While I haven’t done much exp, I reached 410M totals. The bigger event was that my tree navigator spiritual rose turned to golden yellow:

Treebeard [treenav]: What a joyous occasion! Tree herder Thelo's spiritual rose has finally turned fully golden yellow.

In addition, I can now have more trees per continent:

Treebeard tells you 'Your tree herding knowledge has improved and you can now herd 1 additional tree in single continent'

Your tree herding skill and reputation enable you to have 10 trees in single
continent and 29 trees altogether.

You have grown 3 trees in Furnachia.
You have grown 7 trees in Rothikgen.
You have grown 7 trees in Lucentium.
You have grown 3 trees in Desolathya.
You have grown 9 trees in Laenor.

You can grow a new tree with: use 'tree herding' grow [name]

As usual, you can find my tree navigator trees from a separate info page.