That's just asking for the population to be rewrote, which it should be. But TG has no way to discover species, which means a whole framework fro the user to define ecosystems. Enter Vue realms and other software.
However, as far as I've seen ALL populators in ALL software work on random occurrences, ironically, with perlin fractal paths as masks.
I think you need to think about your PFs smarter, not harder.
For example. You could use a Voronoi Billows, with low colour roughness, and high contrast to create "patches" where "stands" of specific species gather, even creating more sparse patches around the radius of the main noise dump.
Reducing noise in general on a PF will give you more solid maps without all the speckling, than you can use your spacing, and spacing variation to place trees accordingly. For example, with voronoi billows you may want tighter spacing, and less variation to keep them in stand like patches.