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[Northstar1989]

I've been trying to establish an underground tree farm in my DF 0.40.12  succession fort, but haven't seen any saplings grow up into trees yet...

I was wondering if anyone else has had any luck with tree farms since trees were made multiple z-levels tall?


Basically, what I did was to channel out an underground space 3-5 z-levels deep (I created two chambers, one 3 z-levels deep, another 5) in a very deep soil layer such that the sapling grow naturally on the floor.  However I haven't seen any grow up yet.

I was worried that the 3 z-level chamber might not be tall enough, and the 5 z-level one might not have any additional layers of soil underneath for roots (do underground trees have roots?)

I've seen surface trees grow normally, but can't build a "greenhouse" in the succession fort because it's in a Tundra biome near a volcano, and no trees grow on the surface there (though I've built plenty of "greenhouse garden/pastures" for the grass and blueberries/bilberries/cranberries which grow naturally in this biome).  So underground tree farms are my only potential sustainable source of wood, aside from the caravans.


Regards,
Northstar

[vjek]

As far as I've tested, so far, trees will not grow on muddied stone outside the caverns.  Saplings will sprout, many of them in fact, but they just die off.

I could be mistaken, but that's been my observations to date with 40.08+.  I think they will grow on soil, but you need a mountain above them to grow "inside", which is .. problematic on typical embarks.

It's possible that trees might grow in a very deep soil flat embark, but... I can't remember.    That is, four soil layers, with the saplings starting in the lowest layer.  But... I think the deal with trees is that they need 3 Z above clear and two layers of soil beneath to grow.  Meh.  If someone doesn't offer a more concrete answer, I'll re-test in a day or so.

[Trouserman]

If you have enough soil layers to make a 5z chamber, but trees require additional layers of soil beneath them, you could drop a few layers of soil to a lower level with a cave-in.

[Slackratchet]

I think one of my biggest wishes is the ability to move dirt. Now it just disappears when dug out.

[Gladstone]

Here is my experience with tree farming.  Once I found the first cavern, I mined out a large rectangle of soil near the top of my fortress, a few layers below the surface.  On the z-level above, I channeled out a smaller rectangle that partially overlaps with the rectangle below.  Saplings grew all over the lower rectangle, but they only grew into trees on the portion of the rectangle that had the z-level above channeled out.  It took quite a while before the trees appeared - elsewhere I have seen the claim that trees grow after 3 years, but I didn't rigorously monitor the amount of time it took.  It was several years.  The trees were all fungiwood and tower-caps.

We can conclude from this that once you have pierced the cavern, subterranean trees will (eventually) grow on exposed subterranean soil in your fortress, provided that there is at least one z-level of clearance above.  (I don't remember what is on the z-level below, and I haven't checked for roots - so the z-level below is another possible constraint.)  I strongly suspect that the trees would grow taller if they had additional space above, but sadly my fortress can't accommodate that at the moment for these particular trees.

Separately, I mined out a large rectangle of stone lower in my fort, and I used water to muddy it.  I also channeled out the z-level above.  So far there are a lot of saplings, but no trees have grown.  Possibly they will never grow on muddied stone, but it is also possible that not enough time has passed for the trees to appear.  I will report back if/when that happens.

[khearn]

I've done a couple of forts where I've dug out multiple z-levels for tree farms. Unfortunately, I keep abandoning and doing fresh starts because of new releases, or getting bored. I also haven't kept rigorous records, since I wasn't trying to do science on the trees. But I have seen a couple of times where the sapling grew up into adult trees. I've seen it happen in chambers ranging from 2-4 levels deep, but never in single z-level chambers.

I'm pretty sure I've seen it happen in a chamber where the bottom level was a soil level with a rock level directly below it, so you don't need a full level of dirt for roots. That make sense, since trees grow in caverns with rock directly below. But I'm not 100% sure, so don't bet your fort on it and then get mad at me if it doesn't work.

The earliest I can recall seeing multi-level trees in a tree farm was about three and a half years after the embark, which would have been about 3 years after getting the chamber dug out. I need to do a fort where I record when the chamber is dug, and maybe even record (using notes) when individual saplings are first spotted, just to confirm the timing.

Also note that many underground trees never seem to give more than 1 log, no matter how big they are. I've observed this in natural trees in caverns, as well as my farm-grown trees. It seems to be species-specific, but I haven't kept track of which ones only give one log and which ones give better output. It would be worth knowing, so you can cut the bad trees as soon as they go multi-level, while possibly letting the good species grow more to see if more time would give more wood output. Some data on how much wood a tree gives at various ages would be nice to have.

That's about all I can think of that I've observed. I'm sorry that it's so imprecise, but I haven't really tried to make a study of this yet, I've just noticed stuff as I was doing other things.

   Keith

[m-logik]

I've got a modestly sized underground tree farm working in a fort now. It's 3z deep, but i've seen a few trees grow in my 2z farming areas as well. The real issue is that they take a lot of time to grow. I didn't see results for a few years. Now, though, new trees are coming up often enough I can't keep up with both my tree farm and my outdoor tree cleaning duties. I would say that using underground trees as your sole source of wood is completely viable if you have a lot of soil and you don't mind having a giant empty hole in your fort for a few years.

[Pink Photon]

Also note that many underground trees never seem to give more than 1 log, no matter how big they are. I've observed this in natural trees in caverns, as well as my farm-grown trees. It seems to be species-specific, but I haven't kept track of which ones only give one log and which ones give better output. It would be worth knowing, so you can cut the bad trees as soon as they go multi-level, while possibly letting the good species grow more to see if more time would give more wood output. Some data on how much wood a tree gives at various ages would be nice to have.

From cutting down "wild" trees, I can say that tower-caps only give 1 log (no matter how big they are) and fungiwood give logs equal to the height of the tree trunk. I haven't gone logging below the first cave.

I've been wondering if the tower-cap thing is a bug, but I've been too lazy to investigate/report.

[JesDer]

idk if it changed but in 40.10 it took 4-5 years before saplings would grow into trees underground.

[fourpotatoes]

I have a tree farm growing on muddied stone. It took quite a while before the saplings started growing up, but I finally have trees that are ready to harvest. I'd probably have more if I ever got around to removing the loose stone from excavating the several z-levels of free space.

Nothing's growing close enough to the drain yet for me to see roots, and that's the only thing beneath the farm for several z-levels.

[vjek]

Re-tested this in 40.12 just now.  Three years from cavern pierced on muddied stone, deep below ground, to new bloodthorn mushroom trees.  17 Sandstone year 100 pierced the caverns, saw trees just before 11 Timber year 103.

Going to re-test with smaller mud area to see if it's related to sapling density or just time passing.

EDIT:

Same results with a single sapling;
Sapling sprouted 15 Slate year 102.
Mushroom Tree (Bloodthorn) matured from sapling 21 Granite year 105.

So, growth is apparently not related to sapling density, as that was the only sapling in a 41x21x12 open area.