.), as well as a set of georeferenced occurrence locations, and produces a model of the range of the given species.1

The model for a species is determined from a set of environmental or climate layers (or "coverages") for a set of grid cells in a landscape, together with a set of sample locations where the species has been observed.  The model expresses the suitability of each grid cell as a function of the environmental variables at that grid cell.  A high value of the function at a particular grid cell indicates that the grid cell is predicted to have suitable conditions for that species.  The computed model is a probability distribution over all the grid cells.  The distribution chosen is the one that has maximum entropy subject to some constraints: it must have the same expectation for each feature (derived from the environmental layers) as the average over sample locations. 2

Written by Steven Phillips, Miro Dudik and Rob Schapire, with support from AT&T Labs-Research, Princeton University, and the Center for Biodiversity and Conservation, American Museum of Natural History. 

Function

• Analysis tools
• Species geographic distribution: single algorithm applied once
• Visualisation tools
• Maps

Why use this tool?

To model the geographic distribution of species

 Who will use this tool?

• Data users
• Expert
• Interest group

 How will the tool be used?

• Platform independent
• Requires Java 1.4.2 or later
• Batch mode available

Input files, output directory and algorithm parameters can be specified through the user interface, or on a command line.  The user interface is best for doing single runs, while the command line is useful for repeated runs or automatically performing a sequence of runs with variations in the set of inputs. 3

 Where in the data chain could this tool be used?

• User’s machine

 When could this tool be used?

• As a post process, after data is with the user

Availability

• Source: http://www.cs.princeton.edu/~schapire/maxent/
• Licence: Educational and research only

  see: http://www.cs.princeton.edu/~schapire/maxent/

• Cost: Free
• Version 3.1,   November 2007
• No warranty

Comments

• Documentation includes a tutorial, test data, help file.
• A discussion group is active.