Maxent

Maxent is an application for modeling Habitat Suitability for species. To use this extension, you'll ned to download Maxent and decompress it to a folder. Then, when you run this extension, you'll browse to set a path to the "maxent.jar" file. There is an excellent tutorial with associated data on the same website.

This extension will run Maxent repeatedly to find the best regularization parameter for Maxent. This will be based on a point layer of occurrences, a set of predictor layers, and the settings below. The input and output data will be stored in a "Temporary" file that you specify.

There are four options as the "Repeat Type":

• None: No repeat, just run Maxent once
• Regularization: Try a number of different regularization values from a minimum to a maximum value

When complete, the results including AIC, AICc, BIC, Likelihood, and the best Regularization parameter will set displayed in a dialog when the run is completed.

Note that this extension will place all the Maxent outputs into the folder you specify. These outputs will be deleted each time you run the extension so you'll want to copy any outputs out of the folder that you want to save.

Content Tab

Setup Tab

Temp Folder: A folder for temporary files including the outputs

Maxent Folder: The folder containing the "maxent.jar" file

Table File: A file for a tab-delimited file that will contain the results of the runs. This file can be opened in a spreadsheet application for charting or further analysis.

Amount of Memory: This is the amount of memory that will be allocated to Maxent. Larger amounts of memory will let Maxent run faster but too much will cause your computer to slow down as it "pages" data to the hard disk. A good rule is to set this to no more than 2/3 of your memory (RAM).

Repeat Tab

Number of Runs: The number of try's overall

Start Regularization: The first regularization value to try if "Regularization" is selected as the "Repeat Type". Otherwise, this value will be used for regularization for all runs.

End Regularization: The last regularization value to try

Settings Tab

Do Jackknife: Determines if Maxent will try to find the best combination of predictor variables

Remove Duplications: Cases Maxent to remove any points that are at the same location

Maxent Visible: Causes the Maxent user interface to appear or be hidden from view. If you think you are having problems, you should make the user interface visible to see any potential error messages.

Features: This series of check-boxes allows you to specify which "features" Maxent will use in creating the model (see the Maxent tutorial for more information)

Layers Tab

Occurrences: the layer or file containing points that represent occurrences of the species in their natural habitat

Predictors: layers or files containing the predictor rasters to correlate with the density of the occurrences. Click the "Layer Settings" button to set the layers that are categorical.

Mean Output: The file or layer name for the mean habitat prediction based on multiple runs or the one output from a single run.