We have a locally endemic plant species which distributes just a specific narrow area. It spreads almost everywhere in that area, but it does not occur anywhere except that area. We want to model the distribution of the species with maxent. The bedrock in the distributed area is the same everywhere and the elevation variation is really low. Would it be right to produce artificial presence data and model it by putting artificial (random) sample points into the field?
You can use aerial photography and then you don't have to model it :)
The regular way to use Maxent is to use your presence data and your environmental layers. The extent of the environmental variables should be larger than the range of presence points by 10-50%. Maxent will generate random pseudo-absence points for comparison. Never produce presence points. You may also use R package ENMeval to determine best model parameters.
Mr. Andrew Paul McKenzie Pegman I'm not sure if I understood you.
Mr. Xinhai Li the main problem here is when we want to run the procedure, because of variation value of environmental variables (e.g. bedrock or elevation) is limited, iteration occurs. So what can we do to bypass it?
If the species is found everywhere in the area, is it necessary/important/useful to model its distribution?
If the environmental variables you are using do not correlate well to the distribution, you need to visit the wider area to see if you can see, yourself, differences between areas that support the plant and areas that don’t. Then plug those environmental variables into maxent. In theory, it should then highlight other areas where potential populations may be hiding, but not known. There are a huge array of environmental variables you can use maxent - the trick is finding which ones matter to the plant species for which you are attempting to map the potential distribution. maxent is a model, not an artificial intelligence. Sadly (or happily if you are like me and live fieldwork) we need to do the grunt work of observation ourselves
Mr. Vianny Rodel Nguimdo Vouffo and Mr. Peri Coleman
Actually, the distribution area of the species is about 100 m2 and there are only about 100 individuals of that species in the world. That's why there is no variation for environmental variables as you can imagine. So I wonder if it is sensible to use Maxent to model that species or not.
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