Aster,
Great mod!

I've been trying something similar for some time now without luck.
Some ideas I had for my mod, now abandoned due to your great work was the following:

Only have certain type of trees grow on certain terrain types. I use this in my Bio-Industries mod. Check out the Control.lua

Have trees die occasionally. Replace a living tree with a dead tree.
Have dead trees disappear occasionally. Making space for new trees.

So basically a fully living eco systyem.
Just some thoughts. Great mod again!

Thank you. The most difficult part was to optimize the algorithm so the script execution time won't block the game, even though it scans all trees in the game. I'm satisfied with the result and appreciate you liked it.

By the way, I play Bio-Industries mod too. In fact, it partly inspired me to write this mod. These mods coexist in my game nicely :)

Your idea of dying trees is interesting, since my mod currently adds trees but never removes, so the game will be eventually full of trees. I'd like to examine if it works without breaking performance.

Cool, I'm playing with both also. My nice lines of trees are now starting to look disheveled as they grow :)

Some more thoughts. I think you might already be doing something like this, but to add.
Have trees have a much higher chance of growing on grass vs. desert tiles and also have trees have a much higher chance of dying in deserts vs. grass.

One last thought, let the chance of a tree dying be higher in high pollution areas that now pollution areas. This way it will work very well with the game mechanics and also, ones base won't be overrun by trees.