Introduction 


Geographic Distance is a geographical model that uses the location of known occurrences and predicts that the likelihood of finding a species in an area depends on the distance of that area to a known occurrence point. The predicted values are the inverse linear distance to the nearest known presence point. Distances smaller than or equal to zero are set to 1 (highest score).  

 

This model does not use the input of environmental variables to predict the distribution of a species. 


 

Advantages 

  • Simple and easy to interpret 
     

Limitations 

  • Does not use environmental variables to predict species occurrence 
     

Assumptions 

N/A 

 

Requires absence data 

No 

 
Configuration options  

EcoCommons allows the user to set model arguments as specified below. 


random_seed  

Setting a random seed will not impact this model. 

scale 

scale (in metres) used to divide the distance from occurrence records before computing the inverse distance.  (default = 1000) 

Tails (tails) 

The "tails” argument can be used to ignore the left or right tail of the percentile distribution for a variable. I If supplied, tails should be a character vector with a length equal to the number of variables used in the model. Valid values are "both", "low" and "high". (default = NULL) 

 
 

References 

  • Hijmans, R.J., Elith, J. (2015). Species distribution modeling with R.