Research: Rainfall/Vegetation->Pre Embark Trees/Other Vegetation display

[PatrikLundell]

I DFHacked a pre embark world tile to see what DF presented as the pre embark info about the site. The results were:
Vegetation (Rainfall seems not to have any effect): Text for "Trees:"
0: None (Light Red)
1 - 9: Scarce (Yellow)
10 - 32: Scarce (Light Grey) -- i.e. same text, but different color
33 - 65: Woodland (Light Green)
66 - 100: Heavily Forested (Green)

And for "Other Vegetation:"
0: None (Light Red)
1 - 9: Scarce (Yellow)
10 - 65: Moderate (Light Grey)
66 - 100: Thick (Light Green)

I tried 0 and 100 Drainage on the boundary Rainfall/Vegetation values in addition to the original one (whatever that was), but the boundaries did not shift, indicating Drainage does not affect the result. Note that the investigation was done on a tropical tile, but I don't expect temperate tiles to behave any different.

It can also be noted that actual embark experience with very low Rainfall/Vegetation values were somewhat different. If I remember correctly (it was a few years ago), a Desert Rainfall/Vegetation of 0-1 resulted in no growth of any (surface) vegetation post embark (farm plots still worked), 2-4 (or 5?) resulted in growth of shrubs but no saplings, and higher values allowed saplings to appear as well. One embark had "Scarce" trees consisting of a single Feather Tree (not a Saguaro, luckily) on embark and no saplings. Thus, the pre embark info doesn't tell the whole story.

Finally, I haven't embarked to check DF's pre embark info against the actual situation, but any tree regrowth will result in an end state of complete junglification anyway.

Edit: (Resulted in updates above) After noting that some world tiles actually had differing Rainfall and Vegetation during the 0.47.X mapping (was probably present before), I tried to see if the DF display actually has any dependence on Rainfall, and it seems not: Changing the Vegetation value as per the above for both a Moist Broadleaf and a Desert biome showed that the "Trees" and "Other Vegetation" display matched the list. Embarking in a 0 Vegetation forest (shown as None for both Trees and Other Vegetation) resulted in an embark without any shrubs, but full "grass" cover. There were trees, but only Willow [along ponds] and Date_Palm [WET tag], so it might cut out all [DRY] only trees. The desert, in contrast, was covered by vegetation and jungle level Feather tree cover when Vegetation was set to 100. A 0 Vegetation Swamp matched the Forest experience, i.e. no shrubs and only Willow trees. However, a while after embark in the Swamp there were actually shrubs, and I did find a Walnut tree sapling, which indicates the Vegetation value may have an effect at embark only, with the biome taking over afterwards (haven't done this check on the forest, but expect the same results).